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[sdf] Improve documentation.

This commit is contained in:
Anuj Verma 2021-07-13 10:00:22 +02:00 committed by Werner Lemberg
parent c5516e0f7c
commit e592982a83
2 changed files with 9 additions and 8 deletions
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14
include/freetype/freetype.h
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@ -3307,13 +3307,13 @@ FT_BEGIN_HEADER
* pixels and use the @FT_PIXEL_MODE_LCD_V mode.
*
* FT_RENDER_MODE_SDF ::
* This mode corresponds to 8-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.
* Check the note below on how to convert the output values to usable
* data.
* This mode corresponds to 8-bit, single-channel signed distance field
* (SDF) bitmaps. Each pixel in the SDF grid is the value from the
* pixel's position to the nearest glyph's 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. Check the note below on how to convert the output values
* to usable data.
*
* @note:
* The selected render mode only affects vector glyphs of a font.

3
src/sdf/ftsdf.c
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@ -41,7 +41,8 @@
* file `ftbsdf.c` for more.
*
* * The basic idea of generating the SDF is taken from Viktor Chlumsky's
* research paper.
* research paper. The paper explains both single and multi-channel
* SDF, however, this implementation only generates single-channel SDF.
*
* Chlumsky, Viktor: Shape Decomposition for Multi-channel Distance
* Fields. Master's thesis. Czech Technical University in Prague,