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freetype2/src/smooth/ftgrays.c

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/****************************************************************************
*
* ftgrays.c
*
* A new `perfect' anti-aliasing renderer (body).
*
* Copyright (C) 2000-2023 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_INT( a, b ) \
(int)( (unsigned int)(a) + (unsigned int)(b) )
#define FT_STATIC_BYTE_CAST( type, var ) (type)(unsigned char)(var)
#define ft_memset memset
#define ft_setjmp setjmp
#define ft_longjmp longjmp
#define ft_jmp_buf jmp_buf
typedef ptrdiff_t FT_PtrDist;
#define Smooth_Err_Ok 0
#define Smooth_Err_Invalid_Outline -1
#define Smooth_Err_Cannot_Render_Glyph -2
#define Smooth_Err_Invalid_Argument -3
#define Smooth_Err_Raster_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( Smooth_Err_, e ), \
__LINE__, \
__FILE__ ) | \
FT_ERR_CAT( Smooth_Err_, 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( Smooth_Err_, e )
#endif /* !FT_DEBUG_LEVEL_TRACE */
#define FT_Trace_Enable() do { } while ( 0 ) /* nothing */
#define FT_Trace_Disable() do { } while ( 0 ) /* nothing */
#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 <ft2build.h>
#include FT_CONFIG_CONFIG_H
#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"
#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 )
#undef TRUNC
#define TRUNC( x ) (TCoord)( (x) >> PIXEL_BITS )
#undef FRACT
#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
#if defined( __GNUC__ ) && __GNUC__ < 7 && defined( __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__ */
/* Calculating coverages for a slanted line requires a division each */
/* time the line crosses from cell to cell. These macros speed up */
/* the repetitive divisions by replacing them with multiplications */
/* and right shifts so that at most two divisions are performed for */
/* each slanted line. Nevertheless, these divisions are noticeable */
/* in the overall performance because flattened curves produce a */
/* very large number of slanted lines. */
/* */
/* The division results here are always within ONE_PIXEL. Therefore */
/* the shift magnitude should be at least PIXEL_BITS wider than the */
/* divisors to provide sufficient accuracy of the multiply-shift. */
/* It should not exceed (64 - PIXEL_BITS) to prevent overflowing and */
/* leave enough room for 64-bit unsigned multiplication however. */
#define FT_UDIVPREP( c, b ) \
FT_Int64 b ## _r = c ? (FT_Int64)0xFFFFFFFF / ( b ) : 0
#define FT_UDIV( a, b ) \
(TCoord)( ( (FT_UInt64)( a ) * (FT_UInt64)( b ## _r ) ) >> 32 )
/* Scale area and apply fill rule to calculate the coverage byte. */
/* The top fill bit is used for the non-zero rule. The eighth */
/* fill bit is used for the even-odd rule. The higher coverage */
/* bytes are either clamped for the non-zero-rule or discarded */
/* later for the even-odd rule. */
#define FT_FILL_RULE( coverage, area, fill ) \
FT_BEGIN_STMNT \
coverage = (int)( area >> ( PIXEL_BITS * 2 + 1 - 8 ) ); \
if ( coverage & fill ) \
coverage = ~coverage; \
