ref: 29bac136cbdba649fe47b98d1384e88e87dd940c
dir: /src/smooth/ftgrays.c/
/***************************************************************************/
/* */
/* ftgrays.c */
/* */
/* A new `perfect' anti-aliasing renderer (body). */
/* */
/* Copyright 2000 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/base/ftgrays.c' to your current directory */
/* */
/* - copy `include/freetype/ftimage.h' and */
/* `include/freetype/ftgrays.h' to the same directory */
/* */
/* - compile `ftgrays' with the _STANDALONE_ macro defined, as in */
/* */
/* cc -c -D_STANDALONE_ ftgrays.c */
/* */
/* The renderer can be initialized with a call to */
/* `ft_grays_raster.grays_raster_new'; an anti-aliased bitmap can be */
/* generated with a call to `ft_grays_raster.grays_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. */
/* */
/* 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 <string.h> /* for memcpy() */
/*************************************************************************/
/* */
/* 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 trace_aaraster
#ifdef _STANDALONE_
#define ErrRaster_Invalid_Mode -2
#define ErrRaster_Invalid_Outline -1
#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)
/* Disable the tracing mechanism for simplicity -- developers can */
/* activate it easily by redefining these two macros. */
#ifndef FT_ERROR
#define FT_ERROR( x ) do ; while ( 0 ) /* nothing */
#endif
#ifndef FT_TRACE
#define FT_TRACE( x ) do ; while ( 0 ) /* nothing */
#endif
#else /* _STANDALONE_ */
#include <ft2build.h>
#include FT_SOURCE_FILE(smooth,ftgrays.h)
#include FT_INTERNAL_OBJECTS_H
#include FT_INTERNAL_DEBUG_H
#include FT_OUTLINE_H
#define ErrRaster_Invalid_Mode FT_Err_Cannot_Render_Glyph
#define ErrRaster_Invalid_Outline FT_Err_Invalid_Outline
#endif /* _STANDALONE_ */
/* define this to dump debugging information */
#define xxxDEBUG_GRAYS
/* as usual, for the speed hungry :-) */
#ifndef FT_STATIC_RASTER
#define RAS_ARG PRaster raster
#define RAS_ARG_ PRaster raster,
#define RAS_VAR raster
#define RAS_VAR_ raster,
#define ras (*raster)
#else /* FT_STATIC_RASTER */
#define RAS_ARG /* empty */
#define RAS_ARG_ /* empty */
#define RAS_VAR /* empty */
#define RAS_VAR_ /* empty */
static TRaster ras;
#endif /* FT_STATIC_RASTER */
/* must be at least 6 bits! */
#define PIXEL_BITS 8
#define ONE_PIXEL ( 1L << PIXEL_BITS )
#define PIXEL_MASK ( -1L << PIXEL_BITS )
#define TRUNC( x ) ( (x) >> PIXEL_BITS )
#define SUBPIXELS( x ) ( (x) << PIXEL_BITS )
#define FLOOR( x ) ( (x) & -ONE_PIXEL )
#define CEILING( x ) ( ( (x) + ONE_PIXEL - 1 ) & -ONE_PIXEL )
#define ROUND( x ) ( ( (x) + ONE_PIXEL / 2 ) & -ONE_PIXEL )
#if PIXEL_BITS >= 6
#define UPSCALE( x ) ( (x) << ( PIXEL_BITS - 6 ) )
#define DOWNSCALE( x ) ( (x) >> ( PIXEL_BITS - 6 ) )
#else
#define UPSCALE( x ) ( (x) >> ( 6 - PIXEL_BITS ) )
#define DOWNSCALE( x ) ( (x) << ( 6 - PIXEL_BITS ) )
#endif
/* Define this if you want to use a more compact storage scheme. This */
/* increases the number of cells available in the render pool but slows */
/* down the rendering a bit. It is useful if you have a really tiny */
/* render pool. */
#define xxxGRAYS_COMPACT
/*************************************************************************/
/* */
/* TYPE DEFINITIONS */
/* */
typedef int TScan; /* integer scanline/pixel coordinate */
typedef long TPos; /* sub-pixel coordinate */
/* maximal number of gray spans in a call to the span callback */
#define FT_MAX_GRAY_SPANS 32
#ifdef GRAYS_COMPACT
typedef struct TCell_
{
short x : 14;
short y : 14;
int cover : PIXEL_BITS + 2;
int area : PIXEL_BITS * 2 + 2;
} TCell, *PCell;
#else /* GRAYS_COMPACT */
