/***************************************************************************/ /* */ /* ftgrays.c */ /* */ /* A new `perfect' anti-aliasing renderer (body). */ /* */ /* Copyright 2000-2003, 2005-2014 by */ /* David Turner, Robert Wilhelm, and Werner Lemberg. */ /* */ /* This file is part of the FreeType project, and may only be used, */ /* modified, and distributed under the terms of the FreeType project */ /* license, LICENSE.TXT. By continuing to use, modify, or distribute */ /* this file you indicate that you have read the license and */ /* understand and accept it fully. */ /* */ /***************************************************************************/ /*************************************************************************/ /* */ /* 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. */ /* */ /* It is based on ideas that I initially found in Raph Levien's */ /* excellent LibArt graphics library (see http://www.levien.com/libart */ /* for more information, though the web pages do not tell anything */ /* about the renderer; you'll have to dive into the source code to */ /* understand how it works). */ /* */ /* Note, however, that this is a _very_ different implementation */ /* compared to Raph's. Coverage information is stored in a very */ /* different way, and I don't use sorted vector paths. Also, it doesn't */ /* use floating point values. */ /* */ /* This renderer has the following advantages: */ /* */ /* - It doesn't need an intermediate bitmap. Instead, one can supply a */ /* callback function that will be called by the renderer to draw gray */ /* spans on any target surface. You can thus do direct composition on */ /* any kind of bitmap, provided that you give the renderer the right */ /* callback. */ /* */ /* - A perfect anti-aliaser, i.e., it computes the _exact_ coverage on */ /* each pixel cell. */ /* */ /* - It performs a single pass on the outline (the `standard' FT2 */ /* renderer makes two passes). */ /* */ /* - 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 */ /* renderer. */ /* */ /*************************************************************************/ #include "plutovg-ft-raster.h" #include "plutovg-ft-math.h" #define PVG_FT_BEGIN_STMNT do { #define PVG_FT_END_STMNT } while ( 0 ) #include #define pvg_ft_setjmp setjmp #define pvg_ft_longjmp longjmp #define pvg_ft_jmp_buf jmp_buf #include typedef ptrdiff_t PVG_FT_PtrDist; #define ErrRaster_Invalid_Mode -2 #define ErrRaster_Invalid_Outline -1 #define ErrRaster_Invalid_Argument -3 #define ErrRaster_Memory_Overflow -4 #define ErrRaster_OutOfMemory -6 #include #include #define PVG_FT_MINIMUM_POOL_SIZE 8192 #define RAS_ARG PWorker worker #define RAS_ARG_ PWorker worker, #define RAS_VAR worker #define RAS_VAR_ worker, #define ras (*worker) /* must be at least 6 bits! */ #define PIXEL_BITS 8 #define ONE_PIXEL ( 1L << PIXEL_BITS ) #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 ) ) #define DOWNSCALE( x ) ( (x) >> ( PIXEL_BITS - 6 ) ) #else #define UPSCALE( x ) ( (x) >> ( 6 - PIXEL_BITS ) ) #define DOWNSCALE( x ) ( (x) * ( 64 >> PIXEL_BITS ) ) #endif /* Compute `dividend / divisor' and return both its quotient and */ /* remainder, cast to a specific type. This macro also ensures that */ /* the remainder is always positive. */ #define PVG_FT_DIV_MOD( type, dividend, divisor, quotient, remainder ) \ PVG_FT_BEGIN_STMNT \ (quotient) = (type)( (dividend) / (divisor) ); \ (remainder) = (type)( (dividend) % (divisor) ); \ if ( (remainder) < 0 ) \ { \ (quotient)--; \ (remainder) += (type)(divisor); \ } \ PVG_FT_END_STMNT /* These macros speed up repetitive divisions by replacing them */ /* with multiplications and right shifts. */ #define PVG_FT_UDIVPREP( b ) \ long b ## _r = (long)( ULONG_MAX >> PIXEL_BITS ) / ( b ) #define PVG_FT_UDIV( a, b ) \ ( ( (unsigned long)( a ) * (unsigned long)( b ## _r ) ) >> \ ( sizeof( long ) * CHAR_BIT - PIXEL_BITS ) ) /*************************************************************************/ /* */ /* TYPE DEFINITIONS */ /* */ /* don't change the following types to PVG_FT_Int or PVG_FT_Pos, since we might */ /* need to define them to "float" or "double" when experimenting with */ /* new algorithms */ typedef long TCoord; /* integer scanline/pixel coordinate */ typedef long TPos; /* sub-pixel coordinate */ typedef long TArea ; /* cell areas, coordinate products */ /* maximal number of gray spans in a call to the span callback */ #define PVG_FT_MAX_GRAY_SPANS 256 typedef struct TCell_* PCell; typedef struct TCell_ { int x; int cover; TArea area; PCell next; } TCell; typedef struct TWorker_ { TCoord ex, ey; TPos min_ex, max_ex; TPos min_ey, max_ey; TPos count_ex, count_ey; TArea area; int cover; int invalid; PCell cells; PVG_FT_PtrDist max_cells; PVG_FT_PtrDist num_cells; TPos x, y; PVG_FT_Outline outline; PVG_FT_BBox clip_box; PVG_FT_Span gray_spans[PVG_FT_MAX_GRAY_SPANS]; int num_gray_spans; int skip_spans; PVG_FT_Raster_Span_Func render_span; void* render_span_data; int band_size; int band_shoot; pvg_ft_jmp_buf jump_buffer; void* buffer; long buffer_size; PCell* ycells; TPos ycount; } TWorker, *PWorker; /*************************************************************************/ /* */ /* Initialize the cells table. */ /* */ static void gray_init_cells( RAS_ARG_ void* buffer, long byte_size ) { ras.buffer = buffer; ras.buffer_size = byte_size; ras.ycells = (PCell*) buffer; ras.cells = NULL; ras.max_cells = 0; ras.num_cells = 0; ras.area = 0; ras.cover = 0; ras.invalid = 1; } /*************************************************************************/ /* */ /* Compute the outline bounding box. */ /* */ static void gray_compute_cbox( RAS_ARG ) { PVG_FT_Outline* outline = &ras.outline; PVG_FT_Vector* vec = outline->points; PVG_FT_Vector* limit = vec + outline->n_points; if ( outline->n_points <= 0 ) { ras.min_ex = ras.max_ex = 0; ras.min_ey = ras.max_ey = 0; return; } ras.min_ex = ras.max_ex = vec->x; ras.min_ey = ras.max_ey = vec->y; vec++; for ( ; vec < limit; vec++ ) { TPos x = vec->x; TPos y = vec->y; if ( x < ras.min_ex ) ras.min_ex = x; if ( x > ras.max_ex ) ras.max_ex = x; if ( y < ras.min_ey ) ras.min_ey = y; if ( y > ras.max_ey ) ras.max_ey = y; } /* truncate the bounding box to integer pixels */ ras.min_ex = ras.min_ex >> 6; ras.min_ey = ras.min_ey >> 6; ras.max_ex = ( ras.max_ex + 63 ) >> 6; ras.max_ey = ( ras.max_ey + 63 ) >> 6; } /*************************************************************************/ /* */ /* Record the current cell in the table. */ /* */ static PCell gray_find_cell( RAS_ARG ) { PCell *pcell, cell; TPos x = ras.ex; if ( x > ras.count_ex ) x = ras.count_ex; pcell = &ras.ycells[ras.ey]; for (;;) { cell = *pcell; if ( cell == NULL || cell->x > x ) break; if ( cell->x == x ) goto Exit; pcell = &cell->next; } if ( ras.num_cells >= ras.max_cells ) pvg_ft_longjmp( ras.jump_buffer, 1 ); cell = ras.cells + ras.num_cells++; cell->x = x; cell->area = 0; cell->cover = 0; cell->next = *pcell; *pcell = cell; Exit: return cell; } static void gray_record_cell( RAS_ARG ) { if ( ras.area | ras.cover ) { PCell cell = gray_find_cell( RAS_VAR ); cell->area += ras.area; cell->cover += ras.cover; } } /*************************************************************************/ /* */ /* Set the current cell to a new position. */ /* */ static void gray_set_cell( RAS_ARG_ TCoord ex, TCoord ey ) { /* Move the cell pointer to a new position. We set the `invalid' */ /* flag to indicate that the cell isn't part of those we're interested */ /* in during the render phase. This means that: */ /* */ /* . the new vertical position must be within min_ey..max_ey-1. */ /* . the new horizontal position must be strictly less than max_ex */ /* */ /* Note that if a cell is to the left of the clipping region, it is */ /* actually set to the (min_ex-1) horizontal position. */ /* All cells that are on the left of the clipping