MD WebUI: create a Chrome-only <paper-ripple> that's resistant to JS jank (via web animations API)

third_party/polymer/v1_0/components-chromium/paper-ripple/paper-ripple-extracted.js

 (function() {
-    var Utility = {
-      distance: function(x1, y1, x2, y2) {
-        var xDelta = (x1 - x2);
-        var yDelta = (y1 - y2);
-
-        return Math.sqrt(xDelta * xDelta + yDelta * yDelta);
-      },
-
-      now: window.performance && window.performance.now ?
-          window.performance.now.bind(window.performance) : Date.now
-    };
-
-    /**
-     * @param {HTMLElement} element
-     * @constructor
-     */
-    function ElementMetrics(element) {
-      this.element = element;
-      this.width = this.boundingRect.width;
-      this.height = this.boundingRect.height;
-
-      this.size = Math.max(this.width, this.height);
+
+var MAX_RADIUS_PX = 300;
+var MIN_DURATION_MS = 800;
+
+/**
+ * @param {number} x1
+ * @param {number} y1
+ * @param {number} x2
+ * @param {number} y2
+ * @return {number} The distance between (x1, y1) and (x2, y2).
+ */
+var distance = function(x1, y1, x2, y2) {
+  var xDelta = x1 - x2;
+  var yDelta = y1 - y2;
+  return Math.sqrt(xDelta * xDelta + yDelta * yDelta);
+};
+
+Polymer({
+  is: 'paper-ripple',
+
+  behaviors: [Polymer.IronA11yKeysBehavior],
+
+  properties: {
+    center: {type: Boolean, value: false},
+    holdDown: {type: Boolean, value: false, observer: '_holdDownChanged'},
+    recenters: {type: Boolean, value: false},
+    noink: {type: Boolean, value: false},
+  },
+
+  keyBindings: {
+    'enter:keydown': '_onEnterKeydown',
+    'space:keydown': '_onSpaceKeydown',
+    'space:keyup': '_onSpaceKeyup',
+  },
+
+  /** @override */
+  created: function() {
+    /** @type {Array<!Element>} */
+    this.ripples = [];
+  },
+
+  /** @override */
+  attached: function() {
+    this.keyEventTarget = this.parentNode.nodeType == 11 ?
+        Polymer.dom(this).getOwnerRoot().host : this.parentNode;
+    this.keyEventTarget = /** @type {!EventTarget} */ (this.keyEventTarget);
+    this.listen(this.keyEventTarget, 'up', 'uiUpAction');
+    this.listen(this.keyEventTarget, 'down', 'uiDownAction');
+  },
+
+  /** @override */
+  detached: function() {
+    this.unlisten(this.keyEventTarget, 'up', 'uiUpAction');
+    this.unlisten(this.keyEventTarget, 'down', 'uiDownAction');
+    this.keyEventTarget = null;
+  },
+
+  simulatedRipple: function() {
+    this.downAction();
+    // Using a 1ms delay ensures a macro-task.
+    this.async(function() { this.upAction(); }.bind(this), 1);
+  },
+
+  /** @param {Event=} e */
+  uiDownAction: function(e) {
+    if (!this.noink)
+      this.downAction(e);
+  },
+
+  /** @param {Event=} e */
+  downAction: function(e) {
+    if (this.ripples.length && this.holdDown)
+      return;
+    // TODO(dbeam): some things (i.e. paper-icon-button-light) dynamically
+    // create ripples on 'up', Ripples register an event listener on their
+    // parent (or shadow DOM host) when attached().  This sometimes causes
+    // duplicate events to fire on us.