typedef struct TCell_
{
TScan x;
TScan y;
int cover;
int area;
} TCell, *PCell;
#endif /* GRAYS_COMPACT */
typedef struct TRaster_
{
PCell cells;
int max_cells;
int num_cells;
TScan min_ex, max_ex;
TScan min_ey, max_ey;
int area;
int cover;
int invalid;
TScan ex, ey;
TScan cx, cy;
TPos x, y;
TScan last_ey;
FT_Vector bez_stack[32 * 3];
int lev_stack[32];
FT_Outline outline;
FT_Bitmap target;
FT_BBox clip_box;
FT_Span gray_spans[FT_MAX_GRAY_SPANS];
int num_gray_spans;
FT_Raster_Span_Func render_span;
void* render_span_data;
int span_y;
int band_size;
int band_shoot;
int conic_level;
int cubic_level;
void* memory;
} TRaster, *PRaster;
/*************************************************************************/
/* */
/* Initialize the cells table. */
/* */
static
void init_cells( RAS_ARG_ void* buffer,
long byte_size )
{
ras.cells = (PCell)buffer;
ras.max_cells = byte_size / sizeof ( TCell );
ras.num_cells = 0;
ras.area = 0;
ras.cover = 0;
ras.invalid = 1;
}
/*************************************************************************/
/* */
/* Compute the outline bounding box. */
/* */
static
void compute_cbox( RAS_ARG_ FT_Outline* outline )
{
FT_Vector* vec = outline->points;
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
int record_cell( RAS_ARG )
{
PCell cell;
if ( !ras.invalid && ( ras.area | ras.cover ) )
{
if ( ras.num_cells >= ras.max_cells )
return 1;
cell = ras.cells + ras.num_cells++;
cell->x = ras.ex - ras.min_ex;
cell->y = ras.ey - ras.min_ey;
cell->area = ras.area;
cell->cover = ras.cover;
}
return 0;
}
/*************************************************************************/
/* */
/* Set the current cell to a new position. */
/* */
static
int set_cell( RAS_ARG_ TScan ex,
TScan ey )
{
int invalid, record, clean;
/* 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 = 0;
clean = 1;
invalid = ( ey < ras.min_ey || ey >= ras.max_ey || ex >= ras.max_ex );
if ( !invalid )
{
/* All cells that are on the left of the clipping region go to the */
/* min_ex - 1 horizontal position. */
if ( ex < ras.min_ex )
ex = ras.min_ex - 1;
/* if our position is new, then record the previous cell */
if ( ex != ras.ex || ey != ras.ey )
record = 1;
else
clean = ras.invalid; /* do not clean if we didn't move from */
/* a valid cell */
}
/* record the previous cell if needed (i.e., if we changed the cell */
/* position, of changed the `invalid' flag) */
if ( ( ras.invalid != invalid || record ) && record_cell( RAS_VAR ) )
return 1;
if ( clean )
{
ras.area = 0;
ras.cover = 0;
}
ras.invalid = invalid;
ras.ex = ex;
ras.ey = ey;
return 0;
}
/*************************************************************************/
/* */
/* Start a new contour at a given cell. */
/* */
static
void start_cell( RAS_ARG_ TScan ex,
TScan ey )
{
if ( ex < ras.min_ex )
ex = ras.min_ex - 1;
ras.area = 0;
ras.cover = 0;
ras.ex = ex;
ras.ey = ey;
ras.last_ey = SUBPIXELS( ey );
ras.invalid = 0;
(void)set_cell( RAS_VAR_ ex, ey );
}
/*************************************************************************/
/* */
/* Render a scanline as one or more cells. */
/* */
static
int render_scanline( RAS_ARG_ TScan ey,
TPos x1,
TScan y1,
TPos x2,
TScan y2 )
{
TScan ex1, ex2, fx1, fx2, delta;
long p, first, dx;
int incr, lift, mod, rem;
dx = x2 - x1;
ex1 = TRUNC( x1 ); /* if (ex1 >= ras.max_ex) ex1 = ras.max_ex-1; */
ex2 = TRUNC( x2 ); /* if (ex2 >= ras.max_ex) ex2 = ras.max_ex-1; */
fx1 = x1 - SUBPIXELS( ex1 );
fx2 = x2 - SUBPIXELS( ex2 );
/* trivial case. Happens often */
if ( y1 == y2 )
return set_cell( RAS_VAR_ ex2, ey );
/* everything is located in a single cell. That is easy! */
/* */
if ( ex1 == ex2 )
