void BlendScanline(MemBitmap dstBmp, byte[] expandGreyBuffer,
PixelFarm.Drawing.Color color, int x, int y, int width)
{
byte[] rgb = new byte[3] {
color.R,
color.G,
color.B
};
//-------------------------
//destination
CpuBlit.TempMemPtr memPtr = MemBitmap.GetBufferPtr(dstBmp);
//start pixel
int destImgIndex = (x * 4) + (dstBmp.Stride * y);
//start img src
int srcImgIndex = x + (width * y);
int colorIndex = 0;
int round = 0;
byte color_a = color.A;
unsafe
{
byte *destImgBuffer = (byte *)memPtr.Ptr;
while (width > 3)
{
int a0 = expandGreyBuffer[srcImgIndex] * color_a;
int a1 = expandGreyBuffer[srcImgIndex + 1] * color_a;
int a2 = expandGreyBuffer[srcImgIndex + 2] * color_a;
byte ec0 = destImgBuffer[destImgIndex]; //existing color
byte ec1 = destImgBuffer[destImgIndex + 1]; //existing color
byte ec2 = destImgBuffer[destImgIndex + 2]; //existing color
//------------------------------------------------------
//please note that we swap a2 and a0 on the fly****
//------------------------------------------------------
byte n0 = (byte)((((rgb[colorIndex] - ec0) * a2) + (ec0 << 16)) >> 16);
byte n1 = (byte)((((rgb[colorIndex + 1] - ec1) * a1) + (ec1 << 16)) >> 16);
byte n2 = (byte)((((rgb[colorIndex + 2] - ec2) * a0) + (ec2 << 16)) >> 16);
destImgBuffer[destImgIndex] = n0;
destImgBuffer[destImgIndex + 1] = n1;
destImgBuffer[destImgIndex + 2] = n2;
destImgIndex += 4;
round = 0;
colorIndex = 0;
srcImgIndex += 3;
width -= 3;
}
memPtr.Dispose();
}
}
static byte[] CreateGreyScaleBuffer(MemBitmap bmp)
{
//assume img is 32 rgba img
int imgW = bmp.Width;
int height = bmp.Height;
//56 level grey scale buffer
CpuBlit.TempMemPtr srcMemPtr = MemBitmap.GetBufferPtr(bmp);
int greyScaleBufferLen = imgW * height;
byte[] greyScaleBuffer = new byte[greyScaleBufferLen];
int destIndex = 0;
int srcImgIndex = 0;
int srcImgStride = bmp.Stride;
unsafe
{
byte *srcImgBuffer = (byte *)srcMemPtr.Ptr;
for (int y = 0; y < height; ++y)
{
srcImgIndex = srcImgStride * y;
destIndex = imgW * y;
for (int x = 0; x < imgW; ++x)
{
byte r = srcImgBuffer[srcImgIndex];
byte g = srcImgBuffer[srcImgIndex + 1];
byte b = srcImgBuffer[srcImgIndex + 2];
byte a = srcImgBuffer[srcImgIndex + 3];
if (r != 0 || g != 0 || b != 0)
{
}
if (a != 255)
{
}
//skip alpha
//byte greyScaleValue =
// (byte)((0.333f * (float)r) + (0.5f * (float)g) + (0.1666f * (float)b));
greyScaleBuffer[destIndex] = (byte)(((a + 1) / 256f) * 64f);
destIndex++;
srcImgIndex += 4;
}
}
}
srcMemPtr.Dispose();
return(greyScaleBuffer);
}