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iOS: Animated image should animate at the same speed regardless of framerate

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Summary:
In iOS 11, [CADisplayLink](https://developer.apple.com/documentation/quartzcore/cadisplaylink)'s frameInterval was deprecated in favor of preferredFramesPerSecond, but these two properties have different underlying assumptions.

- set frameInterval to 2 for 30fps
- set preferredFramesPerSecond to 30 for 30fps. When you use preferredFramesPerSecond, assume frameInterval is 1.

This fix ensures gifs in <Image> component will animate at same speed regardless of framerate.

Reviewed By: shergin

Differential Revision: D21414014

fbshipit-source-id: 40ab23bab1990cf65d2802830b6835f350999537
This commit is contained in:
Paige Sun
2020-05-06 10:38:14 -07:00
committed by Facebook GitHub Bot
parent 530dffa342
commit b0d0e51a77
1 changed files with 11 additions and 15 deletions
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Libraries/Image/RCTUIImageViewAnimated.m
+11 -15
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@@ -181,22 +181,17 @@ static NSUInteger RCTDeviceFreeMemory() {
{
#if TARGET_OS_UIKITFORMAC
// TODO: `displayLink.frameInterval` is not available on UIKitForMac
NSTimeInterval duration = displayLink.duration;
NSTimeInterval durationToNextRefresh = displayLink.duration;
#else
NSTimeInterval duration = displayLink.duration;
// displaylink.duration -- time interval between frames, assuming maximumFramesPerSecond
// displayLink.preferredFramesPerSecond (>= iOS 10) -- Set to 30 for displayDidRefresh to be called at 30 fps
// displayLink.frameInterval (< iOS 10) -- # of frames that must pass before each displayDidRefresh. After iOS 10, when this is set to 2, preferredFramesPerSecond becomes 30 fps.
// durationToNextRefresh -- Time interval to the next time displayDidRefresh is called
NSTimeInterval durationToNextRefresh;
if (@available(iOS 10.0, *)) {
// Per https://developer.apple.com/documentation/quartzcore/cadisplaylink
// displayLink.duration provides the amount of time between frames at the maximumFramesPerSecond
// Thus we need to calculate true duration based on preferredFramesPerSecond
if (displayLink.preferredFramesPerSecond != 0) {
double maxFrameRate = 60.0; // default to 60 fps
if (@available(iOS 10.3, tvOS 10.3, *)) {
maxFrameRate = self.window.screen.maximumFramesPerSecond;
}
duration = duration * displayLink.preferredFramesPerSecond / maxFrameRate;
} // else respect maximumFramesPerSecond
} else { // version < (ios 10)
duration = duration * displayLink.frameInterval;
durationToNextRefresh = displayLink.targetTimestamp - displayLink.timestamp;
} else {
durationToNextRefresh = displayLink.duration * displayLink.frameInterval;
}
#endif
NSUInteger totalFrameCount = self.totalFrameCount;
@@ -206,13 +201,14 @@ static NSUInteger RCTDeviceFreeMemory() {
// Check if we have the frame buffer firstly to improve performance
if (!self.bufferMiss) {
// Then check if timestamp is reached
self.currentTime += duration;
self.currentTime += durationToNextRefresh;
NSTimeInterval currentDuration = [self.animatedImage animatedImageDurationAtIndex:currentFrameIndex];
if (self.currentTime < currentDuration) {
// Current frame timestamp not reached, return
return;
}
self.currentTime -= currentDuration;
// nextDuration - duration to wait before displaying next image
NSTimeInterval nextDuration = [self.animatedImage animatedImageDurationAtIndex:nextFrameIndex];
if (self.currentTime > nextDuration) {
// Do not skip frame