{
delta = y2 - y1;
ras.area += ( fx1 + fx2 ) * delta;
ras.cover += delta;
return 0;
}
/* ok, we'll have to render a run of adjacent cells on the same */
/* scanline... */
/* */
p = ( ONE_PIXEL - fx1 ) * ( y2 - y1 );
first = ONE_PIXEL;
incr = 1;
if ( dx < 0 )
{
p = fx1 * ( y2 - y1 );
first = 0;
incr = -1;
dx = -dx;
}
delta = p / dx;
mod = p % dx;
if ( mod < 0 )
{
delta--;
mod += dx;
}
ras.area += ( fx1 + first ) * delta;
ras.cover += delta;
ex1 += incr;
if ( set_cell( RAS_VAR_ ex1, ey ) )
goto Error;
y1 += delta;
if ( ex1 != ex2 )
{
p = ONE_PIXEL * ( y2 - y1 );
lift = p / dx;
rem = p % dx;
if ( rem < 0 )
{
lift--;
rem += dx;
}
mod -= dx;
while ( ex1 != ex2 )
{
delta = lift;
mod += rem;
if ( mod >= 0 )
{
mod -= dx;
delta++;
}
ras.area += ONE_PIXEL * delta;
ras.cover += delta;
y1 += delta;
ex1 += incr;
if ( set_cell( RAS_VAR_ ex1, ey ) )
goto Error;
}
}
delta = y2 - y1;
ras.area += ( fx2 + ONE_PIXEL - first ) * delta;
ras.cover += delta;
return 0;
Error:
return 1;
}
/*************************************************************************/
/* */
/* Render a given line as a series of scanlines. */
/* */
static
int render_line( RAS_ARG_ TPos to_x,
TPos to_y )
{
TScan ey1, ey2, fy1, fy2;
TPos dx, dy, x, x2;
int p, rem, mod, lift, delta, first, incr;
ey1 = TRUNC( ras.last_ey );
ey2 = TRUNC( to_y ); /* if (ey2 >= ras.max_ey) ey2 = ras.max_ey-1; */
fy1 = ras.y - ras.last_ey;
fy2 = to_y - SUBPIXELS( ey2 );
dx = to_x - ras.x;
dy = to_y - ras.y;
/* XXX: we should do something about the trivial case where dx == 0, */
/* as it happens very often! */
/* perform vertical clipping */
{
TScan min, max;
min = ey1;
max = ey2;
if ( ey1 > ey2 )
{
min = ey2;
max = ey1;
}
if ( min >= ras.max_ey || max < ras.min_ey )
goto End;
}
/* everything is on a single scanline */
if ( ey1 == ey2 )
{
if ( render_scanline( RAS_VAR_ ey1, ras.x, fy1, to_x, fy2 ) )
goto Error;
goto End;
}
/* ok, we have to render several scanlines */
p = ( ONE_PIXEL - fy1 ) * dx;
first = ONE_PIXEL;
incr = 1;
if ( dy < 0 )
{
p = fy1 * dx;
first = 0;
incr = -1;
dy = -dy;
}
delta = p / dy;
mod = p % dy;
if ( mod < 0 )
{
delta--;
mod += dy;
}
x = ras.x + delta;
if ( render_scanline( RAS_VAR_ ey1, ras.x, fy1, x, first ) )
goto Error;
ey1 += incr;
if ( set_cell( RAS_VAR_ TRUNC( x ), ey1 ) )
goto Error;
if ( ey1 != ey2 )
{
p = ONE_PIXEL * dx;
lift = p / dy;
rem = p % dy;
if ( rem < 0 )
{
lift--;
rem += dy;
}
mod -= dy;
while ( ey1 != ey2 )
{
delta = lift;
mod += rem;
if ( mod >= 0 )
{
mod -= dy;
delta++;
}
x2 = x + delta;
if ( render_scanline( RAS_VAR_ ey1,
x, ONE_PIXEL - first, x2, first ) )
goto Error;
x = x2;
ey1 += incr;
if ( set_cell( RAS_VAR_ TRUNC( x ), ey1 ) )
goto Error;
}
}
if ( render_scanline( RAS_VAR_ ey1,
x, ONE_PIXEL - first, to_x, fy2 ) )
goto Error;
End:
ras.x = to_x;
ras.y = to_y;
ras.last_ey = SUBPIXELS( ey2 );
return 0;
Error:
return 1;
}
static
void split_conic( 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
int render_conic( RAS_ARG_ FT_Vector* control,
FT_Vector* to )
{
TPos dx, dy;
int top, level;
int* levels;
FT_Vector* arc;
dx = DOWNSCALE( ras.x ) + to->x - ( control->x << 1 );
if ( dx < 0 )
dx = -dx;
dy = DOWNSCALE( ras.y ) + to->y - ( control->y << 1 );
if ( dy < 0 )
dy = -dy;
if ( dx < dy )
dx = dy;
level = 1;
dx = dx / ras.conic_level;
while ( dx > 0 )
{
dx >>= 2;
level++;
}
/* a shortcut to speed things up */
if ( level <= 1 )
{
/* we compute the mid-point directly in order to avoid */
/* calling split_conic() */
TPos to_x, to_y, mid_x, mid_y;
to_x = UPSCALE( to->x );
to_y = UPSCALE( to->y );
mid_x = ( ras.x + to_x + 2 * UPSCALE( control->x ) ) / 4;
mid_y = ( ras.y + to_y + 2 * UPSCALE( control->y ) ) / 4;
