Thread: Taking a screenshot of an application.

Ok, my end goal is to be able to read in the colors of every pixel in a window and process them. I know how to do this with windows, but have little idea where to get started with windows.

With windows its basically a simple process of calling "GetDIBSection" and "BitBlt" and viola, you have an array with the data for every pixel on a given window.

With X, however, the process is much more vague.

I've read up what I could, and guess that you can do something to the effect of calling XGetWindowAttributes and then accessing the pixel data directly through the Value* value; part of the attributes structure. However, I am unsure if that will even work (don't have access to linux right now).

Anyone help from someone with experience programming X would be much appreciated.

Ok, so it is basically a call to XGetWindowsAttributes to get the data about the window. and then XGetImage to get the pixel data from the window. After a little googling, it looks like XGetPixel will give me the pixel values for each pixel on the image. Is this the fastest way to get pixel values or is there a faster on? (Speed is somewhat important)

Ok, Thanks for all the help thus far, I have one last question. I couldn't find this on any of the documentation.

I assume that XCopyArea dynamically allocates memory (and therefore needs to be freed). Does XGetImage dynamically allocate memory as well? Do I need to delete it to avoid memory leaks?

All right then, that makes a lot of sense, Thanks for your help!