基于HTML5 Canvas和Rebound动画的Loading加载动画特效

// Create a SpringSystem.  let springSystem = new rebound.SpringSystem();

// Add a spring to the system.  demo.spring = springSystem.createSpring(settings.tension, settings.friction);

_addSpringListener() {   let ctx = this;   // Add a listener to the spring. Every time the physics  // solver updates the Spring's value onSpringUpdate will  // be called.  this._spring.addListener({    // ...  });}

this._spring.setEndValue((this._spring.getCurrentValue() === 1) ? 0 : 1);

onSpringUpdate(spring) {   let val = spring.getCurrentValue();   // Input range in the `from` parameters.  let fromLow = 0,    fromHigh = 1,    // Property animation range in the `to` parameters.    toLow = ctx._springRangeLow,    toHigh = ctx._springRangeHigh;   val = rebound.MathUtil.mapValueInRange(val, fromLow, fromHigh, toLow, toHigh);   // Note that the render method is  // called with the spring motion value.  ctx.render(val);}