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ftgrays.c
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/***************************************************************************/
/* */
/* ftgrays.c */
/* */
/* A new `perfect' anti-aliasing renderer (body). */
/* */
/* Copyright 2000-2001, 2002, 2003 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 -D_STANDALONE_ 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_grays_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. */
/* */
/* 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. */
/* */
/*************************************************************************/
/* experimental support for gamma correction within the rasterizer */
#define xxxGRAYS_USE_GAMMA
/*************************************************************************/
/* */
/* 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_smooth
#define ErrRaster_MemoryOverflow -4
#ifdef _STANDALONE_
#include <string.h> /* for ft_memcpy() */
#include <setjmp.h>
#include <limits.h>
#define FT_UINT_MAX UINT_MAX
#define ft_memset memset
#define ft_setjmp setjmp
#define ft_longjmp longjmp
#define ft_jmp_buf jmp_buf
#define ErrRaster_Invalid_Mode -2
#define ErrRaster_Invalid_Outline -1
#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 "ftgrays.h"
#include FT_INTERNAL_OBJECTS_H
#include FT_INTERNAL_DEBUG_H
#include FT_OUTLINE_H
#include "ftsmerrs.h"
#define ErrRaster_Invalid_Mode Smooth_Err_Cannot_Render_Glyph
#define ErrRaster_Invalid_Outline Smooth_Err_Invalid_Outline
#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
/* 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 ) ( (TCoord)((x) >> PIXEL_BITS) )
#define SUBPIXELS( x ) ( (TPos)(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. */
#undef GRAYS_COMPACT
/*************************************************************************/
/* */
/* 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 int TCoord; /* integer scanline/pixel coordinate */
typedef long TPos; /* sub-pixel coordinate */
/* determine the type used to store cell areas. This normally takes at */
/* least PIXEL_BYTES*2 + 1. On 16-bit systems, we need to use `long' */
/* instead of `int', otherwise bad things happen */
#if PIXEL_BITS <= 7
typedef int TArea;
#else /* PIXEL_BITS >= 8 */
/* approximately determine the size of integers using an ANSI-C header */
#if FT_UINT_MAX == 0xFFFFU
typedef long TArea;
#else
typedef int TArea;
#endif
#endif /* PIXEL_BITS >= 8 */
/* 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_
{
TCoord x;
TCoord y;
int cover;
TArea area;
} TCell, *PCell;
#endif /* GRAYS_COMPACT */
typedef struct TRaster_
{
PCell cells;
int max_cells;
int num_cells;
TPos min_ex, max_ex;
TPos min_ey, max_ey;
TArea area;
int cover;
int invalid;
TCoord ex, ey;
TCoord cx, cy;
TPos x, y;
TPos last_ey;
FT_Vector bez_stack[32 * 3 + 1];
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;
ft_jmp_buf jump_buffer;
#ifdef GRAYS_USE_GAMMA
unsigned char gamma[257];
#endif
} TRaster, *PRaster;
/*************************************************************************/
/* */
/* Initialize the cells table. */
/* */
static void
gray_init_cells( RAS_ARG_ void* buffer,
long byte_size )
{
ras.cells = (PCell)buffer;
ras.max_cells = (int)( byte_size / sizeof ( TCell ) );
ras.num_cells = 0;
ras.area = 0;
ras.cover = 0;
ras.invalid = 1;
}
/*************************************************************************/
/* */
/* Compute the outline bounding box. */
/* */
static void
gray_compute_cbox( RAS_ARG )
{
FT_Outline* outline = &ras.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 void
gray_record_cell( RAS_ARG )
{
PCell cell;
if ( !ras.invalid && ( ras.area | ras.cover ) )
{
if ( ras.num_cells >= ras.max_cells )
ft_longjmp( ras.jump_buffer, 1 );
cell = ras.cells + ras.num_cells++;
cell->x = (TCoord)(ras.ex - ras.min_ex);
cell->y = (TCoord)(ras.ey - ras.min_ey);
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 )
{
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 = (TCoord)(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 )
gray_record_cell( RAS_VAR );
if ( clean )
{
ras.area = 0;
ras.cover = 0;
}
ras.invalid = invalid;
ras.ex = ex;
ras.ey = ey;
}
/*************************************************************************/
/* */
/* Start a new contour at a given cell. */
/* */
static void
gray_start_cell( RAS_ARG_ TCoord ex,
TCoord ey )
{
if ( ex < ras.min_ex )
ex = (TCoord)(ras.min_ex - 1);
ras.area = 0;
