Refactoring scrolling_benchmark code into scrolling_interaction.py

tools/perf/perf_tools/scroll.js

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// Inject this script on any page to measure framerate as the page is scrolled
-// from top to bottom.
-//
-// Usage:
-//   1. Define a callback that takes a RenderingStats object as a parameter.
-//   2. To start the test, call new __ScrollTest(callback).
-//   3a. When the test is complete, the callback will be called.
-//   3b. If no callback is specified, the results is sent to the console.
-
-(function() {
-  var getTimeMs = (function() {
-    if (window.performance)
-      return (performance.now       ||
-              performance.mozNow    ||
-              performance.msNow     ||
-              performance.oNow      ||
-              performance.webkitNow).bind(window.performance);
-    else
-      return function() { return new Date().getTime(); };
-  })();
-
-  var requestAnimationFrame = (function() {
-    return window.requestAnimationFrame       ||
-           window.webkitRequestAnimationFrame ||
-           window.mozRequestAnimationFrame    ||
-           window.oRequestAnimationFrame      ||
-           window.msRequestAnimationFrame     ||
-           function(callback) {
-             window.setTimeout(callback, 1000 / 60);
-           };
-  })().bind(window);
-
-  /**
-   * Scrolls a given element down a certain amount to emulate user scrolling.
-   * Uses smooth scrolling capabilities provided by the platform, if available.
-   * @constructor
-   */
-  function SmoothScrollDownGesture(opt_element) {
-    this.element_ = opt_element || document.body;
-  };
-
-  function min(a, b) {
-    if (a > b) {
-      return b;
-    }
-    return a;
-  };
-
-  function getBoundingVisibleRect(el) {
-    var bound = el.getBoundingClientRect();
-    var rect = { top: bound.top,
-                 left: bound.left,
-                 width: bound.width,
-                 height: bound.height };
-    var outsideHeight = (rect.top + rect.height) - window.innerHeight;
-    var outsideWidth = (rect.left + rect.width) - window.innerWidth;
-
-    if (outsideHeight > 0) {
-      rect.height -= outsideHeight;
-    }
-    if (outsideWidth > 0) {
-      rect.width -= outsideWidth;
-    }
-    return rect;
-  };
-
-  SmoothScrollDownGesture.prototype.start = function(callback) {
-    this.callback_ = callback;
-    if (chrome &&
-        chrome.gpuBenchmarking &&
-        chrome.gpuBenchmarking.smoothScrollBy) {
-      var rect = getBoundingVisibleRect(this.element_);
-      chrome.gpuBenchmarking.smoothScrollBy(
-          this.element_.scrollHeight, function() {
-        callback();
-      }, rect.left + rect.width / 2, rect.top + rect.height / 2);
-      return;
-    }
-
-    var SCROLL_DELTA = 100;
-    this.element_.scrollTop += SCROLL_DELTA;
-    requestAnimationFrame(callback);
-  };
-
-  /**
-   * Tracks rendering performance using the gpuBenchmarking.renderingStats API.
-   * @constructor
-   */
-  function GpuBenchmarkingRenderingStats() {
-  }
-
-  GpuBenchmarkingRenderingStats.prototype.start = function() {
-    this.initialStats_ = this.getRenderingStats_();
-  }
-  GpuBenchmarkingRenderingStats.prototype.stop = function() {
-    this.finalStats_ = this.getRenderingStats_();
-  }
-
-  GpuBenchmarkingRenderingStats.prototype.getDeltas = function() {
-    if (!this.initialStats_)
-      throw new Error('Start not called.');
-
-    if (!this.finalStats_)
-      throw new Error('Stop was not called.');
-
-    var stats = this.finalStats_;
-    for (var key in stats)
-      stats[key] -= this.initialStats_[key];
-    return stats;
-  };
-
-  GpuBenchmarkingRenderingStats.prototype.getRenderingStats_ = function() {
-    var stats = chrome.gpuBenchmarking.renderingStats();
-    stats.totalTimeInSeconds = getTimeMs() / 1000;
-    return stats;
-  };
-
-  /**
-   * Tracks rendering performance using requestAnimationFrame.
