ref: 7f7aadf4f7edfd29e0b9879791f897464d1d9e9f
dir: /demos/src/ftgrays.c/
/*****************************************************************************/
/* */
/* ftgrays.c - a new 'perfect' anti-aliasing renderer for FreeType 2 */
/* */
/* (c) 2000 David Turner - <[email protected]> */
/* */
/* Beware, this code is still in heavy beta.. */
/* */
/* 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.c". Actually, "ftgrays.c" 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 www.levien.com/libart for more information, */
/* though the web pages do not tell anything about the renderer, you'll */
/* have to dive in the source code to understand how it works..) */
/* */
/* Note however that this is a _very_ different implementation from */
/* 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: */
/* */
/* - doesn't need an intermediate bitmap. Instead, one can supply */
/* a callback fuction 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.. */
/* */
/* - perfect anti-aliaser, i.e. computes the _exact_ coverage on */
/* each pixel cell */
/* */
/* - performs a single pass on the outline (the 'standard' FT2 */
/* renderer performs two passes). */
/* */
/* - can easily be modified to render to _any_ number of gray levels */
/* cheaply.. */
/* */
/* It has the following disadvantages (for now): */
/* */
/* - need more memory than the standard scan-converter to render */
/* a single outline. Note that this may be changed in a near */
/* future (we might be able to pack the data in the TCell structure) */
/* */
/* - apparently, glyphs rendered with this module are a bit more */
/* "fuzzy" than those produced with the standard renderer. I hope */
/* to fix this using a gamma table somewhere.. */
/* */
/* */
#include <ftimage.h>
#define ErrRaster_Invalid_Outline -1
#include "ftgrays.h"
#define xxxDEBUG_GRAYS
#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
#define RAS_ARG
#define RAS_ARG_
#define RAS_VAR
#define RAS_VAR_
static TRaster ras;
#endif
#define PIXEL_BITS 7
#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)
#define UPSCALE(x) (PIXEL_BITS >= 6 ? (x) << (PIXEL_BITS-6) : (x) >> (6-PIXEL_BITS))
/****************************************************************************/
/* */
/* 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_ey */
/* */
/* Note that we 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;
/* we should do something about the trivial case where dx == 0, */
/* as it happens very often !! ... XXXXX */
/* everything is on a single scanline */
if ( ey1 == ey2 )
{
if (render_scanline( RAS_VAR_ ey1, ras.x, fy1, to_x, fy2 )) goto Error;
goto Fin;
}
/* ok, we'll have to render a run of adjacent cells on the same */
/* scanline.. */
/* */
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;
Fin:
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 = ras.x + to->x - (control->x << 1); if (dx < 0) dx = -dx;
dy = ras.y + to->y - (control->y << 1); if (dy < 0) dy = -dy;
if (dx < dy) dx = dy;
level = 1;
dx = dx/64;
while ( dx > 0 )
{
dx >>= 1;
level++;
}
if (level <= 1)
return render_line( RAS_VAR_ UPSCALE(to->x), UPSCALE(to->y) );
arc = ras.bez_stack;
arc[0] = *to;
arc[1] = *control;
arc[2].x = ras.x;
arc[2].y = ras.y;
arc[0].x = UPSCALE(arc[0].x);
arc[0].y = UPSCALE(arc[0].y);
arc[1].x = UPSCALE(arc[1].x);
arc[1].y = UPSCALE(arc[1].y);
levels = ras.lev_stack;
top = 0;
levels[0] = level;
for (;;)
{
level = levels[top];
if (level > 1)
{
split_conic(arc);
arc += 2;
top ++;
levels[top] = levels[top-1] = level-1;
}
else
{
if (render_line( RAS_VAR_ arc[0].x, arc[0].y )) return 1;
top--;
arc-=2;
if (top < 0)
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 = ras.x + to->x - (control1->x << 1); if (dx < 0) dx = -dx;