return render_line( RAS_VAR_ mid_x, mid_y ) ||
render_line( RAS_VAR_ to_x, to_y );
}
arc = ras.bez_stack;
levels = ras.lev_stack;
top = 0;
levels[0] = level;
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;
while ( top >= 0 )
{
level = levels[top];
if ( level > 1 )
{
/* check that the arc crosses the current band */
TPos min, max, y;
min = max = arc[0].y;
y = arc[1].y;
if ( y < min ) min = y;
if ( y > max ) max = y;
y = arc[2].y;
if ( y < min ) min = y;
if ( y > max ) max = y;
if ( TRUNC( min ) >= ras.max_ey || TRUNC( max ) < 0 )
goto Draw;
split_conic( arc );
arc += 2;
top++;
levels[top] = levels[top - 1] = level - 1;
continue;
}
Draw:
{
TPos to_x, to_y, mid_x, mid_y;
to_x = arc[0].x;
to_y = arc[0].y;
mid_x = ( ras.x + to_x + 2 * arc[1].x ) / 4;
mid_y = ( ras.y + to_y + 2 * arc[1].y ) / 4;
if ( render_line( RAS_VAR_ mid_x, mid_y ) ||
render_line( RAS_VAR_ to_x, to_y ) )
return 1;
top--;
arc -= 2;
}
}
return 0;
}
static
void split_cubic( 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
int render_cubic( RAS_ARG_ FT_Vector* control1,
FT_Vector* control2,
FT_Vector* to )
{
TPos dx, dy, da, db;
int top, level;
int* levels;
FT_Vector* arc;
dx = DOWNSCALE( ras.x ) + to->x - ( control1->x << 1 );
if ( dx < 0 )
dx = -dx;
dy = DOWNSCALE( ras.y ) + to->y - ( control1->y << 1 );
if ( dy < 0 )
dy = -dy;
if ( dx < dy )
dx = dy;
da = dx;
dx = DOWNSCALE( ras.x ) + to->x - 3 * ( control1->x + control2->x );
if ( dx < 0 )
dx = -dx;
dy = DOWNSCALE( ras.y ) + to->y - 3 * ( control1->x + control2->y );
if ( dy < 0 )
dy = -dy;
if ( dx < dy )
dx = dy;
db = dx;
level = 1;
da = da / ras.cubic_level;
db = db / ras.conic_level;
while ( da > 0 || db > 0 )
{
da >>= 2;
db >>= 3;
level++;
}
if ( level <= 1 )
{
TPos to_x, to_y, mid_x, mid_y;
to_x = UPSCALE( to->x );
to_y = UPSCALE( to->y );
mid_x = ( ras.x + to_x +
3 * UPSCALE( control1->x + control2->x ) ) / 8;
mid_y = ( ras.y + to_y +
3 * UPSCALE( control1->y + control2->y ) ) / 8;
return render_line( RAS_VAR_ mid_x, mid_y ) ||
render_line( RAS_VAR_ to_x, to_y );
}
arc = ras.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;
levels = ras.lev_stack;
top = 0;
levels[0] = level;
while ( top >= 0 )
{
level = levels[top];
if ( level > 1 )
{
/* check that the arc crosses the current band */
TPos min, max, y;
min = max = arc[0].y;
y = arc[1].y;
if ( y < min ) min = y;
if ( y > max ) max = y;
y = arc[2].y;
if ( y < min ) min = y;
if ( y > max ) max = y;
y = arc[3].y;
if ( y < min ) min = y;
if ( y > max ) max = y;
if ( TRUNC( min ) >= ras.max_ey || TRUNC( max ) < 0 )
goto Draw;
split_cubic( arc );
arc += 3;
top ++;
levels[top] = levels[top - 1] = level - 1;
continue;
}
Draw:
{
TPos to_x, to_y, mid_x, mid_y;
to_x = arc[0].x;
to_y = arc[0].y;
mid_x = ( ras.x + to_x + 3 * ( arc[1].x + arc[2].x ) ) / 8;
mid_y = ( ras.y + to_y + 3 * ( arc[1].y + arc[2].y ) ) / 8;
if ( render_line( RAS_VAR_ mid_x, mid_y ) ||
render_line( RAS_VAR_ to_x, to_y ) )
return 1;
top --;
arc -= 3;
}
}
return 0;
}
/* a macro comparing two cell pointers. Returns true if a <= b. */
#if 1
#define PACK( a ) ( ( (long)(a)->y << 16 ) + (a)->x )
#define LESS_THAN( a, b ) ( PACK( a ) < PACK( b ) )
#else /* 1 */
#define LESS_THAN( a, b ) ( (a)->y < (b)->y || \
( (a)->y == (b)->y && (a)->x < (b)->x ) )
#endif /* 1 */
#define SWAP_CELLS( a, b, temp ) do \
{ \
temp = *(a); \
*(a) = *(b); \
*(b) = temp; \
} while ( 0 )
#define DEBUG_SORT
#define QUICK_SORT
#ifdef SHELL_SORT
/* a simple shell sort algorithm that works directly on our */
/* cells table */
static
void shell_sort ( PCell cells,
int count )
{
PCell i, j, limit = cells + count;
TCell temp;
int gap;
