////test...
//public static readonly double[,] AlphaMatrix040 = { {0.4, 0, 0, 0},
// {0, 1, 0, 0 },
// {0, 0, 1, 0},
// {0, 0, 0, 1}
// };
//Resizing
public static Image Resize(this Image sourceImage, int width, int height)
{
if (width > 0 && height > 0)
{
Image destinationImage = Image.Create(width, height);
//turn off alpha blending to overwrite it right
DLLImports.gdImageAlphaBlending(destinationImage.gdImageStructPtr, 0);
DLLImports.gdImageCopyResized(destinationImage.gdImageStructPtr, sourceImage.gdImageStructPtr, 0, 0, 0, 0,
destinationImage.WidthInPixels, destinationImage.HeightInPixels, sourceImage.WidthInPixels, sourceImage.HeightInPixels);
return(destinationImage);
}
else
{
throw new InvalidOperationException(SR.Format(SR.ResizeInvalidParameters, width, height));
}
}
//Stamping an Image onto another
public static void Draw(this Image destinationImage, Image sourceImage, int xOffset, int yOffset)
{
//turn alpha blending on for drawing
DLLImports.gdImageAlphaBlending(destinationImage.gdImageStructPtr, 1);
unsafe
{
DLLImports.gdImageStruct *pStructSource = (DLLImports.gdImageStruct *)sourceImage.gdImageStructPtr;
DLLImports.gdImageStruct *pStructDest = (DLLImports.gdImageStruct *)destinationImage.gdImageStructPtr;
//loop through the source image
for (int y = 0; y < sourceImage.HeightInPixels; y++)
{
for (int x = 0; x < sourceImage.WidthInPixels; x++)
{
//ignores what falls outside the bounds of dsetination image
if ((y + yOffset) >= destinationImage.HeightInPixels || (x + xOffset) >= destinationImage.WidthInPixels)
{
continue;
}
int sourceColor = pStructSource->tpixels[y][x];
int alpha = (sourceColor >> 24) & 0xff;
//should not have 127 as magic
if (alpha == 127)
{
continue;
}
int destColor = pStructDest->tpixels[y + yOffset][x + xOffset];
int blendedColor = DLLImports.gdAlphaBlend(destColor, sourceColor);
pStructDest->tpixels[y + yOffset][x + xOffset] = blendedColor;
}
}
}
}