WebSVN – Kolibri OS – Blame – /contrib/media/updf/include/freetype/ftlcdfil.h

Rev	Author	Line No.	Line
4680	right-hear	1	/***************************************************************************/
		2	/* */
		3	/* ftlcdfil.h */
		4	/* */
		5	/* FreeType API for color filtering of subpixel bitmap glyphs */
		6	/* (specification). */
		7	/* */
		8	/* Copyright 2006, 2007, 2008, 2010 by */
		9	/* David Turner, Robert Wilhelm, and Werner Lemberg. */
		10	/* */
		11	/* This file is part of the FreeType project, and may only be used, */
		12	/* modified, and distributed under the terms of the FreeType project */
		13	/* license, LICENSE.TXT. By continuing to use, modify, or distribute */
		14	/* this file you indicate that you have read the license and */
		15	/* understand and accept it fully. */
		16	/* */
		17	/***************************************************************************/
		18
		19
		20	#ifndef __FT_LCD_FILTER_H__
		21	#define __FT_LCD_FILTER_H__
		22
		23	#include
		24	#include FT_FREETYPE_H
		25
		26	#ifdef FREETYPE_H
		27	#error "freetype.h of FreeType 1 has been loaded!"
		28	#error "Please fix the directory search order for header files"
		29	#error "so that freetype.h of FreeType 2 is found first."
		30	#endif
		31
		32
		33	FT_BEGIN_HEADER
		34
		35	/***************************************************************************
		36	*
		37	* @section:
		38	* lcd_filtering
		39	*
		40	* @title:
		41	* LCD Filtering
		42	*
		43	* @abstract:
		44	* Reduce color fringes of LCD-optimized bitmaps.
		45	*
		46	* @description:
		47	* The @FT_Library_SetLcdFilter API can be used to specify a low-pass
		48	* filter which is then applied to LCD-optimized bitmaps generated
		49	* through @FT_Render_Glyph. This is useful to reduce color fringes
		50	* which would occur with unfiltered rendering.
		51	*
		52	* Note that no filter is active by default, and that this function is
		53	* not implemented in default builds of the library. You need to
		54	* #define FT_CONFIG_OPTION_SUBPIXEL_RENDERING in your `ftoption.h' file
		55	* in order to activate it.
		56	*/
		57
		58
		59	/****************************************************************************
		60	*
		61	* @enum:
		62	* FT_LcdFilter
		63	*
		64	* @description:
		65	* A list of values to identify various types of LCD filters.
		66	*
		67	* @values:
		68	* FT_LCD_FILTER_NONE ::
		69	* Do not perform filtering. When used with subpixel rendering, this
		70	* results in sometimes severe color fringes.
		71	*
		72	* FT_LCD_FILTER_DEFAULT ::
		73	* The default filter reduces color fringes considerably, at the cost
		74	* of a slight blurriness in the output.
		75	*
		76	* FT_LCD_FILTER_LIGHT ::
		77	* The light filter is a variant that produces less blurriness at the
		78	* cost of slightly more color fringes than the default one. It might
		79	* be better, depending on taste, your monitor, or your personal vision.
		80	*
		81	* FT_LCD_FILTER_LEGACY ::
		82	* This filter corresponds to the original libXft color filter. It
		83	* provides high contrast output but can exhibit really bad color
		84	* fringes if glyphs are not extremely well hinted to the pixel grid.
		85	* In other words, it only works well if the TrueType bytecode
		86	* interpreter is enabled and high-quality hinted fonts are used.
		87	*
		88	* This filter is only provided for comparison purposes, and might be
		89	* disabled or stay unsupported in the future.
		90	*
		91	* @since:
		92	* 2.3.0
		93	*/
		94	typedef enum FT_LcdFilter_
		95	{
		96	FT_LCD_FILTER_NONE = 0,
		97	FT_LCD_FILTER_DEFAULT = 1,
		98	FT_LCD_FILTER_LIGHT = 2,
		99	FT_LCD_FILTER_LEGACY = 16,
		100
		101	FT_LCD_FILTER_MAX /* do not remove */
		102
		103	} FT_LcdFilter;
		104
		105
		106	/**************************************************************************
		107	*
		108	* @func:
		109	* FT_Library_SetLcdFilter
		110	*
		111	* @description:
		112	* This function is used to apply color filtering to LCD decimated
		113	* bitmaps, like the ones used when calling @FT_Render_Glyph with
		114	* @FT_RENDER_MODE_LCD or @FT_RENDER_MODE_LCD_V.
