|[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]|
|I'm trying to draw a Core Image transition using a Core Video display link. My thought was to create a display link and then in the callback generate and display a single frame of the transition. To do that, I need to know what the time stamp in the Display Link callback represents. In particular, I need to know how long has elapsed between the time my animation started, and the time the Display Link's callback is called.|
The documentation on the Display Link seems to be oriented toward getting frames from QuickTime. The Display Link itself doesn't seem to have any idea what time it started. I tried using :
mStartTime.version = 0;
To get the time the display link started. Then in the callback I tried to do some math:
double currentTime = (double)(timeStamp.videoTime - mStartTime.videoTime) / (double)timeStamp.videoTimeScale;
to come up with the time elapsed (in seconds) since the animation started. It appears, however, that my call to CVDisplayLinkGetCurrentTime is not returning what I hoped it would because the elapsed times I get are on the order of 27000 seconds. Certainly I could use NSDate in a similar way to get the information I'm looking for (to the precision I need)... I just thought I would see if I could use the time stamps I was given.
Clearly I'm trying to do something unusual... use the display link without using the buffer services provided by Core Video. Is this even a meaningful strategy? Is there some way to obtain the timing information I am looking for from the callback's time stamp?
_______________________________________________ Do not post admin requests to the list. They will be ignored. Quartz-dev mailing list (email@hidden) Help/Unsubscribe/Update your Subscription: This email sent to email@hidden
Visit the Apple Store online or at retail locations.
Copyright © 2011 Apple Inc. All rights reserved.