mirror of https://github.com/freetype/freetype
Improve handling of color palettes.
This commit adds new functions to streamline palette access: FT_Palette_Set: Set a user-defined palette. FT_Palette_Get: Get palette and palette index. FT_Palette_Get_Foreground_Color: Get foreground color. Fixes issue #1134. * include/freetype/internal/tttypes.h (TT_FaceRec): Change type of `palette_index` to `FT_Int`. Negative values now represent user-defined palettes. * src/base/ftcolor.c (FT_Palette_Set, FT_Palette_Get, FT_Palette_Get_Foreground_Color): New functions. * include/freetype/ftcolor.h: Updated.
This commit is contained in:
Werner Lemberg
parent
1e2eb65048
commit
9d86c63f4a
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@ -45,6 +45,12 @@ FT_BEGIN_HEADER
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* @description:
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* The functions described here allow access and manipulation of color
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* palette entries in OpenType's 'CPAL' tables.
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*
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* FreeType maintains a 'working palette' (together with a corresponding
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* 'working palette index'), which can be set either to a palette stored
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* in the font (function @FT_Palette_Select) or to a user-defined palette
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* (function @FT_Palette_Set). For user-defined palettes, the working
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* palette index is negative, and positive otherwise.
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*/
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@ -218,18 +224,13 @@ FT_BEGIN_HEADER
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* FT_Palette_Select
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*
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* @description:
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* This function has two purposes.
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* This function copies a palette entry in the font's 'CPAL' table into a
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* 'working palette', which is a read-write array managed by FreeType.
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* It also sets the 'working palette index' to the index value given as
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* an argument.
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*
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* (1) It activates a palette for rendering color glyphs, and
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*
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* (2) it retrieves all (unmodified) color entries of this palette. This
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* function returns a read-write array, which means that a calling
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* application can modify the palette entries on demand.
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*
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* A corollary of (2) is that calling the function, then modifying some
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* values, then calling the function again with the same arguments resets
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* all color entries to the original 'CPAL' values; all user modifications
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* are lost.
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* The current working palette and palette index can be retrieved with
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* @FT_Palette_Get.
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*
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* @input:
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* face ::
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@ -240,10 +241,10 @@ FT_BEGIN_HEADER
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*
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* @output:
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* apalette ::
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* An array of color entries for a palette with index `palette_index`,
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* having `num_palette_entries` elements (as found in the
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* `FT_Palette_Data` structure). If `apalette` is set to `NULL`, no
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* array gets returned (and no color entries can be modified).
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* A pointer to the 'working palette', which is an array of color
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* entries for a palette with index `palette_index`, having
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* `num_palette_entries` elements (as found in the `FT_Palette_Data`
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* structure). If `apalette` is set to `NULL`, no array gets returned.
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*
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* In case the font doesn't support color palettes, `NULL` is returned.
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*
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@ -266,6 +267,92 @@ FT_BEGIN_HEADER
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FT_Color* *apalette );
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/**************************************************************************
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*
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* @function:
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* FT_Palette_Set
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*
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* @description:
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* Set FreeType's 'working palette' and 'working palette index' to the
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* given arguments. Use this function if you want to provide a
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* user-defined palette, not being part of the font's 'CPAL' table.
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*
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* The current working palette and palette index can be retrieved with
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* @FT_Palette_Get.
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*
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* @input:
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* face ::
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* The source face handle.
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*
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* palette_index ::
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* A palette index, which must be an arbitrary, negative integer (since
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* positive values are reserved for indices from the 'CPAL' table).
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* FreeType sets the 'working palette index' to this value.
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*
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* palette ::
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* A pointer to an array of color entries, having `num_palette_entries`
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* elements (as found in the `FT_Palette_Data` structure). FreeType
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* copies this array into its 'working palette'.
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*
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* @return:
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* FreeType error code. 0~means success.
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*
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* @note:
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* This function always returns an error if the config macro
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* `TT_CONFIG_OPTION_COLOR_LAYERS` is not defined in `ftoption.h`.
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*
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* @since:
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* 2.12
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*/
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FT_EXPORT( FT_Error )
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FT_Palette_Set( FT_Face face,
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FT_Int index,
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FT_Color* palette );
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/**************************************************************************
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*
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* @function:
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* FT_Palette_Get
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*
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* @description:
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* Get FreeType's 'working palette' and 'working palette index'.
