public void MakeTransparent(Color transparentColor)
{
if (RawFormat.Guid == ImageFormat.Icon.Guid)
{
throw new InvalidOperationException(SR.GetString(SR.CantMakeIconTransparent));
}
Size size = Size;
// The new bitmap must be in 32bppARGB format, because that's the only
// thing that supports alpha. (And that's what the image is initialized to -- transparent)
Bitmap result = null;
Graphics graphics = null;
try {
result = new Bitmap(size.Width, size.Height, PixelFormat.Format32bppArgb);
try {
graphics = Graphics.FromImage(result);
graphics.Clear(Color.Transparent);
Rectangle rectangle = new Rectangle(0, 0, size.Width, size.Height);
ImageAttributes attributes = null;
try {
attributes = new ImageAttributes();
attributes.SetColorKey(transparentColor, transparentColor);
graphics.DrawImage(this, rectangle,
0, 0, size.Width, size.Height,
GraphicsUnit.Pixel, attributes, null, IntPtr.Zero);
}
finally {
if (attributes != null)
{
attributes.Dispose();
}
}
}
finally {
if (graphics != null)
{
graphics.Dispose();
}
}
// Swap nativeImage pointers to make it look like we modified the image in place
IntPtr temp = this.nativeImage;
this.nativeImage = result.nativeImage;
result.nativeImage = temp;
}
finally {
if (result != null)
{
result.Dispose();
}
}
}
public void MakeTransparent(Color transparentColor)
{
// We have to draw always over a 32-bitmap surface that supports alpha channel
Bitmap bmp = new Bitmap(Width, Height, PixelFormat.Format32bppArgb);
Graphics gr = Graphics.FromImage(bmp);
Rectangle destRect = new Rectangle(0, 0, Width, Height);
ImageAttributes imageAttr = new ImageAttributes();
imageAttr.SetColorKey(transparentColor, transparentColor);
gr.DrawImage(this, destRect, 0, 0, Width, Height, GraphicsUnit.Pixel, imageAttr);
IntPtr oldBmp = nativeObject;
nativeObject = bmp.nativeObject;
bmp.nativeObject = oldBmp;
gr.Dispose();
bmp.Dispose();
imageAttr.Dispose();
}