diff options
Diffstat (limited to 'include/freetype/freetype.h')
| -rw-r--r-- | include/freetype/freetype.h | 24 |
1 files changed, 19 insertions, 5 deletions
diff --git a/include/freetype/freetype.h b/include/freetype/freetype.h index b19a1b7c5..8a441744d 100644 --- a/include/freetype/freetype.h +++ b/include/freetype/freetype.h @@ -3204,7 +3204,7 @@ FT_BEGIN_HEADER * * @note: * This function is provided as a convenience, but keep in mind that - * @FT_Matrix coefficients are only 16.16 fixed point values, which can + * @FT_Matrix coefficients are only 16.16 fixed-point values, which can * limit the accuracy of the results. Using floating-point computations * to perform the transform directly in client code instead will always * yield better numbers. @@ -3236,10 +3236,14 @@ FT_BEGIN_HEADER * in the @FT_GlyphSlotRec structure gives the format of the returned * bitmap. * - * All modes except @FT_RENDER_MODE_MONO use 256 levels of opacity, - * indicating pixel coverage. Use linear alpha blending and gamma - * correction to correctly render non-monochrome glyph bitmaps onto a - * surface; see @FT_Render_Glyph. + * All modes except @FT_RENDER_MODE_MONO and @FT_RENDER_MODE_SDF use 256 + * levels of opacity, indicating pixel coverage. Use linear alpha + * blending and gamma correction to correctly render non-monochrome + * glyph bitmaps onto a surface; see @FT_Render_Glyph. + * + * The @FT_RENDER_MODE_SDF is a special render mode that uses up to + * 65536 distance values, indicating the signed distance from the grid + * position to the nearest outline. * * @values: * FT_RENDER_MODE_NORMAL :: @@ -3266,6 +3270,15 @@ FT_BEGIN_HEADER * bitmaps that are 3~times the height of the original glyph outline in * pixels and use the @FT_PIXEL_MODE_LCD_V mode. * + * FT_RENDER_MODE_SDF :: + * This mode corresponds to 16-bit signed distance fields (SDF) + * bitmaps. Each pixel in a SDF bitmap contains information about the + * nearest edge of the glyph outline. The distances are calculated + * from the center of the pixel and are positive if they are filled by + * the outline (i.e., inside the outline) and negative otherwise. The + * output bitmap buffer is represented as 6.10 fixed-point values; use + * @FT_6Dot10 and convert accordingly. + * * @note: * The selected render mode only affects vector glyphs of a font. * Embedded bitmaps often have a different pixel mode like @@ -3279,6 +3292,7 @@ FT_BEGIN_HEADER FT_RENDER_MODE_MONO, FT_RENDER_MODE_LCD, FT_RENDER_MODE_LCD_V, + FT_RENDER_MODE_SDF, FT_RENDER_MODE_MAX |