src/cobalt/debug/devtools/front_end/screencast/ScreencastView.js

/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
/**
 * @implements {SDK.OverlayModel.Highlighter}
 * @unrestricted
 */
Screencast.ScreencastView = class extends UI.VBox {
  /**
   * @param {!SDK.ScreenCaptureModel} screenCaptureModel
   */
  constructor(screenCaptureModel) {
    super();
    this._screenCaptureModel = screenCaptureModel;
    this._domModel = screenCaptureModel.target().model(SDK.DOMModel);
    this._overlayModel = screenCaptureModel.target().model(SDK.OverlayModel);
    this._resourceTreeModel = screenCaptureModel.target().model(SDK.ResourceTreeModel);
    this._networkManager = screenCaptureModel.target().model(SDK.NetworkManager);
    this._inputModel = screenCaptureModel.target().model(Screencast.InputModel);

    this.setMinimumSize(150, 150);
    this.registerRequiredCSS('screencast/screencastView.css');
  }

  initialize() {
    this.element.classList.add('screencast');

    this._createNavigationBar();

    this._viewportElement = this.element.createChild('div', 'screencast-viewport hidden');
    this._canvasContainerElement = this._viewportElement.createChild('div', 'screencast-canvas-container');
    this._glassPaneElement = this._canvasContainerElement.createChild('div', 'screencast-glasspane fill hidden');

    this._canvasElement = this._canvasContainerElement.createChild('canvas');
    this._canvasElement.tabIndex = 0;
    this._canvasElement.addEventListener('mousedown', this._handleMouseEvent.bind(this), false);
    this._canvasElement.addEventListener('mouseup', this._handleMouseEvent.bind(this), false);
    this._canvasElement.addEventListener('mousemove', this._handleMouseEvent.bind(this), false);
    this._canvasElement.addEventListener('mousewheel', this._handleMouseEvent.bind(this), false);
    this._canvasElement.addEventListener('click', this._handleMouseEvent.bind(this), false);
    this._canvasElement.addEventListener('contextmenu', this._handleContextMenuEvent.bind(this), false);
    this._canvasElement.addEventListener('keydown', this._handleKeyEvent.bind(this), false);
    this._canvasElement.addEventListener('keyup', this._handleKeyEvent.bind(this), false);
    this._canvasElement.addEventListener('keypress', this._handleKeyEvent.bind(this), false);
    this._canvasElement.addEventListener('blur', this._handleBlurEvent.bind(this), false);

    this._titleElement = this._canvasContainerElement.createChild('div', 'screencast-element-title monospace hidden');
    this._tagNameElement = this._titleElement.createChild('span', 'screencast-tag-name');
    this._nodeIdElement = this._titleElement.createChild('span', 'screencast-node-id');
    this._classNameElement = this._titleElement.createChild('span', 'screencast-class-name');
    this._titleElement.createTextChild(' ');
    this._nodeWidthElement = this._titleElement.createChild('span');
    this._titleElement.createChild('span', 'screencast-px').textContent = 'px';
    this._titleElement.createTextChild(' \u00D7 ');
    this._nodeHeightElement = this._titleElement.createChild('span');
    this._titleElement.createChild('span', 'screencast-px').textContent = 'px';
    this._titleElement.style.top = '0';
    this._titleElement.style.left = '0';

    this._imageElement = new Image();
    this._isCasting = false;
    this._context = this._canvasElement.getContext('2d');
    this._checkerboardPattern = this._createCheckerboardPattern(this._context);

    this._shortcuts = /** !Object.<number, function(Event=):boolean> */ ({});
    this._shortcuts[UI.KeyboardShortcut.makeKey('l', UI.KeyboardShortcut.Modifiers.Ctrl)] =
        this._focusNavigationBar.bind(this);

    SDK.targetManager.addEventListener(SDK.TargetManager.Events.SuspendStateChanged, this._onSuspendStateChange, this);
    this._updateGlasspane();
  }

