diff options
Diffstat (limited to 'Build/source/libs/freetype2/freetype-src/src/smooth/ftgrays.c')
-rw-r--r-- | Build/source/libs/freetype2/freetype-src/src/smooth/ftgrays.c | 299 |
1 files changed, 148 insertions, 151 deletions
diff --git a/Build/source/libs/freetype2/freetype-src/src/smooth/ftgrays.c b/Build/source/libs/freetype2/freetype-src/src/smooth/ftgrays.c index 91293ac9463..fd357a50fc7 100644 --- a/Build/source/libs/freetype2/freetype-src/src/smooth/ftgrays.c +++ b/Build/source/libs/freetype2/freetype-src/src/smooth/ftgrays.c @@ -45,7 +45,7 @@ * This is a new anti-aliasing scan-converter for FreeType 2. The * algorithm used here is _very_ different from the one in the standard * `ftraster' module. Actually, `ftgrays' computes the _exact_ - * coverage of the outline on each pixel cell. + * coverage of the outline on each pixel cell by straight segments. * * It is based on ideas that I initially found in Raph Levien's * excellent LibArt graphics library (see https://www.levien.com/libart @@ -58,6 +58,14 @@ * different way, and I don't use sorted vector paths. Also, it doesn't * use floating point values. * + * Bézier segments are flattened by splitting them until their deviation + * from straight line becomes much smaller than a pixel. Therefore, the + * pixel coverage by a Bézier curve is calculated approximately. To + * estimate the deviation, we use the distance from the control point + * to the conic chord centre or the cubic chord trisection. These + * distances vanish fast after each split. In the conic case, they vanish + * predictably and the number of necessary splits can be calculated. + * * This renderer has the following advantages: * * - It doesn't need an intermediate bitmap. Instead, one can supply a @@ -67,7 +75,7 @@ * callback. * * - A perfect anti-aliaser, i.e., it computes the _exact_ coverage on - * each pixel cell. + * each pixel cell by straight segments. * * - It performs a single pass on the outline (the `standard' FT2 * renderer makes two passes). @@ -75,7 +83,7 @@ * - It can easily be modified to render to _any_ number of gray levels * cheaply. * - * - For small (< 20) pixel sizes, it is faster than the standard + * - For small (< 80) pixel sizes, it is faster than the standard * renderer. * */ @@ -327,17 +335,9 @@ typedef ptrdiff_t FT_PtrDist; /* must be at least 6 bits! */ #define PIXEL_BITS 8 -#undef FLOOR -#undef CEILING -#undef TRUNC -#undef SCALED - #define ONE_PIXEL ( 1 << PIXEL_BITS ) -#define TRUNC( x ) ( (TCoord)( (x) >> PIXEL_BITS ) ) -#define SUBPIXELS( x ) ( (TPos)(x) * ONE_PIXEL ) -#define FLOOR( x ) ( (x) & -ONE_PIXEL ) -#define CEILING( x ) ( ( (x) + ONE_PIXEL - 1 ) & -ONE_PIXEL ) -#define ROUND( x ) ( ( (x) + ONE_PIXEL / 2 ) & -ONE_PIXEL ) +#define TRUNC( x ) (TCoord)( (x) >> PIXEL_BITS ) +#define FRACT( x ) (TCoord)( (x) & ( ONE_PIXEL - 1 ) ) #if PIXEL_BITS >= 6 #define UPSCALE( x ) ( (x) * ( ONE_PIXEL >> 6 ) ) @@ -388,9 +388,9 @@ typedef ptrdiff_t FT_PtrDist; #define FT_UDIVPREP( c, b ) \ long b ## _r = c ? (long)( FT_ULONG_MAX >> PIXEL_BITS ) / ( b ) \ : 0 -#define FT_UDIV( a, b ) \ - ( ( (unsigned long)( a ) * (unsigned long)( b ## _r ) ) >> \ - ( sizeof( long ) * FT_CHAR_BIT - PIXEL_BITS ) ) +#define FT_UDIV( a, b ) \ + (TCoord)( ( (unsigned long)( a ) * (unsigned long)( b ## _r ) ) >> \ + ( sizeof( long ) * FT_CHAR_BIT - PIXEL_BITS ) ) /************************************************************************** @@ -432,6 +432,9 @@ typedef ptrdiff_t FT_PtrDist; #define FT_MAX_GRAY_POOL ( 2048 / sizeof ( TCell ) ) #endif + /* FT_Span buffer size for direct rendering only */ +#define FT_MAX_GRAY_SPANS 10 + #if defined( _MSC_VER ) /* Visual C++ (and Intel C++) */ /* We disable the warning `structure was padded due to */ @@ -465,6 +468,8 @@ typedef ptrdiff_t FT_PtrDist; FT_Raster_Span_Func render_span; void* render_span_data; + FT_Span spans[FT_MAX_GRAY_SPANS]; + int num_spans; } gray_TWorker, *gray_PWorker; @@ -516,7 +521,7 @@ typedef ptrdiff_t FT_PtrDist; /************************************************************************** * - * Record the current cell in the table. + * Record the current cell in the linked list. */ static void gray_record_cell( RAS_ARG ) @@ -526,10 +531,9 @@ typedef ptrdiff_t FT_PtrDist; pcell = &ras.ycells[ras.ey - ras.min_ey]; - for (;;) + while ( ( cell = *pcell ) ) { - cell = *pcell; - if ( !cell || cell->x > x ) + if ( cell->x > x ) break; if ( cell->x == x ) @@ -577,16 +581,13 @@ typedef ptrdiff_t FT_PtrDist; /* Note that if a cell is to the left of the clipping region, it is */ /* actually set to the (min_ex-1) horizontal position. */ - if ( ex < ras.min_ex ) - ex = ras.min_ex - 1; - /* record the current one if it is valid and substantial */ if ( !ras.invalid && ( ras.area || ras.cover ) ) gray_record_cell( RAS_VAR ); ras.area = 0; ras.cover = 0; - ras.ex = ex; + ras.ex = FT_MAX( ex, ras.min_ex - 1 ); ras.ey = ey; ras.invalid = ( ey >= ras.max_ey || ey < ras.min_ey || @@ -622,8 +623,8 @@ typedef ptrdiff_t FT_PtrDist; return; } - fx1 = (TCoord)( x1 - SUBPIXELS( ex1 ) ); - fx2 = (TCoord)( x2 - SUBPIXELS( ex2 ) ); + fx1 = FRACT( x1 ); + fx2 = FRACT( x2 ); /* everything is located in a single cell. That is easy! */ /* */ @@ -650,6 +651,9 @@ typedef ptrdiff_t FT_PtrDist; dx = -dx; } + /* the fractional part of y-delta is mod/dx. It is essential to */ + /* keep track of its accumulation for accurate rendering. */ + /* XXX: y-delta and x-delta below should be related. */ FT_DIV_MOD( TCoord, p, dx, delta, mod ); ras.area += (TArea)( ( fx1 + first ) * delta ); @@ -715,8 +719,8 @@ typedef ptrdiff_t FT_PtrDist; ( ey1 < ras.min_ey && ey2 < ras.min_ey ) ) goto End; - fy1 = (TCoord)( ras.y - SUBPIXELS( ey1 ) ); - fy2 = (TCoord)( to_y - SUBPIXELS( ey2 ) ); + fy1 = FRACT( ras.y ); + fy2 = FRACT( to_y ); /* everything is on a single scanline */ if ( ey1 == ey2 ) @@ -732,7 +736,7 @@ typedef ptrdiff_t FT_PtrDist; if ( dx == 0 ) { TCoord ex = TRUNC( ras.x ); - TCoord two_fx = (TCoord)( ( ras.x - SUBPIXELS( ex ) ) << 1 ); + TCoord two_fx = FRACT( ras.x ) << 1; TArea area; @@ -787,6 +791,8 @@ typedef ptrdiff_t FT_PtrDist; dy = -dy; } + /* the fractional part of x-delta is mod/dy. It is essential to */ + /* keep track of its accumulation for accurate rendering. */ FT_DIV_MOD( TCoord, p, dy, delta, mod ); x = ras.x + delta; @@ -843,8 +849,9 @@ typedef ptrdiff_t FT_PtrDist; gray_render_line( RAS_ARG_ TPos to_x, TPos to_y ) { - TPos dx, dy, fx1, fy1, fx2, fy2; - TCoord ex1, ex2, ey1, ey2; + TPos dx, dy; + TCoord fx1, fy1, fx2, fy2; + TCoord ex1, ey1, ex2, ey2; ey1 = TRUNC( ras.y ); @@ -858,8 +865,8 @@ typedef ptrdiff_t FT_PtrDist; ex1 = TRUNC( ras.x ); ex2 = TRUNC( to_x ); - fx1 = ras.x - SUBPIXELS( ex1 ); - fy1 = ras.y - SUBPIXELS( ey1 ); + fx1 = FRACT( ras.x ); + fy1 = FRACT( ras.y ); dx = to_x - ras.x; dy = to_y - ras.y; @@ -868,8 +875,8 @@ typedef ptrdiff_t FT_PtrDist; ; else if ( dy == 0 ) /* ex1 != ex2 */ /* any horizontal line */ { - ex1 = ex2; - gray_set_cell( RAS_VAR_ ex1, ey1 ); + gray_set_cell( RAS_VAR_ ex2, ey2 ); + goto End; } else if ( dx == 0 ) { @@ -896,7 +903,7 @@ typedef ptrdiff_t FT_PtrDist; } else /* any other line */ { - TPos prod = dx * fy1 - dy * fx1; + TPos prod = dx * (TPos)fy1 - dy * (TPos)fx1; FT_UDIVPREP( ex1 != ex2, dx ); FT_UDIVPREP( ey1 != ey2, dy ); @@ -910,7 +917,7 @@ typedef ptrdiff_t FT_PtrDist; prod - dx * ONE_PIXEL > 0 ) /* left */ { fx2 = 0; - fy2 = (TPos)FT_UDIV( -prod, -dx ); + fy2 = FT_UDIV( -prod, -dx ); prod -= dy * ONE_PIXEL; ras.cover += ( fy2 - fy1 ); ras.area += ( fy2 - fy1 ) * ( fx1 + fx2 ); @@ -922,7 +929,7 @@ typedef ptrdiff_t FT_PtrDist; prod - dx * ONE_PIXEL + dy * ONE_PIXEL > 0 ) /* up */ { prod -= dx * ONE_PIXEL; - fx2 = (TPos)FT_UDIV( -prod, dy ); + fx2 = FT_UDIV( -prod, dy ); fy2 = ONE_PIXEL; ras.cover += ( fy2 - fy1 ); ras.area += ( fy2 - fy1 ) * ( fx1 + fx2 ); @@ -935,7 +942,7 @@ typedef ptrdiff_t FT_PtrDist; { prod += dy * ONE_PIXEL; fx2 = ONE_PIXEL; - fy2 = (TPos)FT_UDIV( prod, dx ); + fy2 = FT_UDIV( prod, dx ); ras.cover += ( fy2 - fy1 ); ras.area += ( fy2 - fy1 ) * ( fx1 + fx2 ); fx1 = 0; @@ -945,7 +952,7 @@ typedef ptrdiff_t FT_PtrDist; else /* ( prod + dy * ONE_PIXEL < 0 && prod > 0 ) down */ { - fx2 = (TPos)FT_UDIV( prod, -dy ); + fx2 = FT_UDIV( prod, -dy ); fy2 = 0; prod += dx * ONE_PIXEL; ras.cover += ( fy2 - fy1 ); @@ -959,8 +966,8 @@ typedef ptrdiff_t FT_PtrDist; } while ( ex1 != ex2 || ey1 != ey2 ); } - fx2 = to_x - SUBPIXELS( ex2 ); - fy2 = to_y - SUBPIXELS( ey2 ); + fx2 = FRACT( to_x ); + fy2 = FRACT( to_y ); ras.cover += ( fy2 - fy1 ); ras.area += ( fy2 - fy1 ) * ( fx1 + fx2 ); @@ -979,16 +986,18 @@ typedef ptrdiff_t FT_PtrDist; base[4].x = base[2].x; - b = base[1].x; - a = base[3].x = ( base[2].x + b ) / 2; - b = base[1].x = ( base[0].x + b ) / 2; - base[2].x = ( a + b ) / 2; + a = base[0].x + base[1].x; + b = base[1].x + base[2].x; + base[3].x = b >> 1; + base[2].x = ( a + b ) >> 2; + base[1].x = a >> 1; base[4].y = base[2].y; - b = base[1].y; - a = base[3].y = ( base[2].y + b ) / 2; - b = base[1].y = ( base[0].y + b ) / 2; - base[2].y = ( a + b ) / 2; + a = base[0].y + base[1].y; + b = base[1].y + base[2].y; + base[3].y = b >> 1; + base[2].y = ( a + b ) >> 2; + base[1].y = a >> 1; } @@ -1042,12 +1051,11 @@ typedef ptrdiff_t FT_PtrDist; /* many times as there are trailing zeros in the counter. */ do { - split = 1; - while ( ( draw & split ) == 0 ) + split = draw & ( -draw ); /* isolate the rightmost 1-bit */ + while ( ( split >>= 1 ) ) { gray_split_conic( arc ); arc += 2; - split <<= 1; } gray_render_line( RAS_VAR_ arc[0].x, arc[0].y ); @@ -1060,28 +1068,32 @@ typedef ptrdiff_t FT_PtrDist; static void gray_split_cubic( FT_Vector* base ) { - TPos a, b, c, d; + TPos a, b, c; base[6].x = base[3].x; - c = base[1].x; - d = base[2].x; - base[1].x = a = ( base[0].x + c ) / 2; - base[5].x = b = ( base[3].x + d ) / 2; - c = ( c + d ) / 2; - base[2].x = a = ( a + c ) / 2; - base[4].x = b = ( b + c ) / 2; - base[3].x = ( a + b ) / 2; + a = base[0].x + base[1].x; + b = base[1].x + base[2].x; + c = base[2].x + base[3].x; + base[5].x = c >> 1; + c += b; + base[4].x = c >> 2; + base[1].x = a >> 1; + a += b; + base[2].x = a >> 2; + base[3].x = ( a + c ) >> 3; base[6].y = base[3].y; - c = base[1].y; - d = base[2].y; - base[1].y = a = ( base[0].y + c ) / 2; - base[5].y = b = ( base[3].y + d ) / 2; - c = ( c + d ) / 2; - base[2].y = a = ( a + c ) / 2; - base[4].y = b = ( b + c ) / 2; - base[3].y = ( a + b ) / 2; + a = base[0].y + base[1].y; + b = base[1].y + base[2].y; + c = base[2].y + base[3].y; + base[5].y = c >> 1; + c += b; + base[4].y = c >> 2; + base[1].y = a >> 1; + a += b; + base[2].y = a >> 2; + base[3].y = ( a + c ) >> 3; } @@ -1092,9 +1104,6 @@ typedef ptrdiff_t FT_PtrDist; { FT_Vector bez_stack[16 * 3 + 1]; /* enough to accommodate bisections */ FT_Vector* arc = bez_stack; - TPos dx, dy, dx_, dy_; - TPos dx1, dy1, dx2, dy2; - TPos L, s, s_limit; arc[0].x = UPSCALE( to->x ); @@ -1123,45 +1132,13 @@ typedef ptrdiff_t FT_PtrDist; for (;;) { - /* Decide whether to split or draw. See `Rapid Termination */ - /* Evaluation for Recursive Subdivision of Bezier Curves' by Thomas */ - /* F. Hain, at */ - /* http://www.cis.southalabama.edu/~hain/general/Publications/Bezier/Camera-ready%20CISST02%202.pdf */ - - /* dx and dy are x and y components of the P0-P3 chord vector. */ - dx = dx_ = arc[3].x - arc[0].x; - dy = dy_ = arc[3].y - arc[0].y; - - L = FT_HYPOT( dx_, dy_ ); - - /* Avoid possible arithmetic overflow below by splitting. */ - if ( L > 32767 ) - goto Split; - - /* Max deviation may be as much as (s/L) * 3/4 (if Hain's v = 1). */ - s_limit = L * (TPos)( ONE_PIXEL / 6 ); - - /* s is L * the perpendicular distance from P1 to the line P0-P3. */ - dx1 = arc[1].x - arc[0].x; - dy1 = arc[1].y - arc[0].y; - s = FT_ABS( SUB_LONG( MUL_LONG( dy, dx1 ), MUL_LONG( dx, dy1 ) ) ); - - if ( s > s_limit ) - goto Split; - - /* s is L * the perpendicular distance from P2 to the line P0-P3. */ - dx2 = arc[2].x - arc[0].x; - dy2 = arc[2].y - arc[0].y; - s = FT_ABS( SUB_LONG( MUL_LONG( dy, dx2 ), MUL_LONG( dx, dy2 ) ) ); - - if ( s > s_limit ) - goto Split; - - /* Split super curvy segments where the off points are so far - from the chord that the angles P0-P1-P3 or P0-P2-P3 become - acute as detected by appropriate dot products. */ - if ( dx1 * ( dx1 - dx ) + dy1 * ( dy1 - dy ) > 0 || - dx2 * ( dx2 - dx ) + dy2 * ( dy2 - dy ) > 0 ) + /* with each split, control points quickly converge towards */ + /* chord trisection points and the vanishing distances below */ + /* indicate when the segment is flat enough to draw */ + if ( FT_ABS( 2 * arc[0].x - 3 * arc[1].x + arc[3].x ) > ONE_PIXEL / 2 || + FT_ABS( 2 * arc[0].y - 3 * arc[1].y + arc[3].y ) > ONE_PIXEL / 2 || + FT_ABS( arc[0].x - 3 * arc[2].x + 2 * arc[3].x ) > ONE_PIXEL / 2 || + FT_ABS( arc[0].y - 3 * arc[2].y + 2 * arc[3].y ) > ONE_PIXEL / 2 ) goto Split; gray_render_line( RAS_VAR_ arc[0].x, arc[0].y ); @@ -1236,8 +1213,6 @@ typedef ptrdiff_t FT_PtrDist; { /* scale the coverage from 0..(ONE_PIXEL*ONE_PIXEL*2) to 0..256 */ coverage >>= PIXEL_BITS * 2 + 1 - 8; - if ( coverage < 0 ) - coverage = -coverage - 1; /* compute the line's coverage depending on the outline fill rule */ if ( ras.outline.flags & FT_OUTLINE_EVEN_ODD_FILL ) @@ -1247,23 +1222,30 @@ typedef ptrdiff_t FT_PtrDist; if ( coverage >= 256 ) coverage = 511 - coverage; } - else + else /* default non-zero winding rule */ { - /* normal non-zero winding rule */ + if ( coverage < 0 ) + coverage = ~coverage; /* the same as -coverage - 1 */ + if ( coverage >= 256 ) coverage = 255; } - if ( ras.render_span ) /* for FT_RASTER_FLAG_DIRECT only */ + if ( ras.num_spans >= 0 ) /* for FT_RASTER_FLAG_DIRECT only */ { - FT_Span span; + FT_Span* span = ras.spans + ras.num_spans++; - span.x = (short)x; - span.len = (unsigned short)acount; - span.coverage = (unsigned char)coverage; + span->x = (short)x; + span->len = (unsigned short)acount; + span->coverage = (unsigned char)coverage; - ras.render_span( y, 1, &span, ras.render_span_data ); + if ( ras.num_spans == FT_MAX_GRAY_SPANS ) + { + /* flush the span buffer and reset the count */ + ras.render_span( y, ras.num_spans, ras.spans, ras.render_span_data ); + ras.num_spans = 0; + } } else { @@ -1277,14 +1259,29 @@ typedef ptrdiff_t FT_PtrDist; */ switch ( acount ) { - case 7: *q++ = c; - case 6: *q++ = c; - case 5: *q++ = c; - case 4: *q++ = c; - case 3: *q++ = c; - case 2: *q++ = c; - case 1: *q = c; - case 0: break; + case 7: + *q++ = c; + /* fall through */ + case 6: + *q++ = c; + /* fall through */ + case 5: + *q++ = c; + /* fall through */ + case 4: + *q++ = c; + /* fall through */ + case 3: + *q++ = c; + /* fall through */ + case 2: + *q++ = c; + /* fall through */ + case 1: + *q = c; + /* fall through */ + case 0: + break; default: FT_MEM_SET( q, c, acount ); } @@ -1322,6 +1319,13 @@ typedef ptrdiff_t FT_PtrDist; if ( cover != 0 ) gray_hline( RAS_VAR_ x, y, cover, ras.max_ex - x ); + + if ( ras.num_spans > 0 ) /* for FT_RASTER_FLAG_DIRECT only */ + { + /* flush the span buffer and reset the count */ + ras.render_span( y, ras.num_spans, ras.spans, ras.render_span_data ); + ras.num_spans = 0; + } } } @@ -1371,7 +1375,7 @@ typedef ptrdiff_t FT_PtrDist; void* user ) { #undef SCALED -#define SCALED( x ) ( ( (x) << shift ) - delta ) +#define SCALED( x ) ( (x) * ( 1L << shift ) - delta ) FT_Vector v_last; FT_Vector v_control; @@ -1631,7 +1635,7 @@ typedef ptrdiff_t FT_PtrDist; gray_convert_glyph_inner( RAS_ARG, int continued ) { - volatile int error = 0; + int error; if ( ft_setjmp( ras.jump_buffer ) == 0 ) @@ -1755,7 +1759,6 @@ typedef ptrdiff_t FT_PtrDist; { const FT_Outline* outline = (const FT_Outline*)params->source; const FT_Bitmap* target_map = params->target; - FT_BBox clip; #ifndef FT_STATIC_RASTER gray_TWorker worker[1]; @@ -1792,6 +1795,12 @@ typedef ptrdiff_t FT_PtrDist; ras.render_span = (FT_Raster_Span_Func)params->gray_spans; ras.render_span_data = params->user; + ras.num_spans = 0; + + ras.min_ex = params->clip_box.xMin; + ras.min_ey = params->clip_box.yMin; + ras.max_ex = params->clip_box.xMax; + ras.max_ey = params->clip_box.yMax; } else { @@ -1816,27 +1825,15 @@ typedef ptrdiff_t FT_PtrDist; ras.render_span = (FT_Raster_Span_Func)NULL; ras.render_span_data = NULL; - } + ras.num_spans = -1; /* invalid */ - /* compute clipping box */ - if ( params->flags & FT_RASTER_FLAG_DIRECT && - params->flags & FT_RASTER_FLAG_CLIP ) - clip = params->clip_box; - else - { - /* compute clip box from target pixmap */ - clip.xMin = 0; - clip.yMin = 0; - clip.xMax = (FT_Pos)target_map->width; - clip.yMax = (FT_Pos)target_map->rows; + ras.min_ex = 0; + ras.min_ey = 0; + ras.max_ex = (FT_Pos)target_map->width; + ras.max_ey = (FT_Pos)target_map->rows; } - /* clip to target bitmap, exit if nothing to do */ - ras.min_ex = clip.xMin; - ras.min_ey = clip.yMin; - ras.max_ex = clip.xMax; - ras.max_ey = clip.yMax; - + /* exit if nothing to do */ if ( ras.max_ex <= ras.min_ex || ras.max_ey <= ras.min_ey ) return 0; 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