summaryrefslogtreecommitdiff
path: root/macros/luatex/latex/luatodonotes/luatodonotes.lua
blob: 5ef9b8f03bc953a2915378f66ff43d5e747cf55b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
--
-- Copyright (C) 2014-2015 by Fabian Lipp <fabian.lipp@gmx.de>
-- ------------------------------------------------------------
-- 
-- This file may be distributed and/or modified under the
-- conditions of the LaTeX Project Public License, either version 1.2
-- of this license or (at your option) any later version.
-- The latest version of this license is in:
--
--    http://www.latex-project.org/lppl.txt
--
-- and version 1.2 or later is part of all distributions of LaTeX 
-- version 1999/12/01 or later.
--

require("lualibs")
--require("debugger")()
local inspect = require('inspect')

local point = require'path_point'
local pathLine = require'path_line'
--local bezier3 = require'path_bezier3'

luatodonotes = {}

-- strings used to switch to standard catcodes for LaTeX packages
local catcodeStart = "\\makeatletter"
local catcodeEnd = "\\makeatother"

local currentPage = 1

local const1In = string.todimen("1in") -- needed for calculations of page borders
                                       -- (used as a constant in TeX)
-- constants set in sty-file
-- + noteInnerSep (inner sep used for tikz nodes)
-- + noteInterSpace (vertical space between notes)
-- + routingAreaWidth (width of the track routing area for opo-leaders)
-- + minNoteWidth (width that must be available for labels to consider the left or
--     right border of the page for placing labels)
-- + distanceNotesPageBorder (distance from the page borders to the outmost point
--     of the labels)
-- + distanceNotesText (horizontal distance between the labels and the text area)
-- + rasterHeight (height of raster for po leader algorithm)
-- + todonotesDebug (activate debug outputs when true)
--
-- values are filled into local variables in function initTodonotes (from
-- corresponding fields luatodonotes.*)
local noteInnerSep = nil
local noteInterSpace = nil
local routingAreaWidth = nil
local minNoteWidth = nil
local distanceNotesPageBorder = nil
local distanceNotesText = nil
local rasterHeight = nil
local todonotesDebug = nil


-- stores information about available algorithms
local positioningAlgos = {}
local splittingAlgos = {}
local leaderTypes = {}

local positioning = nil
local splitting = nil
local leaderType = nil
function luatodonotes.setPositioningAlgo(algo)
    if positioningAlgos[algo] ~= nil then
        positioning = positioningAlgos[algo]
    else
        positioning = positioningAlgos["inputOrderStacks"]
        tex.print("\\PackageWarningNoLine{luatodonotes}{Invalid value for parameter positioning: " .. algo .. "}")
    end
end
function luatodonotes.setSplittingAlgo(algo)
    if splittingAlgos[algo] ~= nil then
        splitting = splittingAlgos[algo]
    else
        splitting = splittingAlgos["none"]
        tex.print("\\PackageWarningNoLine{luatodonotes}{Invalid value for parameter split: " .. algo .. "}")
    end
end
function luatodonotes.setLeaderType(typ)
    if leaderTypes[typ] ~= nil then
        leaderType = leaderTypes[typ]
    else
        leaderType = leaderTypes["opo"]
        tex.print("\\PackageWarningNoLine{luatodonotes}{Invalid value for parameter leadertype: " .. typ .. "}")
    end
end

-- stores the notes for the current page
luatodonotes.notesForPage = {}
local notesForPage = luatodonotes.notesForPage
luatodonotes.notesForNextPage = {}
local notesForNextPage = luatodonotes.notesForNextPage
-- Fields for each note:
-- index: numbers notes in whole document
-- indexOnPage: index of the note in the notesForPage array
-- textbox: links to a hbox that contains the text, which is displayed inside
--     the note
-- origInputX, origInputY: position in which the todo-command was issued
-- inputX, inputY: position to which the leader should be attached (can have a
--     certain offset to origInputX/Y)
-- heightLeft, heightRight: height of the contained text when placed on
--     left/right side
-- pageNr: absolute number of page on which site for note is placed
-- rightSide: true means the note should be placed on the right side;
--     otherwise left side is meant
-- fontsize: fontsize used for paragraph in that the note was defined
-- baselineskip: \baselineskip in the paragraph in that the note was defined
-- normalbaselineskip: \normalbaselineskip in the paragraph in that the note was defined
-- outputX, outputY: position on which the north west anchor of the note should
--     be placed
-- lineColor: color of line connecting note to text
-- backgroundColor: color of background of note
-- borderColor: color of border of note
-- leaderWidth: width of leader (used as argument for tikz line width)
-- sizeCommand: fontsize command given as parameter for this note
--
-- Additional fields for text area:
-- noteType: constant string "area"
-- origInputEndX, origInputEndY: position at which the todo area ends
-- pageNrEnd: absolute number of page on which todo area ends
-- lineCountInArea: highest line index in area
-- linesInArea: positions of lines in area (to detect page/column break)

-- stores the areas for the labels on the current page
-- (calculated in function calcLabelAreaDimensions())
local labelArea = {}

-- stores the positions of the text lines on every page
local linePositions = {}
-- Fields for every position:
-- 1: position of baseline
-- 2: upper bound of line (baseline + height)
-- 3: lower bound of line (baseline - depth)

-- variables used for construction of linePositions list when reading the file
local linePositionsCurPage = {}
local linePositionsPageNr = 0


-- *** metatable for note objects ***
local noteMt = {}
-- getHeight(): yield heightLeft or heightRight depending on rightSide (implemented by metatable)
function noteMt:getHeight()
    if self.rightSide then
        return self.heightRight
    else
        return self.heightLeft
    end
end
function noteMt:getLabelAnchorY()
    local leaderAnchor = positioning.leaderAnchor
    local y
    if leaderAnchor == "north east" then
        y = self.outputY
    elseif leaderAnchor == "east" then
        y = self.outputY - noteInnerSep - self:getHeight() / 2
    else
        error("Invalid anchor for algorithm")
    end

    if positioning.leaderShift then
        y = y + self.leaderShiftY
    end

    return y
end
function noteMt:getInTextAnchorTikz()
    return "(" .. self.inputX .. "sp," .. self.inputY .. "sp)"
end
function noteMt:getLabelAnchorTikz()
    local leaderAnchor = positioning.leaderAnchor
    if leaderAnchor == "north east" and self.rightSide then
        leaderAnchor = "north west"
    elseif leaderAnchor == "east" and self.rightSide then
        leaderAnchor = "west"
    end

    local shiftStr = ""
    if positioning.leaderShift then
        shiftStr = "[shift={(" .. self.leaderShiftX .. "sp," .. self.leaderShiftY .. "sp)}]"
    end

    return "(" .. shiftStr .. " @todonotes@" .. self.index .. " note." .. leaderAnchor ..  ")"
end
function noteMt:boxForNoteText(rightSide)
    local area = labelArea:getArea(rightSide)
    local noteWidth
    if area == nil then
        noteWidth = minNoteWidth
    else
        noteWidth = area.noteWidth - 2*noteInnerSep
    end
    local retval = "\\directlua{tex.box[\"@todonotes@notetextbox\"] = " ..
        "node.copy_list(luatodonotes.notesForPage[" .. self.indexOnPage .. "].textbox)}"
    retval = retval .. "\\parbox{" .. noteWidth .. "sp}" ..
        "{\\raggedright\\unhbox\\@todonotes@notetextbox}"
    return retval
end

function noteMt:getClipPathForTodoArea()
    -- detext which lines are in same column/page as start of area
    local lineCount = self.lineCountInArea
    local maxLine = 1
    local lines = self.linesInArea
    local lastY = lines[1]
    while maxLine < lineCount do
        if lines[maxLine + 1] < lastY then
            maxLine = maxLine + 1
            lastY = lines[maxLine]
        end
    end

    local function nodename(i, corner)
        return "(@todonotes@" .. self.index .. "@" .. i .. " area" .. corner .. ")"
    end
    local path = nodename(1, "NW")
    local pathLeft = ""
    if maxLine == 1 then
        -- only one line
        path = path .. " -- " .. nodename(1, "NE") ..
            " -- " .. nodename(1, "SE")
    else
        path = path .. " -- " .. nodename(1, "NE") ..
            " decorate[@todonotes@todoarea] { -- " .. nodename(1, "SE") .. "}"
    end
    for i = 2, maxLine do
        if i == lineCount then
            -- area does not use the whole line
            path = path .. " -| " .. nodename(i, "NE") ..
                " -- " .. nodename(i, "SE")
        else
            -- area uses whole line
            path = path .. " -- " .. nodename(i, "NE") ..
                " decorate[@todonotes@todoarea] { -- " .. nodename(i, "SE") .. "}"
        end
        pathLeft = " -- " .. nodename(i, "SW") ..
            " decorate[@todonotes@todoarea] { -- " .. nodename(i, "NW") .. "}" ..
            pathLeft
    end
    path = path .. pathLeft .. " -| " .. nodename(1, "SW") .. "-- cycle"
    return path
end



-- *** label areas ***
-- stores areas for placing labels on current page
function labelArea:getArea(rightSide)
    if rightSide then
        return self.right
    else
        return self.left
    end
end
-- yields the x-coordinate of the boundary of the label that is pointing
-- towards the text
function labelArea:getXTextSide(rightSide)
    if rightSide then
        return self.right.left
    else
        return self.left.right
    end
end
function labelArea:isOneSided()
    if self.right == nil or self.left == nil then
        return true
    else
        return false
    end
end



-- divides notes in two lists (for left and right side)
-- side must be stored in note.rightSide for every note before using this function
local function segmentNotes(notes)
    local availableNotesLeft = {}
    local availableNotesRight = {}
    for k, v in pairs(notes) do
        if v.rightSide == true then
            table.insert(availableNotesRight, k)
        else
            table.insert(availableNotesLeft, k)
        end
    end
    return availableNotesLeft, availableNotesRight
end