		115	*
		116	* @input:
		117	* library ::
		118	* A handle to the target library instance.
		119	*
		120	* filter ::
		121	* The filter type.
		122	*
		123	* You can use @FT_LCD_FILTER_NONE here to disable this feature, or
		124	* @FT_LCD_FILTER_DEFAULT to use a default filter that should work
		125	* well on most LCD screens.
		126	*
		127	* @return:
		128	* FreeType error code. 0~means success.
		129	*
		130	* @note:
		131	* This feature is always disabled by default. Clients must make an
		132	* explicit call to this function with a `filter' value other than
		133	* @FT_LCD_FILTER_NONE in order to enable it.
		134	*
		135	* Due to PATENTS covering subpixel rendering, this function doesn't
		136	* do anything except returning `FT_Err_Unimplemented_Feature' if the
		137	* configuration macro FT_CONFIG_OPTION_SUBPIXEL_RENDERING is not
		138	* defined in your build of the library, which should correspond to all
		139	* default builds of FreeType.
		140	*
		141	* The filter affects glyph bitmaps rendered through @FT_Render_Glyph,
		142	* @FT_Outline_Get_Bitmap, @FT_Load_Glyph, and @FT_Load_Char.
		143	*
		144	* It does _not_ affect the output of @FT_Outline_Render and
		145	* @FT_Outline_Get_Bitmap.
		146	*
		147	* If this feature is activated, the dimensions of LCD glyph bitmaps are
		148	* either larger or taller than the dimensions of the corresponding
		149	* outline with regards to the pixel grid. For example, for
		150	* @FT_RENDER_MODE_LCD, the filter adds up to 3~pixels to the left, and
		151	* up to 3~pixels to the right.
		152	*
		153	* The bitmap offset values are adjusted correctly, so clients shouldn't
		154	* need to modify their layout and glyph positioning code when enabling
		155	* the filter.
		156	*
		157	* @since:
		158	* 2.3.0
		159	*/
		160	FT_EXPORT( FT_Error )
		161	FT_Library_SetLcdFilter( FT_Library library,
		162	FT_LcdFilter filter );
		163
		164
		165	/**************************************************************************
		166	*
		167	* @func:
		168	* FT_Library_SetLcdFilterWeights
		169	*
		170	* @description:
		171	* Use this function to override the filter weights selected by
		172	* @FT_Library_SetLcdFilter. By default, FreeType uses the quintuple
		173	* (0x00, 0x55, 0x56, 0x55, 0x00) for FT_LCD_FILTER_LIGHT, and (0x10,
		174	* 0x40, 0x70, 0x40, 0x10) for FT_LCD_FILTER_DEFAULT and
		175	* FT_LCD_FILTER_LEGACY.
		176	*
		177	* @input:
		178	* library ::
		179	* A handle to the target library instance.
		180	*
		181	* weights ::
		182	* A pointer to an array; the function copies the first five bytes and
		183	* uses them to specify the filter weights.
		184	*
		185	* @return:
		186	* FreeType error code. 0~means success.
		187	*
		188	* @note:
		189	* Due to PATENTS covering subpixel rendering, this function doesn't
		190	* do anything except returning `FT_Err_Unimplemented_Feature' if the
		191	* configuration macro FT_CONFIG_OPTION_SUBPIXEL_RENDERING is not
		192	* defined in your build of the library, which should correspond to all
		193	* default builds of FreeType.
		194	*
		195	* This function must be called after @FT_Library_SetLcdFilter to have
		196	* any effect.
		197	*
		198	* @since:
		199	* 2.4.0
		200	*/
		201	FT_EXPORT( FT_Error )
		202	FT_Library_SetLcdFilterWeights( FT_Library library,
		203	unsigned char *weights );
		204
		205	/* */
		206
		207
		208	FT_END_HEADER
		209
		210	#endif /* __FT_LCD_FILTER_H__ */
		211
		212
		213	/* END */

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