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*
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* The working palette and palette index can be set with @FT_Palette_Set.
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*
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* @input:
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* face ::
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* The source face handle.
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*
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* @output:
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* anindex ::
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* The 'working palette index'. If the value is zero or positive, the
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* working palette represents an entry from the font's 'CPAL' table
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* (with the given index). Otherwise it is a user-defined palette. If
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* `anindex` is set to `NULL`, no value gets returned.
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*
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* apalette ::
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* A pointer to the 'working palette', which is an array of color
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* entries for a palette having `num_palette_entries` elements (as
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* found in the `FT_Palette_Data` structure). If `apalette` is set to
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* `NULL`, no array gets returned.
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*
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* @return:
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* FreeType error code. 0~means success.
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*
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* @note:
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* This function always returns an error if the config macro
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* `TT_CONFIG_OPTION_COLOR_LAYERS` is not defined in `ftoption.h`.
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*
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* @since:
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* 2.12
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*/
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FT_EXPORT( FT_Error )
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FT_Palette_Get( FT_Face face,
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FT_Int *anindex,
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FT_Color* *apalette );
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/**************************************************************************
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*
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* @function:
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@ -286,11 +373,9 @@ FT_BEGIN_HEADER
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* FreeType error code. 0~means success.
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*
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* @note:
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* If this function isn't called, the text foreground color is set to
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* white opaque (BGRA value 0xFFFFFFFF) if
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* @FT_PALETTE_FOR_DARK_BACKGROUND is present for the current palette,
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* and black opaque (BGRA value 0x000000FF) otherwise, including the case
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* that no palette types are available in the 'CPAL' table.
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* See function @FT_Palette_Get_Foreground_Color for details on what
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* foreground color is used if `FT_Palette_Set_Foreground_Color` is not
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* called.
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*
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* This function always returns an error if the config macro
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* `TT_CONFIG_OPTION_COLOR_LAYERS` is not defined in `ftoption.h`.
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@ -303,6 +388,53 @@ FT_BEGIN_HEADER
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FT_Color foreground_color );
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/**************************************************************************
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*
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* @function:
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* FT_Palette_Get_Foreground_Color
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*
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* @description:
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* Get the 'text foreground color' as set by a previous call to
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* @FT_Palette_Set_Foreground_Color.
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*
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* @input:
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* face ::
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* The source face handle.
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*
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* @output:
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* aforeground_color ::
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* The text foreground color.
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*
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* @return:
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* FreeType error code. 0~means success.
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*
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* @note:
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* The returned color is as follows.
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*
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* * If a foreground color was set with @FT_Palette_Get_Foreground_Color,
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* return this value.
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*
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* * Otherwise, return black opaque (BGRA value 0x000000FF) if the
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* 'working palette' is a user-defined palette.
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*
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* * Otherwise, return white opaque (BGRA value 0xFFFFFFFF) if
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* @FT_PALETTE_FOR_DARK_BACKGROUND is present for the current palette.
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*
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* * Otherwise, return black opaque (BGRA value 0x000000FF). This
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* includes the case that no palette types are available in the 'CPAL'
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* table.
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*
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* This function always returns an error if the config macro
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* `TT_CONFIG_OPTION_COLOR_LAYERS` is not defined in `ftoption.h`.