-- is called by the sty-file when all settings (algorithms etc.) are made
function luatodonotes.initTodonotes()
    -- fill local variables (defined at begin of file) with package options
    noteInnerSep = luatodonotes.noteInnerSep
    noteInterSpace = luatodonotes.noteInterSpace
    routingAreaWidth = luatodonotes.routingAreaWidth
    minNoteWidth = luatodonotes.minNoteWidth
    distanceNotesPageBorder = luatodonotes.distanceNotesPageBorder
    distanceNotesText = luatodonotes.distanceNotesText
    rasterHeight = luatodonotes.rasterHeight
    todonotesDebug = luatodonotes.todonotesDebug

    if positioning.needLinePositions then
        luatexbase.add_to_callback("post_linebreak_filter", luatodonotes.callbackOutputLinePositions, "outputLinePositions")
        tex.print("\\@starttoc{lpo}")
        tex.print("\\directlua{lpoFileStream = \\the\\tf@lpo}")
    end
end


-- valid values for noteType: nil/"" (for point in text), "area"
function luatodonotes.addNoteToList(index, drawLeader, noteType)
    if next(notesForPage) ~= nil
        and index <= notesForPage[#notesForPage].index then
        -- Index is the same as for one of the previous note.
        -- This can happen when commands are read multiple times
        -- => don't add anything to list in this case
        return
    end
    local newNote = {}
    newNote.index = index
    newNote.textbox = node.copy_list(tex.box["@todonotes@notetextbox"])
    newNote.baselineskip = tex.dimen["@todonotes@baselineskip"]
    newNote.normalbaselineskip = tex.dimen["@todonotes@normalbaselineskip"]
    newNote.fontsize = tex.dimen["@todonotes@fontsize"]
    newNote.lineColor = tex.toks["@todonotes@toks@currentlinecolor"]
    newNote.backgroundColor = tex.toks["@todonotes@toks@currentbackgroundcolor"]
    newNote.borderColor = tex.toks["@todonotes@toks@currentbordercolor"]
    newNote.leaderWidth = tex.toks["@todonotes@toks@currentleaderwidth"]
    newNote.sizeCommand = tex.toks["@todonotes@toks@sizecommand"]
    newNote.drawLeader = drawLeader
    if noteType == "area" then
        newNote.noteType = "area"
        newNote.lineCountInArea = 0
    -- else: newNote.noteType = nil (default value)
    end
    setmetatable(newNote, {__index = noteMt})
    newNote.indexOnPage = #notesForPage + 1
    notesForPage[newNote.indexOnPage] = newNote
end

function luatodonotes.clearNotes()
    -- delete the texts for the notes on this page from memory
    -- (garbage collection does not work for nodes)
    for _, v in pairs(notesForPage) do
        node.free(v.textbox)
    end
    luatodonotes.notesForPage = notesForNextPage
    notesForPage = luatodonotes.notesForPage
    -- update indexOnPage for the new notes
    for k, v in pairs(notesForPage) do
        v.indexOnPage = k
    end

    currentPage = currentPage + 1
end

function luatodonotes.processLastLineInTodoArea()
    -- LaTeX counter is accessed as TeX count by prefixing c@
    ind = tex.count["c@@todonotes@numberoftodonotes"]
    val = tex.count["c@@todonotes@numberofLinesInArea"]
    notesForPage[#notesForPage].lineCountInArea = val
end


-- *** constructing the linePositions list ***
function luatodonotes.linePositionsNextPage()
    linePositionsPageNr = linePositionsPageNr + 1
    linePositionsCurPage = {}
    linePositions[linePositionsPageNr] = linePositionsCurPage
end

function luatodonotes.linePositionsAddLine(ycoord, lineheight, linedepth)
    local baseline = ycoord - tex.pageheight
    linePositionsCurPage[#linePositionsCurPage + 1] = {baseline, baseline + lineheight, baseline - linedepth}
end


function luatodonotes.getInputCoordinatesForNotes()
    tex.sprint(catcodeStart)
    for k, v in ipairs(notesForPage) do
        local nodename = "@todonotes@" .. v.index .. " inText"

        tex.sprint("\\pgfextractx{\\@todonotes@extractx}{\\pgfpointanchor{" ..
            nodename .. "}{center}}")
        tex.sprint("\\pgfextracty{\\@todonotes@extracty}{\\pgfpointanchor{" ..
            nodename .. "}{center}}")
        tex.print("\\directlua{luatodonotes.notesForPage[" .. k .. "].origInputX = " ..
            "tex.dimen[\"@todonotes@extractx\"]}")
        tex.print("\\directlua{luatodonotes.notesForPage[" .. k .. "].origInputY = " ..
            "tex.dimen[\"@todonotes@extracty\"]}")

        if v.noteType == "area" then
            nodename = nodename .. "End"
            tex.sprint("\\pgfextractx{\\@todonotes@extractx}{\\pgfpointanchor{" ..
                nodename .. "}{center}}")
            tex.sprint("\\pgfextracty{\\@todonotes@extracty}{\\pgfpointanchor{" ..
                nodename .. "}{center}}")
            tex.print("\\directlua{luatodonotes.notesForPage[" .. k .. "].origInputEndX = " ..
                "tex.dimen[\"@todonotes@extractx\"]}")
            tex.print("\\directlua{luatodonotes.notesForPage[" .. k .. "].origInputEndY = " ..
                "tex.dimen[\"@todonotes@extracty\"]}")

            notesForPage[k].linesInArea = {}
            for i = 1, v.lineCountInArea do
                nodename = "@todonotes@" .. v.index .. "@" .. i .. " areaSW"
                    tex.sprint("\\pgfextracty{\\@todonotes@extracty}{\\pgfpointanchor{" ..
                        nodename .. "}{center}}")
                tex.print("\\directlua{luatodonotes.notesForPage[" .. k .. "].linesInArea[" ..
                    i .. "] = " .. "tex.dimen[\"@todonotes@extracty\"]}")
            end
        end
    end
    tex.sprint(catcodeEnd)
end

function luatodonotes.calcLabelAreaDimensions()
    local routingAreaSpace = 0
    if leaderType.needRoutingArea then
        routingAreaSpace = routingAreaWidth
    end

    local top = tex.voffset + tex.dimen.topmargin + const1In
    local bottom = top + tex.dimen.headheight + tex.dimen.headsep + tex.dimen.textheight + tex.dimen.footskip
    local currentsidemargin = tex.hoffset + tex.dimen["@todonotes@currentsidemargin"] + const1In

    local left = {}
    left.top = -top
    left.bottom = -bottom
    left.left = distanceNotesPageBorder
    left.right = currentsidemargin - distanceNotesText - routingAreaSpace
    if left.right - left.left < minNoteWidth then
        -- not enough space left of text
        left = nil
    else
        left.noteWidth = left.right - left.left
    end

    local right = {}
    right.top = -top
    right.bottom = -bottom
    right.left = currentsidemargin + tex.dimen.textwidth + distanceNotesText + routingAreaSpace
    right.right = tex.pagewidth - distanceNotesPageBorder
    if right.right - right.left < minNoteWidth then
        -- not enough space right of text
        right = nil
    else
        right.noteWidth = right.right - right.left
    end

    local text = {}
    text.left = currentsidemargin
    text.right = currentsidemargin + tex.dimen.textwidth

    labelArea.left = left
    labelArea.right = right
    labelArea.text = text
end

function luatodonotes.calcHeightsForNotes()
    -- function has to be called outside of a tikzpicture-environment
    tex.sprint(catcodeStart)
    for k, v in ipairs(notesForPage) do
        -- store height for note
        -- (is determined by creating a box with the text and reading its size)

        -- left side
        tex.sprint("\\savebox{\\@todonotes@heightcalcbox}" ..
            "{" .. v.sizeCommand .. v:boxForNoteText(false) .. "}")
        tex.sprint("\\@todonotes@heightcalcboxdepth=\\dp\\@todonotes@heightcalcbox")
        tex.sprint("\\@todonotes@heightcalcboxheight=\\ht\\@todonotes@heightcalcbox")
        tex.sprint("\\directlua{luatodonotes.notesForPage[" .. k .. "].heightLeft = " ..
            "tex.dimen[\"@todonotes@heightcalcboxheight\"]" ..
            " + tex.dimen[\"@todonotes@heightcalcboxdepth\"]}")

        -- right side
        tex.sprint("\\savebox{\\@todonotes@heightcalcbox}" ..
            "{" .. v.sizeCommand .. v:boxForNoteText(true) .. "}")
        tex.sprint("\\@todonotes@heightcalcboxdepth=\\dp\\@todonotes@heightcalcbox")
        tex.sprint("\\@todonotes@heightcalcboxheight=\\ht\\@todonotes@heightcalcbox")
        tex.sprint("\\directlua{luatodonotes.notesForPage[" .. k .. "].heightRight = " ..
            "tex.dimen[\"@todonotes@heightcalcboxheight\"]" ..
            " + tex.dimen[\"@todonotes@heightcalcboxdepth\"]}")

        -- store pageNr for note
        -- (is determined as reference to a label)
        tex.sprint("\\directlua{luatodonotes.notesForPage[" .. k .. "].pageNr = " ..
            "\\zref@extract{@todonotes@" .. v.index .. "}{abspage}}")
        if v.noteType == "area" then
            tex.sprint("\\directlua{luatodonotes.notesForPage[" .. k .. "].pageNrEnd = " ..
                "\\zref@extract{@todonotes@" .. v.index .. "@end}{abspage}}")
        end
    end
    tex.sprint(catcodeEnd)
end

local inputShiftX = string.todimen("-0.05cm") -- sensible value depends on shape of mark
function luatodonotes.printNotes()
    print("Drawing notes for page " .. currentPage)

    -- seperate notes that should be placed on another page
    -- This can occur when note is in a paragraph which doesn't fit on the
    -- current page and is thus moved to the next one. But the \todo-command is
    -- still read before the shipout of the current page is done
    luatodonotes.notesForNextPage = {}
    notesForNextPage = luatodonotes.notesForNextPage
    local k=1
    while k <= #notesForPage do
        local v = notesForPage[k]
        if v.pageNr == 0 then
            -- Notes without a page number occur when the zref label is not
            -- defined correctly. This happens with notes in a
            -- \caption-command, e.g.
            -- In this case two version of the note are stored and we drop the
            -- note that does not have a valid page number (the other note
            -- seems to have one).
            table.remove(notesForPage, k)
            if todonotesDebug then
                print("deleting note: " .. k .. " (" .. v.index .. ")")
            end
        elseif v.pageNr ~= currentPage then
            table.insert(notesForNextPage, v)
            table.remove(notesForPage, k)
            if todonotesDebug then
                print("moving note to next page: " .. k .. " (" .. v.index .. ")")
            end
        else
            -- update index here (needed if a note was deleted before)
            v.indexOnPage = k
            k = k + 1
        end
    end

