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Add new function `FT_Library_SetLcdFilterWeights'.

Browse Source 
This is based on code written by Lifter
<http://unixforum.org/index.php?showuser=11691>.  It fixes
FreeDesktop bug #27386.

* src/base/ftlcdfil.c (FT_Library_SetLcdFilterWeights): New
function.

* include/freetype/ftlcdfil.h: Updated.

* docs/CHANGES: Updated.
This commit is contained in:
Werner Lemberg 2010-04-05 08:46:26 +02:00
parent 8c4cce5259
commit 460d23f168
4 changed files with 100 additions and 8 deletions
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15
ChangeLog
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@ -1,3 +1,18 @@
2010-04-05 Werner Lemberg <wl@gnu.org>
Add new function `FT_Library_SetLcdFilterWeights'.
This is based on code written by Lifter
<http://unixforum.org/index.php?showuser=11691>. It fixes
FreeDesktop bug #27386.
* src/base/ftlcdfil.c (FT_Library_SetLcdFilterWeights): New
function.
* include/freetype/ftlcdfil.h: Updated.
* docs/CHANGES: Updated.
2010-04-01 John Tytgat <John.Tytgat@esko.com>
Fix Savannah bug #29404.

13
docs/CHANGES
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@ -1,3 +1,13 @@
CHANGES BETWEEN 2.3.12 and 2.3.13
I. IMPORTANT CHANGES
- A new function `FT_Library_SetLcdFilterWeights' is available to
adjust the filter weights set by `FT_Library_SetLcdFilter'.
======================================================================
CHANGES BETWEEN 2.3.11 and 2.3.12
I. IMPORTANT CHANGES
@ -3378,7 +3388,8 @@ Extensions support:
------------------------------------------------------------------------
Copyright 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 by
Copyright 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
2010 by
David Turner, Robert Wilhelm, and Werner Lemberg.
This file is part of the FreeType project, and may only be used,

43
include/freetype/ftlcdfil.h
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@ -5,7 +5,7 @@
/* FreeType API for color filtering of subpixel bitmap glyphs */
/* (specification). */
/* */
/* Copyright 2006, 2007, 2008 by */
/* Copyright 2006, 2007, 2008, 2010 by */
/* David Turner, Robert Wilhelm, and Werner Lemberg. */
/* */
/* This file is part of the FreeType project, and may only be used, */
@ -161,6 +161,47 @@ FT_BEGIN_HEADER
FT_Library_SetLcdFilter( FT_Library library,
FT_LcdFilter filter );
/**************************************************************************
*
* @func:
* FT_Library_SetLcdFilterWeights
*
* @description:
* Use this function to override the filter weights selected by
* @FT_Library_SetLcdFilter. By default, FreeType uses the quintuple
* (0x00, 0x55, 0x56, 0x55, 0x00) for FT_LCD_FILTER_LIGHT, and (0x10,
* 0x40, 0x70, 0x40, 0x10) for FT_LCD_FILTER_DEFAULT and
* FT_LCD_FILTER_LEGACY.
*
* @input:
* library ::
* A handle to the target library instance.
*
* weights ::
* A pointer to an array; the function copies the first five bytes and
* uses them to specify the filter weights.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* Due to *PATENTS* covering subpixel rendering, this function doesn't
* do anything except returning `FT_Err_Unimplemented_Feature' if the
* configuration macro FT_CONFIG_OPTION_SUBPIXEL_RENDERING is not
* defined in your build of the library, which should correspond to all
* default builds of FreeType.
*
* This function must be called after @FT_Library_SetLcdFilter to have
* any effect.
*
* @since:
* 2.3.13
*/
FT_EXPORT( FT_Error )
FT_Library_SetLcdFilterWeights( FT_Library library,
unsigned char *weights );
/* */

37
src/base/ftlcdfil.c
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@ -4,7 +4,7 @@
/* */
/* FreeType API for color filtering of subpixel bitmap glyphs (body). */
/* */
/* Copyright 2006, 2008, 2009 by */
/* Copyright 2006, 2008, 2009, 2010 by */
/* David Turner, Robert Wilhelm, and Werner Lemberg. */
/* */
/* This file is part of the FreeType project, and may only be used, */
@ -267,18 +267,31 @@
FT_EXPORT_DEF( FT_Error )
FT_Library_SetLcdFilter( FT_Library library,
FT_LcdFilter filter )
FT_Library_SetLcdFilterWeights( FT_Library library,
unsigned char *weights )
{
if ( !library || !weights )
return FT_Err_Invalid_Argument;
ft_memcpy( library->lcd_weights, weights, 5 );
return FT_Err_Ok;
}
FT_EXPORT_DEF( FT_Error )
FT_Library_SetLcdFilter( FT_Library library,
FT_LcdFilter filter )
{
static const FT_Byte light_filter[5] =
{ 0, 85, 86, 85, 0 };
{ 0x00, 0x55, 0x56, 0x55, 0x00 };
/* the values here sum up to a value larger than 256, */
/* providing a cheap gamma correction */
static const FT_Byte default_filter[5] =
{ 0x10, 0x40, 0x70, 0x40, 0x10 };
if ( library == NULL )
if ( !library )
return FT_Err_Invalid_Argument;
switch ( filter )
@ -330,11 +343,23 @@
}
library->lcd_filter = filter;
return 0;
return FT_Err_Ok;
}
#else /* !FT_CONFIG_OPTION_SUBPIXEL_RENDERING */
FT_EXPORT_DEF( FT_Error )
FT_Library_SetLcdFilterWeights( FT_Library library,
unsigned char *weights )
{
FT_UNUSED( library );
FT_UNUSED( weights );
return FT_Err_Unimplemented_Feature;
}
FT_EXPORT_DEF( FT_Error )
FT_Library_SetLcdFilter( FT_Library library,
FT_LcdFilter filter )