diff options
Diffstat (limited to 'modules/freetype2/include/freetype/ftlcdfil.h')
| -rw-r--r-- | modules/freetype2/include/freetype/ftlcdfil.h | 43 |
1 files changed, 33 insertions, 10 deletions
diff --git a/modules/freetype2/include/freetype/ftlcdfil.h b/modules/freetype2/include/freetype/ftlcdfil.h index e06a8957f..2a27196cb 100644 --- a/modules/freetype2/include/freetype/ftlcdfil.h +++ b/modules/freetype2/include/freetype/ftlcdfil.h @@ -5,7 +5,7 @@ /* FreeType API for color filtering of subpixel bitmap glyphs */ /* (specification). */ /* */ -/* Copyright 2006-2016 by */ +/* Copyright 2006-2018 by */ /* David Turner, Robert Wilhelm, and Werner Lemberg. */ /* */ /* This file is part of the FreeType project, and may only be used, */ @@ -22,6 +22,7 @@ #include <ft2build.h> #include FT_FREETYPE_H +#include FT_PARAMETER_TAGS_H #ifdef FREETYPE_H #error "freetype.h of FreeType 1 has been loaded!" @@ -44,9 +45,16 @@ FT_BEGIN_HEADER * Reduce color fringes of subpixel-rendered bitmaps. * * @description: - * Subpixel rendering exploits the color-striped structure of LCD - * pixels, increasing the available resolution in the direction of the - * stripe (usually horizontal RGB) by a factor of~3. Since these + * Should you #define FT_CONFIG_OPTION_SUBPIXEL_RENDERING in your + * `ftoption.h', which enables patented ClearType-style rendering, + * the LCD-optimized glyph bitmaps should be filtered to reduce color + * fringes inherent to this technology. The default FreeType LCD + * rendering uses different technology, and API described below, + * although available, does nothing. + * + * ClearType-style LCD rendering exploits the color-striped structure of + * LCD pixels, increasing the available resolution in the direction of + * the stripe (usually horizontal RGB) by a factor of~3. Since these * subpixels are color pixels, using them unfiltered creates severe * color fringes. Use the @FT_Library_SetLcdFilter API to specify a * low-pass filter, which is then applied to subpixel-rendered bitmaps @@ -54,12 +62,6 @@ FT_BEGIN_HEADER * the higher resolution to reduce color fringes, making the glyph image * slightly blurrier. Positional improvements will remain. * - * Note that no filter is active by default, and that this function is - * *not* implemented in default builds of the library. You need to - * #define FT_CONFIG_OPTION_SUBPIXEL_RENDERING in your `ftoption.h' file - * in order to activate it and explicitly call @FT_Library_SetLcdFilter - * to enable it. - * * A filter should have two properties: * * 1) It should be normalized, meaning the sum of the 5~components @@ -268,6 +270,9 @@ FT_BEGIN_HEADER * defined in your build of the library, which should correspond to all * default builds of FreeType. * + * LCD filter weights can also be set per face using @FT_Face_Properties + * with @FT_PARAM_TAG_LCD_FILTER_WEIGHTS. + * * @since: * 2.4.0 */ @@ -275,6 +280,24 @@ FT_BEGIN_HEADER FT_Library_SetLcdFilterWeights( FT_Library library, unsigned char *weights ); + + /* + * @type: + * FT_LcdFiveTapFilter + * + * @description: + * A typedef for passing the five LCD filter weights to + * @FT_Face_Properties within an @FT_Parameter structure. + * + * @since: + * 2.8 + * + */ +#define FT_LCD_FILTER_FIVE_TAPS 5 + + typedef FT_Byte FT_LcdFiveTapFilter[FT_LCD_FILTER_FIVE_TAPS]; + + /* */ |