    -- add offset to input coordinates
    for _, v in pairs(notesForPage) do
        if v.noteType ~= "area" then
            v.inputX = v.origInputX + inputShiftX
            local bls = v.baselineskip
            if v.baselineskip == 0 then
                bls = v.normalbaselineskip
            end
            v.inputY = v.origInputY - 1.3 * (bls - v.fontsize)
        else
            v.inputX = v.origInputX
            v.inputY = v.origInputY
        end
    end

    splitting.algo()
    if positioning.twoSided then
        local notesLeft, notesRight = segmentNotes(notesForPage)
        if #notesLeft > 0 then
            positioning.algo(notesLeft, false)
        end
        if #notesRight > 0 then
            positioning.algo(notesRight, true)
        end
    else
        positioning.algo()
    end
    for k, v in ipairs(notesForPage) do
        if todonotesDebug then
            local function outputWithPoints(val)
                if val ~= nil then
                    return val .. " (" .. number.topoints(val, "%s%s") .. ")"
                else
                    return ""
                end
            end
            print("-----------------")
            print(k .. ": ")
            print("index:        " .. v.index)
            print("origInputX:   " .. v.origInputX)
            print("origInputY:   " .. v.origInputY)
            if (v.noteType ~= nil) then
                print("noteType:     " .. v.noteType)
                print("origInputEndX:" .. v.origInputEndX)
                print("origInputEndY:" .. v.origInputEndY)
                print("lineCountInArea:" .. v.lineCountInArea)
                print("linesInArea  :" .. inspect(v.linesInArea))
            else
                print("noteType:     nil")
            end
            print("inputX:       " .. v.inputX)
            print("inputY:       " .. v.inputY)
            print("outputX:      " .. v.outputX)
            print("outputY:      " .. v.outputY)
            if (v.rasterSlots ~= nil) then
                print("rasterSlots:  " .. v.rasterSlots)
            end
            print("baselineskip: " .. outputWithPoints(v.baselineskip))
            print("nbaselineskip:" .. outputWithPoints(v.normalbaselineskip))
            print("fontsize:     " .. outputWithPoints(v.fontsize))
            print("textbox:      " .. inspect(v.textbox))
            print("height:       " .. outputWithPoints(v:getHeight()))
            print("heightLeft:   " .. outputWithPoints(v.heightLeft))
            print("heightRight:  " .. outputWithPoints(v.heightRight))
            print("rightSide:    " .. tostring(v.rightSide))
            if v.pageNr ~= nil then
                print("pageNr:       " .. v.pageNr)
            end
            print("lineColor:    " .. v.lineColor)
            print("backgroundColor:" .. v.backgroundColor)
            print("borderColor:  " .. v.borderColor)
            print("leaderWidth:  " .. v.leaderWidth)
            print("sizeCommand:  " .. v.sizeCommand)
            print("drawLeader:   " .. tostring(v.drawLeader))
        end

        -- print note
        tex.print(catcodeStart)
        tex.print("\\node[@todonotes@notestyle,anchor=north west," ..
            "fill=" .. v.backgroundColor .. ",draw=" .. v.borderColor .. "," ..
            "font=" .. v.sizeCommand .. "] " ..
            "(@todonotes@" .. v.index ..
            " note) at (" .. v.outputX .. "sp," .. v.outputY .. "sp) {" ..
            v:boxForNoteText(v.rightSide) .. "};")
        tex.print(catcodeEnd)


        -- output debugging hints on page
        if todonotesDebug then
            tex.print("\\node[anchor=north west,text=blue,fill=white,rectangle] at (@todonotes@" .. v.index .. " inText) {" .. v.index .. "};")
            tex.print("\\draw[green,fill] (@todonotes@" .. v.index .. " inText) circle(2pt);")
            tex.print("\\draw[black,fill] (@todonotes@" .. v.index .. " inText) circle(0.2pt);")
            if v.noteType == "area" then
                tex.print("\\draw[red,fill] (@todonotes@" .. v.index .. " inTextEnd) circle(2pt);")
            end

            if (v.noteType ~= nil) then
                print(v:getClipPathForTodoArea())
                tex.print("\\draw[blue] " .. v:getClipPathForTodoArea() .. ";")
                --for i=1, v.lineCountInArea do
                    --tex.print(" (@todonotes@" .. v.index .. "@" .. i .. " areaSW) -- ")
                --end
                --tex.print("cycle;")
            end
        end
    end
    -- draw leader
    leaderType.algo()

    -- draw mark in text
    for _, v in pairs(notesForPage) do
        if v.drawLeader ~= false and v.noteType ~= "area" then
            local shiftStr = "(" .. v.inputX .. "sp," .. v.inputY .. "sp)"
            tex.print("\\draw[@todonotes@textmark," ..
                "draw=" .. v.lineColor .. ",fill=" .. v.lineColor .. "," ..
                "shift={" .. shiftStr .. "}," ..
                "scale around={0.5:(-0,-0)},shift={(-0.5,-0.1)}]" ..
                "(1,0) .. controls (0.5,0.2) and (0.65,0.3) .." ..
                "(0.5,0.7) .. controls (0.35,0.3) and (0.5,0.2) .." .. 
                "(0,0) -- cycle;")
        end
    end

    --- draw label areas when requested
    if todonotesDebug then
        local area = labelArea.left
        if area ~= nil then
            tex.print("\\draw[blue] (" .. area.left .. "sp," .. area.top .. "sp) rectangle (" ..
                area.right .. "sp," .. area.bottom .. "sp);")
        end
        area = labelArea.right
        if area ~= nil then
            tex.print("\\draw[blue] (" .. area.left .. "sp," .. area.top .. "sp) rectangle (" ..
                area.right .. "sp," .. area.bottom .. "sp);")
            end
    end
end




-- ********** Helper Functions **********

-- * comparators for table.sort() *
-- (yields true if first parameter should be placed before second parameter in
-- sorted table)
local function compareNoteInputXAsc(note1, note2)
    if note1.inputX < note2.inputX then
        return true
    end
end

local function compareNoteIndInputXAsc(key1, key2)
    if notesForPage[key1].inputX < notesForPage[key2].inputX then
        return true
    end
end

local function compareNoteIndInputXDesc(key1, key2)
    if notesForPage[key1].inputX > notesForPage[key2].inputX then
        return true
    end
end

local function compareNoteIndInputYDesc(key1, key2)
    local v1 = notesForPage[key1]
    local v2 = notesForPage[key2]
    if v1.inputY > v2.inputY then
        return true
    elseif v1.inputY == v2.inputY then
        if v1.inputX < v2.inputX then
            return true
        end
    end
end

-- * callbacks for Luatex *
local function appendStrToTokenlist(tokenlist, str)
    str:gsub(".", function(c)
        tokenlist[#tokenlist + 1] = {12, c:byte(), 0}
    end)
end
-- writes commands into the node tree that print the absolute position on the
-- page to the output file (streamId is taken from lpoFileStream) at the
-- beginning of every line
-- should be called as post_linebreak_filter
local ID_GLYPH_NODE = node.id("glyph")
local ID_HLIST_NODE = node.id("hlist")
function luatodonotes.callbackOutputLinePositions(head)
    while head do
        if head.id == ID_HLIST_NODE then
            -- check if we are in the main text area (hlists in, e.g.,
            -- tikz nodes should have other widths)
            if head.width == tex.dimen.textwidth then
                -- check if there is a glyph in this hlist
                -- -> then we consider it a text line
                local foundGlyph = false
                local glyphTest = head.head
                while glyphTest do
                    if glyphTest.id == ID_GLYPH_NODE then
                        foundGlyph = true
                        break
                    end
                    glyphTest = glyphTest.next
                end

                if foundGlyph then
                    local w = node.new("whatsit", "write") -- 8/1
                    w.stream = lpoFileStream
                    local tokenlist = {
                        {12,  92, 0}, -- \
                        {12,  64, 0}, -- @
                        {12, 116, 0}, -- t
                        {12, 111, 0}, -- o
                        {12, 100, 0}, -- d
                        {12, 111, 0}, -- o
                        {12, 110, 0}, -- n
                        {12, 111, 0}, -- o
                        {12, 116, 0}, -- t
                        {12, 101, 0}, -- e
                        {12, 115, 0}, -- s
                        {12,  64, 0}, -- @
                        {12, 108, 0}, -- l
                        {12, 105, 0}, -- i
                        {12, 110, 0}, -- n
                        {12, 101, 0}, -- e
                        {12, 112, 0}, -- p
                        {12, 111, 0}, -- o
                        {12, 115, 0}, -- s
                        {12, 105, 0}, -- i
                        {12, 116, 0}, -- t
                        {12, 105, 0}, -- i
                        {12, 111, 0}, -- o
                        {12, 110, 0}, -- n
                        {12, 123, 0} -- {
                    }
                    t = token.create("@todonotes@pdflastypos")
                    tokenlist[#tokenlist + 1] = t
                    tokenlist[#tokenlist + 1] = {12, 125, 0}
                    tokenlist[#tokenlist + 1] = {12, 123, 0}
                    appendStrToTokenlist(tokenlist, tostring(head.height))
                    tokenlist[#tokenlist + 1] = {12, 125, 0}
                    tokenlist[#tokenlist + 1] = {12, 123, 0}
                    appendStrToTokenlist(tokenlist, tostring(head.depth))
                    tokenlist[#tokenlist + 1] = {12, 125, 0}
                    w.data = tokenlist
                    head.head = node.insert_before(head.head,head.head,w)

                    local w = node.new("whatsit", "pdf_save_pos") -- 8/23
                    head.head = node.insert_before(head.head,head.head,w)
                end
            end
        end
        head = head.next
    end
    return true
end