/* compute initial gap */
for ( gap = 0; ++gap < count; gap *= 3 )
;
while ( gap /= 3 )
{
for ( i = cells + gap; i < limit; i++ )
{
for ( j = i - gap; ; j -= gap )
{
PCell k = j + gap;
if ( LESS_THAN( j, k ) )
break;
SWAP_CELLS( j, k, temp );
if ( j < cells + gap )
break;
}
}
}
}
#endif /* SHELL_SORT */
#ifdef QUICK_SORT
/* This is a non-recursive quicksort that directly process our cells */
/* array. It should be faster than calling the stdlib qsort(), and we */
/* can even tailor our insertion threshold... */
#define QSORT_THRESHOLD 9 /* below this size, a sub-array will be sorted */
/* through a normal insertion sort */
static
void quick_sort( PCell cells,
int count )
{
PCell stack[40]; /* should be enough ;-) */
PCell* top; /* top of stack */
PCell base, limit;
TCell temp;
limit = cells + count;
base = cells;
top = stack;
for (;;)
{
int len = (int)( limit - base );
PCell i, j, pivot;
if ( len > QSORT_THRESHOLD )
{
/* we use base + len/2 as the pivot */
pivot = base + len / 2;
SWAP_CELLS( base, pivot, temp );
i = base + 1;
j = limit - 1;
/* now ensure that *i <= *base <= *j */
if ( LESS_THAN( j, i ) )
SWAP_CELLS( i, j, temp );
if ( LESS_THAN( base, i ) )
SWAP_CELLS( base, i, temp );
if ( LESS_THAN( j, base ) )
SWAP_CELLS( base, j, temp );
for (;;)
{
do i++; while ( LESS_THAN( i, base ) );
do j--; while ( LESS_THAN( base, j ) );
if ( i > j )
break;
SWAP_CELLS( i, j, temp );
}
SWAP_CELLS( base, j, temp );
/* now, push the largest sub-array */
if ( j - base > limit - i )
{
top[0] = base;
top[1] = j;
base = i;
}
else
{
top[0] = i;
top[1] = limit;
limit = j;
}
top += 2;
}
else
{
/* the sub-array is small, perform insertion sort */
j = base;
i = j + 1;
for ( ; i < limit; j = i, i++ )
{
for ( ; LESS_THAN( j + 1, j ); j-- )
{
SWAP_CELLS( j + 1, j, temp );
if ( j == base )
break;
}
}
if ( top > stack )
{
top -= 2;
base = top[0];
limit = top[1];
}
else
break;
}
}
}
#endif /* QUICK_SORT */
#ifdef DEBUG_GRAYS
#ifdef DEBUG_SORT
static
int check_sort( PCell cells,
int count )
{
PCell p, q;
for ( p = cells + count - 2; p >= cells; p-- )
{
q = p + 1;
if ( !LESS_THAN( p, q ) )
return 0;
}
return 1;
}
#endif /* DEBUG_SORT */
#endif /* DEBUG_GRAYS */
static
int Move_To( FT_Vector* to,
FT_Raster raster )
{
TPos x, y;
/* record current cell, if any */
record_cell( (PRaster)raster );
/* start to a new position */
x = UPSCALE( to->x );
y = UPSCALE( to->y );
start_cell( (PRaster)raster, TRUNC( x ), TRUNC( y ) );
((PRaster)raster)->x = x;
((PRaster)raster)->y = y;
return 0;
}
static
int Line_To( FT_Vector* to,
FT_Raster raster )
{
return render_line( (PRaster)raster,
UPSCALE( to->x ), UPSCALE( to->y ) );
}
static
int Conic_To( FT_Vector* control,
FT_Vector* to,
FT_Raster raster )
{
return render_conic( (PRaster)raster, control, to );
}
static
int Cubic_To( FT_Vector* control1,
FT_Vector* control2,
FT_Vector* to,
FT_Raster raster )
{
return render_cubic( (PRaster)raster, control1, control2, to );
}
static
void grays_render_span( int y,
int count,
FT_Span* spans,
PRaster raster )
{
unsigned char* p;
FT_Bitmap* map = &raster->target;
/* first of all, compute the scanline offset */
p = (unsigned char*)map->buffer - y * map->pitch;
if ( map->pitch >= 0 )
p += ( map->rows - 1 ) * map->pitch;
for ( ; count > 0; count--, spans++ )
{
if ( spans->coverage )
#if 1
memset( p + spans->x, (unsigned char)spans->coverage, spans->len );
#else /* 1 */
{
q = p + spans->x;
limit = q + spans->len;
for ( ; q < limit; q++ )
q[0] = (unsigned char)spans->coverage;
}
#endif /* 1 */
}
}
#ifdef DEBUG_GRAYS
#include <stdio.h>
static
void dump_cells( RAS_ARG )
{
PCell cell, limit;
int y = -1;
cell = ras.cells;