dy = ras.y + to->y - (control1->y << 1); if (dy < 0) dy = -dy;
if (dx < dy) dx = dy;
da = dx;
dx = ras.x + to->x - 3*(control1->x + control2->x); if (dx < 0) dx = -dx;
dy = ras.y + to->y - 3*(control1->x + control2->y); if (dy < 0) dy = -dy;
if (dx < dy) dx = dy;
db = dx;
level = 1;
while ( da > 0 || db > 0 )
{
da >>= 1;
db >>= 2;
level++;
}
if (level <= 1)
return render_line( RAS_VAR_ UPSCALE(to->x), UPSCALE(to->y) );
arc = ras.bez_stack;
arc[0] = *to;
arc[1] = *control2;
arc[2] = *control1;
arc[3].x = ras.x;
arc[3].y = ras.y;
arc[0].x = UPSCALE(arc[0].x);
arc[0].y = UPSCALE(arc[0].y);
arc[1].x = UPSCALE(arc[1].x);
arc[1].y = UPSCALE(arc[1].y);
arc[2].x = UPSCALE(arc[2].x);
arc[2].y = UPSCALE(arc[2].y);
levels = ras.lev_stack;
top = 0;
levels[0] = level;
for (;;)
{
level = levels[top];
if (level > 1)
{
split_cubic(arc);
arc += 3;
top ++;
levels[top] = levels[top-1] = level-1;
}
else
{
if (render_line( RAS_VAR_ arc[0].x, arc[0].y )) return 1;
top --;
arc -= 3;
if (top < 0)
return 0;
}
}
}
/* a macro comparing two cell pointers. returns true if a <= b */
#define LESS_THAN(a,b) ( (a)->y<(b)->y || ((a)->y==(b)->y && (a)->x<=(b)->x) )
#define SWAP_CELLS(a,b,temp) { temp = *(a); *(a) = *(b); *(b) = temp; }
#define DEBUG_SORT
#define SHELL_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
#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 4 /* 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 = limit-base;
PCell i, j;
if ( len > QSORT_THRESHOLD)
{
/* we use base+len/2 as the pivot */
SWAP_CELLS( base, base+len/2, temp );
i = base+1;
j = limit-1;
/* now ensure that *i <= *base <= *j */
if (LESS_THAN(j,i))
SWAP( i, j, temp );
if (LESS_THAN(base,i))
SWAP( base, i, temp );
if (LESS_THAN(j,base))
SWAP( base, j, temp );
for (;;)
{
do i++ while (LESS_THAN(i,base));
do j-- while (LESS_THAN(base,j));
if (i > j)
break;
SWAP( i,j );
}
/* move pivot to correct place */
SWAP( 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( j+1, j, temp );
if (j == base)
break;
}
}
}
}
}
#endif
#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
#endif
#if 0
static
int FT_Decompose_Outline( FT_Outline* outline,
FT_Outline_Funcs* interface,
void* user )
{
typedef enum _phases
{
phase_point,
phase_conic,
phase_cubic,
phase_cubic2
} TPhase;
FT_Vector v_first;
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 */
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_first = outline->points[first];
v_last = outline->points[last];
v_start = v_control = v_first;
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 */
{
error = interface->line_to( point, user );
if (error) goto Exit;
continue;
}
case FT_Curve_Tag_Conic: /* consume conic arcs */
{
v_control = point[0];
Do_Conic:
if (point < limit)
{
FT_Vector v_middle;
point++;
tags++;
tag = FT_CURVE_TAG( tags[0] );
if (tag == FT_Curve_Tag_On)
{
error = interface->conic_to( &v_control, point, user );
if (error) goto Exit;
continue;
}
if (tag != FT_Curve_Tag_Conic)
goto Invalid_Outline;
v_middle.x = (v_control.x + point->x)/2;
v_middle.y = (v_control.y + point->y)/2;
error = interface->conic_to( &v_control, &v_middle, user );
if (error) goto Exit;
v_control = point[0];
goto Do_Conic;
}
error = interface->conic_to( &v_control, &v_start, user );
goto Close;
}
default: /* FT_Curve_Tag_Cubic */
{
if ( point+1 > limit ||
FT_CURVE_TAG( tags[1] ) != FT_Curve_Tag_Cubic )
goto Invalid_Outline;
point += 2;
tags += 2;
if (point <= limit)
{
error = interface->cubic_to( point-2, point-1, point, user );
if (error) goto Exit;
continue;
}
error = interface->cubic_to( point-2, point-1, &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 -1;
}
#else
static
int FT_Decompose_Outline( FT_Outline* outline,
FT_Outline_Funcs* interface,
