On Sun, Mar 15, 2015, at 02:22 AM, Patrick J. Collins wrote: > My next approach was to save my drawn waveform to an NSImage and use > that as a background for my view... If you have a better suggestion for > how I could handle this, I'd love to hear it.
This is a good idea. It would be better yet if the waveform were rendered in a view that returned YES from -canDrawConcurrently, but you have to be careful about syncing access to your audio data between the view's background thread and the thread that's generating your audio data. > And to answer your question, the selection would be selecting frames of > audio, so that when it is played, the playhead starts there and ends at > the end of the rectangle. The problem with this approach is that it assumes that everything draws into the same bitmap context. To get an XOR effect to work correctly over an arbitrary region of a window, you need to read back the flattened contents of the view hierarchy, invert it, and write it back out. In modern GUI environments (and especially with Core Animation layer-backed views), not everything renders into the same graphics context; they might render into separate bitmaps and let the window manager composite them together. As you drag a selection across your waveform, you could take a note of the selection region and send -setNeedsDisplay to your view, and have -drawRect take care of inverting the colors of the waveform image that it draws in the dirty regions that intersect the selection region. --Kyle Sluder _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
