[fireball] 40074: Evgeniy Boltik <[e-mail]> - Rework 16bit DIB alphablend to do alpha operations in source's palette (32bpp) to obtain much better output quality without data loss. See issue #3708 for more details.

Author: fireball
Date: Tue Mar 17 21:00:28 2009
New Revision: 40074

URL: http://svn.reactos.org/svn/reactos?rev=40074&view=rev
Log:
Evgeniy Boltik <bstsoft(a)narod.ru>
- Rework 16bit DIB alphablend to do alpha operations in source's palette (32bpp) to
obtain much better output quality without data loss.
See issue #3708 for more details.

Modified:
    trunk/reactos/subsystems/win32/win32k/dib/dib16bpp.c

Modified: trunk/reactos/subsystems/win32/win32k/dib/dib16bpp.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/subsystems/win32/win32k/di…
==============================================================================
--- trunk/reactos/subsystems/win32/win32k/dib/dib16bpp.c [iso-8859-1] (original)
+++ trunk/reactos/subsystems/win32/win32k/dib/dib16bpp.c [iso-8859-1] Tue Mar 17 21:00:28
2009
@@ -541,6 +541,12 @@
 }
 
 static __inline UCHAR
+Clamp8(ULONG val)
+{
+    return (val > 255) ? 255 : val;
+}
+
+static __inline UCHAR
 Clamp6(ULONG val)
 {
     return (val > 63) ? 63 : val;
@@ -555,9 +561,13 @@
     register PUSHORT Dst;
     ULONG DstDelta;
     BLENDFUNCTION BlendFunc;
-    register NICEPIXEL16 DstPixel;
-    register NICEPIXEL32 SrcPixel;
+    register NICEPIXEL16 SrcPixel16;
+    register NICEPIXEL16 DstPixel16;
+    register NICEPIXEL32 SrcPixel32;
+    register NICEPIXEL32 DstPixel32;
     UCHAR Alpha, SrcBpp;
+    XLATEGDI* XlateGDI;
+    XLATEOBJ* SrcXlateObj;
 
     DPRINT("DIB_16BPP_AlphaBlend: srcRect: (%d,%d)-(%d,%d), dstRect:
(%d,%d)-(%d,%d)\n",
            SourceRect->left, SourceRect->top, SourceRect->right,
SourceRect->bottom,
@@ -586,6 +596,21 @@
         BitsPerFormat(Source->iBitmapFormat) != 32)
     {
         DPRINT1("Source bitmap must be 32bpp when AC_SRC_ALPHA is set\n");
+        return FALSE;
+    }
+
+    if (!ColorTranslation)
+    {
+        DPRINT1("ColorTranslation must not be NULL!\n");
+        return FALSE;
+    }
+
+    XlateGDI = ObjToGDI(ColorTranslation, XLATE);
+    SrcXlateObj = IntEngCreateXlate(0, 0, XlateGDI->SourcePal, XlateGDI->DestPal);
+
+    if (!SrcXlateObj)
+    {
+        DPRINT1("IntEngCreateXlate failed\n");
         return FALSE;
     }
 