void* user )
{
typedef enum _phases
{
phase_point,
phase_conic,
phase_cubic,
phase_cubic2
} TPhase;
FT_Vector v_first;
FT_Vector v_last;
FT_Vector v_control;
FT_Vector v_control2;
FT_Vector v_start;
FT_Vector* point;
char* tags;
int n; /* index of contour in outline */
int first; /* index of first point in contour */
int index; /* current point's index */
int error;
char tag; /* current point's state */
TPhase phase;
first = 0;
for ( n = 0; n < outline->n_contours; n++ )
{
int last; /* index of last point in contour */
last = outline->contours[n];
v_first = outline->points[first];
v_last = outline->points[last];
v_start = v_control = v_first;
tag = FT_CURVE_TAG( outline->tags[first] );
index = first;
/* A contour cannot start with a cubic control point! */
if ( tag == FT_Curve_Tag_Cubic )
return ErrRaster_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;
}
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;
}
phase = phase_conic;
}
else
phase = phase_point;
/* Begin a new contour with MOVE_TO */
error = interface->move_to( &v_start, user );
if ( error )
return error;
point = outline->points + first;
tags = outline->tags + first;
/* now process each contour point individually */
while ( index < last )
{
index++;
point++;
tags++;
tag = FT_CURVE_TAG( tags[0] );
switch ( phase )
{
case phase_point: /* the previous point was on the curve */
switch ( tag )
{
/* two succesive on points -> emit segment */
case FT_Curve_Tag_On:
error = interface->line_to( point, user );
break;
/* on point + conic control -> remember control point */
case FT_Curve_Tag_Conic:
v_control = point[0];
phase = phase_conic;
break;
/* on point + cubic control -> remember first control */
default:
v_control = point[0];
phase = phase_cubic;
break;
}
break;
case phase_conic: /* the previous point was a conic control */
switch ( tag )
{
/* conic control + on point -> emit conic arc */
case FT_Curve_Tag_On:
error = interface->conic_to( &v_control, point, user );
phase = phase_point;
break;
/* two successive conics -> emit conic arc `in between' */
case FT_Curve_Tag_Conic:
{
FT_Vector v_middle;
v_middle.x = (v_control.x + point->x)/2;
v_middle.y = (v_control.y + point->y)/2;
error = interface->conic_to( &v_control,
&v_middle, user );
v_control = point[0];
}
break;
default:
error = ErrRaster_Invalid_Outline;
}
break;
case phase_cubic: /* the previous point was a cubic control */
/* this point _must_ be a cubic control too */
if ( tag != FT_Curve_Tag_Cubic )
return ErrRaster_Invalid_Outline;
v_control2 = point[0];
phase = phase_cubic2;
break;
case phase_cubic2: /* the two previous points were cubics */
/* this point _must_ be an on point */
if ( tag != FT_Curve_Tag_On )
error = ErrRaster_Invalid_Outline;
else
error = interface->cubic_to( &v_control, &v_control2,
point, user );
phase = phase_point;
break;
}
/* lazy error testing */
if ( error )
return error;
}
/* end of contour, close curve cleanly */
error = 0;
tag = FT_CURVE_TAG( outline->tags[first] );
switch ( phase )
{
case phase_point:
if ( tag == FT_Curve_Tag_On )
error = interface->line_to( &v_first, user );
break;
case phase_conic:
error = interface->conic_to( &v_control, &v_start, user );
break;
case phase_cubic2:
if ( tag == FT_Curve_Tag_On )
error = interface->cubic_to( &v_control, &v_control2,
&v_first, user );
else
error = ErrRaster_Invalid_Outline;
break;
default:
error = ErrRaster_Invalid_Outline;
break;
}
if ( error )
return error;
first = last + 1;
}
return 0;
}
#endif
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_GraySpan* spans, PRaster raster )
{
unsigned char *p, *q, *limit;
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)
{
q = p + spans->x;
limit = q + spans->len;
for ( ; q < limit; q++ )
