ref: 93e6b3e8e955d23d759ef0310c666b4aac915f79
dir: /src/smooth/ftsmooth.c/
/****************************************************************************
*
* ftsmooth.c
*
* Anti-aliasing renderer interface (body).
*
* Copyright (C) 2000-2021 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.
*
*/
#include <freetype/internal/ftdebug.h>
#include <freetype/internal/ftobjs.h>
#include <freetype/ftoutln.h>
#include "ftsmooth.h"
#include "ftgrays.h"
#include "ftsmerrs.h"
/* sets render-specific mode */
static FT_Error
ft_smooth_set_mode( FT_Renderer render,
FT_ULong mode_tag,
FT_Pointer data )
{
/* we simply pass it to the raster */
return render->clazz->raster_class->raster_set_mode( render->raster,
mode_tag,
data );
}
/* transform a given glyph image */
static FT_Error
ft_smooth_transform( FT_Renderer render,
FT_GlyphSlot slot,
const FT_Matrix* matrix,
const FT_Vector* delta )
{
FT_Error error = FT_Err_Ok;
if ( slot->format != render->glyph_format )
{
error = FT_THROW( Invalid_Argument );
goto Exit;
}
if ( matrix )
FT_Outline_Transform( &slot->outline, matrix );
if ( delta )
FT_Outline_Translate( &slot->outline, delta->x, delta->y );
Exit:
return error;
}
/* return the glyph's control box */
static void
ft_smooth_get_cbox( FT_Renderer render,
FT_GlyphSlot slot,
FT_BBox* cbox )
{
FT_ZERO( cbox );
if ( slot->format == render->glyph_format )
FT_Outline_Get_CBox( &slot->outline, cbox );
}
typedef struct TOrigin_
{
unsigned char* origin; /* pixmap origin at the bottom-left */
int pitch; /* pitch to go down one row */
} TOrigin;
#ifndef FT_CONFIG_OPTION_SUBPIXEL_RENDERING
/* initialize renderer -- init its raster */
static FT_Error
ft_smooth_init( FT_Renderer render )
{
FT_Vector* sub = render->root.library->lcd_geometry;
/* set up default subpixel geometry for striped RGB panels. */
sub[0].x = -21;
sub[0].y = 0;
sub[1].x = 0;
sub[1].y = 0;
sub[2].x = 21;
sub[2].y = 0;
render->clazz->raster_class->raster_reset( render->raster, NULL, 0 );
return 0;
}
/* This function writes every third byte in direct rendering mode */
static void
ft_smooth_lcd_spans( int y,
int count,
const FT_Span* spans,
TOrigin* target )
{
unsigned char* dst_line = target->origin - y * target->pitch;
unsigned char* dst;
unsigned short w;
for ( ; count--; spans++ )
for ( dst = dst_line + spans->x * 3, w = spans->len; w--; dst += 3 )
*dst = spans->coverage;
}
static FT_Error
ft_smooth_raster_lcd( FT_Renderer render,
FT_Outline* outline,
FT_Bitmap* bitmap )
{
FT_Error error = FT_Err_Ok;
FT_Vector* sub = render->root.library->lcd_geometry;
FT_Pos x, y;
FT_Raster_Params params;
TOrigin target;
/* Render 3 separate coverage bitmaps, shifting the outline. */
/* Set up direct rendering to record them on each third byte. */
params.source = outline;
params.flags = FT_RASTER_FLAG_AA | FT_RASTER_FLAG_DIRECT;
params.gray_spans = (FT_SpanFunc)ft_smooth_lcd_spans;
params.user = ⌖
params.clip_box.xMin = 0;
params.clip_box.yMin = 0;
params.clip_box.xMax = bitmap->width;
params.clip_box.yMax = bitmap->rows;
if ( bitmap->pitch < 0 )
target.origin = bitmap->buffer;
else
target.origin = bitmap->buffer
+ ( bitmap->rows - 1 ) * (unsigned int)bitmap->pitch;
