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- implement correct alpha blending of icons

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- pixel bits must be pre-multiplied with the alpha channel
- along with the previous LookupIconIdFromDirectoryEx, basic alpha blending is working. some bugfixing is still required.

svn path=/trunk/; revision=25475
This commit is contained in:
Ged Murphy 2007-01-15 23:25:35 +00:00
parent 743b67a342
commit 1e1efd9791
1 changed files with 74 additions and 7 deletions
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81
reactos/subsystems/win32/win32k/ntuser/cursoricon.c
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@ -1400,14 +1400,10 @@ UserDrawIconEx(
IconSize.cy = bmpMask.bmHeight / 2;
}
/* A hack to get alpha-blending support for icons.
Disabled now because of a bug in alpha blending function
(which blends with white background instead of the background).
*/
/*if (bmpColor.bmBitsPixel == 32)
if (bmpColor.bmBitsPixel == 32)
{
bAlpha = TRUE;
}*/
}
if(!diFlags)
diFlags = DI_NORMAL;
@ -1518,11 +1514,82 @@ UserDrawIconEx(
{
if (bAlpha)
{
BITMAPINFO bi;
BITMAP bm;
BITMAPOBJ *Bitmap;
PBYTE pBits;
BLENDFUNCTION BlendFunc;
BlendFunc.BlendOp = AC_SRC_OVER; /* right ? */
BYTE Red, Green, Blue, Alpha;
DWORD Count = 0;
INT i, j;
/* Bitmap header */
bi.bmiHeader.biSize = sizeof(bi.bmiHeader);
bi.bmiHeader.biWidth = cxWidth;
bi.bmiHeader.biHeight = cyHeight;
bi.bmiHeader.biPlanes = 1;
bi.bmiHeader.biBitCount = 32;
bi.bmiHeader.biCompression = BI_RGB;
bi.bmiHeader.biSizeImage = cxWidth * cyHeight * 4;
bi.bmiHeader.biClrUsed = 0;
bi.bmiHeader.biClrImportant = 0;
Bitmap = GDIOBJ_LockObj(GdiHandleTable, hbmOff, GDI_OBJECT_TYPE_BITMAP);
if (Bitmap == NULL)
{
DPRINT1("GDIOBJ_LockObj() failed!\n");
goto cleanup;
}
BITMAP_GetObject(Bitmap, sizeof(BITMAP), &bm);
/* Buffer */
pBits = ExAllocatePoolWithTag(PagedPool, bm.bmWidthBytes * abs(bm.bmHeight), TAG_BITMAP);
if (pBits == NULL)
{
DPRINT1("ExAllocatePoolWithTag() failed!\n");
goto cleanup;
}
/* get icon bits */
NtGdiGetBitmapBits(hbmOff, bm.bmWidthBytes * abs(bm.bmHeight), pBits);
/* premultiply with the alpha channel value */
for (i = 0; i < cyHeight; i++)
{
for (j = 0; j < cxWidth; j++)
{
DWORD OrigPixel = 0;
DWORD AlphaPixel = 0;
OrigPixel = *(DWORD *)(pBits + Count);
Red = (BYTE)((OrigPixel >> 0) & 0xff);
Green = (BYTE)((OrigPixel >> 8) & 0xff);
Blue = (BYTE)((OrigPixel >> 16) & 0xff);
Alpha = (BYTE)((OrigPixel >> 24) & 0xff);
Red = (Red * Alpha) / 0xff;
Green = (Green * Alpha) / 0xff;
Blue = (Blue * Alpha) / 0xff;
AlphaPixel = (DWORD)(Red | (Green << 8) | (Blue << 16) | (Alpha << 24));
*(DWORD *)(pBits + Count) = AlphaPixel;
Count += sizeof (DWORD);
}
}
/* set icon bits */
NtGdiSetBitmapBits(hbmOff, bm.bmWidthBytes * abs(bm.bmHeight), pBits);
ExFreePool(pBits);
GDIOBJ_UnlockObjByPtr(GdiHandleTable, Bitmap);
BlendFunc.BlendOp = AC_SRC_OVER;
BlendFunc.BlendFlags = 0;
BlendFunc.SourceConstantAlpha = 255;
BlendFunc.AlphaFormat = AC_SRC_ALPHA;
NtGdiAlphaBlend(hDc, xLeft, yTop, cxWidth, cyHeight,
hdcOff, 0, 0, cxWidth, cyHeight, BlendFunc);
}