+    this.debounce('show ripple', function() { this.__showRipple(e); }, 1);
+  },
+
+  /**
+   * @param {Event=} e
+   * @private
+   * @suppress {checkTypes}
+   */
+  __showRipple: function(e) {
+    var rect = this.getBoundingClientRect();
+
+    var roundedCenterX = function() { return Math.round(rect.width / 2); };
+    var roundedCenterY = function() { return Math.round(rect.height / 2); };
+
+    var centered = !e || this.center;
+    if (centered) {
+      var x = roundedCenterX();
+      var y = roundedCenterY();
+    } else {
+      var sourceEvent = e.detail.sourceEvent;
+      var x = Math.round(sourceEvent.clientX - rect.left);
+      var y = Math.round(sourceEvent.clientY - rect.top);
     }
 
-    ElementMetrics.prototype = {
-      get boundingRect () {
-        return this.element.getBoundingClientRect();
-      },
-
-      furthestCornerDistanceFrom: function(x, y) {
-        var topLeft = Utility.distance(x, y, 0, 0);
-        var topRight = Utility.distance(x, y, this.width, 0);
-        var bottomLeft = Utility.distance(x, y, 0, this.height);
-        var bottomRight = Utility.distance(x, y, this.width, this.height);
-
-        return Math.max(topLeft, topRight, bottomLeft, bottomRight);
+    var corners = [
+      {x: 0, y: 0},
+      {x: rect.width, y: 0},
+      {x: 0, y: rect.height},
+      {x: rect.width, y: rect.height},
+    ];
+
+    var cornerDistances = corners.map(function(corner) {
+      return Math.round(distance(x, y, corner.x, corner.y));
+    });
+
+    var radius = Math.min(MAX_RADIUS_PX, Math.max.apply(Math, cornerDistances));
+
+    var startTranslate = (x - radius) + 'px, ' + (y - radius) + 'px';
+    if (this.recenters && !centered) {
+      var endTranslate = (roundedCenterX() - radius) + 'px, ' +
+                         (roundedCenterY() - radius) + 'px';
+    } else {
+      var endTranslate = startTranslate;
+    }
+
+    var ripple = document.createElement('div');
+    ripple.classList.add('ripple');
+    ripple.style.height = ripple.style.width = (2 * radius) + 'px';
+
+    this.ripples.push(ripple);
+    this.shadowRoot.appendChild(ripple);
+
+    ripple.animate({
+      // TODO(dbeam): scale to 90% of radius at .75 offset?
+      transform: ['translate(' + startTranslate + ') scale(0)',
+                  'translate(' + endTranslate + ') scale(1)'],
+    }, {
+      duration: Math.max(MIN_DURATION_MS, Math.log(radius) * radius) || 0,
+      easing: 'cubic-bezier(.2, .9, .1, .9)',
+      fill: 'forwards',
+    });
+  },
+
+  /** @param {Event=} e */
+  uiUpAction: function(e) {
+    if (!this.noink)
+      this.upAction();
+  },
+
+  /** @param {Event=} e */
+  upAction: function(e) {
+    if (!this.holdDown)
+      this.debounce('hide ripple', function() { this.__hideRipple(); }, 1);
+  },
+
+  /**
+   * @private
+   * @suppress {checkTypes}
+   */
+  __hideRipple: function() {
+    this.ripples.forEach(function(ripple) {
+      var removeRipple = function() { ripple.remove(); };
+      // TODO(dbeam): should we be firing a transitionend event here? Does
+      // anybody actually use it? It's in the original paper-ripple.
+      var opacity = getComputedStyle(ripple).opacity;
+      if (!opacity.length) {
+        removeRipple();
+      } else {
+        var animation = ripple.animate({
+          opacity: [opacity, 0],
+        }, {
+          duration: 150,
+          fill: 'forwards',
+        });
+        animation.addEventListener('finish', removeRipple);
+        animation.addEventListener('cancel', removeRipple);
       }
-    };
-
-    /**
-     * @param {HTMLElement} element
-     * @constructor
-     */
-    function Ripple(element) {
-      this.element = element;
-      this.color = window.getComputedStyle(element).color;
-
-      this.wave = document.createElement('div');
-      this.waveContainer = document.createElement('div');
-      this.wave.style.backgroundColor = this.color;
-      this.wave.classList.add('wave');
-      this.waveContainer.classList.add('wave-container');
-      Polymer.dom(this.waveContainer).appendChild(this.wave);
-
-      this.resetInteractionState();
-    }
-
-    Ripple.MAX_RADIUS = 300;
-
-    Ripple.prototype = {
-      get recenters() {
-        return this.element.recenters;
-      },
-
-      get center() {
-        return this.element.center;
-      },
-
-      get mouseDownElapsed() {
-        var elapsed;
-
-        if (!this.mouseDownStart) {
-          return 0;
-        }
-
-        elapsed = Utility.now() - this.mouseDownStart;
-
-        if (this.mouseUpStart) {
-          elapsed -= this.mouseUpElapsed;
-        }
-
-        return elapsed;
-      },
-
-      get mouseUpElapsed() {
-        return this.mouseUpStart ?
