问题
Background: My application has a main window which contains a few smaller NSView objects, each of which contains several different controls, labels, images, etc. One of these views (and everything it contains) is disabled in response to a given flag. When the flag is set, I automatically disable and grey-out all of the controls embedded within that NSView.
Question: I would like to know how to darken the disabled NSView. The effect I am looking for would be something like drawing a 50% transparent black box on top of the disabled NSView. The background and all of the controls would still be visible, but the colors would be a darker shade. Is there a simple way to do this?
回答1:
CoreAnimation in 10.5 should provide an easy way to put a translucent layer above a view. You can create a black layer in front of the view, with the opacity at 0%. When you want to darken the view, set the opacity of the black layer to 50%, and the view will be darkened smoothly.
来源：https://stackoverflow.com/questions/466249/how-can-i-darken-everything-displayed-in-a-single-nsview