  /**
   * @override
   */
  wasShown() {
    this._startCasting();
  }

  /**
   * @override
   */
  willHide() {
    this._stopCasting();
  }

  _startCasting() {
    if (SDK.targetManager.allTargetsSuspended())
      return;
    if (this._isCasting)
      return;
    this._isCasting = true;

    const maxImageDimension = 2048;
    const dimensions = this._viewportDimensions();
    if (dimensions.width < 0 || dimensions.height < 0) {
      this._isCasting = false;
      return;
    }
    dimensions.width *= window.devicePixelRatio;
    dimensions.height *= window.devicePixelRatio;
    // Note: startScreencast width and height are expected to be integers so must be floored.
    this._screenCaptureModel.startScreencast(
        'jpeg', 80, Math.floor(Math.min(maxImageDimension, dimensions.width)),
        Math.floor(Math.min(maxImageDimension, dimensions.height)), undefined, this._screencastFrame.bind(this),
        this._screencastVisibilityChanged.bind(this));
    for (const emulationModel of SDK.targetManager.models(SDK.EmulationModel))
      emulationModel.overrideEmulateTouch(true);
    if (this._overlayModel)
      this._overlayModel.setHighlighter(this);
  }

  _stopCasting() {
    if (!this._isCasting)
      return;
    this._isCasting = false;
    this._screenCaptureModel.stopScreencast();
    for (const emulationModel of SDK.targetManager.models(SDK.EmulationModel))
      emulationModel.overrideEmulateTouch(false);
    if (this._overlayModel)
      this._overlayModel.setHighlighter(null);
  }

  /**
   * @param {string} base64Data
   * @param {!Protocol.Page.ScreencastFrameMetadata} metadata
   */
  _screencastFrame(base64Data, metadata) {
    this._imageElement.onload = () => {
      this._pageScaleFactor = metadata.pageScaleFactor;
      this._screenOffsetTop = metadata.offsetTop;
      this._scrollOffsetX = metadata.scrollOffsetX;
      this._scrollOffsetY = metadata.scrollOffsetY;

      const deviceSizeRatio = metadata.deviceHeight / metadata.deviceWidth;
      const dimensionsCSS = this._viewportDimensions();

      this._imageZoom = Math.min(
          dimensionsCSS.width / this._imageElement.naturalWidth,
          dimensionsCSS.height / (this._imageElement.naturalWidth * deviceSizeRatio));
      this._viewportElement.classList.remove('hidden');
      const bordersSize = Screencast.ScreencastView._bordersSize;
      if (this._imageZoom < 1.01 / window.devicePixelRatio)
        this._imageZoom = 1 / window.devicePixelRatio;
      this._screenZoom = this._imageElement.naturalWidth * this._imageZoom / metadata.deviceWidth;
      this._viewportElement.style.width = metadata.deviceWidth * this._screenZoom + bordersSize + 'px';
      this._viewportElement.style.height = metadata.deviceHeight * this._screenZoom + bordersSize + 'px';

      this.highlightDOMNode(this._highlightNode, this._highlightConfig);
    };
    this._imageElement.src = 'data:image/jpg;base64,' + base64Data;
  }

  _isGlassPaneActive() {
    return !this._glassPaneElement.classList.contains('hidden');
  }

  /**
   * @param {boolean} visible
   */
  _screencastVisibilityChanged(visible) {
    this._targetInactive = !visible;
    this._updateGlasspane();
  }

  /**
   * @param {!Common.Event} event
   */
  _onSuspendStateChange(event) {
    if (SDK.targetManager.allTargetsSuspended())
      this._stopCasting();
    else
      this._startCasting();
    this._updateGlasspane();
  }

  _updateGlasspane() {
    if (this._targetInactive) {
      this._glassPaneElement.textContent = Common.UIString('The tab is inactive');
      this._glassPaneElement.classList.remove('hidden');
    } else if (SDK.targetManager.allTargetsSuspended()) {
      this._glassPaneElement.textContent = Common.UIString('Profiling in progress');
      this._glassPaneElement.classList.remove('hidden');
    } else {
      this._glassPaneElement.classList.add('hidden');
    }
  }