-          Utility.now () - this.mouseUpStart : 0;
-      },
-
-      get mouseDownElapsedSeconds() {
-        return this.mouseDownElapsed / 1000;
-      },
-
-      get mouseUpElapsedSeconds() {
-        return this.mouseUpElapsed / 1000;
-      },
-
-      get mouseInteractionSeconds() {
-        return this.mouseDownElapsedSeconds + this.mouseUpElapsedSeconds;
-      },
-
-      get initialOpacity() {
-        return this.element.initialOpacity;
-      },
-
-      get opacityDecayVelocity() {
-        return this.element.opacityDecayVelocity;
-      },
-
-      get radius() {
-        var width2 = this.containerMetrics.width * this.containerMetrics.width;
-        var height2 = this.containerMetrics.height * this.containerMetrics.height;
-        var waveRadius = Math.min(
-          Math.sqrt(width2 + height2),
-          Ripple.MAX_RADIUS
-        ) * 1.1 + 5;
-
-        var duration = 1.1 - 0.2 * (waveRadius / Ripple.MAX_RADIUS);
-        var timeNow = this.mouseInteractionSeconds / duration;
-        var size = waveRadius * (1 - Math.pow(80, -timeNow));
-
-        return Math.abs(size);
-      },
-
-      get opacity() {
-        if (!this.mouseUpStart) {
-          return this.initialOpacity;
-        }
-
-        return Math.max(
-          0,
-          this.initialOpacity - this.mouseUpElapsedSeconds * this.opacityDecayVelocity
-        );
-      },
-
-      get outerOpacity() {
-        // Linear increase in background opacity, capped at the opacity
-        // of the wavefront (waveOpacity).
-        var outerOpacity = this.mouseUpElapsedSeconds * 0.3;
-        var waveOpacity = this.opacity;
-
-        return Math.max(
-          0,
-          Math.min(outerOpacity, waveOpacity)
-        );
-      },
-
-      get isOpacityFullyDecayed() {
-        return this.opacity < 0.01 &&
-          this.radius >= Math.min(this.maxRadius, Ripple.MAX_RADIUS);
-      },
-
-      get isRestingAtMaxRadius() {
-        return this.opacity >= this.initialOpacity &&
-          this.radius >= Math.min(this.maxRadius, Ripple.MAX_RADIUS);
-      },
-
-      get isAnimationComplete() {
-        return this.mouseUpStart ?
-          this.isOpacityFullyDecayed : this.isRestingAtMaxRadius;
-      },
-
-      get translationFraction() {
-        return Math.min(
-          1,
-          this.radius / this.containerMetrics.size * 2 / Math.sqrt(2)
-        );
-      },
-
-      get xNow() {
-        if (this.xEnd) {
-          return this.xStart + this.translationFraction * (this.xEnd - this.xStart);
-        }
-
-        return this.xStart;
-      },
-
-      get yNow() {
-        if (this.yEnd) {
-          return this.yStart + this.translationFraction * (this.yEnd - this.yStart);
-        }
-
-        return this.yStart;
-      },
-
-      get isMouseDown() {
-        return this.mouseDownStart && !this.mouseUpStart;
-      },
-
-      resetInteractionState: function() {
-        this.maxRadius = 0;
-        this.mouseDownStart = 0;
-        this.mouseUpStart = 0;
-
-        this.xStart = 0;
-        this.yStart = 0;
-        this.xEnd = 0;
-        this.yEnd = 0;
-        this.slideDistance = 0;
-
-        this.containerMetrics = new ElementMetrics(this.element);
-      },
-
-      draw: function() {
-        var scale;
-        var translateString;
-        var dx;
-        var dy;
-
-        this.wave.style.opacity = this.opacity;
-
-        scale = this.radius / (this.containerMetrics.size / 2);
-        dx = this.xNow - (this.containerMetrics.width / 2);
-        dy = this.yNow - (this.containerMetrics.height / 2);
-
-
-        // 2d transform for safari because of border-radius and overflow:hidden clipping bug.