q[0] = (spans->coverage+1) >> 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
#if 0
static
void grays_hline( RAS_ARG_ TScan x, TScan y, TPos area, int count )
{
if (area)
fprintf( stderr, "hline( %3d, %3d, %2d, %5.2f )\n",
y, x, count, (float)area/(2.0*ONE_PIXEL*ONE_PIXEL) );
}
#else
static
void grays_hline( RAS_ARG_ TScan x, TScan y, TPos area, int acount )
{
FT_GraySpan* 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 = 0;
else if (coverage == 256)
coverage = 255;
}
else
{
/* normal non-zero winding rule */
if (coverage < 0)
coverage = -coverage;
if (coverage >= 256)
coverage = 255;
}
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)
ras.render_span( ras.span_y, count, ras.gray_spans, ras.render_span_closure );
/* 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
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 char)acount;
span->coverage = (unsigned char)coverage;
ras.num_gray_spans++;
}
}
#endif
static
void grays_sweep( RAS_ARG_ FT_Bitmap* target )
{
TScan x, y, cover;
PCell start, cur, limit;
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;
/* accumulate all start cells */
for (;;)
{
++cur;
if (cur >= limit || cur->y != start->y || cur->x != start->x)
break;
start->area += cur->area;
start->cover += cur->cover;
}
/* compute next cover */
cover += start->cover;
/* if the start cell has a non-null area, we must draw an */
/* individual gray pixel there.. */
if (start->area && x >= 0)
{
grays_hline( RAS_VAR_ x, y, cover*(ONE_PIXEL*2)-start->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)
grays_hline( RAS_VAR_ x, y, cover*(ONE_PIXEL*2), ras.max_ex - x );
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_closure );
#ifdef DEBUG_GRAYS
{
int n;
FT_GraySpan* 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
}
static
int Convert_Glyph( RAS_ARG_ FT_Outline* outline )
{
static
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
};
/* Set up state in the raster object */
compute_cbox( RAS_VAR_ outline );
if (ras.min_ex < 0) ras.min_ex = 0;
if (ras.min_ey < 0) ras.min_ey = 0;
if (ras.max_ex > ras.target.width) ras.max_ex = ras.target.width;
if (ras.max_ey > ras.target.rows) ras.max_ey = ras.target.rows;
ras.num_cells = 0;
/* Now decompose curve */
if ( FT_Decompose_Outline( outline, &interface, &ras ) )
return 1;
/* XXX: the error condition is in ras.error */
/* record the last cell */
return record_cell( RAS_VAR );
}
extern
int grays_raster_render( TRaster* raster,
FT_Outline* outline,
FT_Bitmap* target_map )
{
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 -1;
if ( outline->n_points != outline->contours[outline->n_contours - 1] + 1 )
return -1;
if ( !target_map || !target_map->buffer )
return -1;
ras.outline = *outline;
ras.target = *target_map;
ras.num_cells = 0;
ras.invalid = 1;
if (Convert_Glyph( (PRaster)raster, outline ))
return 1;
shell_sort( ras.cells, ras.num_cells );
#ifdef DEBUG_GRAYS
check_sort( ras.cells, ras.num_cells );
dump_cells( RAS_VAR );
#endif
ras.render_span = (FT_GraySpan_Func)grays_render_span;
ras.render_span_closure = &ras;
grays_sweep( (PRaster)raster, target_map );
return 0;
}
extern
int grays_raster_init( FT_Raster raster,
const char* pool_base,
long pool_size )
{
/* static const char default_palette[5] = { 0, 1, 2, 3, 4 }; */
/* check the object address */
if ( !raster )
return -1;
/* check the render pool - we won't go under 4 Kb */
if ( !pool_base || pool_size < 4096 )
return -1;
/* save the pool */
init_cells( (PRaster)raster, (char*)pool_base, pool_size );
return 0;
}
FT_Raster_Interface ft_grays_raster =
{
sizeof( TRaster ),
ft_glyph_format_outline,
(FT_Raster_Init_Proc) grays_raster_init,
(FT_Raster_Set_Mode_Proc) 0,
(FT_Raster_Render_Proc) grays_raster_render
};