region go to the */ /* min_ex - 1 horizontal position. */ ey -= ras.min_ey; if ( ex > ras.max_ex ) ex = ras.max_ex; ex -= ras.min_ex; if ( ex < 0 ) ex = -1; /* are we moving to a different cell ? */ if ( ex != ras.ex || ey != ras.ey ) { /* record the current one if it is valid */ if ( !ras.invalid ) gray_record_cell( RAS_VAR ); ras.area = 0; ras.cover = 0; ras.ex = ex; ras.ey = ey; } ras.invalid = ( (unsigned int)ey >= (unsigned int)ras.count_ey || ex >= ras.count_ex ); } /*************************************************************************/ /* */ /* Start a new contour at a given cell. */ /* */ static void gray_start_cell( RAS_ARG_ TCoord ex, TCoord ey ) { if ( ex > ras.max_ex ) ex = (TCoord)( ras.max_ex ); if ( ex < ras.min_ex ) ex = (TCoord)( ras.min_ex - 1 ); ras.area = 0; ras.cover = 0; ras.ex = ex - ras.min_ex; ras.ey = ey - ras.min_ey; ras.invalid = 0; gray_set_cell( RAS_VAR_ ex, ey ); } // The new render-line implementation is not yet used #if 1 /*************************************************************************/ /* */ /* Render a scanline as one or more cells. */ /* */ static void gray_render_scanline( RAS_ARG_ TCoord ey, TPos x1, TCoord y1, TPos x2, TCoord y2 ) { TCoord ex1, ex2, fx1, fx2, first, dy, delta, mod; TPos p, dx; int incr; ex1 = TRUNC( x1 ); ex2 = TRUNC( x2 ); /* trivial case. Happens often */ if ( y1 == y2 ) { gray_set_cell( RAS_VAR_ ex2, ey ); return; } fx1 = FRACT( x1 ); fx2 = FRACT( x2 ); /* everything is located in a single cell. That is easy! */ /* */ if ( ex1 == ex2 ) goto End; /* ok, we'll have to render a run of adjacent cells on the same */ /* scanline... */ /* */ dx = x2 - x1; dy = y2 - y1; if ( dx > 0 ) { p = ( ONE_PIXEL - fx1 ) * dy; first = ONE_PIXEL; incr = 1; } else { p = fx1 * dy; first = 0; incr = -1; dx = -dx; } PVG_FT_DIV_MOD( TCoord, p, dx, delta, mod ); ras.area += (TArea)( fx1 + first ) * delta; ras.cover += delta; y1 += delta; ex1 += incr; gray_set_cell( RAS_VAR_ ex1, ey ); if ( ex1 != ex2 ) { TCoord lift, rem; p = ONE_PIXEL * dy; PVG_FT_DIV_MOD( TCoord, p, dx, lift, rem ); do { delta = lift; mod += rem; if ( mod >= (TCoord)dx ) { mod -= (TCoord)dx; delta++; } ras.area += (TArea)( ONE_PIXEL * delta ); ras.cover += delta; y1 += delta; ex1 += incr; gray_set_cell( RAS_VAR_ ex1, ey ); } while ( ex1 != ex2 ); } fx1 = ONE_PIXEL - first; End: dy = y2 - y1; ras.area += (TArea)( ( fx1 + fx2 ) * dy ); ras.cover += dy; } /*************************************************************************/ /* */ /* Render a given line as a series of scanlines. */ /* */ static void gray_render_line( RAS_ARG_ TPos to_x, TPos to_y ) { TCoord ey1, ey2, fy1, fy2, first, delta, mod; TPos p, dx, dy, x, x2; int incr; ey1 = TRUNC( ras.y ); ey2 = TRUNC( to_y ); /* if (ey2 >= ras.max_ey) ey2 = ras.max_ey-1; */ /* perform vertical clipping */ if ( ( ey1 >= ras.max_ey && ey2 >= ras.max_ey ) || ( ey1 < ras.min_ey && ey2 < ras.min_ey ) ) goto End; fy1 = FRACT( ras.y ); fy2 = FRACT( to_y ); /* everything is on a single scanline */ if ( ey1 == ey2 ) { gray_render_scanline( RAS_VAR_ ey1, ras.x, fy1, to_x, fy2 ); goto End; } dx = to_x - ras.x; dy = to_y - ras.y; /* vertical line - avoid calling gray_render_scanline */ if ( dx == 0 ) { TCoord ex = TRUNC( ras.x ); TCoord two_fx = FRACT( ras.x ) << 1; TPos area, max_ey1; if ( dy > 0) { first = ONE_PIXEL; } else { first = 0; } delta = first - fy1; ras.area += (TArea)two_fx * delta; ras.cover += delta; delta = first + first - ONE_PIXEL; area = (TArea)two_fx * delta; max_ey1 = ras.count_ey + ras.min_ey; if (dy < 0) { if (ey1 > max_ey1) { ey1 = (max_ey1 > ey2) ? max_ey1 : ey2; gray_set_cell( &ras, ex, ey1 ); } else { ey1--; gray_set_cell( &ras, ex, ey1 ); } while ( ey1 > ey2 && ey1 >= ras.min_ey) { ras.area += area; ras.cover += delta; ey1--; gray_set_cell( &ras, ex, ey1 ); } if (ey1 != ey2) { ey1 = ey2; gray_set_cell( &ras, ex, ey1 ); } } else { if (ey1 < ras.min_ey) { ey1 = (ras.min_ey < ey2) ? ras.min_ey : ey2; gray_set_cell( &ras, ex, ey1 ); } else { ey1++; gray_set_cell( &ras, ex, ey1 ); } while ( ey1 < ey2 && ey1 < max_ey1) { ras.area += area; ras.cover += delta; ey1++; gray_set_cell( &ras, ex, ey1 ); } if (ey1 != ey2) { ey1 = ey2; gray_set_cell( &ras, ex, ey1 ); } } delta = (int)( fy2 - ONE_PIXEL + first ); ras.area += (TArea)two_fx * delta; ras.cover += delta; goto End; } /* ok, we have to render several scanlines */ if ( dy > 0) { p = ( ONE_PIXEL - fy1 ) * dx; first = ONE_PIXEL; incr = 1; } else { p = fy1 * dx; first = 0; incr = -1; dy = -dy; } /* the fractional part of x-delta is mod/dy. It is essential to */ /* keep track of its accumulation for accurate rendering. */ PVG_FT_DIV_MOD( TCoord, p, dy, delta, mod ); x = ras.x + delta; gray_render_scanline( RAS_VAR_ ey1, ras.x, fy1, x, (TCoord)first ); ey1 += incr; gray_set_cell( RAS_VAR_ TRUNC( x ), ey1 ); if ( ey1 != ey2 ) { TCoord lift, rem; p = ONE_PIXEL * dx; PVG_FT_DIV_MOD( TCoord, p, dy, lift, rem ); do { delta = lift; mod += rem; if ( mod >= (TCoord)dy ) { mod -= (TCoord)dy; delta++; } x2 = x + delta; gray_render_scanline( RAS_VAR_ ey1, x, ONE_PIXEL - first, x2, first ); x = x2; ey1 += incr; gray_set_cell( RAS_VAR_ TRUNC( x ), ey1 ); } while ( ey1 != ey2 ); } gray_render_scanline( RAS_VAR_ ey1, x, ONE_PIXEL - first, to_x, fy2 ); End: ras.x = to_x; ras.y = to_y; } #else /*************************************************************************/ /* */ /* Render a straight line across multiple cells in any direction. */ /* */ static void gray_render_line( RAS_ARG_ TPos to_x, TPos to_y ) { TPos dx, dy, fx1, fy1, fx2, fy2; TCoord ex1, ex2, ey1, ey2; ex1 = TRUNC( ras.x ); ex2 = TRUNC( to_x ); ey1 = TRUNC( ras.y ); ey2 = TRUNC( to_y ); /* perform vertical clipping */ if ( ( ey1 >= ras.max_ey && ey2 >= ras.max_ey ) || ( ey1 < ras.min_ey && ey2 < ras.min_ey ) ) goto End; dx = to_x - ras.x; dy = to_y - ras.y; fx1 = FRACT( ras.x ); fy1 = FRACT( ras.y ); if ( ex1 == ex2 && ey1 == ey2 ) /* inside one cell */ ; else if ( dy == 0 ) /* ex1 != ex2 */ /* any horizontal line */ { ex1 = ex2; gray_set_cell( RAS_VAR_ ex1, ey1 ); } else if ( dx == 0 ) { if ( dy > 0 ) /* vertical line up */ do { fy2 = ONE_PIXEL; ras.cover += ( fy2 - fy1 ); ras.area += ( fy2 - fy1 ) * fx1 * 2; fy1 = 0; ey1++; gray_set_cell( RAS_VAR_ ex1, ey1 ); } while ( ey1 != ey2 ); else /* vertical line down */ do { fy2 = 0; ras.cover += ( fy2 - fy1 ); ras.area += ( fy2 - fy1 ) * fx1 * 2; fy1 = ONE_PIXEL; ey1--; gray_set_cell( RAS_VAR_ ex1, ey1 ); } while ( ey1 != ey2 ); } else /* any other line */ { TArea prod = dx * fy1 - dy * fx1; PVG_FT_UDIVPREP( dx ); PVG_FT_UDIVPREP( dy ); /* The fundamental value `prod' determines which side and the */ /* exact coordinate where the line exits current cell. It is */ /* also easily updated when moving from one cell to the next. */ do { if ( prod <= 0 && prod - dx * ONE_PIXEL > 0 ) /* left */ { fx2 = 0; fy2 = (TPos)PVG_FT_UDIV( -prod, -dx ); prod -= dy * ONE_PIXEL; ras.cover += ( fy2 - fy1 ); ras.area += ( fy2 - fy1 ) * ( fx1 + fx2 ); fx1 = ONE_PIXEL; fy1 = fy2; ex1--; } else if ( prod - dx * ONE_PIXEL <= 0 && prod - dx * ONE_PIXEL + dy * ONE_PIXEL > 0 ) /* up */ { prod -= dx * ONE_PIXEL; fx2 = (TPos)PVG_FT_UDIV( -prod, dy ); fy2 = ONE_PIXEL; ras.cover += ( fy2 - fy1 ); ras.area += ( fy2 - fy1 ) * ( fx1 + fx2 ); fx1 = fx2; fy1 = 0; ey1++; } else if ( prod - dx * ONE_PIXEL + dy * ONE_PIXEL <= 0 && prod + dy * ONE_PIXEL >= 0 ) /* right */ { prod += dy * ONE_PIXEL; fx2 = ONE_PIXEL; fy2 = (TPos)PVG_FT_UDIV( prod, dx ); ras.cover += ( fy2 - fy1 ); ras.area += ( fy2 - fy1 ) * ( fx1 + fx2 ); fx1 = 0; fy1 = fy2; ex1++; } else /* ( prod + dy * ONE_PIXEL < 0 && prod > 0 ) down */ { fx2 = (TPos)PVG_FT_UDIV( prod, -dy ); fy2 = 0; prod += dx * ONE_PIXEL; ras.cover += ( fy2 - fy1 ); ras.area += ( fy2 - fy1 ) * ( fx1 + fx2 ); fx1 = fx2; fy1 = ONE_PIXEL; ey1--; } gray_set_cell( RAS_VAR_ ex1, ey1 ); } while ( ex1 != ex2 || ey1 != ey2 ); } fx2 = FRACT( to_x ); fy2 = FRACT( to_y ); ras.cover += ( fy2 - fy1 ); ras.area += ( fy2 - fy1 ) * ( fx1 + fx2 ); End: ras.x = to_x; ras.y = to_y; } #endif static void gray_split_conic( PVG_FT_Vector* base ) { TPos a, b; 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; 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; } static void gray_render_conic( RAS_ARG_ const PVG_FT_Vector* control, const PVG_FT_Vector* to ) { PVG_FT_Vector bez_stack[16 * 2 + 1]; /* enough to accommodate bisections */ PVG_FT_Vector* arc = bez_stack; TPos dx, dy; int draw, split; arc[0].x = UPSCALE( to->x ); arc[0].y = UPSCALE( to->y ); arc[1].x = UPSCALE( control->x ); arc[1].y = UPSCALE( control->y ); arc[2].x = ras.x; arc[2].y = ras.y; /* short-cut the arc that crosses the current band */ if ( ( TRUNC( arc[0].y ) >= ras.max_ey && TRUNC( arc[1].y ) >= ras.max_ey && TRUNC( arc[2].y ) >= ras.max_ey ) || ( TRUNC( arc[0].y ) < ras.min_ey && TRUNC( arc[1].y ) < ras.min_ey && TRUNC( arc[2].y ) < ras.min_ey ) ) { ras.x = arc[0].x; ras.y = arc[0].y; return; } dx = PVG_FT_ABS( arc[2].x + arc[0].x - 2 * arc[1].x ); dy = PVG_FT_ABS( arc[2].y + arc[0].y - 2 * arc[1].y ); if ( dx < dy ) dx = dy; /* We can calculate the number of necessary bisections because */ /* each bisection predictably reduces deviation exactly 4-fold. */ /* Even 32-bit deviation would vanish after 16 bisections. */ draw = 1; while ( dx > ONE_PIXEL / 4 ) { dx >>= 2; draw <<= 1; } /* We use decrement counter to count the total number of segments */ /* to draw starting from 2^level. Before each draw we split as */ /* many times as there are trailing zeros in the counter. */ do { split = 1; while ( ( draw & split ) == 0 ) { gray_split_conic( arc ); arc += 2; split <<= 1; } gray_render_line( RAS_VAR_ arc[0].x, arc[0].y ); arc -= 2; } while ( --draw ); } static void gray_split_cubic( PVG_FT_Vector* base ) { TPos a, b, c, d; 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; 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; } static void gray_render_cubic( RAS_ARG_ const PVG_FT_Vector* control1, const PVG_FT_Vector* control2, const PVG_FT_Vector* to ) { PVG_FT_Vector bez_stack[16 * 3 + 1]; /* enough to accommodate bisections */ PVG_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 ); arc[0].y = UPSCALE( to->y ); arc[1].x = UPSCALE( control2->x ); arc[1].y = UPSCALE( control2->y ); arc[2].x = UPSCALE( control1->x ); arc[2].y = UPSCALE( control1->y ); arc[3].x = ras.x; arc[3].y = ras.y; /* short-cut the arc that crosses the current band */ if ( ( TRUNC( arc[0].y ) >= ras.max_ey && TRUNC( arc[1].y ) >= ras.max_ey && TRUNC( arc[2].y ) >= ras.max_ey && TRUNC( arc[3].y ) >= ras.max_ey ) || ( TRUNC( arc[0].y ) < ras.min_ey && TRUNC( arc[1].y ) < ras.min_ey && TRUNC( arc[2].y ) < ras.min_ey && TRUNC( arc[3].y ) < ras.min_ey ) ) { ras.x = arc[0].x; ras.y = arc[0].y; return; } 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 = PVG_FT_HYPOT( dx_, dy_ ); /* Avoid possible arithmetic overflow below by splitting. */ if ( L >= (1 << 23) ) 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 = PVG_FT_ABS( dy * dx1 - 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 = PVG_FT_ABS( dy * dx2 - 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 ) goto Split; gray_render_line( RAS_VAR_ arc[0].x, arc[0].y ); if ( arc == bez_stack ) return; arc -= 3; continue; Split: gray_split_cubic( arc ); arc += 3; } } static int gray_move_to( const PVG_FT_Vector* to, PWorker worker ) { TPos x, y; /* record current cell, if any */ if ( !ras.invalid ) gray_record_cell( worker ); /* start to a new position */ x = UPSCALE( to->x ); y = UPSCALE( to->y ); gray_start_cell( worker, TRUNC( x ), TRUNC( y ) ); ras.x = x; ras.y = y; return 0; } static void gray_hline( RAS_ARG_ TCoord x, TCoord y, TPos area, int acount ) { int coverage; /* compute the coverage line's coverage, depending on the */ /* outline fill rule */ /* */ /* the