  /**
   * @param {!Event} event
   */
  async _handleMouseEvent(event) {
    if (this._isGlassPaneActive()) {
      event.consume();
      return;
    }

    if (!this._pageScaleFactor || !this._domModel)
      return;

    if (!this._inspectModeConfig || event.type === 'mousewheel') {
      if (this._inputModel)
        this._inputModel.emitTouchFromMouseEvent(event, this._screenOffsetTop, this._screenZoom);
      event.preventDefault();
      if (event.type === 'mousedown')
        this._canvasElement.focus();
      return;
    }

    const position = this._convertIntoScreenSpace(event);

    const node = await this._domModel.nodeForLocation(
        Math.floor(position.x / this._pageScaleFactor + this._scrollOffsetX),
        Math.floor(position.y / this._pageScaleFactor + this._scrollOffsetY),
        Common.moduleSetting('showUAShadowDOM').get());

    if (!node)
      return;
    if (event.type === 'mousemove') {
      this.highlightDOMNode(node, this._inspectModeConfig);
      this._domModel.overlayModel().nodeHighlightRequested(node.id);
    } else if (event.type === 'click') {
      Common.Revealer.reveal(node);
    }
  }

  /**
   * @param {!Event} event
   */
  _handleKeyEvent(event) {
    if (this._isGlassPaneActive()) {
      event.consume();
      return;
    }

    const shortcutKey = UI.KeyboardShortcut.makeKeyFromEvent(/** @type {!KeyboardEvent} */ (event));
    const handler = this._shortcuts[shortcutKey];
    if (handler && handler(event)) {
      event.consume();
      return;
    }

    if (this._inputModel)
      this._inputModel.emitKeyEvent(event);
    event.consume();
    this._canvasElement.focus();
  }

  /**
   * @param {!Event} event
   */
  _handleContextMenuEvent(event) {
    event.consume(true);
  }

  /**
   * @param {!Event} event
   */
  _handleBlurEvent(event) {
    if (this._inputModel)
      this._inputModel.cancelTouch();
  }

  /**
   * @param {!Event} event
   * @return {!{x: number, y: number}}
   */
  _convertIntoScreenSpace(event) {
    const position = {};
    position.x = Math.round(event.offsetX / this._screenZoom);
    position.y = Math.round(event.offsetY / this._screenZoom - this._screenOffsetTop);
    return position;
  }

  /**
   * @override
   */
  onResize() {
    if (this._deferredCasting) {
      clearTimeout(this._deferredCasting);
      delete this._deferredCasting;
    }

    this._stopCasting();
    this._deferredCasting = setTimeout(this._startCasting.bind(this), 100);
  }

  /**
   * @override
   * @param {?SDK.DOMNode} node
   * @param {?Protocol.Overlay.HighlightConfig} config
   * @param {!Protocol.DOM.BackendNodeId=} backendNodeId
   * @param {!Protocol.Runtime.RemoteObjectId=} objectId
   */
  highlightDOMNode(node, config, backendNodeId, objectId) {
    this._highlightNode = node;
    this._highlightConfig = config;
    if (!node) {
      this._model = null;
      this._config = null;
      this._node = null;
      this._titleElement.classList.add('hidden');
      this._repaint();
      return;
    }

    this._node = node;
    node.boxModel().then(model => {
      if (!model || !this._pageScaleFactor) {
        this._repaint();
        return;
      }
      this._model = this._scaleModel(model);
      this._config = config;
      this._repaint();
    });
  }

