Thanks for the suggestion Steve. Unfortunately this causes the background to turn black and not transparent. I would need the view to become transparent (so the WebView underneath is visible).
On 8.6.2010, at 16:04, Steve Christensen wrote: > Perhaps call NSRectFillUsingOperation(rect, NSCompositeClear) before drawing > each rectangle? > > > On Jun 8, 2010, at 5:32 AM, Matej Bukovinski wrote: > >> * PGP Bad Signature, Signed by an unverified key >> >> Hi, >> >> In a cocoa application that I'm developing I have a custom NSView subclass >> that I use as an overlay view for annotating a WebView. The overlay view >> draws semi-trasparent rectangles in its drawRect: method for DOM elements >> that were selected by the user. >> >> Since the fill color for the drawn rectangles is semi-transparent, the pixel >> values get added up when a smaller rectangle is drawn over a larger one >> (here's an example http://cl.ly/4fecb8fac0abff6ef6ac , as you can see the >> smaller rectangle has a darker background because of the larger rectangle, >> that was drawn first). This is especially problematic if the rectangles are >> of different colors, since color mixing occurs. >> >> I would like to prevent this sort of behavior by somehow "erasing" the >> content that was perviously drawn (i.e., making the background transparent >> again) before drawing with a new element. Does anyone have an idea how to >> achieve this? >> >> Thank you for your time. >> >> Best regards, >> Matej >> >> >> * Matej Bukovinski <ma...@bukovinski.com> >> * Issuer: The USERTRUST Network - Unverified >
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