-        // https://bugs.webkit.org/show_bug.cgi?id=98538
-        this.waveContainer.style.webkitTransform = 'translate(' + dx + 'px, ' + dy + 'px)';
-        this.waveContainer.style.transform = 'translate3d(' + dx + 'px, ' + dy + 'px, 0)';
-        this.wave.style.webkitTransform = 'scale(' + scale + ',' + scale + ')';
-        this.wave.style.transform = 'scale3d(' + scale + ',' + scale + ',1)';
-      },
-
-      /** @param {Event=} event */
-      downAction: function(event) {
-        var xCenter = this.containerMetrics.width / 2;
-        var yCenter = this.containerMetrics.height / 2;
-
-        this.resetInteractionState();
-        this.mouseDownStart = Utility.now();
-
-        if (this.center) {
-          this.xStart = xCenter;
-          this.yStart = yCenter;
-          this.slideDistance = Utility.distance(
-            this.xStart, this.yStart, this.xEnd, this.yEnd
-          );
-        } else {
-          this.xStart = event ?
-              event.detail.x - this.containerMetrics.boundingRect.left :
-              this.containerMetrics.width / 2;
-          this.yStart = event ?
-              event.detail.y - this.containerMetrics.boundingRect.top :
-              this.containerMetrics.height / 2;
-        }
-
-        if (this.recenters) {
-          this.xEnd = xCenter;
-          this.yEnd = yCenter;
-          this.slideDistance = Utility.distance(
-            this.xStart, this.yStart, this.xEnd, this.yEnd
-          );
-        }
-
-        this.maxRadius = this.containerMetrics.furthestCornerDistanceFrom(
-          this.xStart,
-          this.yStart
-        );
-
-        this.waveContainer.style.top =
-          (this.containerMetrics.height - this.containerMetrics.size) / 2 + 'px';
-        this.waveContainer.style.left =
-          (this.containerMetrics.width - this.containerMetrics.size) / 2 + 'px';
-
-        this.waveContainer.style.width = this.containerMetrics.size + 'px';
-        this.waveContainer.style.height = this.containerMetrics.size + 'px';
-      },
-
-      /** @param {Event=} event */
-      upAction: function(event) {
-        if (!this.isMouseDown) {
-          return;
-        }
-
-        this.mouseUpStart = Utility.now();
-      },
-
-      remove: function() {
-        Polymer.dom(this.waveContainer.parentNode).removeChild(
-          this.waveContainer
-        );
-      }
-    };
-
-    Polymer({
-      is: 'paper-ripple',
-
-      behaviors: [
-        Polymer.IronA11yKeysBehavior
-      ],
-
-      properties: {
-        /**
-         * The initial opacity set on the wave.
-         *
-         * @attribute initialOpacity
-         * @type number
-         * @default 0.25
-         */
-        initialOpacity: {
-          type: Number,
-          value: 0.25
-        },
-
-        /**
-         * How fast (opacity per second) the wave fades out.
-         *
-         * @attribute opacityDecayVelocity
-         * @type number
-         * @default 0.8
-         */
-        opacityDecayVelocity: {
-          type: Number,
-          value: 0.8
-        },
-
-        /**
-         * If true, ripples will exhibit a gravitational pull towards
-         * the center of their container as they fade away.
