How to make an NSView transparent and show what's under the NSWindow? [duplicate]

Answer 1

Perhaps try NSWindow's setOpaque: and you also need to set the window's background color with a transparent color (setBackgroundColor:)

Here is my quick sample I just did:

custom NSView named myView :

-(void)drawRect:(NSRect)dirtyRect
{
    [[NSColor windowBackgroundColor] set];  // Using the default window colour,
    dirtyRect.size.width /= 2;
    NSRectFill(dirtyRect);      // Only draw the part you need.
}

Next I set a window's contentView an instance of myView. I did it in IB but you can manually set it via setContentView.

And I configured the window like this :

[myWin setOpaque:NO];  //Tells the window manager that the window might have transparent parts.
[myWin setBackgroundColor:[NSColor colorWithCalibratedWhite:1.0 alpha:0.0]];  //Tells the window to use a transparent colour.

And this is what I get.

So like I said, you need to tell the window to use an invisible colour as background, then redraw the parts you actually do need drawn.