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Alternative animation implementation for beta.jisho.org, using an easing function to accelerate towards the middle of a stroke, and decelerate at the end
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var Animation = Class(function Animation() {}); | |
Animation.mixin(Canvas); | |
Animation.prototype.extend(Event.Listener); | |
Animation.prototype.extend({ | |
reset: function() { | |
this.relativePosition = 0; | |
this.maxPosition = this.totalFrames - 1; | |
this.completed = false; | |
this.animating = false; | |
}, | |
ease: function(v, vmax) { | |
return -vmax/ 2 * (Math.cos(Math.PI * v / vmax) - 1); | |
}, | |
getCurrentFrame: function() { | |
var easedPosition = this.ease(this.relativePosition, this.maxPosition); | |
return Math.min(1 + Math.round(easedPosition), this.totalFrames); | |
}, | |
advance: function() { | |
if (this.relativePosition >= this.maxPosition) { | |
if (!this.completed) { | |
this.animating = false; | |
this.completed = true; | |
this.broadcast('AnimationComplete', this); | |
} | |
} else { | |
this.relativePosition += this.speed; | |
} | |
}, | |
drawCurrentFrameAndAdvance: function() { | |
this.drawFrame(this.getCurrentFrame()); | |
this.advance(); | |
}, | |
drawCurrentFrameAndRequestNext: function() { | |
var self = this; | |
this.clear(); | |
this.animating = true; | |
this.drawCurrentFrameAndAdvance(); | |
if(this.animating) { | |
window.requestAnimationFrame(function() { | |
self.drawCurrentFrameAndRequestNext(); | |
}); | |
} | |
}, | |
animate: function() { | |
if(this.animating) return; | |
this.reset(); | |
this.drawCurrentFrameAndRequestNext(); | |
} | |
}); |
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