-         *
-         * @attribute recenters
-         * @type boolean
-         * @default false
-         */
-        recenters: {
-          type: Boolean,
-          value: false
-        },
-
-        /**
-         * If true, ripples will center inside its container
-         *
-         * @attribute recenters
-         * @type boolean
-         * @default false
-         */
-        center: {
-          type: Boolean,
-          value: false
-        },
-
-        /**
-         * A list of the visual ripples.
-         *
-         * @attribute ripples
-         * @type Array
-         * @default []
-         */
-        ripples: {
-          type: Array,
-          value: function() {
-            return [];
-          }
-        },
-
-        /**
-         * True when there are visible ripples animating within the
-         * element.
-         */
-        animating: {
-          type: Boolean,
-          readOnly: true,
-          reflectToAttribute: true,
-          value: false
-        },
-
-        /**
-         * If true, the ripple will remain in the "down" state until `holdDown`
-         * is set to false again.
-         */
-        holdDown: {
-          type: Boolean,
-          value: false,
-          observer: '_holdDownChanged'
-        },
-
-        /**
-         * If true, the ripple will not generate a ripple effect
-         * via pointer interaction.
-         * Calling ripple's imperative api like `simulatedRipple` will
-         * still generate the ripple effect.
-         */
-        noink: {
-          type: Boolean,
-          value: false
-        },
-
-        _animating: {
-          type: Boolean
-        },
-
-        _boundAnimate: {
-          type: Function,
-          value: function() {
-            return this.animate.bind(this);
-          }
-        }
-      },
-
-      get target () {
-        return this.keyEventTarget;
-      },
-
-      keyBindings: {
-        'enter:keydown': '_onEnterKeydown',
-        'space:keydown': '_onSpaceKeydown',
-        'space:keyup': '_onSpaceKeyup'
-      },
-
-      attached: function() {
-        // Set up a11yKeysBehavior to listen to key events on the target,
-        // so that space and enter activate the ripple even if the target doesn't
-        // handle key events. The key handlers deal with `noink` themselves.
-        if (this.parentNode.nodeType == 11) { // DOCUMENT_FRAGMENT_NODE
-          this.keyEventTarget = Polymer.dom(this).getOwnerRoot().host;
-        } else {
-          this.keyEventTarget = this.parentNode;
-        }
-        var keyEventTarget = /** @type {!EventTarget} */ (this.keyEventTarget);
-        this.listen(keyEventTarget, 'up', 'uiUpAction');
-        this.listen(keyEventTarget, 'down', 'uiDownAction');
-      },
-
-      detached: function() {
-        this.unlisten(this.keyEventTarget, 'up', 'uiUpAction');
-        this.unlisten(this.keyEventTarget, 'down', 'uiDownAction');
-        this.keyEventTarget = null;
-      },
-
-      get shouldKeepAnimating () {
-        for (var index = 0; index < this.ripples.length; ++index) {
-          if (!this.ripples[index].isAnimationComplete) {
-            return true;
-          }
-        }
-
-        return false;
-      },
-
-      simulatedRipple: function() {
-        this.downAction(null);
-
-        // Please see polymer/polymer#1305
-        this.async(function() {
-          this.upAction();
-        }, 1);
-      },
-
-      /**
-       * Provokes a ripple down effect via a UI event,
-       * respecting the `noink` property.
-       * @param {Event=} event
-       */
-      uiDownAction: function(event) {
-        if (!this.noink) {
-          this.downAction(event);
-        }
-      },
-
-      /**
-       * Provokes a ripple down effect via a UI event,
-       * *not* respecting the `noink` property.
-       * @param {Event=} event
-       */
-      downAction: function(event) {
-        if (this.holdDown && this.ripples.length > 0) {
-          return;
-        }
-
-        var ripple = this.addRipple();
-
-        ripple.downAction(event);
-
-        if (!this._animating) {
-          this._animating = true;
-          this.animate();
-        }
-      },
-
-      /**
-       * Provokes a ripple up effect via a UI event,
-       * respecting the `noink` property.