-- ********** Leader Drawing Algorithms **********

local function drawLeaderPath(note, path)
    if note.drawLeader == false then
        return
    end
    local clipPath
    if note.noteType == "area" then
        clipPath = note:getClipPathForTodoArea()
        tex.print("\\begin{scope}")
        tex.print("\\clip (current page.north west) rectangle (current page.south east) ")
        tex.print(clipPath)
        tex.print(";")
    end
    tex.print("\\draw[@todonotes@leader,draw=" .. note.lineColor ..
        ",line width=" .. note.leaderWidth .. ",name path=leader] " .. path .. ";")
    if note.noteType == "area" then
        tex.print("\\path[name path=clipping] " .. clipPath .. ";")
        tex.print("\\fill[@todonotes@leader,name intersections={of=leader and clipping, by=x,sort by=leader},fill=" .. note.lineColor .. "] (x) circle(3pt);")
        tex.print("\\end{scope}")
    end
end


-- ** leader drawing: s-leaders
local function drawSLeaders()
    for k, v in ipairs(notesForPage) do
        drawLeaderPath(v, v:getLabelAnchorTikz() ..
            " -- " .. v:getInTextAnchorTikz())
    end
end
leaderTypes["s"] = {algo = drawSLeaders}



-- ** leader drawing: opo-leaders
local function drawOpoLeader(v, opoShift, rightSide)
    if rightSide then
        opoShift = - opoShift
    end
    drawLeaderPath(v, v:getLabelAnchorTikz() .. " -- +(" .. opoShift .. "sp,0) " ..
        "|- " .. v:getInTextAnchorTikz())
end
local function drawOpoGroup(group, directionDown, rightSide)
    if directionDown == nil then
        for _, v2 in ipairs(group) do
            drawOpoLeader(notesForPage[v2], 0, rightSide)
        end
    else
        if #group == 1 then
            -- place p-section of leader in center of routing area
            local opoShift = distanceNotesText / 2 + routingAreaWidth / 2
            drawOpoLeader(notesForPage[group[1]], opoShift, rightSide)
        else
            local leaderDistance = routingAreaWidth / (#group - 1)

            -- initialise shift value
            local nextOpoShift, move
            if directionDown then
                nextOpoShift = distanceNotesText / 2 + routingAreaWidth
                move = -leaderDistance
            else
                nextOpoShift = distanceNotesText / 2
                move = leaderDistance
            end

            -- cycle through group
            for _, v2 in ipairs(group) do
                drawOpoLeader(notesForPage[v2], nextOpoShift, rightSide)
                nextOpoShift = nextOpoShift + move
            end
        end
    end
end
local function drawOpoLeadersSide(notes, rightSide)
    table.sort(notes, compareNoteIndInputYDesc)

    local lastDirectionDown = nil
    local group = {}
    local prevNote
    for _, ind in ipairs(notes) do
        local v = notesForPage[ind]

        local leaderAnchorY = v:getLabelAnchorY()
        if leaderAnchorY > v.inputY then
            newDirectionDown = true
        elseif leaderAnchorY < v.inputY then
            newDirectionDown = false
        else
            newDirectionDown = nil
        end

        if lastDirectionDown == newDirectionDown and
                prevNote ~= nil and
                -- following conditions check that leaders would really intersect
                -- otherwise we can start a new group
                ((newDirectionDown and leaderAnchorY >= prevNote.inputY) or
                (not newDirectionDown and v.inputY >= prevNote:getLabelAnchorY())) then
            -- note belongs to group
            table.insert(group, ind)
        else
            -- draw leaders for group
            drawOpoGroup(group, lastDirectionDown, rightSide)

            -- initialise new group with this note
            lastDirectionDown = newDirectionDown
            group = {ind}
        end

        prevNote = v
    end
    drawOpoGroup(group, lastDirectionDown, rightSide)
end
local function drawOpoLeaders()
    local notesLeft, notesRight = segmentNotes(notesForPage)
    if #notesLeft > 0 then
        drawOpoLeadersSide(notesLeft, false)
    end
    if #notesRight > 0 then
        drawOpoLeadersSide(notesRight, true)
    end
end
leaderTypes["opo"] = {algo = drawOpoLeaders,
    needRoutingArea = true}



-- ** leader drawing: po-leaders
local function drawPoLeaders()
    for _, v in ipairs(notesForPage) do
        drawLeaderPath(v, v:getLabelAnchorTikz() .. " -| " .. v:getInTextAnchorTikz())
    end
end
leaderTypes["po"] = {algo = drawPoLeaders}



-- ** leader drawing: os-leaders
local function drawOsLeaders()
    for _, v in ipairs(notesForPage) do
        local cornerX
        if v.rightSide then
            cornerX = labelArea.right.left - distanceNotesText / 2 - routingAreaWidth
        else
            cornerX = labelArea.left.right + distanceNotesText / 2 + routingAreaWidth
        end
        drawLeaderPath(v, v:getInTextAnchorTikz() ..
            " -- (" .. cornerX .. "sp,0 |- 0," .. v.inputY .. "sp) -- " ..
            v:getLabelAnchorTikz())
    end
end
leaderTypes["os"] = {algo = drawOsLeaders,
    needRoutingArea = true}



-- ** leader drawing: s-Bezier-leaders
-- additional fields for each note:
--   leaderArmY
--   movableControlPointX
--   optimalPositionX
--   currentForce
--   forceLimitDec
--   forceLimitInc

-- settings for algorithm
local maxIterations = 1000
local factorRepulsiveControlPoint = 1
local factorAttractingControlPoint = 1
local stopCondition = 65536 -- corresponds to 1pt

local function constructCurve(l)
    local curve = {}

    -- site
    curve[1] = {}
    curve[1].x = l.inputX
    curve[1].y = l.inputY

    -- unmovable control point (middle point of site and movable control point)
    curve[2] = {}
    curve[2].x = (l.inputX + l.movableControlPointX) / 2
    curve[2].y = (l.inputY + l.leaderArmY) / 2

    -- movable control point
    curve[3] = {}
    curve[3].x = l.movableControlPointX
    curve[3].y = l.leaderArmY

    -- port
    curve[4] = {}
    curve[4].x = labelArea:getXTextSide(l.rightSide)
    curve[4].y = l.leaderArmY

    return curve
end
local function getPointOnCurve(t, curve)
    if #curve ~= 4 then
        error("4 points needed for a Bezier-curve. Given size was: " .. #curve)
    end

    local x = (1 - t) * (1 - t) * (1 - t) * curve[1].x +
        3 * t * (1 - t) * (1 - t) * curve[2].x +
        3 * t * t * (1 - t) * curve[3].x +
        t * t * t * curve[4].x

    local y = (1 - t) * (1 - t) * (1 - t) * curve[1].y +
        3 * t * (1 - t) * (1 - t) * curve[2].y +
        3 * t * t * (1 - t) * curve[3].y +
        t * t * t * curve[4].y;

    return x, y
end
local function getDistance(line1, line2)
    local t1, t2 = pathLine.line_line_intersection(line1.x1, line1.y1, line1.x2, line1.y2,
            line2.x1, line2.y1, line2.x2, line2.y2)
    if 0 <= t1 and t1 <= 1 and 0 <= t2 and t2 <= 1 then
        -- the lines do intersect
        return 0
    end

    local d1 = pathLine.hit(line2.x1, line2.y1, line1.x1, line1.y1, line1.x2, line1.y2)
    local d2 = pathLine.hit(line2.x2, line2.y2, line1.x1, line1.y1, line1.x2, line1.y2)
    local d3 = pathLine.hit(line1.x1, line1.y1, line2.x1, line2.y1, line2.x2, line2.y2)
    local d4 = pathLine.hit(line1.x2, line1.y2, line2.x1, line2.y1, line2.x2, line2.y2)
    return math.sqrt(math.min(d1, d2, d3, d4))
end
local function checkCurveApproximation(curve1, curve2)
    -- these lists will contain the sections of the approximation of the two curves
    local sectionsCurve1 = {}
    local sectionsCurve2 = {}

    -- get line segments of the first curve
    local numberOfSectionsCurve1 = luatodonotes.numberOfCurvePartitions
    local temp1X, temp1Y = getPointOnCurve(0, curve1)
    local i = 1
    while i <= numberOfSectionsCurve1 do
        local t = i / numberOfSectionsCurve1
        local temp2X, temp2Y = getPointOnCurve(t, curve1)
        local line = {}
        line.x1 = temp1X
        line.y1 = temp1Y
        line.x2 = temp2X
        line.y2 = temp2Y
        table.insert(sectionsCurve1, line)
        temp1X, temp1Y = temp2X, temp2Y
        i = i + 1
    end

    -- get line segments of the second curve
    local numberOfSectionsCurve2 = luatodonotes.numberOfCurvePartitions
    temp1X, temp1Y = getPointOnCurve(0, curve2)
    i = 1
    while i <= numberOfSectionsCurve2 do
        local t = i / numberOfSectionsCurve2
        local temp2X, temp2Y = getPointOnCurve(t, curve2)
        local line = {}
        line.x1 = temp1X
        line.y1 = temp1Y
        line.x2 = temp2X
        line.y2 = temp2Y
        table.insert(sectionsCurve2, line)
        temp1X, temp1Y = temp2X, temp2Y
        i = i + 1
    end

    -- get the minimal distance of the 2 curve approximations
    local minDistance = math.huge
    for _, line1 in pairs(sectionsCurve1) do
        for _, line2 in pairs(sectionsCurve2) do
            local distance = getDistance(line1, line2)
            if distance <= minDistance then
                minDistance = distance
            end
        end
    end

    return minDistance
end
local function computeRepulsiveControlPointForces()
    for k1, l1 in pairs(notesForPage) do
        for k2, l2 in pairs(notesForPage) do
            if k1 ~= k2 then
                -- curves of the leaders
                local curve1 = constructCurve(l1)
                local curve2 = constructCurve(l2)

                local distance = checkCurveApproximation(curve1, curve2);