if ( coverage > 255 && fill & INT_MIN ) \
coverage = 255; \
FT_END_STMNT
/* It is faster to write small spans byte-by-byte than calling */
/* `memset'. This is mainly due to the cost of the function call. */
#define FT_GRAY_SET( d, s, count ) \
FT_BEGIN_STMNT \
unsigned char* q = d; \
switch ( count ) \
{ \
case 7: *q++ = (unsigned char)s; FALL_THROUGH; \
case 6: *q++ = (unsigned char)s; FALL_THROUGH; \
case 5: *q++ = (unsigned char)s; FALL_THROUGH; \
case 4: *q++ = (unsigned char)s; FALL_THROUGH; \
case 3: *q++ = (unsigned char)s; FALL_THROUGH; \
case 2: *q++ = (unsigned char)s; FALL_THROUGH; \
case 1: *q = (unsigned char)s; FALL_THROUGH; \
case 0: break; \
default: FT_MEM_SET( d, s, count ); \
} \
FT_END_STMNT
/**************************************************************************
*
* 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 16
#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 min_ex, max_ex; /* min and max integer pixel coordinates */
TCoord min_ey, max_ey;
TCoord count_ey; /* same as (max_ey - min_ey) */
PCell cell; /* current cell */
PCell cell_free; /* call allocation next free slot */
PCell cell_null; /* last cell, used as dumpster and limit */
PCell* ycells; /* array of cell linked-lists; one per */
/* vertical coordinate in the current band */
TPos x, y; /* last point position */
FT_Outline outline; /* input outline */
TPixmap target; /* target pixmap */
FT_Raster_Span_Func render_span;
void* render_span_data;
} 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
/* The |x| value of the null cell. Must be the largest possible */
/* integer value stored in a `TCell.x` field. */
#define CELL_MAX_X_VALUE INT_MAX
#define FT_INTEGRATE( ras, a, b ) \
ras.cell->cover = ADD_INT( ras.cell->cover, a ), \
ras.cell->area = ADD_INT( ras.cell->area, (a) * (TArea)(b) )
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 != ras.cell_null; cell = cell->next )
printf( " (%3d, c:%4d, a:%6d)",
cell->x, cell->cover, cell->area );
printf( "\n" );
}
}
#endif /* FT_DEBUG_LEVEL_TRACE */
/**************************************************************************
*
* 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 in the linked list. We use */
/* a dumpster null cell for everything outside of the clipping region */
/* 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. */
TCoord ey_index = ey - ras.min_ey;
if ( ey_index < 0 || ey_index >= ras.count_ey || ex >= ras.max_ex )
ras.cell = ras.cell_null;
else
{
PCell* pcell = ras.ycells + ey_index;
PCell cell;
ex = FT_MAX( ex, ras.min_ex - 1 );
while ( 1 )
{
cell = *pcell;
if ( cell->x > ex )
break;
if ( cell->x == ex )
goto Found;
pcell = &cell->next;
}
/* insert new cell */
cell = ras.cell_free++;
if ( cell >= ras.cell_null )
ft_longjmp( ras.jump_buffer, 1 );
cell->x = ex;
cell->area = 0;
cell->cover = 0;
cell->next = *pcell;
*pcell = cell;
Found:
ras.cell = cell;
}
}
#ifndef FT_INT64
/**************************************************************************
*
* 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 );
FT_INTEGRATE( ras, delta, fx1 + first );