target.pitch = bitmap->pitch;
FT_Outline_Translate( outline,
-sub[0].x,
-sub[0].y );
error = render->raster_render( render->raster, ¶ms );
x = sub[0].x;
y = sub[0].y;
if ( error )
goto Exit;
target.origin++;
FT_Outline_Translate( outline,
sub[0].x - sub[1].x,
sub[0].y - sub[1].y );
error = render->raster_render( render->raster, ¶ms );
x = sub[1].x;
y = sub[1].y;
if ( error )
goto Exit;
target.origin++;
FT_Outline_Translate( outline,
sub[1].x - sub[2].x,
sub[1].y - sub[2].y );
error = render->raster_render( render->raster, ¶ms );
x = sub[2].x;
y = sub[2].y;
Exit:
FT_Outline_Translate( outline, x, y );
return error;
}
static FT_Error
ft_smooth_raster_lcdv( FT_Renderer render,
FT_Outline* outline,
FT_Bitmap* bitmap )
{
FT_Error error = FT_Err_Ok;
int pitch = bitmap->pitch;
FT_Vector* sub = render->root.library->lcd_geometry;
FT_Pos x, y;
FT_Raster_Params params;
params.target = bitmap;
params.source = outline;
params.flags = FT_RASTER_FLAG_AA;
/* Render 3 separate coverage bitmaps, shifting the outline. */
/* Notice that the subpixel geometry vectors are rotated. */
/* Triple the pitch to render on each third row. */
bitmap->pitch *= 3;
bitmap->rows /= 3;
FT_Outline_Translate( outline,
-sub[0].y,
sub[0].x );
error = render->raster_render( render->raster, ¶ms );
x = sub[0].y;
y = -sub[0].x;
if ( error )
goto Exit;
bitmap->buffer += pitch;
FT_Outline_Translate( outline,
sub[0].y - sub[1].y,
sub[1].x - sub[0].x );
error = render->raster_render( render->raster, ¶ms );
x = sub[1].y;
y = -sub[1].x;
bitmap->buffer -= pitch;
if ( error )
goto Exit;
bitmap->buffer += 2 * pitch;
FT_Outline_Translate( outline,
sub[1].y - sub[2].y,
sub[2].x - sub[1].x );
error = render->raster_render( render->raster, ¶ms );
x = sub[2].y;
y = -sub[2].x;
bitmap->buffer -= 2 * pitch;
Exit:
FT_Outline_Translate( outline, x, y );
bitmap->pitch /= 3;
bitmap->rows *= 3;
return error;
}
#else /* FT_CONFIG_OPTION_SUBPIXEL_RENDERING */
/* initialize renderer -- init its raster */
static FT_Error
ft_smooth_init( FT_Renderer render )
{
/* set up default LCD filtering */
FT_Library_SetLcdFilter( render->root.library, FT_LCD_FILTER_DEFAULT );
render->clazz->raster_class->raster_reset( render->raster, NULL, 0 );
return 0;
}
static FT_Error
ft_smooth_raster_lcd( FT_Renderer render,
FT_Outline* outline,
FT_Bitmap* bitmap )
{
FT_Error error = FT_Err_Ok;
FT_Vector* points = outline->points;
FT_Vector* points_end = FT_OFFSET( points, outline->n_points );
FT_Vector* vec;
FT_Raster_Params params;
params.target = bitmap;
params.source = outline;
params.flags = FT_RASTER_FLAG_AA;
/* implode outline */
for ( vec = points; vec < points_end; vec++ )
vec->x *= 3;
/* render outline into the bitmap */
error = render->raster_render( render->raster, ¶ms );
/* deflate outline */
for ( vec = points; vec < points_end; vec++ )
vec->x /= 3;
return error;
}
static FT_Error
ft_smooth_raster_lcdv( FT_Renderer render,
FT_Outline* outline,
FT_Bitmap* bitmap )
{
FT_Error error = FT_Err_Ok;
FT_Vector* points = outline->points;
FT_Vector* points_end = FT_OFFSET( points, outline->n_points );
FT_Vector* vec;
FT_Raster_Params params;
params.target = bitmap;
params.source = outline;
