Alexandre Julliard : gdi32: Pre-multiply RGB values by alpha for subpixel font rendering.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: aff0eac21b7d66a0ba4869cade6368a988ab34ee
URL:    http://source.winehq.org/git/wine.git/?a=commit;h=aff0eac21b7d66a0ba4869cade...

Author: Alexandre Julliard <julliard(a)winehq.org>
Date:   Mon May 17 14:25:14 2010 +0200

gdi32: Pre-multiply RGB values by alpha for subpixel font rendering.

---

 dlls/gdi32/freetype.c |   19 +++++++++++--------
 1 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/dlls/gdi32/freetype.c b/dlls/gdi32/freetype.c
index c384218..129245a 100644
--- a/dlls/gdi32/freetype.c
+++ b/dlls/gdi32/freetype.c
@@ -5044,19 +5044,22 @@ DWORD WineEngGetGlyphOutline(GdiFont *incoming_font, UINT glyph, UINT format,
             {
                 for ( x = 0; x < src_width / hmul; x++ )
                 {
+                    unsigned int alpha = (src[hmul * x + rgb_interval * 0] +
+                                          src[hmul * x + rgb_interval * 1] +
+                                          src[hmul * x + rgb_interval * 2]) / 3;
                     if ( rgb )
                     {
-                        dst[x] = ((unsigned int)src[hmul * x + rgb_interval * 0] << 16) |
-                                 ((unsigned int)src[hmul * x + rgb_interval * 1] <<  8) |
-                                 ((unsigned int)src[hmul * x + rgb_interval * 2] <<  0) |
-                                 ((unsigned int)src[hmul * x + rgb_interval * 1] << 24) ;
+                        dst[x] = ((src[hmul * x + rgb_interval * 0] * alpha / 255) << 16) |
+                                 ((src[hmul * x + rgb_interval * 1] * alpha / 255) <<  8) |
+                                 ((src[hmul * x + rgb_interval * 2] * alpha / 255) <<  0) |
+                                 (alpha << 24);
                     }
                     else
                     {
-                        dst[x] = ((unsigned int)src[hmul * x + rgb_interval * 2] << 16) |
-                                 ((unsigned int)src[hmul * x + rgb_interval * 1] <<  8) |
-                                 ((unsigned int)src[hmul * x + rgb_interval * 0] <<  0) |
-                                 ((unsigned int)src[hmul * x + rgb_interval * 1] << 24) ;
+                        dst[x] = ((src[hmul * x + rgb_interval * 2] * alpha / 255) << 16) |
+                                 ((src[hmul * x + rgb_interval * 1] * alpha / 255) <<  8) |
+                                 ((src[hmul * x + rgb_interval * 0] * alpha / 255) <<  0) |
+                                 (alpha << 24);
                     }
                 }
                 src += src_pitch * vmul;