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++;
}
FT_INTEGRATE( ras, delta, ONE_PIXEL );
y1 += delta;
ex1 += incr;
gray_set_cell( RAS_VAR_ ex1, ey );
} while ( ex1 != ex2 );
}
fx1 = ONE_PIXEL - first;
End:
FT_INTEGRATE( ras, y2 - y1, fx1 + fx2 );
}
/**************************************************************************
*
* 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;
if ( dy > 0)
{
first = ONE_PIXEL;
incr = 1;
}
else
{
first = 0;
incr = -1;
}
delta = first - fy1;
FT_INTEGRATE( ras, delta, two_fx);
ey1 += incr;
gray_set_cell( RAS_VAR_ ex, ey1 );
delta = first + first - ONE_PIXEL;
while ( ey1 != ey2 )
{
FT_INTEGRATE( ras, delta, two_fx);
ey1 += incr;
gray_set_cell( RAS_VAR_ ex, ey1 );
}
delta = fy2 - ONE_PIXEL + first;
FT_INTEGRATE( ras, delta, two_fx);
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;
FT_INTEGRATE( ras, fy2 - fy1, fx1 * 2 );
fy1 = 0;
ey1++;
gray_set_cell( RAS_VAR_ ex1, ey1 );
} while ( ey1 != ey2 );
else /* vertical line down */
do
{
fy2 = 0;
FT_INTEGRATE( ras, fy2 - fy1, fx1 * 2 );
fy1 = ONE_PIXEL;
ey1--;
gray_set_cell( RAS_VAR_ ex1, ey1 );
} while ( ey1 != ey2 );
}
else /* any other line */
{
FT_Int64 prod = dx * (FT_Int64)fy1 - dy * (FT_Int64)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 - dx * ONE_PIXEL > 0 &&
prod <= 0 ) /* left */
{
fx2 = 0;
fy2 = FT_UDIV( -prod, -dx );
prod -= dy * ONE_PIXEL;
FT_INTEGRATE( ras, fy2 - fy1, fx1 + fx2 );
fx1 = ONE_PIXEL;
fy1 = fy2;
ex1--;
}
else if ( prod - dx * ONE_PIXEL + dy * ONE_PIXEL > 0 &&
prod - dx * ONE_PIXEL <= 0 ) /* up */
{
prod -= dx * ONE_PIXEL;
fx2 = FT_UDIV( -prod, dy );
fy2 = ONE_PIXEL;
FT_INTEGRATE( ras, fy2 - fy1, fx1 + fx2 );
fx1 = fx2;
fy1 = 0;
ey1++;
}
else if ( prod + dy * ONE_PIXEL >= 0 &&
prod - dx * ONE_PIXEL + dy * ONE_PIXEL <= 0 ) /* right */
{
prod += dy * ONE_PIXEL;
fx2 = ONE_PIXEL;
fy2 = FT_UDIV( prod, dx );
FT_INTEGRATE( ras, fy2 - fy1, fx1 + fx2 );
fx1 = 0;
fy1 = fy2;
ex1++;
}
else /* ( prod > 0 &&
prod + dy * ONE_PIXEL < 0 ) down */
{
fx2 = FT_UDIV( prod, -dy );
fy2 = 0;
prod += dx * ONE_PIXEL;
FT_INTEGRATE( ras, 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 );
FT_INTEGRATE( ras, fy2 - fy1, fx1 + fx2 );
End:
ras.x = to_x;
ras.y = to_y;
}
#endif
/*
* Benchmarking shows that using DDA to flatten the quadratic Bézier arcs
* is slightly faster in the following cases:
*
* - When the host CPU is 64-bit.
* - When SSE2 SIMD registers and instructions are available (even on
* x86).
*
* For other cases, using binary splits is actually slightly faster.
*/
#if defined( __SSE2__ ) || \
defined( __x86_64__ ) || \
defined( _M_AMD64 ) || \
( defined( _M_IX86_FP ) && _M_IX86_FP >= 2 )
# define FT_SSE2 1
#else
# define FT_SSE2 0
#endif
#if FT_SSE2 || \
defined( __aarch64__ ) || \
defined( _M_ARM64 )
# define BEZIER_USE_DDA 1
#else
# define BEZIER_USE_DDA 0
#endif
/*
* For now, the code that depends on `BEZIER_USE_DDA` requires `FT_Int64`
* to be defined. If `FT_INT64` is not defined, meaning there is no
* 64-bit type available, disable it to avoid compilation errors. See for
* example https://gitlab.freedesktop.org/freetype/freetype/-/issues/1071.