params.flags = FT_RASTER_FLAG_AA;
/* implode outline */
for ( vec = points; vec < points_end; vec++ )
vec->y *= 3;
/* render outline into the bitmap */
error = render->raster_render( render->raster, ¶ms );
/* deflate outline */
for ( vec = points; vec < points_end; vec++ )
vec->y /= 3;
return error;
}
#endif /* FT_CONFIG_OPTION_SUBPIXEL_RENDERING */
/* Oversampling scale to be used in rendering overlaps */
#define SCALE ( 1 << 2 )
/* This function averages inflated spans in direct rendering mode */
static void
ft_smooth_overlap_spans( int y,
int count,
const FT_Span* spans,
TOrigin* target )
{
unsigned char* dst = target->origin - ( y / SCALE ) * target->pitch;
unsigned short x;
unsigned int cover, sum;
/* When accumulating the oversampled spans we need to assure that */
/* fully covered pixels are equal to 255 and do not overflow. */
/* It is important that the SCALE is a power of 2, each subpixel */
/* cover can also reach a power of 2 after rounding, and the total */
/* is clamped to 255 when it adds up to 256. */
for ( ; count--; spans++ )
{
cover = ( spans->coverage + SCALE * SCALE / 2 ) / ( SCALE * SCALE );
for ( x = 0; x < spans->len; x++ )
{
sum = dst[( spans->x + x ) / SCALE] + cover;
dst[( spans->x + x ) / SCALE] = (unsigned char)( sum - ( sum >> 8 ) );
}
}
}
static FT_Error
ft_smooth_raster_overlap( FT_Renderer render,
FT_Outline* outline,
FT_Bitmap* bitmap )
{
FT_Error error = FT_Err_Ok;
FT_Vector* points = outline->points;
FT_Vector* points_end = FT_OFFSET( points, outline->n_points );
FT_Vector* vec;
FT_Raster_Params params;
TOrigin target;
/* Reject outlines that are too wide for 16-bit FT_Span. */
/* Other limits are applied upstream with the same error code. */
if ( bitmap->width * SCALE > 0x7FFF )
return FT_THROW( Raster_Overflow );
/* Set up direct rendering to average oversampled spans. */
params.source = outline;
params.flags = FT_RASTER_FLAG_AA | FT_RASTER_FLAG_DIRECT;
params.gray_spans = (FT_SpanFunc)ft_smooth_overlap_spans;
params.user = ⌖
params.clip_box.xMin = 0;
params.clip_box.yMin = 0;
params.clip_box.xMax = bitmap->width * SCALE;
params.clip_box.yMax = bitmap->rows * SCALE;
if ( bitmap->pitch < 0 )
target.origin = bitmap->buffer;
else
target.origin = bitmap->buffer
+ ( bitmap->rows - 1 ) * (unsigned int)bitmap->pitch;
target.pitch = bitmap->pitch;
/* inflate outline */
for ( vec = points; vec < points_end; vec++ )
{
vec->x *= SCALE;
vec->y *= SCALE;
}
/* render outline into the bitmap */
error = render->raster_render( render->raster, ¶ms );
/* deflate outline */
for ( vec = points; vec < points_end; vec++ )
{
vec->x /= SCALE;
vec->y /= SCALE;
}
return error;
}
#undef SCALE
static FT_Error
ft_smooth_render( FT_Renderer render,
FT_GlyphSlot slot,
FT_Render_Mode mode,
const FT_Vector* origin )
{
FT_Error error = FT_Err_Ok;
FT_Outline* outline = &slot->outline;
FT_Bitmap* bitmap = &slot->bitmap;
FT_Memory memory = render->root.memory;
FT_Pos x_shift = 0;
FT_Pos y_shift = 0;
/* check glyph image format */
if ( slot->format != render->glyph_format )
{
error = FT_THROW( Invalid_Argument );
goto Exit;
}
/* check mode */
if ( mode != FT_RENDER_MODE_NORMAL &&