                -- check if R1 has to be increased or decreased to increase the distance of the 2 curves
                -- if curve1 is bent into the direction of curve2, R1 has to be decreased
                local actualR = math.abs(labelArea:getXTextSide(l1.rightSide) - l1.movableControlPointX)
                if ((l1.inputY < l1.leaderArmY and
                        l2.leaderArmY < l1.leaderArmY) or
                        (l1.inputY > l1.leaderArmY and
                        l2.leaderArmY > l1.leaderArmY)) then
                    -- R1 has to be increased
                    local desiredR = math.abs(labelArea:getXTextSide(l1.rightSide) - l1.optimalPositionX)
                    local diff = math.abs(desiredR - actualR)
                    if distance == 0 then
                        distance = 0.01
                    end
                    local force = diff / distance
                    local newForce = force * factorRepulsiveControlPoint
                    l1.currentForce = l1.currentForce + newForce
                    l1.forceLimitDec = math.min(l1.forceLimitDec, distance * 0.45)
                else
                    -- R1 has to be decreased
                    if distance == 0 then
                        distance = 0.01
                    end
                    local force = actualR / distance
                    local newForce = -force * factorRepulsiveControlPoint
                    l1.currentForce = l1.currentForce + newForce
                    local oldLim = l1.forceLimitInc
                    l1.forceLimitInc = math.min(l1.forceLimitInc, distance * 0.45)
                    --if oldLim ~= l1.forceLimitInc then
                        --print(k1 .. ": Reduced forceLimitInc from " .. oldLim .. " to " .. l1.forceLimitInc .. " because of " .. k2 .. " (distance: " .. distance .. ")")
                    --end
                end
            end
        end
    end
end
local function computeAttractingControlPointForces()
    for _, l in pairs(notesForPage) do
        local desiredR = math.abs(labelArea:getXTextSide(l.rightSide) - l.optimalPositionX)
        local actualR = math.abs(labelArea:getXTextSide(l.rightSide) - l.movableControlPointX)
        local newForce = (desiredR - actualR) * factorAttractingControlPoint
        l.currentForce = l.currentForce + newForce
    end
end
local function applyForces(v)
    --print("force on note " .. v.index .. ": " .. v.currentForce .. " (limit: +" .. v.forceLimitInc .. ", -" .. v.forceLimitDec .. ")")

    -- limit the force so the movable control point is between the port and the optimal position
    local actualR = math.abs(labelArea:getXTextSide(v.rightSide) - v.movableControlPointX)
    local differenceR = math.abs(labelArea:getXTextSide(v.rightSide) - v.optimalPositionX) - actualR
    if (v.currentForce < 0 and math.abs(v.currentForce) > actualR) then
        v.currentForce = (-1) * actualR
    end
    if (v.currentForce > 0 and v.currentForce > differenceR) then
        v.currentForce = differenceR
    end

    -- limit the force so 2 curves do not get too close to each other and do not cross
    if v.currentForce > v.forceLimitInc then
        v.currentForce = v.forceLimitInc
    end
    if v.currentForce < (-1) * v.forceLimitDec then
        v.currentForce = (-1) * v.forceLimitDec
    end
    v.forceLimitDec = math.huge
    v.forceLimitInc = math.huge

    if v.rightSide then
        v.movableControlPointX = v.movableControlPointX - v.currentForce
    else
        v.movableControlPointX = v.movableControlPointX + v.currentForce
    end

    --print("force on note " .. v.index .. ": " .. v.currentForce)
    local c = v.currentForce
    v.currentForce = 0
    return c
end
local function getAngle(centerX, centerY, x, y)
    local vectorX = x - centerX
    local vectorY = y - centerY
    local length = math.sqrt((vectorX ^ 2) + (vectorY ^ 2))

    vectorX = vectorX / length
    vectorY = vectorY / length

    local radAngle = math.acos(vectorX)
    local degAngle = (radAngle * 180) / math.pi

    if vectorY < 0 then
        degAngle = 360 - degAngle
    end

    return degAngle
end
local function solveQuadraticEquation(a, b, c)
    local discr = (b * b) - (4 * a * c)

    if discr < 0 then
        error("Fehler bei der Berechnung das optimalen Punktes")
    end

    local solution1 = ((-b) + math.sqrt(discr)) / (2 * a)
    local solution2 = ((-b) - math.sqrt(discr)) / (2 * a)

    if solution1 < 0 and solution2 < 0 then
        error("no positive solution")
    end

    if solution1 < solution2 then
        return solution2
    else
        return solution1
    end
end
local function computeOptimalPosition(v)
    local distance = point.distance(v.inputX, v.inputY, labelArea:getXTextSide(v.rightSide), v.leaderArmY)

    -- the angle at the port between the point and the movable control point
    local tempAngle = getAngle(v.inputX, v.inputY, labelArea:getXTextSide(v.rightSide), v.leaderArmY)

    local gamma
    if v.rightSide then
        if tempAngle < 180 then
            gamma = tempAngle
        else
            gamma = 360 - tempAngle
        end
    else
        if tempAngle < 180 then
            gamma = 180 - tempAngle
        else
            gamma = tempAngle - 180
        end
    end

    -- a quadratic formula has to be solved to get the optimal position
    local a = 3
    local b = 2 * distance * math.cos(math.rad(gamma))
    local c = -(distance * distance)

    local r = solveQuadraticEquation(a, b, c)

    if v.rightSide then
        v.optimalPositionX = labelArea:getXTextSide(v.rightSide) - r
    else
        v.optimalPositionX = labelArea:getXTextSide(v.rightSide) + r
    end
end
local function drawSBezierLeaders()
    for _, v in pairs(notesForPage) do
        -- initialise leader
        v.leaderArmY = v:getLabelAnchorY()
        v.movableControlPointX = labelArea:getXTextSide(v.rightSide)
        v.currentForce = 0
        v.forceLimitDec = math.huge
        v.forceLimitInc = math.huge
    end

    luatodonotes.numberOfCurvePartitions = #notesForPage * 3

    for _, v in pairs(notesForPage) do
        computeOptimalPosition(v)
    end

    -- main loop
    local proceed = true
    local loopCounter = 0
    while (proceed and loopCounter < maxIterations) do
        if todonotesDebug then
            print("Iteration " .. loopCounter)
        end

        -- compute forces
        computeRepulsiveControlPointForces()
        computeAttractingControlPointForces()

        -- apply forces
        proceed = false
        for _, l in pairs(notesForPage) do
            local diff = applyForces(l)
            if diff > stopCondition then
                proceed = true
            end
        end

        loopCounter = loopCounter + 1
    end

    if todonotesDebug then
        print("End of Force-directed algo, number of iterations: " .. loopCounter)
    end

    -- draw
    for _, v in pairs(notesForPage) do
        local curve = constructCurve(v)
        local unmovableStr = "(" .. curve[2].x .. "sp," .. curve[2].y .. "sp)"
        local movableStr = "(" .. curve[3].x .. "sp," .. curve[3].y .. "sp)"
        drawLeaderPath(v, v:getLabelAnchorTikz() .. " .. controls " ..
            movableStr .. " and " .. unmovableStr .. " .. " ..
            v:getInTextAnchorTikz())

        -- draw control points when requested
        if todonotesDebug then
            local optimalStr = "(" .. v.optimalPositionX .. "sp," .. v.leaderArmY .. "sp)"
            tex.print("\\node[anchor=north west,text=pink,fill=white,rectangle] at " .. optimalStr .. " {" .. v.index .. "};")
            tex.print("\\node[anchor=north west,text=red,fill=white,rectangle] at " .. movableStr .. " {" .. v.index .. "};")
            tex.print("\\node[anchor=north west,text=orange,fill=white,rectangle] at " .. unmovableStr .. " {" .. v.index .. "};")
            tex.print("\\draw[red,fill] " .. movableStr .. " circle(2pt);")
            tex.print("\\draw[orange,fill] " .. unmovableStr .. " circle(2pt);")
            tex.print("\\draw[pink,fill] " .. optimalStr .. " circle(1pt);")
        end
    end
end
leaderTypes["sBezier"] = {algo = drawSBezierLeaders}





-- ********** Positioning Algorithms **********

-- ** helper functions

-- finds the index in the list given as parameter with the minimum angle
-- the function used for computation of the angle is given as second parameter
-- (the alphaFormula gets the note, to which the angle should be computed, as
-- the only parameter)
local function findIndexMinAlpha(availableNotesIndex, alphaFormula)
    local minAlpha = math.huge -- infinity
    local minIndex = -1

    for k, v in pairs(availableNotesIndex) do
        local alpha = alphaFormula(notesForPage[v])
        if alpha < minAlpha then
            minAlpha = alpha
            minIndex = k
        end
    end

    return minIndex
end



-- ** partition into stacks
local function getMeanYHeight(stack)
    -- TODO: Alternative: nicht das arithmetische Mittel verwenden, sondern
    -- Mittelpunkt zwischen dem obersten und untersten Punkt
    local sumY = 0
    local height = 0
    for _, v in pairs(stack) do
        sumY = sumY + notesForPage[v].inputY
        height = height + notesForPage[v]:getHeight() + 2 * noteInnerSep + noteInterSpace
    end

    local area = labelArea:getArea(notesForPage[stack[1]].rightSide)

    local meanY = sumY / #stack
    local height = height - noteInterSpace
    if meanY + (height/2) > area.top then
        meanY = area.top - (height/2)
    elseif meanY - (height/2) < area.bottom then
        meanY = area.bottom + (height/2)
    end
    return meanY, height
end
local function stacksIntersect(stackTop, stackBottom)
    local topMeanY, topHeight = getMeanYHeight(stackTop)
    local topLower = topMeanY - topHeight/2

    local bottomMeanY, bottomHeight = getMeanYHeight(stackBottom)
    local bottomUpper = bottomMeanY + bottomHeight/2

    if topLower - bottomUpper < noteInterSpace then
        return true
    else
        return false
    end
end
local function findStacks(notesOnSide)
    local notes = table.copy(notesOnSide)
    table.sort(notes, compareNoteIndInputYDesc)

    -- list that contains stacks
    -- is initialized by putting all notes as single stacks ordered by their inputY
    local stacks = {}
    for _, v in pairs(notes) do
        table.insert(stacks, {v})
    end

