Edit
kc3-lang/freetype/src/smooth/ftgrays.c
Werner Lemberg
- src/smooth/ftgrays.c
-
/**************************************************************************** * * ftgrays.c * * A new `perfect' anti-aliasing renderer (body). * * Copyright (C) 2000-2020 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 file can be compiled without the rest of the FreeType engine, by * defining the STANDALONE_ macro when compiling it. You also need to * put the files `ftgrays.h' and `ftimage.h' into the current * compilation directory. Typically, you could do something like * * - copy `src/smooth/ftgrays.c' (this file) to your current directory * * - copy `include/freetype/ftimage.h' and `src/smooth/ftgrays.h' to the * same directory * * - compile `ftgrays' with the STANDALONE_ macro defined, as in * * cc -c -DSTANDALONE_ ftgrays.c * * The renderer can be initialized with a call to * `ft_gray_raster.raster_new'; an anti-aliased bitmap can be generated * with a call to `ft_gray_raster.raster_render'. * * See the comments and documentation in the file `ftimage.h' for more * details on how the raster works. * */ /************************************************************************** * * 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 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 * 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. * * 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 * 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 by straight segments. * * - 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 (< 80) pixel sizes, it is faster than the standard * renderer. * */ /************************************************************************** * * The macro FT_COMPONENT is used in trace mode. It is an implicit * parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log * messages during execution. */ #undef FT_COMPONENT #define FT_COMPONENT smooth #ifdef STANDALONE_ /* The size in bytes of the render pool used by the scan-line converter */ /* to do all of its work. */ #define FT_RENDER_POOL_SIZE 16384L /* Auxiliary macros for token concatenation. */ #define FT_ERR_XCAT( x, y ) x ## y #define FT_ERR_CAT( x, y ) FT_ERR_XCAT( x, y ) #define FT_BEGIN_STMNT do { #define FT_END_STMNT } while ( 0 ) #define FT_MIN( a, b ) ( (a) < (b) ? (a) : (b) ) #define FT_MAX( a, b ) ( (a) > (b) ? (a) : (b) ) #define FT_ABS( a ) ( (a) < 0 ? -(a) : (a) ) /* * Approximate sqrt(x*x+y*y) using the `alpha max plus beta min' * algorithm. We use alpha = 1, beta = 3/8, giving us results with a * largest error less than 7% compared to the exact value. */ #define FT_HYPOT( x, y ) \ ( x = FT_ABS( x ), \ y = FT_ABS( y ), \ x > y ? x + ( 3 * y >> 3 ) \ : y + ( 3 * x >> 3 ) ) /* define this to dump debugging information */ /* #define FT_DEBUG_LEVEL_TRACE */ #ifdef FT_DEBUG_LEVEL_TRACE #include <stdio.h> #include <stdarg.h> #endif #include <stddef.h> #include <string.h> #include <setjmp.h> #include <limits.h> #define FT_CHAR_BIT CHAR_BIT #define FT_UINT_MAX UINT_MAX #define FT_INT_MAX INT_MAX #define FT_ULONG_MAX ULONG_MAX #define ADD_LONG( a, b ) \ (long)( (unsigned long)(a) + (unsigned long)(b) ) #define SUB_LONG( a, b ) \ (long)( (unsigned long)(a) - (unsigned long)(b) ) #define MUL_LONG( a, b ) \ (long)( (unsigned long)(a) * (unsigned long)(b) ) #define NEG_LONG( a ) \ (long)( -(unsigned long)(a) ) #define ft_memset memset #define ft_setjmp setjmp #define ft_longjmp longjmp #define ft_jmp_buf