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Added render mode and data type required for the `sdf' module.

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* include/freetype/freetype.h (FT_Render_Mode): Added a new render mode
  `FT_RENDER_MODE_SDF', which will be used to generate SDF.

* include/freetype/ftimage.h (FT_Pixel_Mode): Added a new pixel mode
  `FT_PIXEL_MODE_GRAY16', which will be the output of the `sdf' module.

* include/freetype/ftimage.h (FT_RASTER_FLAG_SDF): Added a new raster flag
  to be used internally by the `sdf' module.
This commit is contained in:
Anuj Verma 2020-08-16 10:47:41 +05:30
parent 6ed3c34a0e
commit 6b81c538ed
2 changed files with 29 additions and 4 deletions
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20
include/freetype/freetype.h
View File

@ -3208,10 +3208,14 @@ 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 s special render mode which uses as much
* 65536 distance values, indicating the signed distance from the grid
* position to the nearest outline.
*
* @values:
* FT_RENDER_MODE_NORMAL ::
@ -3238,6 +3242,13 @@ 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 bitmap. 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.
*
* @note:
* The selected render mode only affects vector glyphs of a font.
* Embedded bitmaps often have a different pixel mode like
@ -3251,6 +3262,7 @@ FT_BEGIN_HEADER
FT_RENDER_MODE_MONO,
FT_RENDER_MODE_LCD,
FT_RENDER_MODE_LCD_V,
FT_RENDER_MODE_SDF,
FT_RENDER_MODE_MAX

13
include/freetype/ftimage.h
View File

@ -157,6 +157,12 @@ FT_BEGIN_HEADER
* in font files according to the OpenType specification. We haven't
* found a single font using this format, however.
*
* FT_PIXEL_MODE_GRAY16 ::
* A 16-bit per pixel bitmap used to represent signed distances in a
* signed distance field bitmap. This is currently only used while
* rendering using @FT_RENDER_MODE_SDF. Note that this is a 2.14
* fixed-point fractional value.
*
* FT_PIXEL_MODE_LCD ::
* An 8-bit bitmap, representing RGB or BGR decimated glyph images used
* for display on LCD displays; the bitmap is three times wider than
@ -184,6 +190,7 @@ FT_BEGIN_HEADER
FT_PIXEL_MODE_GRAY,
FT_PIXEL_MODE_GRAY2,
FT_PIXEL_MODE_GRAY4,
FT_PIXEL_MODE_GRAY16,
FT_PIXEL_MODE_LCD,
FT_PIXEL_MODE_LCD_V,
FT_PIXEL_MODE_BGRA,
@ -962,11 +969,17 @@ FT_BEGIN_HEADER
* will be clipped to a box specified in the `clip_box` field of the
* @FT_Raster_Params structure. Otherwise, the `clip_box` is
* effectively set to the bounding box and all spans are generated.
*
* FT_RASTER_FLAG_SDF ::
* This flag is set to indicate that a signed distance field glyph
* image should be generated. This is only used while rendering with
* `FT_RENDER_MODE_SDF' render mode.
*/
#define FT_RASTER_FLAG_DEFAULT 0x0
#define FT_RASTER_FLAG_AA 0x1
#define FT_RASTER_FLAG_DIRECT 0x2
#define FT_RASTER_FLAG_CLIP 0x4
#define FT_RASTER_FLAG_SDF 0x8
/* these constants are deprecated; use the corresponding */
/* `FT_RASTER_FLAG_XXX` values instead */