*/
#if !defined( FT_INT64 )
# undef BEZIER_USE_DDA
# define BEZIER_USE_DDA 0
#endif
#if BEZIER_USE_DDA
#if FT_SSE2
# include <emmintrin.h>
#endif
#define LEFT_SHIFT( a, b ) (FT_Int64)( (FT_UInt64)(a) << (b) )
static void
gray_render_conic( RAS_ARG_ const FT_Vector* control,
const FT_Vector* to )
{
FT_Vector p0, p1, p2;
TPos ax, ay, bx, by, dx, dy;
int shift;
FT_Int64 rx, ry;
FT_Int64 qx, qy;
FT_Int64 px, py;
FT_UInt count;
p0.x = ras.x;
p0.y = ras.y;
p1.x = UPSCALE( control->x );
p1.y = UPSCALE( control->y );
p2.x = UPSCALE( to->x );
p2.y = UPSCALE( to->y );
/* short-cut the arc that crosses the current band */
if ( ( TRUNC( p0.y ) >= ras.max_ey &&
TRUNC( p1.y ) >= ras.max_ey &&
TRUNC( p2.y ) >= ras.max_ey ) ||
( TRUNC( p0.y ) < ras.min_ey &&
TRUNC( p1.y ) < ras.min_ey &&
TRUNC( p2.y ) < ras.min_ey ) )
{
ras.x = p2.x;
ras.y = p2.y;
return;
}
bx = p1.x - p0.x;
by = p1.y - p0.y;
ax = p2.x - p1.x - bx; /* p0.x + p2.x - 2 * p1.x */
ay = p2.y - p1.y - by; /* p0.y + p2.y - 2 * p1.y */
dx = FT_ABS( ax );
dy = FT_ABS( ay );
if ( dx < dy )
dx = dy;
if ( dx <= ONE_PIXEL / 4 )
{
gray_render_line( RAS_VAR_ p2.x, p2.y );
return;
}
/* 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. */
shift = 0;
do
{
dx >>= 2;
shift += 1;
} while ( dx > ONE_PIXEL / 4 );
/*
* The (P0,P1,P2) arc equation, for t in [0,1] range:
*
* P(t) = P0*(1-t)^2 + P1*2*t*(1-t) + P2*t^2
*
* P(t) = P0 + 2*(P1-P0)*t + (P0+P2-2*P1)*t^2
* = P0 + 2*B*t + A*t^2
*
* for A = P0 + P2 - 2*P1
* and B = P1 - P0
*
* Let's consider the difference when advancing by a small
* parameter h:
*
* Q(h,t) = P(t+h) - P(t) = 2*B*h + A*h^2 + 2*A*h*t
*
* And then its own difference:
*
* R(h,t) = Q(h,t+h) - Q(h,t) = 2*A*h*h = R (constant)
*
* Since R is always a constant, it is possible to compute
* successive positions with:
*
* P = P0
* Q = Q(h,0) = 2*B*h + A*h*h
* R = 2*A*h*h
*
* loop:
* P += Q
* Q += R
* EMIT(P)
*
* To ensure accurate results, perform computations on 64-bit
* values, after scaling them by 2^32.
*
* h = 1 / 2^N
*
* R << 32 = 2 * A << (32 - N - N)
* = A << (33 - 2*N)
*
* Q << 32 = (2 * B << (32 - N)) + (A << (32 - N - N))
* = (B << (33 - N)) + (A << (32 - 2*N))
*/
#if FT_SSE2
/* Experience shows that for small shift values, */
/* SSE2 is actually slower. */
if ( shift > 2 )
{
union
{
struct { FT_Int64 ax, ay, bx, by; } i;
struct { __m128i a, b; } vec;
} u;
union
{
struct { FT_Int32 px_lo, px_hi, py_lo, py_hi; } i;
__m128i vec;
} v;
__m128i a, b;
__m128i r, q, q2;
__m128i p;
u.i.ax = ax;
u.i.ay = ay;
u.i.bx = bx;
u.i.by = by;
a = _mm_load_si128( &u.vec.a );
b = _mm_load_si128( &u.vec.b );
r = _mm_slli_epi64( a, 33 - 2 * shift );
q = _mm_slli_epi64( b, 33 - shift );
q2 = _mm_slli_epi64( a, 32 - 2 * shift );
q = _mm_add_epi64( q2, q );
v.i.px_lo = 0;
v.i.px_hi = p0.x;
v.i.py_lo = 0;
v.i.py_hi = p0.y;
p = _mm_load_si128( &v.vec );
for ( count = 1U << shift; count > 0; count-- )
{
p = _mm_add_epi64( p, q );
q = _mm_add_epi64( q, r );
_mm_store_si128( &v.vec, p );
gray_render_line( RAS_VAR_ v.i.px_hi, v.i.py_hi );
}
return;
}
#endif /* FT_SSE2 */
rx = LEFT_SHIFT( ax, 33 - 2 * shift );
ry = LEFT_SHIFT( ay, 33 - 2 * shift );
qx = LEFT_SHIFT( bx, 33 - shift ) + LEFT_SHIFT( ax, 32 - 2 * shift );
qy = LEFT_SHIFT( by, 33 - shift ) + LEFT_SHIFT( ay, 32 - 2 * shift );
px = LEFT_SHIFT( p0.x, 32 );
py = LEFT_SHIFT( p0.y, 32 );
for ( count = 1U << shift; count > 0; count-- )
{
px += qx;
py += qy;
qx += rx;
qy += ry;
gray_render_line( RAS_VAR_ (FT_Pos)( px >> 32 ),
(FT_Pos)( py >> 32 ) );
}
}
#else /* !BEZIER_USE_DDA */
/*
* Note that multiple attempts to speed up the function below
* with SSE2 intrinsics, using various data layouts, have turned
* out to be slower than the non-SIMD code below.
