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Add `FT_Bitmap_Blend' API. 

Still missing: Support for negative bitmap pitch and subpixel offset
of source bitmap.

* include/freetype/ftbitmap.h, src/base/ftbitmap.c
(FT_Bitmap_Blend): New function.
This commit is contained in:
Werner Lemberg 2018-06-16 09:39:29 +02:00
parent 9b31c44620
commit 68bc56f864
3 changed files with 364 additions and 1 deletions
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10
ChangeLog
View File

@ -1,3 +1,13 @@
2018-06-16 Werner Lemberg <wl@gnu.org>
Add `FT_Bitmap_Blend' API.
Still missing: Support for negative bitmap pitch and subpixel offset
of source bitmap.
* include/freetype/ftbitmap.h, src/base/ftbitmap.c
(FT_Bitmap_Blend): New function.
2018-06-14 Werner Lemberg <wl@gnu.org>
Replace `FT_Get_GlyphLayers' with `FT_Get_Color_Glyph_Layer'.

59
include/freetype/ftbitmap.h
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@ -22,6 +22,7 @@
#include <ft2build.h>
#include FT_FREETYPE_H
#include FT_COLOR_H
#ifdef FREETYPE_H
#error "freetype.h of FreeType 1 has been loaded!"
@ -194,6 +195,64 @@ FT_BEGIN_HEADER
FT_Int alignment );
/**************************************************************************
*
* @Function:
* FT_Bitmap_Blend
*
* @Description:
* Blend a bitmap onto another bitmap, using a given color.
*
* @Input:
* library ::
* A handle to a library object.
*
* source ::
* The source bitmap, which can have any @FT_Pixel_Mode format.
*
* source_offset ::
* The offset vector to the upper left corner of the source bitmap in
* 26.6 pixel format. This can be a fractional pixel value.
*
* color ::
* The color used to draw `source' onto `target'.
*
* @InOut:
* target ::
* A handle to an `FT_Bitmap' object. It should be either initialized
* as empty with a call to @FT_Bitmap_Init, or it should be of type
* @FT_PIXEL_MODE_BGRA.
*
* atarget_offset ::
* The offset vector to the upper left corner of the target bitmap in
* 26.6 pixel format. It should represent an integer offset; the
* function will set the lowest six bits to zero to enforce that.
*
* @Return:
* FreeType error code. 0~means success.
*
* @Note:
* This function doesn't perform clipping.
*
* The bitmap in `target' gets allocated or reallocated as needed; the
* vector `atarget_offset' is updated accordingly.
*
* In case of allocation or reallocation, the bitmap's pitch is set to
* `4~*~width'. Both `source' and `target' must have the same bitmap
* flow (as indicated by the sign of the `pitch' field).
*
* @Since:
* 2.10
*/
FT_EXPORT( FT_Error )
FT_Bitmap_Blend( FT_Library library,
const FT_Bitmap* source,
const FT_Vector source_offset,
FT_Bitmap* target,
FT_Vector *atarget_offset,
FT_Color color );
/**************************************************************************
*
* @Function:

296
src/base/ftbitmap.c
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@ -25,7 +25,7 @@
static
const FT_Bitmap null_bitmap = { 0, 0, 0, 0, 0, 0, 0, 0 };
const FT_Bitmap null_bitmap = { 0, 0, 0, NULL, 0, 0, 0, NULL };
/* documentation is in ftbitmap.h */
@ -783,6 +783,300 @@
}
/* documentation is in ftbitmap.h */
FT_EXPORT_DEF( FT_Error )
FT_Bitmap_Blend( FT_Library library,
const FT_Bitmap* source_,
const FT_Vector source_offset_,
FT_Bitmap* target,
FT_Vector *atarget_offset,
FT_Color color )
{
FT_Error error = FT_Err_Ok;
FT_Memory memory;
FT_Bitmap source_bitmap;
const FT_Bitmap* source;
FT_Vector source_offset;
FT_Vector target_offset;
FT_Vector frac_offset;
FT_Bool free_source_bitmap = 0;
FT_Bool free_target_bitmap_on_error = 0;
FT_Pos source_llx, source_lly, source_urx, source_ury;
FT_Pos target_llx, target_lly, target_urx, target_ury;
FT_Pos final_llx, final_lly, final_urx, final_ury;
unsigned int final_rows, final_width;
long x, y;
if ( !library || !target || !source_ || !atarget_offset )
return FT_THROW( Invalid_Argument );
memory = library->memory;
if ( !( target->pixel_mode == FT_PIXEL_MODE_NONE ||
( target->pixel_mode == FT_PIXEL_MODE_BGRA &&
target->buffer ) ) )
return FT_THROW( Invalid_Argument );
if ( source_->pixel_mode == FT_PIXEL_MODE_NONE )
return FT_Err_Ok; /* nothing to do */
/* pitches must have the same sign */
if ( target->pixel_mode == FT_PIXEL_MODE_BGRA &&
( source_->pitch ^ target->pitch ) < 0 )
return FT_THROW( Invalid_Argument );
if ( !( source_->width && source_->rows ) )
return FT_Err_Ok; /* nothing to do */
/* we isolate a fractional shift of `source', */
/* to be less than one pixel and always positive; */
/* `source_offset' now holds full-pixel shift values */
source_offset.x = FT_PIX_FLOOR( source_offset_.x );
frac_offset.x = source_offset_.x - source_offset.x;
source_offset.y = FT_PIX_FLOOR( source_offset_.y );
frac_offset.y = source_offset_.y - source_offset.y;
/* assure integer pixel offset for target bitmap */
target_offset.x = FT_PIX_FLOOR( atarget_offset->x );
target_offset.y = FT_PIX_FLOOR( atarget_offset->y );
/* get source bitmap dimensions */
source_llx = source_offset.x;
if ( FT_LONG_MIN + ( source_->rows << 6 ) + 64 > source_offset.y )
return FT_THROW( Invalid_Argument );
source_lly = source_offset.y - ( source_->rows << 6 );
if ( FT_LONG_MAX - ( source_->width << 6 ) - 64 < source_llx )
return FT_THROW( Invalid_Argument );
source_urx = source_llx + ( source_->width << 6 );
source_ury = source_offset.y;
/* get target bitmap dimensions */
if ( target->width && target->rows )
{
target_llx = target_offset.x;
if ( FT_LONG_MIN + ( target->rows << 6 ) > target_offset.y )
return FT_THROW( Invalid_Argument );
target_lly = target_offset.y - ( target->rows << 6 );
if ( FT_LONG_MAX - ( target->width << 6 ) < target_llx )
return FT_THROW( Invalid_Argument );
target_urx = target_llx + ( target->width << 6 );
target_ury = target_offset.y;
}
else
{
target_llx = FT_LONG_MAX;
target_lly = FT_LONG_MAX;
target_urx = FT_LONG_MIN;
target_ury = FT_LONG_MIN;
}
/* move upper right corner up and to the right */
/* if we have a fractional offset */
if ( source_urx >= target_urx && frac_offset.x )
source_urx += 64;
if ( source_ury >= target_ury && frac_offset.y )
source_ury += 64;
/* compute final bitmap dimensions */
final_llx = FT_MIN( source_llx, target_llx );
final_lly = FT_MIN( source_lly, target_lly );
final_urx = FT_MAX( source_urx, target_urx );
final_ury = FT_MAX( source_ury, target_ury );
final_width = ( final_urx - final_llx ) >> 6;
final_rows = ( final_ury - final_lly ) >> 6;