limit = cell + ras.num_cells;
for ( ; cell < limit; cell++ )
{
if ( cell->y != y )
{
fprintf( stderr, "\n%2d: ", cell->y );
y = cell->y;
}
fprintf( stderr, "[%d %d %d]",
cell->x, cell->area, cell->cover );
}
fprintf(stderr, "\n" );
}
#endif /* DEBUG_GRAYS */
static
void grays_hline( RAS_ARG_ TScan x,
TScan y,
TPos area,
int acount )
{
FT_Span* span;
int count;
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 = area >> ( PIXEL_BITS * 2 + 1 - 8); /* use range 0..256 */
if ( ras.outline.flags & ft_outline_even_odd_fill )
{
if ( coverage < 0 )
coverage = -coverage;
while ( coverage >= 512 )
coverage -= 512;
if ( coverage > 256 )
coverage = 512 - coverage;
else if ( coverage == 256 )
coverage = 255;
}
else
{
/* normal non-zero winding rule */
if ( coverage < 0 )
coverage = -coverage;
if ( coverage >= 256 )
coverage = 255;
}
y += ras.min_ey;
x += ras.min_ex;
if ( coverage )
{
/* see if we can add this span to the current list */
count = ras.num_gray_spans;
span = ras.gray_spans + count - 1;
if ( count > 0 &&
ras.span_y == y &&
(int)span->x + span->len == (int)x &&
span->coverage == coverage )
{
span->len += acount;
return;
}
if ( ras.span_y != y || count >= FT_MAX_GRAY_SPANS )
{
if ( ras.render_span && count > 0 )
ras.render_span( ras.span_y, count, ras.gray_spans,
ras.render_span_data );
/* ras.render_span( span->y, ras.gray_spans, count ); */
#ifdef DEBUG_GRAYS
if ( ras.span_y >= 0 )
{
int n;
fprintf( stderr, "y=%3d ", ras.span_y );
span = ras.gray_spans;
for ( n = 0; n < count; n++, span++ )
fprintf( stderr, "[%d..%d]:%02x ",
span->x, span->x + span->len - 1, span->coverage );
fprintf( stderr, "\n" );
}
#endif /* DEBUG_GRAYS */
ras.num_gray_spans = 0;
ras.span_y = y;
count = 0;
span = ras.gray_spans;
}
else
span++;
/* add a gray span to the current list */
span->x = (short)x;
span->len = (unsigned short)acount;
span->coverage = (unsigned char)coverage;
ras.num_gray_spans++;
}
}
static
void grays_sweep( RAS_ARG_ FT_Bitmap* target )
{
TScan x, y, cover, area;
PCell start, cur, limit;
FT_UNUSED( target );
if ( ras.num_cells == 0 )
return;
cur = ras.cells;
limit = cur + ras.num_cells;
cover = 0;
ras.span_y = -1;
ras.num_gray_spans = 0;
for (;;)
{
start = cur;
y = start->y;
x = start->x;
area = start->area;
cover += start->cover;
/* accumulate all start cells */
for (;;)
{
++cur;
if ( cur >= limit || cur->y != start->y || cur->x != start->x )
break;
area += cur->area;
cover += cur->cover;
}
/* if the start cell has a non-null area, we must draw an */
/* individual gray pixel there */
if ( area && x >= 0 )
{
grays_hline( RAS_VAR_ x, y, cover * ( ONE_PIXEL * 2 ) - area, 1 );
x++;
}
if ( x < 0 )
x = 0;
if ( cur < limit && start->y == cur->y )
{
/* draw a gray span between the start cell and the current one */
if ( cur->x > x )
grays_hline( RAS_VAR_ x, y,
cover * ( ONE_PIXEL * 2 ), cur->x - x );
}
else
{
/* draw a gray span until the end of the clipping region */
if ( cover && x < ras.max_ex - ras.min_ex )
grays_hline( RAS_VAR_ x, y,
cover * ( ONE_PIXEL * 2 ),
ras.max_ex - x - ras.min_ex );
cover = 0;
}
if ( cur >= limit )
break;
}
if ( ras.render_span && ras.num_gray_spans > 0 )
ras.render_span( ras.span_y, ras.num_gray_spans,
ras.gray_spans, ras.render_span_data );
#ifdef DEBUG_GRAYS
{
int n;
FT_Span* span;
fprintf( stderr, "y=%3d ", ras.span_y );
span = ras.gray_spans;
for ( n = 0; n < ras.num_gray_spans; n++, span++ )
fprintf( stderr, "[%d..%d]:%02x ",
span->x, span->x + span->len - 1, span->coverage );
fprintf( stderr, "\n" );
}
#endif /* DEBUG_GRAYS */
}
#ifdef _STANDALONE_
/*************************************************************************/
/* */
