Re: NSScrollView bug or misunderstood behavior?
Re: NSScrollView bug or misunderstood behavior?
- Subject: Re: NSScrollView bug or misunderstood behavior?
- From: Ivan Kourtev <email@hidden>
- Date: Fri, 17 Nov 2006 00:47:07 -0500
A while ago I asked a question about how to overlay more than one
layer of visual information in a view for performance reasons --
after looking at the suggestions I settled on using transparent child
windows layered on top of my app's document window. The current
architecture from bottom to top is:
A) a normal document window with a custom view in it
B) a transparent child window above containing a custom view in a
scrollview
C) another transparent child window above with a custom view
The idea is that the middle window (B) contains the app's view that
changes most often. What's drawn in this view is "sandwiched"
between the rarely changing content of the custom views in windows
(A) and (C).
The problem is that the scrollers in the scroll view in the middle
window (B) -- although perfectly working -- are colorless (don't have
the blue pulsating aqua behavior) and I cannot figure out how to fix
this? Is it because the child window (created with a
NSBorderlessWindowMask) is not the main window?
Can anyone suggest a way to work around this?
Thanks,
-- ivan
On Nov 11, 2006, at 5:40 PM, Ivan Kourtev wrote:
On Nov 11, 2006, at 3:01 PM, Erik Buck wrote:
2) Use an overlay window (child window): Let the Window Server do
the work for you by using an additional window and therefore an
additional backing store. Put whatever transparent drawing you
want in a child window that is layered correctly. The Window
Server will composite from both layered windows to produce the
final result in the frame buffer. You can have a transparent
document view layered above the child window or visa versa. It's
all good to the Window Server. I use this technique to layer
Cocoa controls over pure OpenGL drawing all the time.
I did several versions of this and was able to get them to work
nicely for stuff above the main drawing in the document view -- I
am using an overlay transparent view (a subview of my custom view)
all the time. In your suggestion above, if I create a child window
and order it below the window with the document view, then how will
I make the content of this child window seen through the document
view (enclosed in a scroll view) in the main window? Even if the
scroll view doesn't draw its background, wouldn't the main window
(above the child window) be in the way? I think this would be
the most attractive option for me, if it can be made to work.
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