*/
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;
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
{
int 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 );
}
#endif /* !BEZIER_USE_DDA */
/*
* For cubic Bézier, binary splits are still faster than DDA
* because the splits are adaptive to how quickly each sub-arc
* approaches their chord trisection points.
*
* It might be useful to experiment with SSE2 to speed up
* `gray_split_cubic`, though.
*/
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,
void* worker_ ) /* gray_PWorker */
{
gray_PWorker worker = (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,
void* worker_ ) /* gray_PWorker */
{
gray_PWorker worker = (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,
void* worker_ ) /* gray_PWorker */
{
gray_PWorker worker = (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,
void* worker_ ) /* gray_PWorker */
{
gray_PWorker worker = (gray_PWorker)worker_;
gray_render_cubic( RAS_VAR_ control1, control2, to );
return 0;
}
static void
gray_sweep( RAS_ARG )
{
int fill = ( ras.outline.flags & FT_OUTLINE_EVEN_ODD_FILL ) ? 0x100
: INT_MIN;
int coverage;
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;
unsigned char* line = ras.target.origin - ras.target.pitch * y;
for ( ; cell != ras.cell_null; cell = cell->next )
{
TArea area;
if ( cover != 0 && cell->x > x )
{
FT_FILL_RULE( coverage, cover, fill );
FT_GRAY_SET( line + x, coverage, cell->x - x );
}
cover += (TArea)cell->cover * ( ONE_PIXEL * 2 );
area = cover - cell->area;
if ( area != 0 && cell->x >= ras.min_ex )
{
FT_FILL_RULE( coverage, area, fill );
line[cell->x] = (unsigned char)coverage;
}
x = cell->x + 1;
}
if ( cover != 0 ) /* only if cropped */
{
FT_FILL_RULE( coverage, cover, fill );
FT_GRAY_SET( line + x, coverage, ras.max_ex - x );
}
}
}
static void
gray_sweep_direct( RAS_ARG )
{
int fill = ( ras.outline.flags & FT_OUTLINE_EVEN_ODD_FILL ) ? 0x100
: INT_MIN;
int coverage;
int y;
FT_Span span[FT_MAX_GRAY_SPANS];
int n = 0;
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;
for ( ; cell != ras.cell_null; cell = cell->next )
{
TArea area;
if ( cover != 0 && cell->x > x )
{
FT_FILL_RULE( coverage, cover, fill );
span[n].coverage = (unsigned char)coverage;
span[n].x = (short)x;
span[n].len = (unsigned short)( cell->x - x );
if ( ++n == FT_MAX_GRAY_SPANS )
{
/* flush the span buffer and reset the count */
ras.render_span( y, n, span, ras.render_span_data );
n = 0;
}
}
cover += (TArea)cell->cover * ( ONE_PIXEL * 2 );
area = cover - cell->area;
if ( area != 0 && cell->x >= ras.min_ex )
{
FT_FILL_RULE( coverage, area, fill );
span[n].coverage = (unsigned char)coverage;
span[n].x = (short)cell->x;
span[n].len = 1;
if ( ++n == FT_MAX_GRAY_SPANS )
{
/* flush the span buffer and reset the count */
ras.render_span( y, n, span, ras.render_span_data );
n = 0;
}
}
x = cell->x + 1;
}
if ( cover != 0 ) /* only if cropped */
{
FT_FILL_RULE( coverage, cover, fill );
span[n].coverage = (unsigned char)coverage;
span[n].x = (short)x;
span[n].len = (unsigned short)( ras.max_ex - x );
++n;
}
if ( n )
{
/* flush the span buffer and reset the count */