  /**
   * @param {!Protocol.DOM.BoxModel} model
   * @return {!Protocol.DOM.BoxModel}
   */
  _scaleModel(model) {
    /**
     * @param {!Protocol.DOM.Quad} quad
     * @this {Screencast.ScreencastView}
     */
    function scaleQuad(quad) {
      for (let i = 0; i < quad.length; i += 2) {
        quad[i] = quad[i] * this._pageScaleFactor * this._screenZoom;
        quad[i + 1] = (quad[i + 1] * this._pageScaleFactor + this._screenOffsetTop) * this._screenZoom;
      }
    }

    scaleQuad.call(this, model.content);
    scaleQuad.call(this, model.padding);
    scaleQuad.call(this, model.border);
    scaleQuad.call(this, model.margin);
    return model;
  }

  _repaint() {
    const model = this._model;
    const config = this._config;

    const canvasWidth = this._canvasElement.getBoundingClientRect().width;
    const canvasHeight = this._canvasElement.getBoundingClientRect().height;
    this._canvasElement.width = window.devicePixelRatio * canvasWidth;
    this._canvasElement.height = window.devicePixelRatio * canvasHeight;

    this._context.save();
    this._context.scale(window.devicePixelRatio, window.devicePixelRatio);

    // Paint top and bottom gutter.
    this._context.save();
    this._context.fillStyle = this._checkerboardPattern;
    this._context.fillRect(0, 0, canvasWidth, this._screenOffsetTop * this._screenZoom);
    this._context.fillRect(
        0, this._screenOffsetTop * this._screenZoom + this._imageElement.naturalHeight * this._imageZoom, canvasWidth,
        canvasHeight);
    this._context.restore();

    if (model && config) {
      this._context.save();
      const transparentColor = 'rgba(0, 0, 0, 0)';
      const quads = [];
      if (model.content && config.contentColor !== transparentColor)
        quads.push({quad: model.content, color: config.contentColor});
      if (model.padding && config.paddingColor !== transparentColor)
        quads.push({quad: model.padding, color: config.paddingColor});
      if (model.border && config.borderColor !== transparentColor)
        quads.push({quad: model.border, color: config.borderColor});
      if (model.margin && config.marginColor !== transparentColor)
        quads.push({quad: model.margin, color: config.marginColor});

      for (let i = quads.length - 1; i > 0; --i)
        this._drawOutlinedQuadWithClip(quads[i].quad, quads[i - 1].quad, quads[i].color);
      if (quads.length > 0)
        this._drawOutlinedQuad(quads[0].quad, quads[0].color);
      this._context.restore();

      this._drawElementTitle();

      this._context.globalCompositeOperation = 'destination-over';
    }

    this._context.drawImage(
        this._imageElement, 0, this._screenOffsetTop * this._screenZoom,
        this._imageElement.naturalWidth * this._imageZoom, this._imageElement.naturalHeight * this._imageZoom);
    this._context.restore();
  }

  /**
   * @param {!Protocol.DOM.RGBA} color
   * @return {string}
   */
  _cssColor(color) {
    if (!color)
      return 'transparent';
    return Common.Color.fromRGBA([color.r, color.g, color.b, color.a]).asString(Common.Color.Format.RGBA) || '';
  }

  /**
   * @param {!Protocol.DOM.Quad} quad
   * @return {!CanvasRenderingContext2D}
   */
  _quadToPath(quad) {
    this._context.beginPath();
    this._context.moveTo(quad[0], quad[1]);
    this._context.lineTo(quad[2], quad[3]);
    this._context.lineTo(quad[4], quad[5]);
    this._context.lineTo(quad[6], quad[7]);
    this._context.closePath();
    return this._context;
  }

  /**
   * @param {!Protocol.DOM.Quad} quad
   * @param {!Protocol.DOM.RGBA} fillColor
   */
  _drawOutlinedQuad(quad, fillColor) {
    this._context.save();
    this._context.lineWidth = 2;
    this._quadToPath(quad).clip();
    this._context.fillStyle = this._cssColor(fillColor);
    this._context.fill();
    this._context.restore();
  }