    -- Collapse Stacks where needed
    local i = 1
    while i <= #stacks - 1 do
        if stacksIntersect(stacks[i], stacks[i+1]) then
            collapsedStacks = true
            for _, v in pairs(stacks[i+1]) do
                table.insert(stacks[i], v)
            end
            table.remove(stacks,i+1)
            if i > 1 then
                -- as stack i has increased in size we look at the previous
                -- stack again in next iteration
                i = i - 1
            end
        else
             -- look at next stack in next iteration
            i = i + 1
        end
    end

    return stacks
end


-- ** positioning: inText
local function posInText()
    -- trivial algorithm
    -- places notes in text on position where todo-command was issued
    for k, v in ipairs(notesForPage) do
        v.outputX = v.inputX
        v.outputY = v.inputY
    end
end
positioningAlgos["inText"] = {algo = posInText,
    leaderAnchor = "north west",
    leaderShift = false,
    twoSided = false}



-- ** positioning: inputOrderStacks
local function placeNotesInputOrder(stack, yStart, rightSide)
    local freeY = yStart

    for _, k in ipairs(stack) do
        local v = notesForPage[k]
        v.outputX = labelArea:getArea(rightSide).left
        v.outputY = freeY
        freeY = freeY - v:getHeight() - 2 * noteInnerSep - noteInterSpace
    end
end
local function posInputOrderStacks(notesOnSide, rightSide)
    table.sort(notesOnSide, compareNoteIndInputYDesc)

    local stacks = findStacks(notesOnSide)

    -- place stacks
    for k, stack in pairs(stacks) do
        local meanY, height = getMeanYHeight(stack)
        local stackStart = meanY + height / 2
        placeNotesInputOrder(stack, stackStart, rightSide)
    end
end
positioningAlgos["inputOrderStacks"] = {algo = posInputOrderStacks,
    leaderAnchor = "east",
    leaderShift = false,
    twoSided = true}



-- ** positioning: inputOrder
-- start at top and place notes below each other on left/right side
-- notes are placed in the order induced by their y-coordinates
local function posInputOrder(notes, rightSide)
    table.sort(notes, compareNoteIndInputYDesc)
    placeNotesInputOrder(notes, labelArea:getArea(rightSide).top, rightSide)
end
positioningAlgos["inputOrder"] = {algo = posInputOrder,
    leaderAnchor = "east",
    leaderShift = false,
    twoSided = true}



-- ** positioning: sLeaderNorthEast
local function posSLeaderNorthEast(notes, rightSide)
    local noteY = labelArea:getArea(rightSide).top

    local alphaFormula
    local noteX = labelArea:getXTextSide(rightSide)
    local outputX = labelArea:getArea(rightSide).left
    if rightSide then
        alphaFormula = function (note)
            return (noteY - note.inputY) / (noteX - note.inputX)
        end
    else
        alphaFormula = function (note)
            return (noteY - note.inputY) / (note.inputX - noteX)
        end
    end

    while #notes > 0 do
        local minIndex = findIndexMinAlpha(notes, alphaFormula)

        -- place note identified by minIndex
        local note = notesForPage[notes[minIndex]]
        note.outputX = outputX
        note.outputY = noteY
        noteY = noteY - note:getHeight() - 2 * noteInnerSep - noteInterSpace

        table.remove(notes, minIndex)
    end
end
positioningAlgos["sLeaderNorthEast"] = {algo = posSLeaderNorthEast,
    leaderAnchor = "north east",
    leaderShift = false,
    twoSided = true}



-- ** positioning: sLeaderNorthEastBelow
local function placeNotesNorthEastBelow(stack, yStart, rightSide)
    -- calculate minimum height of all notes
    local minHeight = math.huge -- (infinity)
    for _, v in pairs(stack) do
        if notesForPage[v]:getHeight() < minHeight then
            minHeight = notesForPage[v]:getHeight()
        end
    end
    local leaderShiftY = (- minHeight - 2 * noteInnerSep) / 2

    local noteY = yStart
    local availableNotes = table.copy(stack)

    local alphaFormula
    local noteX = labelArea:getXTextSide(rightSide)
    local outputX = labelArea:getArea(rightSide).left
    if rightSide == true then
        alphaFormula = function (note)
            return ((noteY + leaderShiftY) - note.inputY) / (noteX - note.inputX)
        end
    else
        alphaFormula = function (note)
            return ((noteY + leaderShiftY) - note.inputY) / (note.inputX - noteX)
        end
    end
    while #availableNotes > 0 do
        local minIndex = findIndexMinAlpha(availableNotes, alphaFormula)

        -- place note identified by minIndex
        local note = notesForPage[availableNotes[minIndex]]
        note.outputX = outputX
        note.outputY = noteY
        note.leaderShiftX = 0
        note.leaderShiftY = leaderShiftY
        noteY = noteY - note:getHeight() - 2 * noteInnerSep - noteInterSpace

        table.remove(availableNotes, minIndex)
    end
end
local function posSLeaderNorthEastBelow(notes, rightSide)
    placeNotesNorthEastBelow(notes, labelArea:getArea(rightSide).top, rightSide)
end
positioningAlgos["sLeaderNorthEastBelow"] = {algo = posSLeaderNorthEastBelow,
    leaderAnchor = "north east",
    leaderShift = true,
    twoSided = true}



-- ** positioning: sLeaderNorthEastBelowStacks
local function posSLeaderNorthEastBelowStacks(notesOnSide, rightSide)
    local stacks = findStacks(notesOnSide)

    -- place stacks
    for k, stack in pairs(stacks) do
        local meanY, height = getMeanYHeight(stack)
        local stackStart = meanY + height / 2
        placeNotesNorthEastBelow(stack, stackStart, rightSide)
    end
end
positioningAlgos["sLeaderNorthEastBelowStacks"] = {algo = posSLeaderNorthEastBelowStacks,
    leaderAnchor = "north east",
    leaderShift = true,
    twoSided = true}



-- ** positioning: sLeaderEast
local function posSLeaderEast(notes, rightSide)
    local leaderPosY
    local noteY = labelArea:getArea(rightSide).top

    local alphaFormula
    local noteX = labelArea:getXTextSide(rightSide)
    local outputX = labelArea:getArea(rightSide).left
    if rightSide == true then
        alphaFormula = function (note)
            return (leaderPosY - note.inputY) / (noteX - note.inputX)
        end
    else
        alphaFormula = function (note)
            return (leaderPosY - note.inputY) / (note.inputX - noteX)
        end
    end

    local placedNotes = {}
    while #notes > 0 do
        -- build a array with all distinct heights of the notes
        -- first create a set and then convert to sorted array
        local heights = {}
        for _, v in pairs(notes) do
            heights[notesForPage[v]:getHeight()] = true
        end
        heights = table.keys(heights)
        table.sort(heights)

        local chosenIndex = -1
        local chosenH = -1
        for _, h in pairs(heights) do
            if todonotesDebug then
                print("testing height: " .. h)
            end
            leaderPosY = noteY - noteInnerSep - h/2

            -- find point with highest angle
            local minIndex = findIndexMinAlpha(notes, alphaFormula)

            -- found a valid note
            if notesForPage[notes[minIndex]]:getHeight() <= h then
                chosenIndex = minIndex
                chosenH = h
                if todonotesDebug then
                    print("placed note " .. notesForPage[notes[chosenIndex]].index)
                end
                break
            end
        end

        -- place note identified by chosenIndex
        local note = notesForPage[notes[chosenIndex]]
        note.outputX = outputX
        -- let free space above note if needed (if chosenH ~= note:getHeight())
        note.outputY = noteY - (chosenH - note:getHeight()) / 2
        -- no extraordinary free space below note (even if chosenH ~= note:getHeight())
        noteY = note.outputY - note:getHeight() - 2 * noteInnerSep - noteInterSpace
        if todonotesDebug and chosenH ~= note:getHeight() then
            print("Creating free space above note " .. note.index)
        end

        table.insert(placedNotes, notes[chosenIndex])
        table.remove(notes, chosenIndex)
    end

    -- postprocessing: reduce spaces between notes where possible
    for ind, noteNr in pairs(placedNotes) do
        local note = notesForPage[noteNr]

        local aimedPos
        if ind == 1 then
            aimedPos = labelArea:getArea(rightSide).top
        else
            local prevNote = notesForPage[placedNotes[ind-1]]
            aimedPos = prevNote.outputY - prevNote:getHeight() - 2 * noteInnerSep - noteInterSpace
        end

        if todonotesDebug and aimedPos ~= note.outputY then
            print("note " .. note.index .. " got moved:")
            print("aimed: " .. aimedPos)
            print("real:  " .. note.outputY)
        end

        local aimedLeaderAnchorY = aimedPos - noteInnerSep - note:getHeight() / 2
        local realLeaderAnchorY = note.outputY - noteInnerSep - note:getHeight() / 2
        -- it holds: realLeaderAnchorY < aimedLeaderAnchorY (realLeaderAnchor is lower on page)

        -- check if there are points in triangle (aimedLeaderAnchor, note.input, realLeaderAnchor)
        -- we perform this check by calculating the angle of the points referred to note.input
        local pointsInTriangle = false
        local denom
        if rightSide then
            denom = noteX - note.inputX
        else
            denom = note.inputX - noteX
        end
        local aimedLeaderAnchorAngle = (aimedLeaderAnchorY - note.inputY) / denom
        local realLeaderAnchorAngle = (realLeaderAnchorY - note.inputY) / denom
        local minAngle = math.huge
        local minAngleIndex = -1 -- takes index of lowest point in triangle
        for otherInd, otherNote in pairs(notesForPage) do
            if otherInd ~= noteNr and
                ((not rightSide and otherNote.inputX < note.inputX) or
                 (rightSide and otherNote.inputX > note.inputX)) then
                local otherNoteAngle
                if rightSide then
                    otherNoteAngle = (otherNote.inputY - note.inputY) / (otherNote.inputX - note.inputX)
                else
                    otherNoteAngle = (otherNote.inputY - note.inputY) / (note.inputX - otherNote.inputX)
                end

                if (realLeaderAnchorAngle < otherNoteAngle)
                        and (otherNoteAngle < aimedLeaderAnchorAngle) then
                    pointsInTriangle = true
                    if otherNoteAngle < minAngle then
                        minAngle = otherNoteAngle
                        minAngleIndex = otherInd
                    end
                    if todonotesDebug then
                        print(otherNote.index .. " is in triangle for " .. note.index)
                    end
                end
            end
        end

        if not pointsInTriangle then
            -- no points in triangle
            -- => we can move this note to aimedPos
            note.outputY = aimedPos
        else
            -- move note upwards so that leader touches lowest point in triangle
            -- new point for leader anchor is determined by the ray from note.input through the lowest point in triangle (otherNote.input)
            -- TODO: force a certain distance between leader and other points (at the moment a leader can contain endpoints of other leaders)
            local otherNote = notesForPage[minAngleIndex]
            local aimedLeaderAnchorY = note.inputY - (note.inputY - otherNote.inputY) * (note.inputX - noteX) / (note.inputX - otherNote.inputX)
            note.outputY = aimedLeaderAnchorY + noteInnerSep + note:getHeight() / 2
        end
    end
end
positioningAlgos["sLeaderEast"] = {algo = posSLeaderEast,
    leaderAnchor = "east",
    leaderShift = false,
    twoSided = true}



