Changing alpha of window background, not the whole window

so i have a quick question i have the method below which sets the alpha value of a window depending on the value from a slider, however the cont开发者_开发百科ent of the window also becomes translucent and eventually disappears with the window.

Is there a way to just change the alpha value of the window and not the content view inside it?

- (IBAction)changeTransparency:(id)sender { 
// Set the window's alpha value. This will cause the views in the window to redraw.
[self.window setAlphaValue:[sender floatValue]];}

Thanks, Sami.

Apple's docs gives a way to do this. The key is to set the window's backgroundColor's alpha to the desired value. You must also make sure to set the window's opaque property to NO (which is YES by default.)

e.x.

// At some point in your code...
[window setOpaque:NO];

// Then in your changeTransparency: method...
NSColor *backgroundColor = [window backgroundColor];
backgroundColor = [backgroundColor colorWithAlphaComponent:[sender floatValue]];

[window setBackgroundColor:backgroundColor];

Here is another way.

Suppose, self.window <--- base view and this alpha will be changed (but exacatly fake). subView1, subView2 <-- these views are contents of self.window. and theier alpha should not be changed.

self.window.backgroundColor = [UIColor clearColor];

UIView* anAlphaView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, self.window.frame.size.widht, self.window.frame.size.height)];
anAlphaView.backgroundColor = [UIColor blackColor]; // as you want
anAlphaView.alpha = 0.5f; // as you want.
[self.window addSubview:anAlphaView];
[anAlphaView release];

[self.window addSubview:subView1]; // you should add sub views to self.window
[self.window addSubview:subView2];

You can make a method using above code :)