coverage percentage is area/(PIXEL_BITS*PIXEL_BITS*2) */ /* */ coverage = (int)( area >> ( PIXEL_BITS * 2 + 1 - 8 ) ); /* use range 0..256 */ if ( coverage < 0 ) coverage = -coverage; if ( ras.outline.flags & PVG_FT_OUTLINE_EVEN_ODD_FILL ) { coverage &= 511; if ( coverage > 256 ) coverage = 512 - coverage; else if ( coverage == 256 ) coverage = 255; } else { /* normal non-zero winding rule */ if ( coverage >= 256 ) coverage = 255; } y += (TCoord)ras.min_ey; x += (TCoord)ras.min_ex; /* PVG_FT_Span.x is an int, so limit our coordinates appropriately */ if ( x >= (1 << 23) ) x = (1 << 23) - 1; /* PVG_FT_Span.y is an int, so limit our coordinates appropriately */ if ( y >= (1 << 23) ) y = (1 << 23) - 1; if ( coverage ) { PVG_FT_Span* span; int count; int skip; /* see whether we can add this span to the current list */ count = ras.num_gray_spans; span = ras.gray_spans + count - 1; if ( count > 0 && span->y == y && span->x + span->len == x && span->coverage == coverage ) { span->len = span->len + acount; return; } if ( count >= PVG_FT_MAX_GRAY_SPANS ) { if ( ras.render_span && count > ras.skip_spans ) { skip = ras.skip_spans > 0 ? ras.skip_spans : 0; ras.render_span( ras.num_gray_spans - skip, ras.gray_spans + skip, ras.render_span_data ); } ras.skip_spans -= ras.num_gray_spans; /* ras.render_span( span->y, ras.gray_spans, count ); */ ras.num_gray_spans = 0; span = ras.gray_spans; } else span++; /* add a gray span to the current list */ span->x = x; span->len = acount; span->y = y; span->coverage = (unsigned char)coverage; ras.num_gray_spans++; } } static void gray_sweep( RAS_ARG) { int yindex; if ( ras.num_cells == 0 ) return; for ( yindex = 0; yindex < ras.ycount; yindex++ ) { PCell cell = ras.ycells[yindex]; TCoord cover = 0; TCoord x = 0; for ( ; cell != NULL; cell = cell->next ) { TArea area; if ( cell->x > x && cover != 0 ) gray_hline( RAS_VAR_ x, yindex, cover * ( ONE_PIXEL * 2 ), cell->x - x ); cover += cell->cover; area = cover * ( ONE_PIXEL * 2 ) - cell->area; if ( area != 0 && cell->x >= 0 ) gray_hline( RAS_VAR_ cell->x, yindex, area, 1 ); x = cell->x + 1; } if ( ras.count_ex > x && cover != 0 ) gray_hline( RAS_VAR_ x, yindex, cover * ( ONE_PIXEL * 2 ), ras.count_ex - x ); } } /*************************************************************************/ /* */ /* The following function should only compile in stand_alone mode, */ /* i.e., when building this component without the rest of FreeType. */ /* */ /*************************************************************************/ /*************************************************************************/ /* */ /* */ /* PVG_FT_Outline_Decompose */ /* */ /* */ /* Walks over an outline's structure to decompose it into individual */ /* segments and Bezier arcs. This function is also able to emit */ /* `move to' and `close to' operations to indicate the start and end */ /* of new contours in the outline. */ /* */ /* */ /* outline :: A pointer to the source target. */ /* */ /* user :: A typeless pointer which is passed to each */ /* emitter during the decomposition. It can be */ /* used to store the state during the */ /* decomposition. */ /* */ /* */ /* Error code. 0 means success. */ /* */ static int PVG_FT_Outline_Decompose( const PVG_FT_Outline* outline, void* user ) { #undef SCALED #define SCALED( x ) (x) PVG_FT_Vector v_last; PVG_FT_Vector v_control; PVG_FT_Vector v_start; PVG_FT_Vector* point; PVG_FT_Vector* limit; char* tags; int n; /* index of contour in outline */ int first; /* index of first point in contour */ int error; char tag; /* current point's state */ if ( !outline ) return ErrRaster_Invalid_Outline; first = 0; for ( n = 0; n < outline->n_contours; n++ ) { int last; /* index of last point in contour */ last = outline->contours[n]; if ( last < 0 ) goto Invalid_Outline; limit = outline->points + last; v_start = outline->points[first]; v_start.x = SCALED( v_start.x ); v_start.y = SCALED( v_start.y ); v_last = outline->points[last]; v_last.x = SCALED( v_last.x ); v_last.y = SCALED( v_last.y ); v_control = v_start; point = outline->points + first; tags = outline->tags + first; tag = PVG_FT_CURVE_TAG( tags[0] ); /* A contour cannot start with a cubic control point! */ if ( tag == PVG_FT_CURVE_TAG_CUBIC ) goto Invalid_Outline; /* check first point to determine origin */ if ( tag == PVG_FT_CURVE_TAG_CONIC ) { /* first point is conic control. Yes, this happens. */ if ( PVG_FT_CURVE_TAG( outline->tags[last] ) == PVG_FT_CURVE_TAG_ON ) { /* start at last point if it is on the curve */ v_start = v_last; limit--; } else { /* if both first and last points are conic, */ /* start at their middle and record its position */ /* for closure */ v_start.x = ( v_start.x + v_last.x ) / 2; v_start.y = ( v_start.y + v_last.y ) / 2; v_last = v_start; } point--; tags--; } error = gray_move_to( &v_start, user ); if ( error ) goto Exit; while ( point < limit ) { point++; tags++; tag = PVG_FT_CURVE_TAG( tags[0] ); switch ( tag ) { case PVG_FT_CURVE_TAG_ON: /* emit a single line_to */ { PVG_FT_Vector vec; vec.x = SCALED( point->x ); vec.y = SCALED( point->y ); gray_render_line(user, UPSCALE(vec.x), UPSCALE(vec.y)); continue; } case PVG_FT_CURVE_TAG_CONIC: /* consume conic arcs */ { v_control.x = SCALED( point->x ); v_control.y = SCALED( point->y ); Do_Conic: if ( point < limit ) { PVG_FT_Vector vec; PVG_FT_Vector v_middle; point++; tags++; tag = PVG_FT_CURVE_TAG( tags[0] ); vec.x = SCALED( point->x ); vec.y = SCALED( point->y ); if ( tag == PVG_FT_CURVE_TAG_ON ) { gray_render_conic(user, &v_control, &vec); continue; } if ( tag != PVG_FT_CURVE_TAG_CONIC ) goto Invalid_Outline; v_middle.x = ( v_control.x + vec.x ) / 2; v_middle.y = ( v_control.y + vec.y ) / 2; gray_render_conic(user, &v_control, &v_middle); v_control = vec; goto Do_Conic; } gray_render_conic(user, &v_control, &v_start); goto Close; } default: /* PVG_FT_CURVE_TAG_CUBIC */ { PVG_FT_Vector vec1, vec2; if ( point + 1 > limit || PVG_FT_CURVE_TAG( tags[1] ) != PVG_FT_CURVE_TAG_CUBIC ) goto Invalid_Outline; point += 2; tags += 2; vec1.x = SCALED( point[-2].x ); vec1.y = SCALED( point[-2].y ); vec2.x = SCALED( point[-1].x ); vec2.y = SCALED( point[-1].y ); if ( point <= limit ) { PVG_FT_Vector vec; vec.x = SCALED( point->x ); vec.y = SCALED( point->y ); gray_render_cubic(user, &vec1, &vec2, &vec); continue; } gray_render_cubic(user, &vec1, &vec2, &v_start); goto Close; } } } /* close the contour with a line segment */ gray_render_line(user, UPSCALE(v_start.x), UPSCALE(v_start.y)); Close: first = last + 1; } return 0; Exit: return error; Invalid_Outline: return ErrRaster_Invalid_Outline; } typedef struct TBand_ { TPos min, max; } TBand; static int gray_convert_glyph_inner( RAS_ARG ) { volatile int error = 0; if ( pvg_ft_setjmp( ras.jump_buffer ) == 0 ) { error = PVG_FT_Outline_Decompose( &ras.outline, &ras ); if ( !ras.invalid ) gray_record_cell( RAS_VAR ); } else { error = ErrRaster_Memory_Overflow; } return error; } static int gray_convert_glyph( RAS_ARG ) { TBand bands[40]; TBand* volatile band; int volatile n, num_bands; TPos volatile min, max, max_y; PVG_FT_BBox* clip; int skip; ras.num_gray_spans = 0; /* Set up state in the raster object */ gray_compute_cbox( RAS_VAR ); /* clip to target bitmap, exit if nothing to do */ clip = &ras.clip_box; if ( ras.max_ex <= clip->xMin || ras.min_ex >= clip->xMax || ras.max_ey <= clip->yMin || ras.min_ey >= clip->yMax ) return 0; if ( ras.min_ex < clip->xMin ) ras.min_ex = clip->xMin; if ( ras.min_ey < clip->yMin ) ras.min_ey = clip->yMin; if ( ras.max_ex > clip->xMax ) ras.max_ex = clip->xMax; if ( ras.max_ey > clip->yMax ) ras.max_ey = clip->yMax; ras.count_ex = ras.max_ex - ras.min_ex; ras.count_ey = ras.max_ey - ras.min_ey; /* set up vertical bands */ num_bands = (int)( ( ras.max_ey - ras.min_ey ) / ras.band_size ); if ( num_bands == 0 ) num_bands = 1; if ( num_bands >= 39 ) num_bands = 39; ras.band_shoot = 0; min = ras.min_ey; max_y = ras.max_ey; for ( n = 0; n < num_bands; n++, min = max ) { max = min + ras.band_size; if ( n == num_bands - 1 || max > max_y ) max = max_y; bands[0].min = min; bands[0].max = max; band = bands; while ( band >= bands ) { TPos bottom, top, middle; int error; { PCell cells_max; int yindex; int cell_start, cell_end, cell_mod; ras.ycells = (PCell*)ras.buffer; ras.ycount = band->max - band->min; cell_start = sizeof ( PCell ) * ras.ycount; cell_mod = cell_start % sizeof ( TCell ); if ( cell_mod > 0 ) cell_start += sizeof ( TCell ) - cell_mod; cell_end = ras.buffer_size; cell_end -= cell_end % sizeof( TCell ); cells_max = (PCell)( (char*)ras.buffer + cell_end ); ras.cells = (PCell)( (char*)ras.buffer + cell_start ); if ( ras.cells >= cells_max ) goto ReduceBands; ras.max_cells = (int)(cells_max - ras.cells); if ( ras.max_cells < 2 ) goto ReduceBands; for ( yindex = 0; yindex < ras.ycount; yindex++ ) ras.ycells[yindex] = NULL; } ras.num_cells = 0; ras.invalid = 1; ras.min_ey = band->min; ras.max_ey = band->max; ras.count_ey = band->max - band->min; error = gray_convert_glyph_inner( RAS_VAR ); if ( !error ) { gray_sweep( RAS_VAR); band--; continue; } else if ( error != ErrRaster_Memory_Overflow ) return 1; ReduceBands: /* render pool overflow; we will reduce the render band by half */ bottom = band->min; top = band->max; middle = bottom + ( ( top - bottom ) >> 1 ); /* This is too complex for a single scanline; there must */ /* be some problems. */ if ( middle == bottom ) { return ErrRaster_OutOfMemory; } if ( bottom-top >= ras.band_size ) ras.band_shoot++; band[1].min = bottom; band[1].max = middle; band[0].min = middle; band[0].max = top; band++; } } if ( ras.render_span && ras.num_gray_spans > ras.skip_spans ) { skip = ras.skip_spans > 0 ? ras.skip_spans : 0; ras.render_span( ras.num_gray_spans - skip, ras.gray_spans + skip, ras.render_span_data ); } ras.skip_spans -= ras.num_gray_spans; if ( ras.band_shoot > 8 && ras.band_size > 16 ) ras.band_size = ras.band_size / 2; return 0; } static int gray_raster_render( RAS_ARG_ void* buffer, long buffer_size, const PVG_FT_Raster_Params* params ) { const PVG_FT_Outline* outline = (const PVG_FT_Outline*)params->source; if ( outline == NULL ) return ErrRaster_Invalid_Outline; /* return immediately if the outline is empty */ if ( outline->n_points == 0 || outline->n_contours <= 0 ) return 0; if ( !outline->contours || !outline->points ) return ErrRaster_Invalid_Outline; if ( outline->n_points != outline->contours[outline->n_contours - 1] + 1 ) return ErrRaster_Invalid_Outline; /* this version does not support monochrome rendering */ if ( !( params->flags & PVG_FT_RASTER_FLAG_AA ) ) return ErrRaster_Invalid_Mode; if ( !( params->flags & PVG_FT_RASTER_FLAG_DIRECT ) ) return ErrRaster_Invalid_Mode; /* compute clipping box */ if ( params->flags & PVG_FT_RASTER_FLAG_CLIP ) { ras.clip_box = params->clip_box; } else { ras.clip_box.xMin = -(1 << 23); ras.clip_box.yMin = -(1 << 23); ras.clip_box.xMax = (1 << 23) - 1; ras.clip_box.yMax = (1 << 23) - 1; } gray_init_cells( RAS_VAR_ buffer, buffer_size ); ras.outline = *outline; ras.num_cells = 0; ras.invalid = 1; ras.band_size = (int)(buffer_size / (long)(sizeof(TCell) * 8)); ras.render_span = (PVG_FT_Raster_Span_Func)params->gray_spans; ras.render_span_data = params->user; return gray_convert_glyph( RAS_VAR ); } void PVG_FT_Raster_Render(const PVG_FT_Raster_Params *params) { char stack[PVG_FT_MINIMUM_POOL_SIZE]; size_t length = PVG_FT_MINIMUM_POOL_SIZE; TWorker worker; worker.skip_spans = 0; int rendered_spans = 0; int error = gray_raster_render(&worker, stack, length, params); while(error == ErrRaster_OutOfMemory) { if(worker.skip_spans < 0) rendered_spans += -worker.skip_spans; worker.skip_spans = rendered_spans; length *= 2; void* heap = malloc(length); error = gray_raster_render(&worker, heap, length, params); free(heap); } } /* END */