  /**
   * @param {!Protocol.DOM.Quad} quad
   * @param {!Protocol.DOM.Quad} clipQuad
   * @param {!Protocol.DOM.RGBA} fillColor
   */
  _drawOutlinedQuadWithClip(quad, clipQuad, fillColor) {
    this._context.fillStyle = this._cssColor(fillColor);
    this._context.save();
    this._context.lineWidth = 0;
    this._quadToPath(quad).fill();
    this._context.globalCompositeOperation = 'destination-out';
    this._context.fillStyle = 'red';
    this._quadToPath(clipQuad).fill();
    this._context.restore();
  }

  _drawElementTitle() {
    if (!this._node)
      return;

    const canvasWidth = this._canvasElement.getBoundingClientRect().width;
    const canvasHeight = this._canvasElement.getBoundingClientRect().height;

    const lowerCaseName = this._node.localName() || this._node.nodeName().toLowerCase();
    this._tagNameElement.textContent = lowerCaseName;
    this._nodeIdElement.textContent = this._node.getAttribute('id') ? '#' + this._node.getAttribute('id') : '';
    this._nodeIdElement.textContent = this._node.getAttribute('id') ? '#' + this._node.getAttribute('id') : '';
    let className = this._node.getAttribute('class');
    if (className && className.length > 50)
      className = className.substring(0, 50) + '\u2026';
    this._classNameElement.textContent = className || '';
    this._nodeWidthElement.textContent = this._model.width;
    this._nodeHeightElement.textContent = this._model.height;

    this._titleElement.classList.remove('hidden');
    const titleWidth = this._titleElement.offsetWidth + 6;
    const titleHeight = this._titleElement.offsetHeight + 4;

    const anchorTop = this._model.margin[1];
    const anchorBottom = this._model.margin[7];

    const arrowHeight = 7;
    let renderArrowUp = false;
    let renderArrowDown = false;

    let boxX = Math.max(2, this._model.margin[0]);
    if (boxX + titleWidth > canvasWidth)
      boxX = canvasWidth - titleWidth - 2;

    let boxY;
    if (anchorTop > canvasHeight) {
      boxY = canvasHeight - titleHeight - arrowHeight;
      renderArrowDown = true;
    } else if (anchorBottom < 0) {
      boxY = arrowHeight;
      renderArrowUp = true;
    } else if (anchorBottom + titleHeight + arrowHeight < canvasHeight) {
      boxY = anchorBottom + arrowHeight - 4;
      renderArrowUp = true;
    } else if (anchorTop - titleHeight - arrowHeight > 0) {
      boxY = anchorTop - titleHeight - arrowHeight + 3;
      renderArrowDown = true;
    } else {
      boxY = arrowHeight;
    }

    this._context.save();
    this._context.translate(0.5, 0.5);
    this._context.beginPath();
    this._context.moveTo(boxX, boxY);
    if (renderArrowUp) {
      this._context.lineTo(boxX + 2 * arrowHeight, boxY);
      this._context.lineTo(boxX + 3 * arrowHeight, boxY - arrowHeight);
      this._context.lineTo(boxX + 4 * arrowHeight, boxY);
    }
    this._context.lineTo(boxX + titleWidth, boxY);
    this._context.lineTo(boxX + titleWidth, boxY + titleHeight);
    if (renderArrowDown) {
      this._context.lineTo(boxX + 4 * arrowHeight, boxY + titleHeight);
      this._context.lineTo(boxX + 3 * arrowHeight, boxY + titleHeight + arrowHeight);
      this._context.lineTo(boxX + 2 * arrowHeight, boxY + titleHeight);
    }
    this._context.lineTo(boxX, boxY + titleHeight);
    this._context.closePath();
    this._context.fillStyle = 'rgb(255, 255, 194)';
    this._context.fill();
    this._context.strokeStyle = 'rgb(128, 128, 128)';
    this._context.stroke();

    this._context.restore();

    this._titleElement.style.top = (boxY + 3) + 'px';
    this._titleElement.style.left = (boxX + 3) + 'px';
  }

