I'm having this problem with the transparency in GDI+.
I have 2 pictureBoxes, one over the other, and one of them has its' alpha color set to magenta(255, 0, 255).
My goal is that when the upper pictureBox has a picture on it with a section of the magenta color, that section on the upper pictureBox would show the pictureBox that's below it, at that section, like drawing with 2 layers.

Now, the way I did it, was define the lower picture's BackColor as BackColor::Control(Default), and the upper's as BackColor::Transparent, and when the picture is put to the upper box, the following would be part of the painting code:


What this does is when I put a transparent section on the upper, it would show the color of the panel below the pictureBox below it, which I actually want to show.

My question is why does it not show the pictureBox below, and how can I make it so that it does? Or is it even possible at all?

Thanks much for any comments.

Add your picture to an ImageList then set the transparent color to the imagelist:

ImageList myImages = new ImageList();
myImageList.TransparentColor = Color.Magenta;

Then when you need to add it to the picturebox:

pictureBox.Image = myImageList.Images[index_of_image];

Please note that I used C# as the coding format as this is the C# forum, not the C++ forum.

Yea, I'm sorry about the C++ format, but I wasn't really sure what it was on GDI+ for C#, I don't use C# much. I came here because no one knew to answer me on the C++ board, and I was tipped to come here since .NET has more support in the C# scene, so I just hope that it's ok?

As for the actual problem, I don't really know, that doesn't seem to have solved it, it still shows the color of the panel underneath the pictureBox that I want to see, and if I remove the MakeTransparent() function I referred to in my original post, then it'll just show the Magenta color, as if the ImageList helps with nothing.

The only difference it did, to which I am a little confused, is that it shrunk the pictures to 16x16 pixels from their original size, however, the pictureBoxes stayed in their proper size..

Am I doing something wrong here?

I'm sorry for the double post, but I have some new input on this.

I've looked over at MSDN to try and realize what the ImageList actually is and why I did it wrong, and I found the errors and fixed them, but then I also got stumped when I realized that the ImageList can only contain images of up to 256x256 pixels...

What do I do if I want transparent layers on larger images?

Well, no, not really.

But I found a solution to my problem already, it's a little cheaty on my part, but atleast it works.

Instead of trying to display the pictureBox contents on a control below the one I want transparent, I made the contents copy out to the backgroundImage value of the pictureBox I want transparent, as the transparency shows the backColor of the control you're currently using, it shows the backgroundImage I set, which is actually the same as the pictureBox I wanted to show, except that I can still work and edit that one as well.

I just hope this could help any other people struggling with transparency here in the future.

Oh, and by the way, I like your signature there, very nice.