-       * @param {Event=} event
-       */
-      uiUpAction: function(event) {
-        if (!this.noink) {
-          this.upAction(event);
-        }
-      },
-
-      /**
-       * Provokes a ripple up effect via a UI event,
-       * *not* respecting the `noink` property.
-       * @param {Event=} event
-       */
-      upAction: function(event) {
-        if (this.holdDown) {
-          return;
-        }
-
-        this.ripples.forEach(function(ripple) {
-          ripple.upAction(event);
-        });
-
-        this._animating = true;
-        this.animate();
-      },
-
-      onAnimationComplete: function() {
-        this._animating = false;
-        this.$.background.style.backgroundColor = null;
-        this.fire('transitionend');
-      },
-
-      addRipple: function() {
-        var ripple = new Ripple(this);
-
-        Polymer.dom(this.$.waves).appendChild(ripple.waveContainer);
-        this.$.background.style.backgroundColor = ripple.color;
-        this.ripples.push(ripple);
-
-        this._setAnimating(true);
-
-        return ripple;
-      },
-
-      removeRipple: function(ripple) {
-        var rippleIndex = this.ripples.indexOf(ripple);
-
-        if (rippleIndex < 0) {
-          return;
-        }
-
-        this.ripples.splice(rippleIndex, 1);
-
-        ripple.remove();
-
-        if (!this.ripples.length) {
-          this._setAnimating(false);
-        }
-      },
-
-      /**
-       * This conflicts with Element#antimate().
-       * https://developer.mozilla.org/en-US/docs/Web/API/Element/animate
-       * @suppress {checkTypes}
-       */
-      animate: function() {
-        if (!this._animating) {
-          return;
-        }
-        var index;
-        var ripple;
-
-        for (index = 0; index < this.ripples.length; ++index) {
-          ripple = this.ripples[index];
-
-          ripple.draw();
-
-          this.$.background.style.opacity = ripple.outerOpacity;
-
-          if (ripple.isOpacityFullyDecayed && !ripple.isRestingAtMaxRadius) {
-            this.removeRipple(ripple);
-          }
-        }
-
-        if (!this.shouldKeepAnimating && this.ripples.length === 0) {
-          this.onAnimationComplete();
-        } else {
-          window.requestAnimationFrame(this._boundAnimate);
-        }
-      },
-
-      _onEnterKeydown: function() {
-        this.uiDownAction();
-        this.async(this.uiUpAction, 1);
-      },
-
-      _onSpaceKeydown: function() {
-        this.uiDownAction();
-      },
-
-      _onSpaceKeyup: function() {
-        this.uiUpAction();
-      },
-
-      // note: holdDown does not respect noink since it can be a focus based
-      // effect.
-      _holdDownChanged: function(newVal, oldVal) {
-        if (oldVal === undefined) {
-          return;
-        }
-        if (newVal) {
-          this.downAction();
-        } else {
-          this.upAction();
-        }
-      }
-
-      /**
-      Fired when the animation finishes.
-      This is useful if you want to wait until
-      the ripple animation finishes to perform some action.
-
-      @event transitionend
-      @param {{node: Object}} detail Contains the animated node.
-      */
     });
-  })();
+    this.ripples = [];
+  },
+
+  /** @protected */
+  _onEnterKeydown: function() {
+    this.uiDownAction();
+    this.async(this.uiUpAction, 1);
+  },
+
+  /** @protected */
+  _onSpaceKeydown: function() {
+    this.uiDownAction();
+  },
+
+  /** @protected */
+  _onSpaceKeyup: function() {
+    this.uiUpAction();
+  },
+
+  /** @protected */
+  _holdDownChanged: function(newHoldDown, oldHoldDown) {
+    if (oldHoldDown === undefined)
+      return;
+    if (newHoldDown)
+      this.downAction();
+    else
+      this.upAction();
+  },
+});
+
+})();