Re: NSImageView

[Fred Kiefer]

Jeff Teunissen wrote:

> Nicola Pero wrote:
>
>
> > We can't change the API, so we probably can't just use a composite
> > operation in NSImageView, but must do things properly and optimize
> > properly the image drawing to the clipped area in the backend.
>
> NSImageCells with alpha need to clear their background (or something)
> before drawing, otherwise they draw over the tops of themselves, making
> the sections with nonzero alpha get progressively opaque.


I am not sure, if you are right. The way this should be handled is 
different. When a cell does not fill the total background it returns YES 
from the isOpaque method. Otherwise, and this is the default, NO is 
returned, which should result in all the views below the NSImageCell to 
redraw themselves first. If this simple and correct mechnism does not 
work for the redrawing of NSImageCells, than we have a more general 
problem with the drawing of all views. Do you have a small program to 
show this problem?


> The same thing happens with antialiased text; text gets drawn over itself,
> making it darker and darker the more times it's drawn.


This I have seen myself. This looks like the text is drawn more often 
than the background is. This is of course an error, but I could not 
trace down where this happens.