/* The following function should only compile in stand_alone mode, */
/* i.e., when building this component without the rest of FreeType. */
/* */
/*************************************************************************/
/*************************************************************************/
/* */
/* <Function> */
/* FT_Outline_Decompose */
/* */
/* <Description> */
/* 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. */
/* */
/* <Input> */
/* outline :: A pointer to the source target. */
/* */
/* interface :: A table of `emitters', i.e,. function pointers called */
/* during decomposition to indicate path operations. */
/* */
/* 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 sucess. */
/* */
static
int FT_Outline_Decompose( FT_Outline* outline,
const FT_Outline_Funcs* interface,
void* user )
{
#undef SCALED
#define SCALED( x ) ( ( (x) << shift ) - delta )
FT_Vector v_last;
FT_Vector v_control;
FT_Vector v_start;
FT_Vector* point;
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 */
int shift = interface->shift;
FT_Pos delta = interface->delta;
first = 0;
for ( n = 0; n < outline->n_contours; n++ )
{
int last; /* index of last point in contour */
last = outline->contours[n];
limit = outline->points + last;
v_start = outline->points[first];
v_last = outline->points[last];
v_start.x = SCALED( v_start.x ); v_start.y = SCALED( v_start.y );
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--;
}
error = 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 );
error = 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 )
{
error = 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;
error = interface->conic_to( &v_control, &v_middle, user );
if ( error )
goto Exit;
v_control = vec;
goto Do_Conic;
}
error = 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 );
error = interface->cubic_to( &vec1, &vec2, &vec, user );
if ( error )
goto Exit;
continue;
}
error = interface->cubic_to( &vec1, &vec2, &v_start, user );
goto Close;
}
}
}
/* close the contour with a line segment */
error = interface->line_to( &v_start, user );
Close:
if ( error )
goto Exit;
first = last + 1;
}
return 0;
Exit:
return error;
Invalid_Outline:
return ErrRaster_Invalid_Outline;
}
#endif /* _STANDALONE_ */
typedef struct TBand_
{
FT_Pos min, max;
} TBand;
static
int grays_convert_glyph( RAS_ARG_ FT_Outline* outline )
{
static
const FT_Outline_Funcs interface =
{
(FT_Outline_MoveTo_Func) Move_To,
(FT_Outline_LineTo_Func) Line_To,
(FT_Outline_ConicTo_Func)Conic_To,
(FT_Outline_CubicTo_Func)Cubic_To,
0,
0
};
TBand bands[40], *band;
int n, num_bands;
TPos min, max, max_y;
FT_BBox* clip;
/* Set up state in the raster object */
compute_cbox( RAS_VAR_ outline );
/* 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;
/* simple heuristic used to speed-up the bezier decomposition -- see */
/* the code in render_conic() and render_cubic() for more details */
ras.conic_level = 32;
ras.cubic_level = 16;
{
int level = 0;
if ( ras.max_ex > 24 || ras.max_ey > 24 )
level++;
if ( ras.max_ex > 120 || ras.max_ey > 120 )
level++;
ras.conic_level <<= level;
ras.cubic_level <<= level;
}
/* setup vertical bands */
num_bands = ( 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 )
{
FT_Pos bottom, top, middle;
int error;
ras.num_cells = 0;
ras.invalid = 1;
ras.min_ey = band->min;
ras.max_ey = band->max;
error = FT_Outline_Decompose( outline, &interface, &ras ) ||
record_cell( RAS_VAR );
if ( !error )
{
#ifdef SHELL_SORT
shell_sort( ras.cells, ras.num_cells );
#else
quick_sort( ras.cells, ras.num_cells );
#endif
#ifdef DEBUG_GRAYS
check_sort( ras.cells, ras.num_cells );
dump_cells( RAS_VAR );
#endif
