Cocoa: take screenshot of desktop wallpaper (without icons and windows)

Question

Is is possible to capture the Mac OS X desktop without desktop items and any windows that may be open (i.e. just the wallpaper)?

I've experimented with CGWindowListCreateImage, CGWindowListCreateImageFromArray, and CGDisplayCreateImage, but no luck.

Essentially I'm trying to capture the desktop wallpaper without using [NSWorkspace desktopImageURLForScreen:] (it's a sandboxed app without access to the file system).

Answer 1

You'll need to be careful to test that this is still correct, but the desktop window sits below the Finder (it's drawn by the Dock). Passing the kCGWindowListOptionOnScreenBelowWindow CGWindowListOption to CGWindowListCreateImage should get you what you want (unless something else is drawing below that level).

Otherwise, you'll need to use CGWindowListCreate and iterate through the response excluding anything that isn't drawn by the dock at the window level kCGMinimumWindowLevel + 19.

It gets kind of tricky when there are multiple screens, but hopefully this information is enough for you to do what you need.