ras.cover = 0;
ras.ex = ex;
ras.ey = ey;
ras.last_ey = SUBPIXELS( ey );
ras.invalid = 0;
gray_set_cell( RAS_VAR_ ex, ey );
}
/*************************************************************************/
/* */
/* 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, 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 = (TCoord)( x1 - SUBPIXELS( ex1 ) );
fx2 = (TCoord)( x2 - SUBPIXELS( ex2 ) );
/* trivial case. Happens often */
if ( y1 == y2 )
{
gray_set_cell( RAS_VAR_ ex2, ey );
return;
}
/* everything is located in a single cell. That is easy! */
/* */
if ( ex1 == ex2 )
{
delta = y2 - y1;
ras.area += (TArea)( fx1 + fx2 ) * delta;
ras.cover += delta;
return;
}
/* 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 = (TCoord)( p / dx );
mod = (TCoord)( p % dx );
if ( mod < 0 )
{
delta--;
mod += (TCoord)dx;
}
ras.area += (TArea)( fx1 + first ) * delta;
ras.cover += delta;
ex1 += incr;
gray_set_cell( RAS_VAR_ ex1, ey );
y1 += delta;
if ( ex1 != ex2 )
{
p = ONE_PIXEL * ( y2 - y1 + delta );
lift = (TCoord)( p / dx );
rem = (TCoord)( p % dx );
if ( rem < 0 )
{
lift--;
rem += (TCoord)dx;
}
mod -= (int)dx;
while ( ex1 != ex2 )
{
delta = lift;
mod += rem;
if ( mod >= 0 )
{
mod -= (TCoord)dx;
delta++;
}
ras.area += (TArea)ONE_PIXEL * delta;
ras.cover += delta;
y1 += delta;
ex1 += incr;
gray_set_cell( RAS_VAR_ ex1, ey );
}
}
delta = y2 - y1;
ras.area += (TArea)( fx2 + ONE_PIXEL - first ) * delta;
ras.cover += delta;
}
/*************************************************************************/
/* */
/* 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;
TPos dx, dy, x, x2;
long p, first;
int delta, rem, mod, lift, incr;
ey1 = TRUNC( ras.last_ey );
ey2 = TRUNC( to_y ); /* if (ey2 >= ras.max_ey) ey2 = ras.max_ey-1; */
fy1 = (TCoord)( ras.y - ras.last_ey );
fy2 = (TCoord)( 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 */
{
TCoord 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 )
{
gray_render_scanline( RAS_VAR_ ey1, ras.x, fy1, to_x, fy2 );
goto End;
}
/* vertical line - avoid calling gray_render_scanline */
incr = 1;
if ( dx == 0 )
{
TCoord ex = TRUNC( ras.x );
TCoord two_fx = (TCoord)( ( ras.x - SUBPIXELS( ex ) ) << 1 );
TPos area;
first = ONE_PIXEL;
if ( dy < 0 )
{
first = 0;
incr = -1;
}
delta = (int)( first - fy1 );
ras.area += (TArea)two_fx * delta;
ras.cover += delta;
ey1 += incr;
gray_set_cell( raster, ex, ey1 );
delta = (int)( first + first - ONE_PIXEL );
area = (TArea)two_fx * delta;
while ( ey1 != ey2 )
{
ras.area += area;
ras.cover += delta;
ey1 += incr;
gray_set_cell( raster, ex, ey1 );
}
delta = (int)( fy2 - ONE_PIXEL + first );
ras.area += (TArea)two_fx * delta;
ras.cover += delta;
goto End;
}
/* ok, we have to render several scanlines */
p = ( ONE_PIXEL - fy1 ) * dx;
first = ONE_PIXEL;
incr = 1;
if ( dy < 0 )
{
p = fy1 * dx;
first = 0;
incr = -1;
dy = -dy;
}
delta = (int)( p / dy );
mod = (int)( p % dy );
if ( mod < 0 )
{
delta--;
mod += (TCoord)dy;
}
x = ras.x + delta;
gray_render_scanline( RAS_VAR_ ey1, ras.x, fy1, x, (TCoord)first );
ey1 += incr;
gray_set_cell( RAS_VAR_ TRUNC( x ), ey1 );
if ( ey1 != ey2 )
{
p = ONE_PIXEL * dx;
lift = (int)( p / dy );
rem = (int)( p % dy );
if ( rem < 0 )
{
lift--;
rem += (int)dy;
}
mod -= (int)dy;
while ( ey1 != ey2 )
{
delta = lift;
mod += rem;
if ( mod >= 0 )
{
mod -= (int)dy;
delta++;
}
x2 = x + delta;
gray_render_scanline( RAS_VAR_ ey1, x,
(TCoord)( ONE_PIXEL - first ), x2,
(TCoord)first );
x = x2;
ey1 += incr;
gray_set_cell( RAS_VAR_ TRUNC( x ), ey1 );
}
}
gray_render_scanline( RAS_VAR_ ey1, x,
(TCoord)( ONE_PIXEL - first ), to_x,
fy2 );
End:
ras.x = to_x;
ras.y = to_y;
ras.last_ey = SUBPIXELS( ey2 );
}
static void
gray_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 void
gray_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 gray_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;
gray_render_line( RAS_VAR_ mid_x, mid_y );
gray_render_line( RAS_VAR_ to_x, to_y );
return;
}
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 ) < ras.min_ey )
goto Draw;
gray_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;
gray_render_line( RAS_VAR_ mid_x, mid_y );
gray_render_line( RAS_VAR_ to_x, to_y );
top--;
arc -= 2;
}
}
return;
}
static void
gray_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 void
gray_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;
gray_render_line( RAS_VAR_ mid_x, mid_y );
gray_render_line( RAS_VAR_ to_x, to_y );
return;
}
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;