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-rw-r--r--Build/source/libs/freetype2/freetype-src/include/freetype/ftimage.h97
1 files changed, 61 insertions, 36 deletions
diff --git a/Build/source/libs/freetype2/freetype-src/include/freetype/ftimage.h b/Build/source/libs/freetype2/freetype-src/include/freetype/ftimage.h
index 74911620d2a..66a8b89aa5a 100644
--- a/Build/source/libs/freetype2/freetype-src/include/freetype/ftimage.h
+++ b/Build/source/libs/freetype2/freetype-src/include/freetype/ftimage.h
@@ -5,7 +5,7 @@
* FreeType glyph image formats and default raster interface
* (specification).
*
- * Copyright (C) 1996-2020 by
+ * Copyright (C) 1996-2021 by
* David Turner, Robert Wilhelm, and Werner Lemberg.
*
* This file is part of the FreeType project, and may only be used,
@@ -201,6 +201,11 @@ FT_BEGIN_HEADER
#define ft_pixel_mode_pal2 FT_PIXEL_MODE_GRAY2
#define ft_pixel_mode_pal4 FT_PIXEL_MODE_GRAY4
+ /* */
+
+ /* For debugging, the @FT_Pixel_Mode enumeration must stay in sync */
+ /* with the `pixel_modes` array in file `ftobjs.c`. */
+
/**************************************************************************
*
@@ -772,17 +777,6 @@ FT_BEGIN_HEADER
/*************************************************************************/
- /**************************************************************************
- *
- * A raster is a scan converter, in charge of rendering an outline into a
- * bitmap. This section contains the public API for rasters.
- *
- * Note that in FreeType 2, all rasters are now encapsulated within
- * specific modules called 'renderers'. See `ftrender.h` for more details
- * on renderers.
- *
- */
-
/**************************************************************************
*
@@ -796,16 +790,35 @@ FT_BEGIN_HEADER
* How vectorial outlines are converted into bitmaps and pixmaps.
*
* @description:
- * This section contains technical definitions.
+ * A raster or a rasterizer is a scan converter in charge of producing a
+ * pixel coverage bitmap that can be used as an alpha channel when
+ * compositing a glyph with a background. FreeType comes with two
+ * rasterizers: bilevel `raster1` and anti-aliased `smooth` are two
+ * separate modules. They are usually called from the high-level
+ * @FT_Load_Glyph or @FT_Render_Glyph functions and produce the entire
+ * coverage bitmap at once, while staying largely invisible to users.
+ *
+ * Instead of working with complete coverage bitmaps, it is also possible
+ * to intercept consecutive pixel runs on the same scanline with the same
+ * coverage, called _spans_, and process them individually. Only the
+ * `smooth` rasterizer permits this when calling @FT_Outline_Render with
+ * @FT_Raster_Params as described below.
+ *
+ * Working with either complete bitmaps or spans it is important to think
+ * of them as colorless coverage objects suitable as alpha channels to
+ * blend arbitrary colors with a background. For best results, it is
+ * recommended to use gamma correction, too.
+ *
+ * This section also describes the public API needed to set up alternative
+ * @FT_Renderer modules.
*
* @order:
- * FT_Raster
* FT_Span
* FT_SpanFunc
- *
* FT_Raster_Params
* FT_RASTER_FLAG_XXX
*
+ * FT_Raster
* FT_Raster_NewFunc
* FT_Raster_DoneFunc
* FT_Raster_ResetFunc
@@ -818,24 +831,12 @@ FT_BEGIN_HEADER
/**************************************************************************
*
- * @type:
- * FT_Raster
- *
- * @description:
- * An opaque handle (pointer) to a raster object. Each object can be
- * used independently to convert an outline into a bitmap or pixmap.
- */
- typedef struct FT_RasterRec_* FT_Raster;
-
-
- /**************************************************************************
- *
* @struct:
* FT_Span
*
* @description:
- * A structure used to model a single span of gray pixels when rendering
- * an anti-aliased bitmap.
+ * A structure to model a single span of consecutive pixels when
+ * rendering an anti-aliased bitmap.
*
* @fields:
* x ::
@@ -852,8 +853,8 @@ FT_BEGIN_HEADER
* This structure is used by the span drawing callback type named
* @FT_SpanFunc that takes the y~coordinate of the span as a parameter.
*
- * The coverage value is always between 0 and 255. If you want less gray
- * values, the callback function has to reduce them.
+ * The anti-aliased rasterizer produces coverage values from 0 to 255,
+ * this is, from completely transparent to completely opaque.
*/
typedef struct FT_Span_
{
@@ -871,8 +872,8 @@ FT_BEGIN_HEADER
*
* @description:
* A function used as a call-back by the anti-aliased renderer in order
- * to let client applications draw themselves the gray pixel spans on
- * each scan line.
+ * to let client applications draw themselves the pixel spans on each
+ * scan line.
*
* @input:
* y ::
@@ -888,11 +889,12 @@ FT_BEGIN_HEADER
* User-supplied data that is passed to the callback.
*
* @note:
- * This callback allows client applications to directly render the gray
- * spans of the anti-aliased bitmap to any kind of surfaces.
+ * This callback allows client applications to directly render the spans
+ * of the anti-aliased bitmap to any kind of surfaces.
*
* This can be used to write anti-aliased outlines directly to a given
- * background bitmap, and even perform translucency.
+ * background bitmap using alpha compositing. It can also be used for
+ * oversampling and averaging.
*/
typedef void
(*FT_SpanFunc)( int y,
@@ -962,11 +964,17 @@ 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
+ * the @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 */
@@ -1049,6 +1057,23 @@ FT_BEGIN_HEADER
/**************************************************************************
*
+ * @type:
+ * FT_Raster
+ *
+ * @description:
+ * An opaque handle (pointer) to a raster object. Each object can be
+ * used independently to convert an outline into a bitmap or pixmap.
+ *
+ * @note:
+ * In FreeType 2, all rasters are now encapsulated within specific
+ * @FT_Renderer modules and only used in their context.
+ *
+ */
+ typedef struct FT_RasterRec_* FT_Raster;
+
+
+ /**************************************************************************
+ *
* @functype:
* FT_Raster_NewFunc
*