jmp_buf typedef ptrdiff_t FT_PtrDist; #define ErrRaster_Invalid_Mode -2 #define ErrRaster_Invalid_Outline -1 #define ErrRaster_Invalid_Argument -3 #define ErrRaster_Memory_Overflow -4 #define FT_BEGIN_HEADER #define FT_END_HEADER #include "ftimage.h" #include "ftgrays.h" /* This macro is used to indicate that a function parameter is unused. */ /* Its purpose is simply to reduce compiler warnings. Note also that */ /* simply defining it as `(void)x' doesn't avoid warnings with certain */ /* ANSI compilers (e.g. LCC). */ #define FT_UNUSED( x ) (x) = (x) /* we only use level 5 & 7 tracing messages; cf. ftdebug.h */ #ifdef FT_DEBUG_LEVEL_TRACE void FT_Message( const char* fmt, ... ) { va_list ap; va_start( ap, fmt ); vfprintf( stderr, fmt, ap ); va_end( ap ); } /* empty function useful for setting a breakpoint to catch errors */ int FT_Throw( int error, int line, const char* file ) { FT_UNUSED( error ); FT_UNUSED( line ); FT_UNUSED( file ); return 0; } /* we don't handle tracing levels in stand-alone mode; */ #ifndef FT_TRACE5 #define FT_TRACE5( varformat ) FT_Message varformat #endif #ifndef FT_TRACE7 #define FT_TRACE7( varformat ) FT_Message varformat #endif #ifndef FT_ERROR #define FT_ERROR( varformat ) FT_Message varformat #endif #define FT_THROW( e ) \ ( FT_Throw( FT_ERR_CAT( ErrRaster_, e ), \ __LINE__, \ __FILE__ ) | \ FT_ERR_CAT( ErrRaster_, e ) ) #else /* !FT_DEBUG_LEVEL_TRACE */ #define FT_TRACE5( x ) do { } while ( 0 ) /* nothing */ #define FT_TRACE7( x ) do { } while ( 0 ) /* nothing */ #define FT_ERROR( x ) do { } while ( 0 ) /* nothing */ #define FT_THROW( e ) FT_ERR_CAT( ErrRaster_, e ) #endif /* !FT_DEBUG_LEVEL_TRACE */ #define FT_DEFINE_OUTLINE_FUNCS( class_, \ move_to_, line_to_, \ conic_to_, cubic_to_, \ shift_, delta_ ) \ static const FT_Outline_Funcs class_ = \ { \ move_to_, \ line_to_, \ conic_to_, \ cubic_to_, \ shift_, \ delta_ \ }; #define FT_DEFINE_RASTER_FUNCS( class_, glyph_format_, \ raster_new_, raster_reset_, \ raster_set_mode_, raster_render_, \ raster_done_ ) \ const FT_Raster_Funcs class_ = \ { \ glyph_format_, \ raster_new_, \ raster_reset_, \ raster_set_mode_, \ raster_render_, \ raster_done_ \ }; #else /* !STANDALONE_ */ #include "ftgrays.h" #include <freetype/internal/ftobjs.h> #include <freetype/internal/ftdebug.h> #include <freetype/internal/ftcalc.h> #include <freetype/ftoutln.h> #include "ftsmerrs.h" #define Smooth_Err_Invalid_Mode Smooth_Err_Cannot_Render_Glyph #define Smooth_Err_Memory_Overflow Smooth_Err_Out_Of_Memory #define ErrRaster_Memory_Overflow Smooth_Err_Out_Of_Memory #endif /* !STANDALONE_ */ #ifndef FT_MEM_SET #define FT_MEM_SET( d, s, c ) ft_memset( d, s, c ) #endif #ifndef FT_MEM_ZERO #define FT_MEM_ZERO( dest, count ) FT_MEM_SET( dest, 0, count ) #endif #ifndef FT_ZERO #define FT_ZERO( p ) FT_MEM_ZERO( p, sizeof ( *(p) ) ) #endif /* as usual, for the speed hungry :-) */ #undef RAS_ARG #undef RAS_ARG_ #undef RAS_VAR #undef RAS_VAR_ #ifndef FT_STATIC_RASTER #define RAS_ARG gray_PWorker worker #define RAS_ARG_ gray_PWorker worker, #define RAS_VAR worker #define RAS_VAR_ worker, #else /* FT_STATIC_RASTER */ #define RAS_ARG void #define RAS_ARG_ /* empty */ #define RAS_VAR /* empty */ #define RAS_VAR_ /* empty */ #endif /* FT_STATIC_RASTER */ /* must be at least 6 bits! */ #define PIXEL_BITS 8 #define ONE_PIXEL ( 1 << 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. We use the remainder to keep */ /* track of accumulating errors and compensate