-   * @constructor
-   */
-  function RafRenderingStats() {
-    this.recording_ = false;
-    this.frameTimes_ = [];
-  }
-
-  RafRenderingStats.prototype.start = function() {
-    if (this.recording_)
-      throw new Error('Already started.');
-    this.recording_ = true;
-    requestAnimationFrame(this.recordFrameTime_.bind(this));
-  }
-
-  RafRenderingStats.prototype.stop = function() {
-    this.recording_ = false;
-  }
-
-  RafRenderingStats.prototype.getDeltas = function() {
-    var results = {};
-    results.numAnimationFrames = this.frameTimes_.length - 1;
-    results.numFramesSentToScreen = results.numAnimationFrames;
-    results.droppedFrameCount = this.getDroppedFrameCount_(this.frameTimes_);
-    results.totalTimeInSeconds = (
-        this.frameTimes_[this.frameTimes_.length - 1] -
-        this.frameTimes_[0]) / 1000;
-    return results;
-  };
-
-  RafRenderingStats.prototype.recordFrameTime_ = function(timestamp) {
-    if (!this.recording_)
-      return;
-
-    this.frameTimes_.push(timestamp);
-    requestAnimationFrame(this.recordFrameTime_.bind(this));
-  };
-
-  RafRenderingStats.prototype.getDroppedFrameCount_ = function(frameTimes) {
-    var droppedFrameCount = 0;
-    for (var i = 1; i < frameTimes.length; i++) {
-      var frameTime = frameTimes[i] - frameTimes[i-1];
-      if (frameTime > 1000 / 55)
-        droppedFrameCount++;
-    }
-    return droppedFrameCount;
-  };
-
-  // This class scrolls a page from the top to the bottom once.
-  //
-  // The page is scrolled down by a set of scroll gestures. These gestures
-  // correspond to a reading gesture on that platform.
-  //
-  // start -> startPass_ -> ...scrolling... -> onGestureComplete_ ->
-  //       -> startPass_ -> .. scrolling... -> onGestureComplete_ -> callback_
-  function ScrollTest(opt_callback) {
-    var self = this;
-
-    this.callback_ = opt_callback;
-  }
-
-  ScrollTest.prototype.start = function(opt_element) {
-    // Assign this.element_ here instead of constructor, because the constructor
-    // ensures this method will be called after the document is loaded.
-    this.element_ = opt_element || document.body;
-    // Some pages load more content when you scroll to the bottom. Record
-    // the original element height here and only scroll to that point.
-    this.scrollHeight_ = this.element_.scrollHeight
-    requestAnimationFrame(this.startPass_.bind(this));
-  };
-
-  ScrollTest.prototype.startPass_ = function() {
-    this.element_.scrollTop = 0;
-    if (window.chrome && chrome.gpuBenchmarking &&
-        chrome.gpuBenchmarking.renderingStats)
-      this.renderingStats_ = new GpuBenchmarkingRenderingStats();
-    else
-      this.renderingStats_ = new RafRenderingStats();
-    this.renderingStats_.start();
-
-    this.gesture_ = new SmoothScrollDownGesture(this.element_);
-    this.gesture_.start(this.onGestureComplete_.bind(this));
-  };
-
-  ScrollTest.prototype.onGestureComplete_ = function(timestamp) {
-    // clientHeight is "special" for the body element.
-    var clientHeight;
-    if (this.element_ == document.body)
-      clientHeight = window.innerHeight;
-    else
-      clientHeight = this.element_.clientHeight;
-
-    // If the scrollHeight went down, only scroll to the new scrollHeight.
-    this.scrollHeight_ = Math.min(this.scrollHeight_,
-                                  this.element_.scrollHeight);
-
-    // -1 to allow for rounding errors on scaled viewports (like mobile).
-    var isPassComplete =
-        this.element_.scrollTop + clientHeight >= this.scrollHeight_ - 1;
-
-    if (!isPassComplete) {
-      this.gesture_.start(this.onGestureComplete_.bind(this));
-      return;
-    }
-
-    this.endPass_();
-
-    // We're done.
-    if (this.callback_)
-      this.callback_(this.renderingStats_.getDeltas());
-    else
-      console.log(this.renderingStats_.getDeltas());
-  };
-
-  ScrollTest.prototype.endPass_ = function() {
-    this.renderingStats_.stop();
-  };
-
-  window.__ScrollTest = ScrollTest;
-  window.__ScrollTest_GetBoundingVisibleRect = getBoundingVisibleRect;
-})();