reactos/win32ss/gdi/dib/alphablend.c

   1 /*
   2  * PROJECT:         Win32 subsystem
   3  * LICENSE:         See COPYING in the top level directory
   4  * FILE:            subsystems/win32/win32k/dib/stretchblt.c
   5  * PURPOSE:         AlphaBlend implementation suitable for all bit depths
   6  * PROGRAMMERS:     Jérôme Gardou
   7  */
   8
   9 #include <win32k.h>
  10
  11 #define NDEBUG
  12 #include <debug.h>
  13
  14 typedef union
  15 {
  16   ULONG ul;
  17   struct
  18   {
  19     UCHAR red;
  20     UCHAR green;
  21     UCHAR blue;
  22     UCHAR alpha;
  23   } col;
  24 } NICEPIXEL32;
  25
  26 static __inline UCHAR
  27 Clamp8(ULONG val)
  28 {
  29   return (val > 255) ? 255 : (UCHAR)val;
  30 }
  31
  32 BOOLEAN
  33 DIB_XXBPP_AlphaBlend(SURFOBJ* Dest, SURFOBJ* Source, RECTL* DestRect,
  34                      RECTL* SourceRect, CLIPOBJ* ClipRegion,
  35                      XLATEOBJ* ColorTranslation, BLENDOBJ* BlendObj)
  36 {
  37   INT DstX, DstY, SrcX, SrcY;
  38   BLENDFUNCTION BlendFunc;
  39   register NICEPIXEL32 DstPixel32;
  40   register NICEPIXEL32 SrcPixel32;
  41   UCHAR Alpha, SrcBpp = BitsPerFormat(Source->iBitmapFormat);
  42   EXLATEOBJ* pexlo;
  43   EXLATEOBJ exloSrcRGB, exloDstRGB, exloRGBSrc;
  44   PFN_DIB_PutPixel pfnDibPutPixel = DibFunctionsForBitmapFormat[Dest->iBitmapFormat].DIB_PutPixel;
  45
  46   DPRINT("DIB_16BPP_AlphaBlend: srcRect: (%d,%d)-(%d,%d), dstRect: (%d,%d)-(%d,%d)\n",
  47     SourceRect->left, SourceRect->top, SourceRect->right, SourceRect->bottom,
  48     DestRect->left, DestRect->top, DestRect->right, DestRect->bottom);
  49
  50   BlendFunc = BlendObj->BlendFunction;
  51   if (BlendFunc.BlendOp != AC_SRC_OVER)
  52   {
  53     DPRINT1("BlendOp != AC_SRC_OVER\n");
  54     return FALSE;
  55   }
  56   if (BlendFunc.BlendFlags != 0)
  57   {
  58     DPRINT1("BlendFlags != 0\n");
  59     return FALSE;
  60   }
  61   if ((BlendFunc.AlphaFormat & ~AC_SRC_ALPHA) != 0)
  62   {
  63     DPRINT1("Unsupported AlphaFormat (0x%x)\n", BlendFunc.AlphaFormat);
  64     return FALSE;
  65   }
  66   if ((BlendFunc.AlphaFormat & AC_SRC_ALPHA) != 0 &&
  67     SrcBpp != 32)
  68   {
  69     DPRINT1("Source bitmap must be 32bpp when AC_SRC_ALPHA is set\n");
  70     return FALSE;
  71   }
  72
  73   if (!ColorTranslation)
  74   {
  75     DPRINT1("ColorTranslation must not be NULL!\n");
  76     return FALSE;
  77   }
  78
  79   pexlo = CONTAINING_RECORD(ColorTranslation, EXLATEOBJ, xlo);
  80   EXLATEOBJ_vInitialize(&exloSrcRGB, pexlo->ppalSrc, &gpalRGB, 0, 0, 0);
  81   EXLATEOBJ_vInitialize(&exloDstRGB, pexlo->ppalDst, &gpalRGB, 0, 0, 0);
  82   EXLATEOBJ_vInitialize(&exloRGBSrc, &gpalRGB, pexlo->ppalSrc, 0, 0, 0);
  83
  84   SrcY = SourceRect->top;
  85   DstY = DestRect->top;
  86   while ( DstY < DestRect->bottom )
  87   {
  88     SrcX = SourceRect->left;
  89     DstX = DestRect->left;
  90     while(DstX < DestRect->right)
  91     {
  92       SrcPixel32.ul = DIB_GetSource(Source, SrcX, SrcY, &exloSrcRGB.xlo);
  93       SrcPixel32.col.red = (SrcPixel32.col.red * BlendFunc.SourceConstantAlpha) / 255;
  94       SrcPixel32.col.green = (SrcPixel32.col.green * BlendFunc.SourceConstantAlpha) / 255;
  95       SrcPixel32.col.blue = (SrcPixel32.col.blue * BlendFunc.SourceConstantAlpha) / 255;
  96
  97       Alpha = ((BlendFunc.AlphaFormat & AC_SRC_ALPHA) != 0) ?
  98            (SrcPixel32.col.alpha * BlendFunc.SourceConstantAlpha) / 255 :
  99            BlendFunc.SourceConstantAlpha ;
 100
 101       DstPixel32.ul = DIB_GetSource(Dest, DstX, DstY, &exloDstRGB.xlo);
 102       DstPixel32.col.red = Clamp8((DstPixel32.col.red * (255 - Alpha)) / 255 + SrcPixel32.col.red) ;
 103       DstPixel32.col.green = Clamp8((DstPixel32.col.green * (255 - Alpha)) / 255 + SrcPixel32.col.green) ;
 104       DstPixel32.col.blue = Clamp8((DstPixel32.col.blue * (255 - Alpha)) / 255 + SrcPixel32.col.blue) ;
 105       DstPixel32.ul = XLATEOBJ_iXlate(&exloRGBSrc.xlo, DstPixel32.ul);
 106       pfnDibPutPixel(Dest, DstX, DstY, XLATEOBJ_iXlate(ColorTranslation, DstPixel32.ul));
 107
 108       DstX++;
 109       SrcX = SourceRect->left + ((DstX-DestRect->left)*(SourceRect->right - SourceRect->left))
 110                                             /(DestRect->right-DestRect->left);
 111     }
 112     DstY++;
 113     SrcY = SourceRect->top + ((DstY-DestRect->top)*(SourceRect->bottom - SourceRect->top))
 114                                             /(DestRect->bottom-DestRect->top);
 115   }
 116
 117   EXLATEOBJ_vCleanup(&exloDstRGB);
 118   EXLATEOBJ_vCleanup(&exloRGBSrc);
 119   EXLATEOBJ_vCleanup(&exloSrcRGB);
 120
 121   return TRUE;
 122 }
 123