Living Code

I noticed that jwz is trying to take a screenshot in Cocoa and having trouble. I'm happy to see that he's porting his awesome collection of screensavers to OS X, that's great news. As for taking screen shots, I'm amazed it is as hard as it seems to be--heck even the new Nokia Series 60 give you the ability to take screeenshots from Python now. In any case, here is a method that works for me under PyObjC. It assumes it is part of a Cocoa object and that you've done a from AppKit import * already. Since I can't comment on jwz's blog (whether it's because I don't use LiveJournal or because I do use Safari, I don't know), I'll post it here instead.

def screenShot(self):
    rect = NSScreen.mainScreen().frame()
    image = NSImage.alloc().initWithSize_((rect.size.width, rect.size.height
))
    window = NSWindow.alloc().initWithContentRect_styleMask_backing_defer_(
            rect, 
            NSBorderlessWindowMask, 
            NSBackingStoreNonretained, 
            False)
    view = NSView.alloc().initWithFrame_(rect)
    window.setLevel_(NSScreenSaverWindowLevel + 100)
    window.setHasShadow_(False)
    window.setAlphaValue_(0.0)
    window.setContentView_(view)
    window.orderFront_(self)
    view.lockFocus()
    screenRep= NSBitmapImageRep.alloc().initWithFocusedViewRect_(rect)
    image.addRepresentation_(screenRep)
    view.unlockFocus()
    window.orderOut_(self)
    window.close()
    return image

I cribbed this several months ago from some example Cocoa code, but forgot to make a note of where I got it. If anyone recognizes this pattern, please let me know so I can attribute it.