ras.render_span( y, n, span, ras.render_span_data );
n = 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 */
int last; /* index of last 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;
last = -1;
for ( n = 0; n < outline->n_contours; n++ )
{
FT_TRACE5(( "FT_Outline_Decompose: Contour %d\n", n ));
first = last + 1;
last = outline->contours[n];
if ( last < first )
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;
}
FT_TRACE5(( "FT_Outline_Decompose: Done\n", n ));
return Smooth_Err_Ok;
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 )
{
volatile 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();
FT_TRACE7(( "band [%d..%d]: %ld cell%s remaining/\n",
ras.min_ey,
ras.max_ey,
ras.cell_null - ras.cell_free,
ras.cell_null - ras.cell_free == 1 ? "" : "s" ));
}
else
{
error = FT_THROW( Raster_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;
/* Initialize the null cell at the end of the poll. */
ras.cell_null = buffer + FT_MAX_GRAY_POOL - 1;
ras.cell_null->x = CELL_MAX_X_VALUE;
ras.cell_null->area = 0;
ras.cell_null->cover = 0;
ras.cell_null->next = NULL;
/* set up vertical bands */
ras.ycells = (PCell*)buffer;
if ( height > n )
{
/* two divisions rounded up */
n = ( height + n - 1 ) / n;
height = ( height + n - 1 ) / n;
}
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];
TCoord w;
int error;
for ( w = 0; w < width; ++w )
ras.ycells[w] = ras.cell_null;
/* memory management: skip ycells */
n = ( (size_t)width * sizeof ( PCell ) + sizeof ( TCell ) - 1 ) /
sizeof ( TCell );
ras.cell_free = buffer + n;
ras.cell = ras.cell_null;
ras.min_ey = band[1];
ras.max_ey = band[0];
ras.count_ey = width;
error = gray_convert_glyph_inner( RAS_VAR_ continued );
continued = 1;
if ( !error )
{
if ( ras.render_span ) /* for FT_RASTER_FLAG_DIRECT only */
gray_sweep_direct( RAS_VAR );
else
gray_sweep( RAS_VAR );
band--;
continue;
}
else if ( error != Smooth_Err_Raster_Overflow )
return error;
/* 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 FT_THROW( Raster_Overflow );
}
band++;
band[1] = band[0];
band[0] += width;
} while ( band >= bands );
}
return Smooth_Err_Ok;
}
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( Cannot_Render_Glyph );
if ( !outline )
return FT_THROW( Invalid_Outline );
/* return immediately if the outline is empty */
if ( outline->n_points == 0 || outline->n_contours <= 0 )
return Smooth_Err_Ok;
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 Smooth_Err_Ok;
ras.render_span = (FT_Raster_Span_Func)params->gray_spans;
ras.render_span_data = params->user;
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 Smooth_Err_Ok;
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.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 Smooth_Err_Ok;
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( void* memory_,
FT_Raster* araster_ )
{
FT_Memory memory = (FT_Memory)memory_;
gray_PRaster* araster = (gray_PRaster*)araster_;
FT_Error error;
gray_PRaster raster = NULL;
if ( !FT_NEW( raster ) )
raster->memory = memory;
*araster = 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: */
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