-- ** positioning: poLeaders
local function getRasterAbsolute(rasterHeight, top, rasterIndex)
    return top - (rasterIndex - 1) * rasterHeight
end
 -- distance between line and leader that algorithm tries to reach when there is
 -- no neighbouring line
local poMinDistLine = string.todimen("4pt")
local function getPosAboveLine(linePositionsCurPage, lineInd)
    local line = linePositionsCurPage[lineInd]
    local posAbove
    if linePositionsCurPage[lineInd - 1] ~= nil then
        posAbove = (line[2] + linePositionsCurPage[lineInd - 1][3]) / 2
    end
    if posAbove == nil or posAbove - line[2] > poMinDistLine then
        posAbove = line[2] + poMinDistLine
    end
    return posAbove
end
local function getPosBelowLine(linePositionsCurPage, lineInd)
    local line = linePositionsCurPage[lineInd]
    local posBelow
    if linePositionsCurPage[lineInd + 1] ~= nil then
        posBelow = (line[3] + (linePositionsCurPage[lineInd + 1][2])) / 2
    end
    if posBelow == nil or line[3] - posBelow > poMinDistLine then
        posBelow = line[3] - poMinDistLine
    end
    return posBelow
end
local function posPoLeaders(notes, rightSide, avoidLines)
    local linePositionsCurPage
    if avoidLines then
        linePositionsCurPage = linePositions[currentPage] or {}
    end

    -- number of slots on the whole page
    local area = labelArea:getArea(rightSide)
    local totalNumSlots = math.floor((area.top - area.bottom) / rasterHeight)

    -- calculate number of raster slots for each note
    for _, ind in pairs(notes) do
        local v = notesForPage[ind]
        local height = v:getHeight() + 2 * noteInnerSep + noteInterSpace
        v.rasterSlots = math.ceil(height / rasterHeight)
    end

    -- sort notes by inputY
    table.sort(notes, compareNoteIndInputYDesc)

    -- draw slots
    if todonotesDebug then
        for i = 1,totalNumSlots+1 do
            local pos = area.top - (i-1) * rasterHeight
            tex.print("\\draw[blue,dashed] (0," .. pos .. "sp) -- +(21cm,0);") 
        end
    end

    -- initialise table opt for dynamic program
    -- opt[topPoint, bottomPoint, topSlot, bottomSlot, numberLabeledSites]
    -- opt[a][b][c][d][e] describes length-minimal placement of the labels for
    -- sites from a to b in the raster slots c to d
    -- the leftmost/rightmost e sites between a and b are selected until there
    -- are no more free slots
    local opt = {}
    for a = 1, #notes do
        opt[a] = {}
        for b = a, #notes do
            opt[a][b] = {}
            -- TODO: needed label slots are restricted by points
            -- only create tables for needed slots
            for i = 1, totalNumSlots do
                opt[a][b][i] = {}
                for j = i, totalNumSlots do
                    if i == j then
                        opt[a][b][i][j] = {}
                        opt[a][b][i][j][0] = {}
                        opt[a][b][i][j][0].totalLength = 0
                        opt[a][b][i][j][0].positions = {}
                        opt[a][b][i][j][0].leaderShiftY = {}
                    end
                end
            end
        end
    end

    -- constant use an partial solution without labeled points
    local optEmpty = {}
    optEmpty.totalLength = 0
    optEmpty.positions = {}
    optEmpty.leaderShiftY = {}

    -- fill table opt for dynamic program
    -- numberOfPoints is difference between topPoint and bottomPoint when computing opt
    for numberOfPoints = 1, #notes do
        for topPoint = 1, (#notes - numberOfPoints + 1) do
            -- compute opt[topStrip][bottomStrip]
            local bottomPoint = topPoint + numberOfPoints - 1

            local pointsBetween = {}
            for i = topPoint, bottomPoint do
                table.insert(pointsBetween, notes[i])
            end
            if rightSide then
                table.sort(pointsBetween, compareNoteIndInputXDesc)
            else
                table.sort(pointsBetween, compareNoteIndInputXAsc)
            end

            -- TODO: Einschränken, nicht alle Kombinationen von Slots notwendig
            --       (siehe auch oben)
            -- numberOfSlots is difference between topSlot and bottomSlot when computing opt
            for numberOfSlots = 1, totalNumSlots do
                for topSlot = 1, (totalNumSlots - numberOfSlots + 1) do
                    local bottomSlot = topSlot + numberOfSlots - 1

                    -- DEBUG
                    --print("computing opt[" .. topPoint .. "][" .. bottomPoint ..
                          --"][" .. topSlot .. "][" .. bottomSlot .. "]")

                    opt[topPoint][bottomPoint][topSlot][bottomSlot] = {}
                    opt[topPoint][bottomPoint][topSlot][bottomSlot][0] = {}
                    opt[topPoint][bottomPoint][topSlot][bottomSlot][0].totalLength = 0
                    opt[topPoint][bottomPoint][topSlot][bottomSlot][0].positions = {}
                    opt[topPoint][bottomPoint][topSlot][bottomSlot][0].leaderShiftY = {}

                    -- stelle fest, wie viele Punkte gelabelt werden (bestimme also r)
                    local labeledSites = {}
                    local usedSlots = 0
                    for _, v in pairs(pointsBetween) do
                        local note = notesForPage[v]
                        if usedSlots + note.rasterSlots <= numberOfSlots then
                            usedSlots = usedSlots + note.rasterSlots
                            table.insert(labeledSites, v)
                        else
                            break
                        end
                    end

                    -- TODO: Teste, ob bei kleinerer Anzahl an Slots gleiche Punkte gelabelt werden
                    --  -> dann kann Teillösung übernommen werden

                    -- Mögliche Aufteilungen (Positionierung des Labels für r) testen
                    -- und Optimum auswählen
                    if #labeledSites > 0 then
                        for numLabeledSites = 1, #labeledSites do
                            -- we place rightmost point: labeledSites[#labeledSites]
                            local rIndex = labeledSites[numLabeledSites]
                            local r = notesForPage[rIndex]

                            -- slotIndexR is the slot in that the label for r begins (topmost slot)
                            local bestVal = math.huge
                            local bestOpt = {}
                            -- try all label positions for r (leader should enter the label at east-anchor)
                            for slotIndexR = topSlot, (bottomSlot + 1 - r.rasterSlots) do
                                -- calculate position in which leader arm is placed
                                local labelTopR = getRasterAbsolute(rasterHeight, area.top, slotIndexR)
                                local leaderArmR, leaderShiftR
                                if avoidLines then
                                    leaderArmR = labelTopR - noteInnerSep - r:getHeight() / 2 -- east anchor

                                    -- find first line (from the top) which lower bound is below leaderArmR
                                    local lineBelowInd
                                    for ind, v in pairs(linePositionsCurPage) do
                                        if v[3] <= leaderArmR then
                                            lineBelowInd = ind
                                            break
                                        end
                                    end

                                    -- choose the desired position for the leader arm
                                    -- (later we check if the label is high enough to shift the port to this position)
                                    local desiredPos = leaderArmR
                                    if lineBelowInd == nil then
                                        -- there is no line below the leaderArmR
                                        local lowestLine = linePositionsCurPage[#linePositionsCurPage]
                                        if lowestLine ~= nil and lowestLine[3] - leaderArmR < poMinDistLine then
                                            -- leader is too near to lowest line on page
                                            -- -> use the valid position below this line
                                            desiredPos = getPosBelowLine(linePositionsCurPage, #linePositionsCurPage)
                                        end
                                    else
                                        local lineBelow = linePositionsCurPage[lineBelowInd]
                                        local lineAbove = linePositionsCurPage[lineBelowInd - 1]
                                        if lineBelow ~= nil and leaderArmR - lineBelow[2] < poMinDistLine then
                                            -- leader is too near (or conflicting) to the line below
                                            -- -> move below or above this line (using the position closer to the original one)

                                            local posAbove = getPosAboveLine(linePositionsCurPage, lineBelowInd)
                                            local posBelow = getPosBelowLine(linePositionsCurPage, lineBelowInd)

                                            -- chose position which is closer to east anchor
                                            if posAbove - leaderArmR <= leaderArmR - posBelow then
                                                desiredPos = posAbove
                                            else
                                                desiredPos = posBelow
                                            end
                                        elseif lineAbove ~= nil and lineAbove[3] - leaderArmR < poMinDistLine then
                                            -- leader is too near to the line below
                                            -- -> use the valid position above this line
                                            desiredPos = getPosAboveLine(linePositionsCurPage, lineBelowInd)
                                        end
                                    end

                                    -- check if label is high enough to move leader to desired position
                                    if math.abs(desiredPos - leaderArmR) <= r:getHeight() / 2 + noteInnerSep then
                                        leaderShiftR = desiredPos - leaderArmR
                                        leaderArmR = desiredPos
                                    else
                                        leaderShiftR = 0
                                    end
                                else
                                    leaderArmR = labelTopR - noteInnerSep - r:getHeight() / 2
                                end

