如何使我的图像透明？

Question

I know how to make an image control transparent in C#, but is there a way to make the image (the .jpeg file, not the image control) transparent? Or, is there a way, when I make the image control transparent, to create new image, save it in some path and give it the other image control's content?

Answer 1

The JPEG file cannot be transparent. However, if you save it as a PNG image it will have a transparency channel.

GIFS also support transparency, but only either completely opaque or completely transparent. Nothing in between.

PNG is your best bet here IMO.

Answer 2

You can set the Image-Controls's Opacity-Property to view it with transparence. But to get an image-file with transparency, you'll have to render it into a new file.

Here's an example how you can do it.

Image image = new Image(); //or however you get this
image.Opacity = 0.5;
RenderTargetBitmap bmp = new RenderTargetBitmap(image.Source.Width, image.Source.Height, 96, 96, PixelFormats.Pbgra32);
bmp.Render(image);

PngBitmapEncoder png = new PngBitmapEncoder();
png.Frames.Add(BitmapFrame.Create(bmp));
using (Stream fs= File.Create("test.png"))
{
png.Save(fs);
}

Answer 3

There is property transparencycolor. That is what you need if you want to display image on control.