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|
-- Copyright 2012 by Till Tantau
--
-- This file may be distributed an/or modified
--
-- 1. under the LaTeX Project Public License and/or
-- 2. under the GNU Public License
--
-- See the file doc/generic/pgf/licenses/LICENSE for more information
-- @release $Header$
---
-- @section subsubsection {The Reingold--Tilford Layout}
--
-- @end
local ReingoldTilford1981 = {}
-- Imports
local layered = require "pgf.gd.layered"
local declare = require("pgf.gd.interface.InterfaceToAlgorithms").declare
local Storage = require "pgf.gd.lib.Storage"
---
declare {
key = "tree layout",
algorithm = ReingoldTilford1981,
preconditions = {
connected = true,
tree = true
},
postconditions = {
upward_oriented = true
},
documentation_in = "pgf.gd.trees.doc"
}
---
declare {
key = "missing nodes get space",
type = "boolean",
documentation_in = "pgf.gd.trees.doc"
}
---
declare {
key = "significant sep",
type = "length",
initial = "0",
documentation_in = "pgf.gd.trees.doc"
}
---
declare {
key = "binary tree layout",
use = {
{ key = "tree layout" },
{ key = "minimum number of children" , value=2 },
{ key = "significant sep", value = 10 },
},
documentation_in = "pgf.gd.trees.doc"
}
---
declare {
key = "extended binary tree layout",
use = {
{ key = "tree layout" },
{ key = "minimum number of children" , value=2 },
{ key = "missing nodes get space" },
{ key = "significant sep", value = 0 },
},
documentation_in = "pgf.gd.trees.doc"
}
-- Now comes the implementation:
function ReingoldTilford1981:run()
local root = self.spanning_tree.root
local layers = Storage.new()
local descendants = Storage.new()
self.extended_version = self.digraph.options['missing nodes get space']
self:precomputeDescendants(root, 1, layers, descendants)
self:computeHorizontalPosition(root, layers, descendants)
layered.arrange_layers_by_baselines(layers, self.adjusted_bb, self.ugraph)
end
function ReingoldTilford1981:precomputeDescendants(node, depth, layers, descendants)
local my_descendants = { node }
for _,arc in ipairs(self.spanning_tree:outgoing(node)) do
local head = arc.head
self:precomputeDescendants(head, depth+1, layers, descendants)
for _,d in ipairs(descendants[head]) do
my_descendants[#my_descendants + 1] = d
end
end
layers[node] = depth
descendants[node] = my_descendants
end
function ReingoldTilford1981:computeHorizontalPosition(node, layers, descendants)
local children = self.spanning_tree:outgoing(node)
node.pos.x = 0
local child_depth = layers[node] + 1
if #children > 0 then
-- First, compute positions for all children:
for i=1,#children do
self:computeHorizontalPosition(children[i].head, layers, descendants)
end
-- Now, compute minimum distances and shift them
local right_borders = {}
for i=1,#children-1 do
local local_right_borders = {}
-- Advance "right border" of the subtree rooted at
-- the i-th child
for _,d in ipairs(descendants[children[i].head]) do
local layer = layers[d]
local x = d.pos.x
if self.extended_version or not (layer > child_depth and d.kind == "dummy") then
if not right_borders[layer] or right_borders[layer].pos.x < x then
right_borders[layer] = d
end
if not local_right_borders[layer] or local_right_borders[layer].pos.x < x then
local_right_borders[layer] = d
end
end
end
local left_borders = {}
-- Now left for i+1 st child
for _,d in ipairs(descendants[children[i+1].head]) do
local layer = layers[d]
local x = d.pos.x
if self.extended_version or not (layer > child_depth and d.kind == "dummy") then
if not left_borders[layer] or left_borders[layer].pos.x > x then
left_borders[layer] = d
end
end
end
-- Now walk down the lines and try to find out what the minimum
-- distance needs to be.
local shift = -math.huge
local first_dist = left_borders[child_depth].pos.x - local_right_borders[child_depth].pos.x
local is_significant = false
for layer,n2 in pairs(left_borders) do
local n1 = right_borders[layer]
if n1 then
shift = math.max(
shift,
layered.ideal_sibling_distance(self.adjusted_bb, self.ugraph, n1, n2) + n1.pos.x - n2.pos.x
)
end
if local_right_borders[layer] then
if layer > child_depth and
(left_borders[layer].pos.x - local_right_borders[layer].pos.x <= first_dist) then
is_significant = true
end
end
end
if is_significant then
shift = shift + self.ugraph.options['significant sep']
end
-- Shift all nodes in the subtree by shift:
for _,d in ipairs(descendants[children[i+1].head]) do
d.pos.x = d.pos.x + shift
end
end
-- Finally, position root in the middle:
node.pos.x = (children[1].head.pos.x + children[#children].head.pos.x) / 2
end
end
return ReingoldTilford1981
|