fdo-mirrors/freetype
1
0
Fork 0
mirror of https://gitlab.freedesktop.org/freetype/freetype.git synced 2026-05-05 08:58:00 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions

[base] Remove legacy LCD filter.

Browse source 
* src/base/ftlcdfil.c (_ft_lcd_filter_legacy): Removed.
(FT_Library_SetLcdFilter): Updated.
* include/freetype/ftlcdfil.h (FT_LcdFilter): Updated.
* doc/CHANGES: Updated.
This commit is contained in:
Alexei Podtelezhnikov 2026-01-25 14:51:59 -05:00
parent 83f543a82b
commit 084bf2898b
3 changed files with 12 additions and 129 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

12
docs/CHANGES
View file

@ -1,6 +1,14 @@
CHANGES BETWEEN 2.14.1 and 2.14.2 (2025-Mmm-DD)
CHANGES BETWEEN 2.14.1 and 2.14.2 (2026-Mmm-DD)
I. IMPORTANT BUG FIXES
I. IMPORTANT CHANGES
- Several changes related to LCD filtering are implemented to
achieve better performance and encourage sound practices.
. The legacy libXft LCD filter algorithm is no longer provided.
II. IMPORTANT BUG FIXES
- The italic angle in `PS_FontInfo` is now stored as a fixed-point
value in degrees for all Type 1 fonts and their derivatives,

10
include/freetype/ftlcdfil.h
View file

@ -145,16 +145,10 @@ FT_BEGIN_HEADER
*
* FT_LCD_FILTER_LEGACY ::
* FT_LCD_FILTER_LEGACY1 ::
* This filter corresponds to the original libXft color filter. It
* provides high contrast output but can exhibit really bad color
* fringes if glyphs are not extremely well hinted to the pixel grid.
* This filter is only provided for comparison purposes, and might be
* disabled or stay unsupported in the future. The second value is
* provided for compatibility with FontConfig, which historically used
* different enumeration, sometimes incorrectly forwarded to FreeType.
* The legacy libXft color filter is no longer supported and ignored.
*
* @since:
* 2.3.0 (`FT_LCD_FILTER_LEGACY1` since 2.6.2)
* 2.3.0
*/
typedef enum FT_LcdFilter_
{

119
src/base/ftlcdfil.c
View file

@ -25,9 +25,6 @@
#ifdef FT_CONFIG_OPTION_SUBPIXEL_RENDERING
/* define USE_LEGACY to implement the legacy filter */
#define USE_LEGACY
#define FT_SHIFTCLAMP( x ) ( x >>= 8, (FT_Byte)( x > 255 ? 255 : x ) )
@ -177,113 +174,6 @@
}
#ifdef USE_LEGACY
/* intra-pixel filter used by the legacy filter */
static void
_ft_lcd_filter_legacy( FT_Bitmap* bitmap,
FT_Byte* weights )
{
FT_UInt width = (FT_UInt)bitmap->width;
FT_UInt height = (FT_UInt)bitmap->rows;
FT_Int pitch = bitmap->pitch;
FT_Byte* origin = bitmap->buffer;
FT_Byte mode = bitmap->pixel_mode;
static const unsigned int filters[3][3] =
{
{ 65538 * 9/13, 65538 * 1/6, 65538 * 1/13 },
{ 65538 * 3/13, 65538 * 4/6, 65538 * 3/13 },
{ 65538 * 1/13, 65538 * 1/6, 65538 * 9/13 }
};
FT_UNUSED( weights );
/* take care of bitmap flow */
if ( pitch > 0 && height > 0 )
origin += pitch * (FT_Int)( height - 1 );
/* horizontal in-place intra-pixel filter */
if ( mode == FT_PIXEL_MODE_LCD && width >= 3 )
{
FT_Byte* line = origin;
for ( ; height > 0; height--, line -= pitch )
{
FT_UInt xx;
for ( xx = 0; xx < width; xx += 3 )
{
FT_UInt r, g, b;
FT_UInt p;
p = line[xx];
r = filters[0][0] * p;
g = filters[0][1] * p;
b = filters[0][2] * p;
p = line[xx + 1];
r += filters[1][0] * p;
g += filters[1][1] * p;
b += filters[1][2] * p;
p = line[xx + 2];
r += filters[2][0] * p;
g += filters[2][1] * p;
b += filters[2][2] * p;
line[xx] = (FT_Byte)( r / 65536 );
line[xx + 1] = (FT_Byte)( g / 65536 );
line[xx + 2] = (FT_Byte)( b / 65536 );
}
}
}
else if ( mode == FT_PIXEL_MODE_LCD_V && height >= 3 )
{
FT_Byte* column = origin;
for ( ; width > 0; width--, column++ )
{
FT_Byte* col = column - 2 * pitch;
for ( ; height > 0; height -= 3, col -= 3 * pitch )
{
FT_UInt r, g, b;
FT_UInt p;
p = col[0];
r = filters[0][0] * p;
g = filters[0][1] * p;
b = filters[0][2] * p;
p = col[pitch];
r += filters[1][0] * p;
g += filters[1][1] * p;
b += filters[1][2] * p;
p = col[pitch * 2];
r += filters[2][0] * p;
g += filters[2][1] * p;
b += filters[2][2] * p;
col[0] = (FT_Byte)( r / 65536 );
col[pitch] = (FT_Byte)( g / 65536 );
col[pitch * 2] = (FT_Byte)( b / 65536 );
}
}
}
}
#endif /* USE_LEGACY */
/* documentation in ftlcdfil.h */
FT_EXPORT_DEF( FT_Error )
@ -338,15 +228,6 @@
library->lcd_filter_func = ft_lcd_filter_fir;
break;
#ifdef USE_LEGACY
case FT_LCD_FILTER_LEGACY:
case FT_LCD_FILTER_LEGACY1:
library->lcd_filter_func = _ft_lcd_filter_legacy;
break;
#endif
default:
return FT_THROW( Invalid_Argument );
}