grays_sweep( RAS_VAR_ &ras.target );
band--;
continue;
}
/* render pool overflow, we will reduce the render band by half */
bottom = band->min;
top = band->max;
middle = bottom + ( ( top - bottom ) >> 1 );
/* waoow! This is too complex for a single scanline, something */
/* must be really rotten here! */
if ( middle == bottom )
{
#ifdef DEBUG_GRAYS
fprintf( stderr, "Rotten glyph!\n" );
#endif
return 1;
}
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.band_shoot > 8 && ras.band_size > 16 )
ras.band_size = ras.band_size / 2;
return 0;
}
extern
int grays_raster_render( PRaster raster,
FT_Raster_Params* params )
{
FT_Outline* outline = (FT_Outline*)params->source;
FT_Bitmap* target_map = params->target;
if ( !raster || !raster->cells || !raster->max_cells )
return -1;
/* return immediately if the outline is empty */
if ( outline->n_points == 0 || outline->n_contours <= 0 )
return 0;
if ( !outline || !outline->contours || !outline->points )
return ErrRaster_Invalid_Outline;
if ( outline->n_points !=
outline->contours[outline->n_contours - 1] + 1 )
return ErrRaster_Invalid_Outline;
/* if direct mode is not set, we must have a target bitmap */
if ( ( params->flags & ft_raster_flag_direct ) == 0 &&
( !target_map || !target_map->buffer ) )
return -1;
/* this version does not support monochrome rendering */
if ( !( params->flags & ft_raster_flag_aa ) )
return ErrRaster_Invalid_Mode;
/* compute clipping box */
if ( ( params->flags & ft_raster_flag_direct ) == 0 )
{
/* compute clip box from target pixmap */
ras.clip_box.xMin = 0;
ras.clip_box.yMin = 0;
ras.clip_box.xMax = target_map->width;
ras.clip_box.yMax = target_map->rows;
}
else if ( params->flags & ft_raster_flag_clip )
{
ras.clip_box = params->clip_box;
}
else
{
ras.clip_box.xMin = -32768;
ras.clip_box.yMin = -32768;
ras.clip_box.xMax = 32767;
ras.clip_box.yMax = 32767;
}
ras.outline = *outline;
ras.num_cells = 0;
ras.invalid = 1;
if ( target_map )
ras.target = *target_map;
ras.render_span = (FT_Raster_Span_Func)grays_render_span;
ras.render_span_data = &ras;
if ( params->flags & ft_raster_flag_direct )
{
ras.render_span = (FT_Raster_Span_Func)params->gray_spans;
ras.render_span_data = params->user;
}
return grays_convert_glyph( (PRaster)raster, outline );
}
/**** RASTER OBJECT CREATION: In standalone mode, we simply use *****/
/**** a static object. *****/
#ifdef _STANDALONE_
static
int grays_raster_new( void* memory,
FT_Raster* araster )
{
static TRaster the_raster;
FT_UNUSED( memory );
*araster = (FT_Raster)&the_raster;
memset( &the_raster, 0, sizeof ( the_raster ) );
return 0;
}
static
void grays_raster_done( FT_Raster raster )
{
/* nothing */
FT_UNUSED( raster );
}
#else /* _STANDALONE_ */
static
int grays_raster_new( FT_Memory memory,
FT_Raster* araster )
{
FT_Error error;
PRaster raster;
*araster = 0;
if ( !ALLOC( raster, sizeof ( TRaster ) ) )
{
raster->memory = memory;
*araster = (FT_Raster)raster;
}
return error;
}
static
void grays_raster_done( FT_Raster raster )
{
FT_Memory memory = (FT_Memory)((PRaster)raster)->memory;
FREE( raster );
}
#endif /* _STANDALONE_ */
static
void grays_raster_reset( FT_Raster raster,
const char* pool_base,
long pool_size )
{
PRaster rast = (PRaster)raster;
if ( raster && pool_base && pool_size >= 4096 )
init_cells( rast, (char*)pool_base, pool_size );
rast->band_size = ( pool_size / sizeof ( TCell ) ) / 8;
}
const FT_Raster_Funcs ft_grays_raster =
{
ft_glyph_format_outline,
(FT_Raster_New_Func) grays_raster_new,
(FT_Raster_Reset_Func) grays_raster_reset,
(FT_Raster_Set_Mode_Func)0,
(FT_Raster_Render_Func) grays_raster_render,
(FT_Raster_Done_Func) grays_raster_done
};
/* END */