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*
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* @since:
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* 2.12
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*/
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FT_EXPORT( FT_Error )
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FT_Palette_Get_Foreground_Color( FT_Face face,
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FT_Color* aforeground_color );
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/**************************************************************************
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*
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* @section:
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@ -1537,7 +1537,7 @@ FT_BEGIN_HEADER
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/* glyph colors */
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FT_Palette_Data palette_data; /* since 2.10 */
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FT_UShort palette_index;
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FT_Int palette_index;
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FT_Color* palette;
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FT_Bool have_foreground_color;
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FT_Color foreground_color;
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@ -36,7 +36,7 @@
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{
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if ( !face )
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return FT_THROW( Invalid_Face_Handle );
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if ( !apalette_data)
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if ( !apalette_data )
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return FT_THROW( Invalid_Argument );
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if ( FT_IS_SFNT( face ) )
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@ -88,6 +88,57 @@
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}
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/* documentation is in ftcolor.h */
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FT_EXPORT_DEF( FT_Error )
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FT_Palette_Set( FT_Face face,
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FT_Int index,
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FT_Color* palette )
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{
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TT_Face ttface;
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FT_UShort i;
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if ( !face || !FT_IS_SFNT( face ) )
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return FT_THROW( Invalid_Face_Handle );
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if ( !palette || index >= 0 )
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return FT_THROW( Invalid_Argument );
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ttface = (TT_Face)face;
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for ( i = 0; i < ttface->palette_data.num_palette_entries; i++ )
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ttface->palette[i] = palette[i];
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ttface->palette_index = index;
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return FT_Err_Ok;
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}
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/* documentation is in ftcolor.h */
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FT_EXPORT_DEF( FT_Error )
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FT_Palette_Get( FT_Face face,
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FT_Int *anindex,
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FT_Color* *apalette )
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{
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TT_Face ttface;
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if ( !face || !FT_IS_SFNT( face ) )
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return FT_THROW( Invalid_Face_Handle );
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ttface = (TT_Face)face;
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if ( anindex )
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*anindex = ttface->palette_index;
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if ( apalette )
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*apalette = ttface->palette;
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return FT_Err_Ok;
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}
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/* documentation is in ftcolor.h */
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FT_EXPORT_DEF( FT_Error )
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@ -111,6 +162,44 @@
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return FT_Err_Ok;
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}
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/* documentation is in ftcolor.h */
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FT_EXPORT_DEF( FT_Error )
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FT_Palette_Get_Foreground_Color( FT_Face face,
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FT_Color* aforeground_color )
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{
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TT_Face ttface;
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FT_Color white = { 0xFF, 0xFF, 0xFF, 0xFF };
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FT_Color black = { 0x00, 0x00, 0x00, 0xFF };
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if ( !face || !FT_IS_SFNT( face ) )
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return FT_THROW( Invalid_Face_Handle );
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if ( !aforeground_color )
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return FT_THROW( Invalid_Argument );
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ttface = (TT_Face)face;
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if ( ttface->have_foreground_color )
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*aforeground_color = ttface->foreground_color;
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else if ( ttface->palette_index < 0 )
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*aforeground_color = black;
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else
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{
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if ( ttface->palette_data.palette_flags &&
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( ttface->palette_data.palette_flags[ttface->palette_index] &
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FT_PALETTE_FOR_DARK_BACKGROUND ) )
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*aforeground_color = white;
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else
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*aforeground_color = black;
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}
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return FT_Err_Ok;
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}
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#else /* !TT_CONFIG_OPTION_COLOR_LAYERS */
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FT_EXPORT_DEF( FT_Error )
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@ -139,6 +228,34 @@
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}
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FT_EXPORT_DEF( FT_Error )
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FT_Palette_Set( FT_Face face,
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FT_Int index,
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FT_Color* palette )
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{
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FT_UNUSED( face );
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FT_UNUSED( index );
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FT_UNUSED( palette );
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return FT_THROW( Unimplemented_Feature );
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}
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FT_EXPORT_DEF( FT_Error )
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FT_Palette_Get( FT_Face face,
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FT_Int *anindex,
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FT_Color* *apalette )
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{
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FT_UNUSED( face );
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FT_UNUSED( anindex );
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FT_UNUSED( apalette );
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return FT_THROW( Unimplemented_Feature );
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}
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FT_EXPORT_DEF( FT_Error )
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FT_Palette_Set_Foreground_Color( FT_Face face,
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FT_Color foreground_color )
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@ -150,6 +267,18 @@
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return FT_THROW( Unimplemented_Feature );
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}
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FT_EXPORT_DEF( FT_Error )
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FT_Palette_Get_Foreground_Color( FT_Face face,
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FT_Color* aforeground_color )
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{
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FT_UNUSED( face );
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FT_UNUSED( aforeground_color );
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return FT_THROW( Unimplemented_Feature );
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}
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#endif /* !TT_CONFIG_OPTION_COLOR_LAYERS */
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