  /**
   * @return {!{width: number, height: number}}
   */
  _viewportDimensions() {
    const gutterSize = 30;
    const bordersSize = Screencast.ScreencastView._bordersSize;
    const width = this.element.offsetWidth - bordersSize - gutterSize;
    const height = this.element.offsetHeight - bordersSize - gutterSize - Screencast.ScreencastView._navBarHeight;
    return {width: width, height: height};
  }

  /**
   * @override
   * @param {!Protocol.Overlay.InspectMode} mode
   * @param {!Protocol.Overlay.HighlightConfig} config
   * @return {!Promise}
   */
  setInspectMode(mode, config) {
    this._inspectModeConfig = mode !== Protocol.Overlay.InspectMode.None ? config : null;
    return Promise.resolve();
  }

  /**
   * @override
   * @param {!Protocol.Page.FrameId} frameId
   */
  highlightFrame(frameId) {
  }

  /**
   * @param {!CanvasRenderingContext2D} context
   */
  _createCheckerboardPattern(context) {
    const pattern = /** @type {!HTMLCanvasElement} */ (createElement('canvas'));
    const size = 32;
    pattern.width = size * 2;
    pattern.height = size * 2;
    const pctx = pattern.getContext('2d');

    pctx.fillStyle = 'rgb(195, 195, 195)';
    pctx.fillRect(0, 0, size * 2, size * 2);

    pctx.fillStyle = 'rgb(225, 225, 225)';
    pctx.fillRect(0, 0, size, size);
    pctx.fillRect(size, size, size, size);
    return context.createPattern(pattern, 'repeat');
  }

  _createNavigationBar() {
    this._navigationBar = this.element.createChild('div', 'screencast-navigation');
    this._navigationBack = this._navigationBar.createChild('button', 'back');
    this._navigationBack.disabled = true;
    this._navigationForward = this._navigationBar.createChild('button', 'forward');
    this._navigationForward.disabled = true;
    this._navigationReload = this._navigationBar.createChild('button', 'reload');
    this._navigationUrl = UI.createInput();
    this._navigationBar.appendChild(this._navigationUrl);
    this._navigationUrl.type = 'text';
    this._navigationProgressBar = new Screencast.ScreencastView.ProgressTracker(
        this._resourceTreeModel, this._networkManager, this._navigationBar.createChild('div', 'progress'));

    if (this._resourceTreeModel) {
      this._navigationBack.addEventListener('click', this._navigateToHistoryEntry.bind(this, -1), false);
      this._navigationForward.addEventListener('click', this._navigateToHistoryEntry.bind(this, 1), false);
      this._navigationReload.addEventListener('click', this._navigateReload.bind(this), false);
      this._navigationUrl.addEventListener('keyup', this._navigationUrlKeyUp.bind(this), true);
      this._requestNavigationHistory();
      this._resourceTreeModel.addEventListener(
          SDK.ResourceTreeModel.Events.MainFrameNavigated, this._requestNavigationHistory, this);
      this._resourceTreeModel.addEventListener(
          SDK.ResourceTreeModel.Events.CachedResourcesLoaded, this._requestNavigationHistory, this);
    }
  }

  /**
   * @param {number} offset
   */
  _navigateToHistoryEntry(offset) {
    const newIndex = this._historyIndex + offset;
    if (newIndex < 0 || newIndex >= this._historyEntries.length)
      return;
    this._resourceTreeModel.navigateToHistoryEntry(this._historyEntries[newIndex]);
    this._requestNavigationHistory();
  }