@@ -604,52 +629,61 @@
         {
             if (SrcBpp <= 16)
             {
-                DstPixel.us = DIB_GetSource(Source, SrcX++, SrcY, ColorTranslation);
-                SrcPixel.col.red = (DstPixel.col.red << 3) | (DstPixel.col.red
>> 2);
-
-                SrcPixel.col.green = (DstPixel.col.green << 2) |
-                                     (DstPixel.col.green >> 4);
-
-                SrcPixel.col.blue = (DstPixel.col.blue << 3) | (DstPixel.col.blue
>> 2);
+                SrcPixel16.us = DIB_GetSource(Source, SrcX++, SrcY, ColorTranslation);
+                SrcPixel32.col.red = (SrcPixel16.col.red << 3);
+                SrcPixel32.col.green = (SrcPixel16.col.green << 2);
+                SrcPixel32.col.blue = (SrcPixel16.col.blue << 3);
+
+                SrcPixel32.col.red = SrcPixel32.col.red * BlendFunc.SourceConstantAlpha /
255;
+                SrcPixel32.col.green = SrcPixel32.col.green *
BlendFunc.SourceConstantAlpha / 255;
+                SrcPixel32.col.blue = SrcPixel32.col.blue * BlendFunc.SourceConstantAlpha
/ 255;
+                SrcPixel32.col.alpha = (SrcBpp == 32) ?
+                    (SrcPixel32.col.alpha * BlendFunc.SourceConstantAlpha / 255) :
+                    BlendFunc.SourceConstantAlpha;
+
+                Alpha = ((BlendFunc.AlphaFormat & AC_SRC_ALPHA) != 0) ?
+                    SrcPixel32.col.alpha : BlendFunc.SourceConstantAlpha;
+
+                DstPixel16.us = *Dst;
+                DstPixel16.col.red = Clamp5(DstPixel16.col.red * (255 - Alpha) / 255 +
+                                   (SrcPixel32.col.red >> 3));
+
+                DstPixel16.col.green = Clamp6(DstPixel16.col.green * (255 - Alpha) / 255
+
+                                     (SrcPixel32.col.green >> 2));
+
+                DstPixel16.col.blue = Clamp5(DstPixel16.col.blue * (255 - Alpha) / 255 +
+                                    (SrcPixel32.col.blue >> 3));
+
+                *Dst++ = DstPixel16.us;
             }
             else
             {
-                SrcPixel.ul = DIB_GetSourceIndex(Source, SrcX++, SrcY);
-            }
-            SrcPixel.col.red = SrcPixel.col.red *
-                               BlendFunc.SourceConstantAlpha / 255;
-
-            SrcPixel.col.green = SrcPixel.col.green *
-                                 BlendFunc.SourceConstantAlpha / 255;
-
-            SrcPixel.col.blue = SrcPixel.col.blue *
-                                BlendFunc.SourceConstantAlpha / 255;
-
-            SrcPixel.col.alpha = (SrcBpp == 32) ?
-                                 (SrcPixel.col.alpha *
-                                 BlendFunc.SourceConstantAlpha / 255) :
-                                 BlendFunc.SourceConstantAlpha;
-
-            Alpha = ((BlendFunc.AlphaFormat & AC_SRC_ALPHA) != 0) ?
-                    SrcPixel.col.alpha : BlendFunc.SourceConstantAlpha;
-
-         DstPixel.us = *Dst;
-         DstPixel.col.red = Clamp5(DstPixel.col.red * (255 - Alpha) / 255 +
-                                   (SrcPixel.col.red >> 3));
-
-         DstPixel.col.green = Clamp6(DstPixel.col.green * (255 - Alpha) / 255 +
-                                     (SrcPixel.col.green >> 2));
-
-         DstPixel.col.blue = Clamp5(DstPixel.col.blue * (255 - Alpha) / 255 +
-                                    (SrcPixel.col.blue >> 3));
-
-         *Dst++ = DstPixel.us;
+                SrcPixel32.ul = DIB_GetSourceIndex(Source, SrcX++, SrcY);
+
+                SrcPixel32.col.red = SrcPixel32.col.red * BlendFunc.SourceConstantAlpha 
/ 255;
+                SrcPixel32.col.green = SrcPixel32.col.green *
BlendFunc.SourceConstantAlpha  / 255;
+                SrcPixel32.col.blue = SrcPixel32.col.blue * BlendFunc.SourceConstantAlpha
/ 255;
+                SrcPixel32.col.alpha = (SrcBpp == 32) ?
+                    (SrcPixel32.col.alpha * BlendFunc.SourceConstantAlpha / 255) :
+                    BlendFunc.SourceConstantAlpha;     
+
+                Alpha = ((BlendFunc.AlphaFormat & AC_SRC_ALPHA) != 0) ?
+                    SrcPixel32.col.alpha : BlendFunc.SourceConstantAlpha;
+
+                DstPixel32.ul = XLATEOBJ_iXlate(SrcXlateObj, *Dst);
+                SrcPixel32.col.red = Clamp8(DstPixel32.col.red * (255 - Alpha) / 255 +
SrcPixel32.col.red);
+                SrcPixel32.col.green = Clamp8(DstPixel32.col.green * (255 - Alpha) / 255
+ SrcPixel32.col.green);
+                SrcPixel32.col.blue = Clamp8(DstPixel32.col.blue * (255 - Alpha) / 255 + 
SrcPixel32.col.blue);
+                *Dst++ = XLATEOBJ_iXlate(ColorTranslation, SrcPixel32.ul);
+            }
       }
 
       Dst = (PUSHORT)((ULONG_PTR)Dst + DstDelta);
       SrcY++;
     }
 
+    if (SrcXlateObj) EngDeleteXlate(SrcXlateObj);
+
     return TRUE;
 }