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.

ChangeLog

@@ -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.

docs/CHANGES

@@ -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,

include/freetype/ftlcdfil.h

@@ -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 );
+
   /* */
 
 

src/base/ftlcdfil.c

@@ -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,       */
@@ -266,19 +266,32 @@
 #endif /* USE_LEGACY */
 
 
+  FT_EXPORT_DEF( FT_Error )
+  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 )