  _navigateReload() {
    this._resourceTreeModel.reloadPage();
  }

  /**
   * @param {!Event} event
   */
  _navigationUrlKeyUp(event) {
    if (event.key !== 'Enter')
      return;
    let url = this._navigationUrl.value;
    if (!url)
      return;
    if (!url.match(Screencast.ScreencastView._SchemeRegex))
      url = 'http://' + url;
    this._resourceTreeModel.navigate(url);
    this._canvasElement.focus();
  }

  async _requestNavigationHistory() {
    const history = await this._resourceTreeModel.navigationHistory();
    if (!history)
      return;

    this._historyIndex = history.currentIndex;
    this._historyEntries = history.entries;

    this._navigationBack.disabled = this._historyIndex === 0;
    this._navigationForward.disabled = this._historyIndex === (this._historyEntries.length - 1);

    let url = this._historyEntries[this._historyIndex].url;
    const match = url.match(Screencast.ScreencastView._HttpRegex);
    if (match)
      url = match[1];
    InspectorFrontendHost.inspectedURLChanged(url);
    this._navigationUrl.value = url;
  }

  _focusNavigationBar() {
    this._navigationUrl.focus();
    this._navigationUrl.select();
    return true;
  }
};

Screencast.ScreencastView._bordersSize = 44;

Screencast.ScreencastView._navBarHeight = 29;

Screencast.ScreencastView._HttpRegex = /^http:\/\/(.+)/;

Screencast.ScreencastView._SchemeRegex = /^(https?|about|chrome):/;

/**
 * @unrestricted
 */
Screencast.ScreencastView.ProgressTracker = class {
  /**
   * @param {?SDK.ResourceTreeModel} resourceTreeModel
   * @param {?SDK.NetworkManager} networkManager
   * @param {!Element} element
   */
  constructor(resourceTreeModel, networkManager, element) {
    this._element = element;
    if (resourceTreeModel) {
      resourceTreeModel.addEventListener(
          SDK.ResourceTreeModel.Events.MainFrameNavigated, this._onMainFrameNavigated, this);
      resourceTreeModel.addEventListener(SDK.ResourceTreeModel.Events.Load, this._onLoad, this);
    }
    if (networkManager) {
      networkManager.addEventListener(SDK.NetworkManager.Events.RequestStarted, this._onRequestStarted, this);
      networkManager.addEventListener(SDK.NetworkManager.Events.RequestFinished, this._onRequestFinished, this);
    }
  }

  _onMainFrameNavigated() {
    this._requestIds = {};
    this._startedRequests = 0;
    this._finishedRequests = 0;
    this._maxDisplayedProgress = 0;
    this._updateProgress(0.1);  // Display first 10% on navigation start.
  }

  _onLoad() {
    delete this._requestIds;
    this._updateProgress(1);  // Display 100% progress on load, hide it in 0.5s.
    setTimeout(function() {
      if (!this._navigationProgressVisible())
        this._displayProgress(0);
    }.bind(this), 500);
  }

  _navigationProgressVisible() {
    return !!this._requestIds;
  }

  _onRequestStarted(event) {
    if (!this._navigationProgressVisible())
      return;
    const request = /** @type {!SDK.NetworkRequest} */ (event.data);
    // Ignore long-living WebSockets for the sake of progress indicator, as we won't be waiting them anyway.
    if (request.type === Common.resourceTypes.WebSocket)
      return;
    this._requestIds[request.requestId()] = request;
    ++this._startedRequests;
  }

  _onRequestFinished(event) {
    if (!this._navigationProgressVisible())
      return;
    const request = /** @type {!SDK.NetworkRequest} */ (event.data);
    if (!(request.requestId() in this._requestIds))
      return;
    ++this._finishedRequests;
    setTimeout(function() {
      this._updateProgress(
          this._finishedRequests / this._startedRequests * 0.9);  // Finished requests drive the progress up to 90%.
    }.bind(this), 500);  // Delay to give the new requests time to start. This makes the progress smoother.
  }

  _updateProgress(progress) {
    if (!this._navigationProgressVisible())
      return;
    if (this._maxDisplayedProgress >= progress)
      return;
    this._maxDisplayedProgress = progress;
    this._displayProgress(progress);
  }

  _displayProgress(progress) {
    this._element.style.width = (100 * progress) + '%';
  }
};