This program displays an image which is being continuously updated.
The image (which is calculated in a separate thread)
is a random pattern of grey pixels.
One of the calculation parameters is controlled via a slider and
a key goal of this project was to have the calculation ongoing with
the image continuously updating even while the user is moving the slider
around. As this project was a test bed for a compute-intensive program
where performance is important, I tried to make the image display as
efficient as possible.
Statistics on the update rates for the calculation ("model")
and display ("view") are available in a drawer that can be opened via
the Window menu.
This project illustrates several aspects of programming
for Mac OS X using the Cocoa API:
- calculation in a separate thread
- synchronizing use of shared variables via NSLock
- image drawn via NSBitmapImageRep in a subclass of NSView
- regular display updates via NSTimer
- using NSEventTrackingRunLoopMode to get timer events while mouse is down
- handling window resizing via inLiveResize
- auxiliary information displayed in an NSDrawer
You can get the project files via my
"Mac OS X Programming" page
Last modified: May 29, 2002
Cameron Hayne (hayne@mac.com)