Change Alpha value of pixels in Xlib window

Question

I am going through (Change Xlib window background color with C++) & know to set the background color of XWindow.

But how can I set the Alpha value of that Xwindow. I tried several things, but when I do read from XWindow, each pixel has Alpha as 0xff.

Is there any way I can set this alpha as 0x00. Please provide some sample code.

Answer 1

Setting the alpha channel will only work for visuals with a depth of 32 bits. Use XMatchVisualInfo to create 32 bit visuals. That will only work though if your graphics hardware supports it.

Check out this answer where I have posted sample code that generates a completely transparent window.