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Skip frames when minimum frame rate is not reached

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The new minFrameRate option is used to make sure that an animation does not
run longer than the time calculated from that frame rate. Time is made up
by skipping frames, i.e. skipping execution of the eachStep callback.
This commit is contained in:
ahocevar
2012-12-17 14:54:08 +01:00
parent c9fa5aabad
commit f0f1ea0867
2 changed files with 51 additions and 1 deletions
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22
lib/OpenLayers/Tween.js
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@@ -52,6 +52,22 @@ OpenLayers.Tween = OpenLayers.Class({
*/
time: null,
/**
* APIProperty: minFrameRate
* {Number} The minimum framerate for animations. After each step, the time
* spent in the animation is compared to the calculated time at this frame
* rate. If the animation runs longer than the calculated time, the next
* step is skipped.
*/
minFrameRate: 30,
/**
* Property: startTime
* {Number} The timestamp of the first execution step. Used for skipping
* frames
*/
startTime: null,
/**
* Property: animationId
* {int} Loop id returned by OpenLayers.Animation.start
@@ -92,6 +108,7 @@ OpenLayers.Tween = OpenLayers.Class({
this.duration = duration;
this.callbacks = options.callbacks;
this.time = 0;
this.startTime = new Date().getTime();
OpenLayers.Animation.stop(this.animationId);
this.animationId = null;
if (this.callbacks && this.callbacks.start) {
@@ -139,7 +156,10 @@ OpenLayers.Tween = OpenLayers.Class({
this.time++;
if (this.callbacks && this.callbacks.eachStep) {
this.callbacks.eachStep.call(this, value);
// skip frames if frame rate drops below threshold
if ((new Date().getTime() - this.startTime) / this.time <= 1000 / this.minFrameRate) {
this.callbacks.eachStep.call(this, value);
}
}
if (this.time > this.duration) {