/* for blending, set offset vector of final bitmap */
/* temporarily to (0,0) */
source_llx -= final_llx;
source_lly -= final_lly;
target_llx -= final_llx;
target_lly -= final_lly;
/* set up target bitmap */
if ( target->pixel_mode == FT_PIXEL_MODE_NONE )
{
/* create new empty bitmap */
target->width = final_width;
target->rows = final_rows;
target->pixel_mode = FT_PIXEL_MODE_BGRA;
target->pitch = (int)final_width * 4;
target->num_grays = 256;
if ( FT_LONG_MAX / target->pitch < target->rows )
return FT_THROW( Invalid_Argument );
if ( FT_ALLOC( target->buffer, target->pitch * (int)target->rows ) )
return error;
free_target_bitmap_on_error = 1;
}
else if ( target->width != final_width ||
target->rows != final_rows )
{
/* adjust old bitmap to enlarged size */
int pitch, new_pitch;
unsigned char* buffer = NULL;
pitch = target->pitch;
if ( pitch < 0 )
pitch = -pitch;
new_pitch = (int)final_width * 4;
if ( FT_LONG_MAX / new_pitch < final_rows )
return FT_THROW( Invalid_Argument );
/* TODO: provide an in-buffer solution for large bitmaps */
/* to avoid allocation of a new buffer */
if ( FT_ALLOC( buffer, new_pitch * (int)final_rows ) )
goto Error;
/* copy data to new buffer */
x = target_llx >> 6;
y = target_lly >> 6;
/* the bitmap flow is from top to bottom, */
/* but y is measured from bottom to top */
if ( target->pitch < 0 )
{
/* XXX */
}
else
{
unsigned char* p =
target->buffer;
unsigned char* q =
buffer +
( final_rows - y - target->rows ) * new_pitch +
x * 4;
unsigned char* limit_p =
p + pitch * (int)target->rows;
while ( p < limit_p )
{
FT_MEM_COPY( q, p, pitch );
p += pitch;
q += new_pitch;
}
}
FT_FREE( target->buffer );
target->width = final_width;
target->rows = final_rows;
if ( target->pitch < 0 )
target->pitch = -new_pitch;
else
target->pitch = new_pitch;
target->buffer = buffer;
}
/* adjust source bitmap if necessary */
if ( source_->pixel_mode != FT_PIXEL_MODE_GRAY )
{
FT_Bitmap_Init( &source_bitmap );
error = FT_Bitmap_Convert( library, source_, &source_bitmap, 1 );
if ( error )
goto Error;
source = &source_bitmap;
free_source_bitmap = 1;
}
else
source = source_;
/* do blending; the code below returns pre-multiplied channels, */
/* similar to what FreeType gets from `CBDT' tables */
x = source_llx >> 6;
y = source_lly >> 6;
/* XXX handle `frac_offset' */
/* the bitmap flow is from top to bottom, */
/* but y is measured from bottom to top */
if ( target->pitch < 0 )
{
/* XXX */
}
else
{
unsigned char* p =
source->buffer;
unsigned char* q =
target->buffer +
( target->rows - y - source->rows ) * target->pitch +
x * 4;
unsigned char* limit_p =
p + source->pitch * (int)source->rows;
while ( p < limit_p )
{
unsigned char* r = p;
unsigned char* s = q;
unsigned char* limit_r = r + source->width;
while ( r < limit_r )
{
int aa = *r++;
int fa = color.alpha * aa / 255;
int fb = color.blue * fa / 255;
int fg = color.green * fa / 255;
int fr = color.red * fa / 255;
int ba2 = 255 - fa;
int bb = s[0];
int bg = s[1];
int br = s[2];
int ba = s[3];
*s++ = (unsigned char)( bb * ba2 / 255 + fb );
*s++ = (unsigned char)( bg * ba2 / 255 + fg );
*s++ = (unsigned char)( br * ba2 / 255 + fr );
*s++ = (unsigned char)( ba * ba2 / 255 + fa );
}
p += source->pitch;
q += target->pitch;
}
}
atarget_offset->x = final_llx;
atarget_offset->y = final_lly + ( final_rows << 6 );
Error:
if ( error && free_target_bitmap_on_error )
FT_Bitmap_Done( library, target );
if ( free_source_bitmap )
FT_Bitmap_Done( library, &source_bitmap );
return error;
}
/* documentation is in ftbitmap.h */
FT_EXPORT_DEF( FT_Error )