for them. */ #define FT_DIV_MOD( type, dividend, divisor, quotient, remainder ) \ FT_BEGIN_STMNT \ (quotient) = (type)( (dividend) / (divisor) ); \ (remainder) = (type)( (dividend) % (divisor) ); \ if ( (remainder) < 0 ) \ { \ (quotient)--; \ (remainder) += (type)(divisor); \ } \ FT_END_STMNT #ifdef __arm__ /* Work around a bug specific to GCC which make the compiler fail to */ /* optimize a division and modulo operation on the same parameters */ /* into a single call to `__aeabi_idivmod'. See */ /* */ /* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43721 */ #undef FT_DIV_MOD #define FT_DIV_MOD( type, dividend, divisor, quotient, remainder ) \ FT_BEGIN_STMNT \ (quotient) = (type)( (dividend) / (divisor) ); \ (remainder) = (type)( (dividend) - (quotient) * (divisor) ); \ if ( (remainder) < 0 ) \ { \ (quotient)--; \ (remainder) += (type)(divisor); \ } \ FT_END_STMNT #endif /* __arm__ */ /* These macros speed up repetitive divisions by replacing them */ /* with multiplications and right shifts. */ #define FT_UDIVPREP( c, b ) \ long b ## _r = c ? (long)( FT_ULONG_MAX >> PIXEL_BITS ) / ( b ) \ : 0 #define FT_UDIV( a, b ) \ (TCoord)( ( (unsigned long)( a ) * (unsigned long)( b ## _r ) ) >> \ ( sizeof( long ) * FT_CHAR_BIT - PIXEL_BITS ) ) /************************************************************************** * * TYPE DEFINITIONS */ /* don't change the following types to FT_Int or FT_Pos, since we might */ /* need to define them to "float" or "double" when experimenting with */ /* new algorithms */ typedef long TPos; /* subpixel coordinate */ typedef int TCoord; /* integer scanline/pixel coordinate */ typedef int TArea; /* cell areas, coordinate products */ typedef struct TCell_* PCell; typedef struct TCell_ { TCoord x; /* same with gray_TWorker.ex */ TCoord cover; /* same with gray_TWorker.cover */ TArea area; PCell next; } TCell; typedef struct TPixmap_ { unsigned char* origin; /* pixmap origin at the bottom-left */ int pitch; /* pitch to go down one row */ } TPixmap; /* maximum number of gray cells in the buffer */ #if FT_RENDER_POOL_SIZE > 2048 #define FT_MAX_GRAY_POOL ( FT_RENDER_POOL_SIZE / sizeof ( TCell ) ) #else #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 */ /* __declspec(align())' in order to compile cleanly with */ /* the maximum level of warnings. */ #pragma warning( push ) #pragma warning( disable : 4324 ) #endif /* _MSC_VER */ typedef struct gray_TWorker_ { ft_jmp_buf jump_buffer; TCoord ex, ey; TCoord min_ex, max_ex; TCoord min_ey, max_ey; TArea area; TCoord cover; int invalid; PCell* ycells; PCell cells; FT_PtrDist max_cells; FT_PtrDist num_cells; TPos x, y; FT_Outline outline; TPixmap target; FT_Raster_Span_Func render_span; void* render_span_data; FT_Span spans[FT_MAX_GRAY_SPANS]; int num_spans; } gray_TWorker, *gray_PWorker; #if defined( _MSC_VER ) #pragma warning( pop ) #endif #ifndef FT_STATIC_RASTER #define ras (*worker) #else static gray_TWorker ras; #endif typedef struct gray_TRaster_ { void* memory; } gray_TRaster, *gray_PRaster; #ifdef FT_DEBUG_LEVEL_TRACE /* to be called while in the debugger -- */ /* this function causes a compiler warning since it is unused otherwise */ static void gray_dump_cells( RAS_ARG ) { int y; for ( y = ras.min_ey; y < ras.max_ey; y++ ) { PCell cell = ras.ycells[y - ras.min_ey]; printf( "%3d:", y ); for ( ; cell != NULL; cell = cell->next ) printf( " (%3d, c:%4d, a:%6d)", cell->x, cell->cover, cell->area ); printf( "\n" ); } } #endif /* FT_DEBUG_LEVEL_TRACE */ /************************************************************************** * * Record the current cell in the linked list. */ static void gray_record_cell( RAS_ARG ) { PCell *pcell, cell; TCoord x = ras.ex; pcell = &ras.ycells[ras.ey - ras.min_ey]; while ( ( cell = *pcell ) ) { if ( cell->x > x ) break; if ( cell->x == x ) goto Found; pcell = &cell->next; } if ( ras.num_cells >= ras.max_cells ) ft_longjmp( ras.jump_buffer, 1 ); /* insert new cell */ cell = ras.cells + ras.num_cells++; cell->x = x; cell->area = ras.area; cell->cover = ras.cover; cell->next = *pcell; *pcell = cell; return; Found: /* update old cell */ 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. */ /* 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 = FT_MAX( ex, ras.min_ex - 1 ); ras.ey = ey; ras.invalid = ( ey >= ras.max_ey || ey < ras.min_ey || ex >= ras.max_ex ); } #ifndef FT_LONG64 /************************************************************************** * * 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; } /* 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 ); ras.cover += delta; y1 += delta; ex1 += incr; gray_set_cell( RAS_VAR_ ex1, ey ); if ( ex1 != ex2 ) { TCoord lift, rem; p = ONE_PIXEL * dy; 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; TArea area; if ( dy > 0) { first = ONE_PIXEL; incr = 1; } else { first = 0; incr = -1; } delta = first - fy1; ras.area += (TArea)two_fx * delta; ras.cover += delta; ey1 += incr; gray_set_cell( RAS_VAR_ ex, ey1 ); delta = first + first - ONE_PIXEL; area = (TArea)two_fx * delta; while ( ey1 != ey2 ) { ras.area += area; ras.cover += delta; ey1 += incr; gray_set_cell( RAS_VAR_ ex, ey1 ); } delta = 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. */ FT_DIV_MOD( TCoord, p, dy, delta, mod ); x = ras.x + delta; gray_render_scanline( RAS_VAR_ ey1, ras.x, fy1, x, first ); ey1 += incr; gray_set_cell( RAS_VAR_ TRUNC( x ), ey1 ); if ( ey1 != ey2 ) { TCoord lift, rem; p = ONE_PIXEL * dx; 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; TCoord fx1, fy1, fx2, fy2; TCoord ex1, ey1, ex2, ey2; 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; ex1 = TRUNC( ras.x ); ex2 = TRUNC( to_x ); fx1 = FRACT( ras.x ); fy1 = FRACT( ras.y ); dx = to_x - ras.x; dy = to_y - ras.y; if ( ex1 == ex2 && ey1 == ey2 ) /* inside one cell */ ; else if ( dy == 0 ) /* ex1 != ex2 */ /* any horizontal line */ { gray_set_cell( RAS_VAR_ ex2, ey2 ); goto End; } 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 */ { TPos prod = dx * (TPos)fy1 - dy * (TPos)fx1; FT_UDIVPREP( ex1 != ex2, dx ); FT_UDIVPREP( ey1 != ey2, 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 = 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 = 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 = 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 = 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( FT_Vector* base ) { TPos a, b; base[4].x = base[2].x; 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; 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; } static void gray_render_conic( RAS_ARG_ const FT_Vector* control, const FT_Vector* to ) { FT_Vector bez_stack[16 * 2 + 1]; /* enough to accommodate bisections */ 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 = FT_ABS( arc[2].x + arc[0].x - 2 * arc[1].x ); dy = 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 = draw & ( -draw ); /* isolate the rightmost 1-bit */ while ( ( split >>= 1 ) ) { gray_split_conic( arc ); arc += 2; } gray_render_line( RAS_VAR_ arc[0].x, arc[0].y ); arc -= 2; } while ( --draw ); } static void gray_split_cubic( FT_Vector* base ) { TPos a, b, c; base[6].x = base[3].x; 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; 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; } static void gray_render_cubic( RAS_ARG_ const FT_Vector* control1, const FT_Vector* control2, const FT_Vector* to ) { FT_Vector bez_stack[16 * 3 + 1]; /* enough to accommodate bisections */ FT_Vector* arc = bez_stack; 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 (;;) { /* 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 ); if ( arc == bez_stack ) return; arc -= 3; continue; Split: gray_split_cubic( arc ); arc += 3; } } static int gray_move_to( const FT_Vector* to, gray_PWorker worker ) { TPos x, y; /* start to a new position */ x = UPSCALE( to->x ); y = UPSCALE( to->y ); gray_set_cell( RAS_VAR_ TRUNC( x ), TRUNC( y ) ); ras.x = x; ras.y = y; return 0; } static int gray_line_to( const FT_Vector* to, gray_PWorker worker ) { gray_render_line( RAS_VAR_ UPSCALE( to->x ), UPSCALE( to->y ) ); return 0; } static int gray_conic_to( const FT_Vector* control, const FT_Vector* to, gray_PWorker worker ) { gray_render_conic( RAS_VAR_ control, to ); return 0; } static int gray_cubic_to( const FT_Vector* control1, const FT_Vector* control2, const FT_Vector* to, gray_PWorker worker ) { gray_render_cubic( RAS_VAR_ control1, control2, to ); return 0; } static void gray_hline( RAS_ARG_ TCoord x, TCoord y, TArea coverage, TCoord acount ) { /* scale the coverage from 0..(ONE_PIXEL*ONE_PIXEL*2) to 0..256 */ coverage >>= PIXEL_BITS * 2 + 1 - 8; /* compute the line's coverage depending on the outline fill rule */ if ( ras.outline.flags & FT_OUTLINE_EVEN_ODD_FILL ) { coverage &= 511; if ( coverage >= 256 ) coverage = 511 - coverage; } else /* default non-zero winding rule */ { if ( coverage < 0 ) coverage = ~coverage; /* the same as -coverage - 1 */ if ( coverage >= 256 ) coverage = 255; } if ( ras.num_spans >= 0 ) /* for FT_RASTER_FLAG_DIRECT only */ { FT_Span* span = ras.spans + ras.num_spans++; span->x = (short)x; span->len = (unsigned short)acount; span->coverage = (unsigned char)coverage; 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 { unsigned char* q = ras.target.origin - ras.target.pitch * y + x; unsigned char c = (unsigned char)coverage; /* For small-spans it is faster to do it by ourselves than * calling `memset'. This is mainly due to the cost of the * function call. */ switch ( acount ) { 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 ); } } } static void gray_sweep( RAS_ARG ) { int y; for ( y = ras.min_ey; y < ras.max_ey; y++ ) { PCell cell = ras.ycells[y - ras.min_ey]; TCoord x = ras.min_ex; TArea cover = 0; TArea area; for ( ; cell != NULL; cell = cell->next ) { if ( cover != 0 && cell->x > x ) gray_hline( RAS_VAR_ x, y, cover, cell->x - x ); cover += (TArea)cell->cover * ( ONE_PIXEL * 2 ); area = cover - cell->area; if ( area != 0 && cell->x >= ras.min_ex ) gray_hline( RAS_VAR_ cell->x, y, area, 1 ); x = cell->x + 1; } 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; } } } #ifdef STANDALONE_ /************************************************************************** * * The following functions should only compile in stand-alone mode, * i.e., when building this component without the rest of FreeType. * */ /************************************************************************** * * @Function: * FT_Outline_Decompose * * @Description: * Walk over an outline's structure to decompose it into individual * segments and Bézier 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. * * @Input: * outline :: * A pointer to the source target. * * func_interface :: * A table of `emitters', i.e., function pointers * called during decomposition to indicate path * operations. * * @InOut: * user :: * A typeless pointer which is passed to each * emitter during the decomposition. It can be * used to store the state during the * decomposition. * * @Return: * Error code. 0 means success. */ static int FT_Outline_Decompose( const FT_Outline* outline, const FT_Outline_Funcs* func_interface, void* user ) { #undef SCALED #define SCALED( x ) ( (x) * ( 1L << shift ) - delta ) FT_Vector v_last; FT_Vector v_control; FT_Vector v_start; FT_Vector* point; FT_Vector* limit; char* tags; int error; int n; /* index of contour in outline */ int first; /* index of first point in contour */ char tag; /* current point's state */ int shift; TPos delta; if ( !outline ) return FT_THROW( Invalid_Outline ); if ( !func_interface ) return FT_THROW( Invalid_Argument ); shift = func_interface->shift; delta = func_interface->delta; first = 0; for ( n = 0; n < outline->n_contours; n++ ) { int last; /* index of last point in contour */ FT_TRACE5(( "FT_Outline_Decompose: Outline %d\n", n )); 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 = FT_CURVE_TAG( tags[0] ); /* A contour cannot start with a cubic control point! */ if ( tag == FT_CURVE_TAG_CUBIC ) goto Invalid_Outline; /* check first point to determine origin */ if ( tag == FT_CURVE_TAG_CONIC ) { /* first point is conic control. Yes, this happens. */ if ( FT_CURVE_TAG( outline->tags[last] ) == 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--; } FT_TRACE5(( " move to (%.2f, %.2f)\n", v_start.x / 64.0, v_start.y / 64.0 )); error = func_interface->move_to( &v_start, user ); if ( error ) goto Exit; while ( point < limit ) { point++; tags++; tag = FT_CURVE_TAG( tags[0] ); switch ( tag ) { case FT_CURVE_TAG_ON: /* emit a single line_to */ { FT_Vector vec; vec.x = SCALED( point->x ); vec.y = SCALED( point->y ); FT_TRACE5(( " line to (%.2f, %.2f)\n", vec.x / 64.0, vec.y / 64.0 )); error = func_interface->line_to( &vec, user ); if ( error ) goto Exit; continue; } case FT_CURVE_TAG_CONIC: /* consume conic arcs */ v_control.x = SCALED( point->x ); v_control.y = SCALED( point->y ); Do_Conic: if ( point < limit ) { FT_Vector vec; FT_Vector v_middle; point++; tags++; tag = FT_CURVE_TAG( tags[0] ); vec.x = SCALED( point->x ); vec.y = SCALED( point->y ); if ( tag == FT_CURVE_TAG_ON ) { FT_TRACE5(( " conic to (%.2f, %.2f)" " with control (%.2f, %.2f)\n", vec.x / 64.0, vec.y / 64.0, v_control.x / 64.0, v_control.y / 64.0 )); error = func_interface->conic_to( &v_control, &vec, user ); if ( error ) goto Exit; continue; } if ( tag != 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; FT_TRACE5(( " conic to (%.2f, %.2f)" " with control (%.2f, %.2f)\n", v_middle.x / 64.0, v_middle.y / 64.0, v_control.x / 64.0, v_control.y / 64.0 )); error = func_interface->conic_to( &v_control, &v_middle, user ); if ( error ) goto Exit; v_control = vec; goto Do_Conic; } FT_TRACE5(( " conic to (%.2f, %.2f)" " with control (%.2f, %.2f)\n", v_start.x / 64.0, v_start.y / 64.0, v_control.x / 64.0, v_control.y / 64.0 )); error = func_interface->conic_to( &v_control, &v_start, user ); goto Close; default: /* FT_CURVE_TAG_CUBIC */ { FT_Vector vec1, vec2; if ( point + 1 > limit || FT_CURVE_TAG( tags[1] ) != 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 ) { FT_Vector vec; vec.x = SCALED( point->x ); vec.y = SCALED( point->y ); FT_TRACE5(( " cubic to (%.2f, %.2f)" " with controls (%.2f, %.2f) and (%.2f, %.2f)\n", vec.x / 64.0, vec.y / 64.0, vec1.x / 64.0, vec1.y / 64.0, vec2.x / 64.0, vec2.y / 64.0 )); error = func_interface->cubic_to( &vec1, &vec2, &vec, user ); if ( error ) goto Exit; continue; } FT_TRACE5(( " cubic to (%.2f, %.2f)" " with controls (%.2f, %.2f) and (%.2f, %.2f)\n", v_start.x / 64.0, v_start.y / 64.0, vec1.x / 64.0, vec1.y / 64.0, vec2.x / 64.0, vec2.y / 64.0 )); error = func_interface->cubic_to( &vec1, &vec2, &v_start, user ); goto Close; } } } /* close the contour with a line segment */ FT_TRACE5(( " line to (%.2f, %.2f)\n", v_start.x / 64.0, v_start.y / 64.0 )); error = func_interface->line_to( &v_start, user ); Close: if ( error ) goto Exit; first = last + 1; } FT_TRACE5(( "FT_Outline_Decompose: Done\n", n )); return 0; Exit: FT_TRACE5(( "FT_Outline_Decompose: Error 0x%x\n", error )); return error; Invalid_Outline: return FT_THROW( Invalid_Outline ); } #endif /* STANDALONE_ */ FT_DEFINE_OUTLINE_FUNCS( func_interface, (FT_Outline_MoveTo_Func) gray_move_to, /* move_to */ (FT_Outline_LineTo_Func) gray_line_to, /* line_to */ (FT_Outline_ConicTo_Func)gray_conic_to, /* conic_to */ (FT_Outline_CubicTo_Func)gray_cubic_to, /* cubic_to */ 0, /* shift */ 0 /* delta */ ) static int gray_convert_glyph_inner( RAS_ARG, int continued ) { int error; if ( ft_setjmp( ras.jump_buffer ) == 0 ) { if ( continued ) FT_Trace_Disable(); error = FT_Outline_Decompose( &ras.outline, &func_interface, &ras ); if ( continued ) FT_Trace_Enable(); if ( !ras.invalid ) gray_record_cell( RAS_VAR ); FT_TRACE7(( "band [%d..%d]: %d cell%s\n", ras.min_ey, ras.max_ey, ras.num_cells, ras.num_cells == 1 ? "" : "s" )); } else { error = FT_THROW( Memory_Overflow ); FT_TRACE7(( "band [%d..%d]: to be bisected\n", ras.min_ey, ras.max_ey )); } return error; } static int gray_convert_glyph( RAS_ARG ) { const TCoord yMin = ras.min_ey; const TCoord yMax = ras.max_ey; TCell buffer[FT_MAX_GRAY_POOL]; size_t height = (size_t)( yMax - yMin ); size_t n = FT_MAX_GRAY_POOL / 8; TCoord y; TCoord bands[32]; /* enough to accommodate bisections */ TCoord* band; int continued = 0; /* set up vertical bands */ if ( height > n ) { /* two divisions rounded up */ n = ( height + n - 1 ) / n; height = ( height + n - 1 ) / n; } /* memory management */ n = ( height * sizeof ( PCell ) + sizeof ( TCell ) - 1 ) / sizeof ( TCell ); ras.cells = buffer + n; ras.max_cells = (FT_PtrDist)( FT_MAX_GRAY_POOL - n ); ras.ycells = (PCell*)buffer; for ( y = yMin; y < yMax; ) { ras.min_ey = y; y += height; ras.max_ey = FT_MIN( y, yMax ); band = bands; band[1] = ras.min_ey; band[0] = ras.max_ey; do { TCoord width = band[0] - band[1]; int error; FT_MEM_ZERO( ras.ycells, height * sizeof ( PCell ) ); ras.num_cells = 0; ras.invalid = 1; ras.min_ey = band[1]; ras.max_ey = band[0]; error = gray_convert_glyph_inner( RAS_VAR, continued ); continued = 1; if ( !error ) { gray_sweep( RAS_VAR ); band--; continue; } else if ( error != ErrRaster_Memory_Overflow ) return 1; /* render pool overflow; we will reduce the render band by half */ width >>= 1; /* this should never happen even with tiny rendering pool */ if ( width == 0 ) { FT_TRACE7(( "gray_convert_glyph: rotten glyph\n" )); return 1; } band++; band[1] = band[0]; band[0] += width; } while ( band >= bands ); } return 0; } static int gray_raster_render( FT_Raster raster, const FT_Raster_Params* params ) { const FT_Outline* outline = (const FT_Outline*)params->source; const FT_Bitmap* target_map = params->target; #ifndef FT_STATIC_RASTER gray_TWorker worker[1]; #endif if ( !raster ) return FT_THROW( Invalid_Argument ); /* this version does not support monochrome rendering */ if ( !( params->flags & FT_RASTER_FLAG_AA ) ) return FT_THROW( Invalid_Mode ); if ( !outline ) return FT_THROW( 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 FT_THROW( Invalid_Outline ); if ( outline->n_points != outline->contours[outline->n_contours - 1] + 1 ) return FT_THROW( Invalid_Outline ); ras.outline = *outline; if ( params->flags & FT_RASTER_FLAG_DIRECT ) { if ( !params->gray_spans ) return 0; 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 { /* if direct mode is not set, we must have a target bitmap */ if ( !target_map ) return FT_THROW( Invalid_Argument ); /* nothing to do */ if ( !target_map->width || !target_map->rows ) return 0; if ( !target_map->buffer ) return FT_THROW( Invalid_Argument ); if ( target_map->pitch < 0 ) ras.target.origin = target_map->buffer; else ras.target.origin = target_map->buffer + ( target_map->rows - 1 ) * (unsigned int)target_map->pitch; ras.target.pitch = target_map->pitch; ras.render_span = (FT_Raster_Span_Func)NULL; ras.render_span_data = NULL; ras.num_spans = -1; /* invalid */ ras.min_ex = 0; ras.min_ey = 0; ras.max_ex = (FT_Pos)target_map->width; ras.max_ey = (FT_Pos)target_map->rows; } /* exit if nothing to do */ if ( ras.max_ex <= ras.min_ex || ras.max_ey <= ras.min_ey ) return 0; return gray_convert_glyph( RAS_VAR ); } /**** RASTER OBJECT CREATION: In stand-alone mode, we simply use *****/ /**** a static object. *****/ #ifdef STANDALONE_ static int gray_raster_new( void* memory, FT_Raster* araster ) { static gray_TRaster the_raster; FT_UNUSED( memory ); *araster = (FT_Raster)&the_raster; FT_ZERO( &the_raster ); return 0; } static void gray_raster_done( FT_Raster raster ) { /* nothing */ FT_UNUSED( raster ); } #else /* !STANDALONE_ */ static int gray_raster_new( FT_Memory memory, FT_Raster* araster ) { FT_Error error; gray_PRaster raster = NULL; *araster = 0; if ( !FT_ALLOC( raster, sizeof ( gray_TRaster ) ) ) { raster->memory = memory; *araster = (FT_Raster)raster; } return error; } static void gray_raster_done( FT_Raster raster ) { FT_Memory memory = (FT_Memory)((gray_PRaster)raster)->memory; FT_FREE( raster ); } #endif /* !STANDALONE_ */ static void gray_raster_reset( FT_Raster raster, unsigned char* pool_base, unsigned long pool_size ) { FT_UNUSED( raster ); FT_UNUSED( pool_base ); FT_UNUSED( pool_size ); } static int gray_raster_set_mode( FT_Raster raster, unsigned long mode, void* args ) { FT_UNUSED( raster ); FT_UNUSED( mode ); FT_UNUSED( args ); return 0; /* nothing to do */ } FT_DEFINE_RASTER_FUNCS( ft_grays_raster, FT_GLYPH_FORMAT_OUTLINE, (FT_Raster_New_Func) gray_raster_new, /* raster_new */ (FT_Raster_Reset_Func) gray_raster_reset, /* raster_reset */ (FT_Raster_Set_Mode_Func)gray_raster_set_mode, /* raster_set_mode */ (FT_Raster_Render_Func) gray_raster_render, /* raster_render */ (FT_Raster_Done_Func) gray_raster_done /* raster_done */ ) /* END */ /* Local Variables: */ /* coding: utf-8 */ /* End: */