mode != FT_RENDER_MODE_LIGHT &&
mode != FT_RENDER_MODE_LCD &&
mode != FT_RENDER_MODE_LCD_V )
{
error = FT_THROW( Cannot_Render_Glyph );
goto Exit;
}
/* release old bitmap buffer */
if ( slot->internal->flags & FT_GLYPH_OWN_BITMAP )
{
FT_FREE( bitmap->buffer );
slot->internal->flags &= ~FT_GLYPH_OWN_BITMAP;
}
if ( ft_glyphslot_preset_bitmap( slot, mode, origin ) )
{
error = FT_THROW( Raster_Overflow );
goto Exit;
}
if ( !bitmap->rows || !bitmap->pitch )
goto Exit;
/* allocate new one */
if ( FT_ALLOC_MULT( bitmap->buffer, bitmap->rows, bitmap->pitch ) )
goto Exit;
slot->internal->flags |= FT_GLYPH_OWN_BITMAP;
x_shift = 64 * -slot->bitmap_left;
y_shift = 64 * -slot->bitmap_top;
if ( bitmap->pixel_mode == FT_PIXEL_MODE_LCD_V )
y_shift += 64 * (FT_Int)bitmap->rows / 3;
else
y_shift += 64 * (FT_Int)bitmap->rows;
if ( origin )
{
x_shift += origin->x;
y_shift += origin->y;
}
/* translate outline to render it into the bitmap */
if ( x_shift || y_shift )
FT_Outline_Translate( outline, x_shift, y_shift );
if ( mode == FT_RENDER_MODE_NORMAL ||
mode == FT_RENDER_MODE_LIGHT )
{
if ( outline->flags & FT_OUTLINE_OVERLAP )
error = ft_smooth_raster_overlap( render, outline, bitmap );
else
{
FT_Raster_Params params;
params.target = bitmap;
params.source = outline;
params.flags = FT_RASTER_FLAG_AA;
error = render->raster_render( render->raster, ¶ms );
}
}
else
{
if ( mode == FT_RENDER_MODE_LCD )
error = ft_smooth_raster_lcd ( render, outline, bitmap );
else if ( mode == FT_RENDER_MODE_LCD_V )
error = ft_smooth_raster_lcdv( render, outline, bitmap );
#ifdef FT_CONFIG_OPTION_SUBPIXEL_RENDERING
/* finally apply filtering */
{
FT_Byte* lcd_weights;
FT_Bitmap_LcdFilterFunc lcd_filter_func;
/* Per-face LCD filtering takes priority if set up. */
if ( slot->face && slot->face->internal->lcd_filter_func )
{
lcd_weights = slot->face->internal->lcd_weights;
lcd_filter_func = slot->face->internal->lcd_filter_func;
}
else
{
lcd_weights = slot->library->lcd_weights;
lcd_filter_func = slot->library->lcd_filter_func;
}
if ( lcd_filter_func )
lcd_filter_func( bitmap, lcd_weights );
}
#endif /* FT_CONFIG_OPTION_SUBPIXEL_RENDERING */
}
Exit:
if ( !error )
{
/* everything is fine; the glyph is now officially a bitmap */
slot->format = FT_GLYPH_FORMAT_BITMAP;
}
else if ( slot->internal->flags & FT_GLYPH_OWN_BITMAP )
{
FT_FREE( bitmap->buffer );
slot->internal->flags &= ~FT_GLYPH_OWN_BITMAP;
}
if ( x_shift || y_shift )
FT_Outline_Translate( outline, -x_shift, -y_shift );
return error;
}
FT_DEFINE_RENDERER(
ft_smooth_renderer_class,
FT_MODULE_RENDERER,
sizeof ( FT_RendererRec ),
"smooth",
0x10000L,
0x20000L,
NULL, /* module specific interface */
(FT_Module_Constructor)ft_smooth_init, /* module_init */
(FT_Module_Destructor) NULL, /* module_done */
(FT_Module_Requester) NULL, /* get_interface */
FT_GLYPH_FORMAT_OUTLINE,
(FT_Renderer_RenderFunc) ft_smooth_render, /* render_glyph */
(FT_Renderer_TransformFunc)ft_smooth_transform, /* transform_glyph */
(FT_Renderer_GetCBoxFunc) ft_smooth_get_cbox, /* get_glyph_cbox */
(FT_Renderer_SetModeFunc) ft_smooth_set_mode, /* set_mode */
(FT_Raster_Funcs*)&ft_grays_raster /* raster_class */
)
/* END */