                                -- determine index of last point above arm
                                local pointAboveArm = 0
                                for k, ind in pairs(notes) do
                                    v = notesForPage[ind]
                                    if v.inputY >= leaderArmR then
                                        pointAboveArm = k
                                    else
                                        break
                                    end
                                end
                                local numPointsAbove = 0
                                local numPointsBelow = 0
                                for _, v in pairs(pointsBetween) do
                                    if v == rIndex then
                                        break
                                    end

                                    local note = notesForPage[v]
                                    if note.inputY >= leaderArmR then
                                        numPointsAbove = numPointsAbove + 1
                                    else
                                        numPointsBelow = numPointsBelow + 1
                                    end
                                end

                                local optAbove, optBelow
                                if pointAboveArm < topPoint then
                                    optAbove = optEmpty
                                elseif slotIndexR - 1 < topSlot then
                                    optAbove = optEmpty
                                elseif pointAboveArm > bottomPoint then
                                    optAbove = opt[topPoint][bottomPoint][topSlot][slotIndexR - 1][numPointsAbove]
                                else
                                    optAbove = opt[topPoint][pointAboveArm][topSlot][slotIndexR - 1][numPointsAbove]
                                end
                                if pointAboveArm + 1 > bottomPoint then
                                    optBelow = optEmpty
                                elseif slotIndexR + r.rasterSlots > bottomSlot then
                                    optBelow = optEmpty
                                elseif pointAboveArm + 1 < topPoint then
                                    optBelow = opt[topPoint][bottomPoint][slotIndexR + r.rasterSlots][bottomSlot][numPointsBelow]
                                else
                                    optBelow = opt[pointAboveArm + 1][bottomPoint][slotIndexR + r.rasterSlots][bottomSlot][numPointsBelow]
                                end

                                local partitionValid = true
                                if optAbove == nil or optBelow == nil then
                                    partitionValid = false
                                else
                                    local labeledAboveArm = table.keys(optAbove.positions)
                                    local labeledBelowArm = table.keys(optBelow.positions)
                                    if #labeledAboveArm + #labeledBelowArm + 1 ~= numLabeledSites then
                                        partitionValid = false
                                    else
                                        -- test if all of labeledNotes are in one of the sets
                                        -- last element (= r) must not be tested
                                        for testIndex = 1, (numLabeledSites - 1) do
                                            if not table.contains(labeledAboveArm, labeledSites[testIndex])
                                                and not table.contains(labeledBelowArm, labeledSites[testIndex]) then
                                                partitionValid = false
                                            end
                                        end
                                    end
                                end

                                if partitionValid then
                                    local newVal = math.abs(r.inputY - leaderArmR) + optAbove.totalLength + optBelow.totalLength
                                    if newVal < bestVal then
                                        bestVal = newVal
                                        bestOpt = {}
                                        bestOpt.totalLength = newVal
                                        bestOpt.positions = {}
                                        for k, v in pairs(optAbove.positions) do
                                            bestOpt.positions[k] = v
                                        end
                                        for k, v in pairs(optBelow.positions) do
                                            bestOpt.positions[k] = v
                                        end
                                        -- DEBUG
                                        if bestOpt.positions[rIndex] ~= nil then
                                            error("WARNING: Overwriting position of " .. rIndex .. " from " .. bestOpt.positions[rIndex] .. " to " .. slotIndexR)
                                        end
                                        bestOpt.positions[rIndex] = slotIndexR
                                        bestOpt.leaderShiftY = {}
                                        if avoidLines then
                                            for k, v in pairs(optAbove.leaderShiftY) do
                                                bestOpt.leaderShiftY[k] = v
                                            end
                                            for k, v in pairs(optBelow.leaderShiftY) do
                                                bestOpt.leaderShiftY[k] = v
                                            end
                                            bestOpt.leaderShiftY[rIndex] = leaderShiftR
                                        end
                                    end
                                end
                            end
                            if next(bestOpt) ~= nil then -- bestOpt is not an empty table
                                --print("setting opt[" .. topPoint .. "][" .. bottomPoint ..
                                      --"][" .. topSlot .. "][" .. bottomSlot .. "][" .. numLabeledSites .. "] = " .. inspect(bestOpt))
                                opt[topPoint][bottomPoint][topSlot][bottomSlot][numLabeledSites] = bestOpt
                            else
                                --print ("WARNING: Found no valid position for label in opt[" .. topPoint .. "][" .. bottomPoint ..
                                      --"][" .. topSlot .. "][" .. bottomSlot .. "][" .. numLabeledSites .. "] = " .. inspect(bestOpt))
                                opt[topPoint][bottomPoint][topSlot][bottomSlot][numLabeledSites] = nil
                            end
                        end
                    end
                end
            end
        end
    end

    if #notes > 0 then
        --DEBUG
        local maxPlaced = 0
        for i = 1,#notes do
            if opt[1][#notes][1][totalNumSlots][i] ~= nil then
                maxPlaced = i
            end
        end

        if maxPlaced < #notes then
            print("WARNING: could not fit all labels on page")
        end

        local res = opt[1][#notes][1][totalNumSlots][maxPlaced]
        local positions = res.positions
        local leaderShiftY = res.leaderShiftY
        if todonotesDebug then
            local length = res.totalLength
            -- in console
            print("----------------")
            print("po-leader algorithm: Using result: opt[1][" .. #notes ..
                                  "][1][" .. totalNumSlots .. "][" .. maxPlaced .. "]")

            print("resulting length: " .. length)
            print("resulting positions:")
            print(inspect(positions))
            print("resulting leaderShifts:")
            print(inspect(leaderShiftY))
            print("----------------")

            -- on page
            tex.print("\\node[text=blue,fill=white,rectangle,align=center] at (10.5cm,-27cm) {" ..
                "total length: " .. number.tocentimeters(length, "%s%s") .. "\\\\ " ..
                "rasterHeight: " .. number.tocentimeters(rasterHeight, "%s%s") ..
                "};")
        end

        for _, ind in pairs(notes) do
            local v = notesForPage[ind]
            v.outputX = area.left
            v.leaderShiftX = 0
            if positions[ind] == nil then
                print("did not define a position for note " .. v.index)
                v.outputY = 0
                v.leaderShiftY = 0
            else
                v.outputY = getRasterAbsolute(rasterHeight, area.top, positions[ind])
                if leaderShiftY[ind] ~= nil then
                    v.leaderShiftY = leaderShiftY[ind]
                end
            end
        end
    end
end
positioningAlgos["poLeaders"] = {algo = posPoLeaders,
    leaderAnchor = "east",
    leaderShift = false,
    twoSided = true}

local function posPoLeadersAvoid(notes, rightSide)
    posPoLeaders(notes, rightSide, true)
end
positioningAlgos["poLeadersAvoidLines"] = {algo = posPoLeadersAvoid,
    leaderAnchor = "east",
    leaderShift = true,
    twoSided = true,
    needLinePositions = true}




-- ********** Splitting Algorithms **********

-- ** splittingAlgorithm: none
-- place all notes on the wider side
local function splitNone()
    local rightSideSelected = false
    if labelArea.left == nil and labelArea.right == nil then
        error("Cannot place labels on any side of text (not enough space). " ..
            "Consider using the additionalMargin option of the package to " ..
            "extend the page margins " ..
            "or minNoteWidth to decrease the minimum width required")
    elseif labelArea.left == nil then
        rightSideSelected = true
    elseif labelArea.right ~= nil and
            labelArea.right.noteWidth > labelArea.left.noteWidth then
        rightSideSelected = true
    end

    for _, v in pairs(notesForPage) do
        v.rightSide = rightSideSelected
    end
end
splittingAlgos["none"] = {algo = splitNone}



-- ** splittingAlgorithm: middle
-- split on middle of page
local function splitMiddle()
    if labelArea:isOneSided() then
        splitNone()
    else
        local splitLine = (labelArea.text.right + labelArea.text.left)/2
        for _, v in pairs(notesForPage) do
            if v.inputX <= splitLine then
                v.rightSide = false
            else
                v.rightSide = true
            end
        end
    end
end
splittingAlgos["middle"] = {algo = splitMiddle}



-- ** splittingAlgorithm: median
-- split at median (sites sorted by x-coordinate)
local function splitMedian()
    if labelArea:isOneSided() then
        splitNone()
    else
        if #notesForPage == 0 then
            return
        end

        -- list that contains notes sorted by their inputX-coordinate
        local notesSorted = {}
        for _, v in pairs(notesForPage) do
            table.insert(notesSorted, v)
        end
        table.sort(notesSorted, compareNoteInputXAsc)

        local maxIndLeft
        if #notesSorted % 2 == 1 then
            maxIndLeft = math.ceil(#notesSorted / 2)
        else
            maxIndLeft = #notesSorted / 2
        end

        for k, v in pairs(notesSorted) do
            if k <= maxIndLeft then
                v.rightSide = false
            else
                v.rightSide = true
            end
        end
    end
end
splittingAlgos["median"] = {algo = splitMedian}



-- ** splittingAlgorithm: weightedMedian
-- split at weighted median (sites sorted by x-coordinate)
-- sum of heights of labels on both sides are similiar to each other
local function splitWeightedMedian()
    if labelArea:isOneSided() then
        splitNone()
    else
        if #notesForPage == 0 then
            return
        end

        -- list that contains notes sorted by their inputX-coordinate
        local notesSorted = {}
        for _, v in pairs(notesForPage) do
            table.insert(notesSorted, v)
        end
        table.sort(notesSorted, compareNoteInputXAsc)

        local heightLeft = 0
        local heightRight = 0
        while #notesSorted > 0 do
            if heightRight < heightLeft then
                -- place next note on the right side
                local note = notesSorted[#notesSorted]
                note.rightSide = true
                heightRight = heightRight + note:getHeight() + 2 * noteInnerSep + noteInterSpace
                table.remove(notesSorted, #notesSorted)
            else
                -- place next note on the left side
                local note = notesSorted[1]
                note.rightSide = false
                heightLeft = heightLeft + note:getHeight() + 2 * noteInnerSep + noteInterSpace
                table.remove(notesSorted, 1)
            end
        end
    end
end
splittingAlgos["weightedMedian"] = {algo = splitWeightedMedian}