Extract DisplayLayoutManager from display_options.js

chrome/browser/resources/options/chromeos/display_layout_manager.js

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Copyright 2016 The Chromium Authors. All rights reserved.

[stevenjb, 2016/01/26 01:31:26]

Note: This is a new file diffing from display_options.js so the diff is a little
odd. (I used a low similarity value so that you can see the actual changes).
Also: This may make more sense if display_options.js is reviewed first.

 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 cr.exportPath('options');
 
 /**
  * Enumeration of display layout. These values must match the C++ values in
  * ash::DisplayController.
  * @enum {number}
  */
 options.DisplayLayoutType = {
   TOP: 0,
   RIGHT: 1,
   BOTTOM: 2,
   LEFT: 3
 };
 
 /**
- * Enumeration of multi display mode. These values must match the C++ values in
- * ash::DisplayManager.
- * @enum {number}
- */
-options.MultiDisplayMode = {
-  EXTENDED: 0,
-  MIRRORING: 1,
-  UNIFIED: 2,
-};
-
-/**
  * @typedef {{
  *   left: number,
  *   top: number,
  *   width: number,
  *   height: number
  * }}
  */
 options.DisplayBounds;
 
 /**
  * @typedef {{
  *   x: number,
  *   y: number
  * }}
  */
 options.DisplayPosition;
 
 /**
  * @typedef {{
- *   width: number,
- *   height: number,
- *   originalWidth: number,
- *   originalHeight: number,
- *   deviceScaleFactor: number,
- *   scale: number,
- *   refreshRate: number,
- *   isBest: boolean,
- *   selected: boolean
- * }}
- */
-options.DisplayMode;
-
-/**
- * @typedef {{
- *   profileId: number,
- *   name: string
- * }}
- */
-options.ColorProfile;
-
-/**
- * @typedef {{
- *   availableColorProfiles: !Array<!options.ColorProfile>,
- *   bounds: !options.DisplayBounds,
- *   colorProfileId: number,
- *   id: string,
- *   isInternal: boolean,
- *   isPrimary: boolean,
- *   resolutions: !Array<!options.DisplayMode>,
- *   name: string,
- *   rotation: number
- * }}
- */
-options.DisplayInfo;
-
-/**
- * @typedef {{
  *   bounds: !options.DisplayBounds,
  *   div: ?HTMLElement,
  *   id: string,
- *   isPrimary: boolean,
  *   layoutType: options.DisplayLayoutType,
  *   name: string,
- *   originalPosition: !options.DisplayPosition
+ *   offset: number,
+ *   originalPosition: !options.DisplayPosition,
+ *   parentId: string
  * }}
  */
 options.DisplayLayout;
 
 cr.define('options', function() {
-  var Page = cr.ui.pageManager.Page;
-  var PageManager = cr.ui.pageManager.PageManager;
-
-  // The scale ratio of the display rectangle to its original size.
-  /** @const */ var VISUAL_SCALE = 1 / 10;
-
-  // The number of pixels to share the edges between displays.
-  /** @const */ var MIN_OFFSET_OVERLAP = 5;
+  'use strict';
 
   /**
    * Gets the layout type of |point| relative to |rect|.
    * @param {!options.DisplayBounds} rect The base rectangle.
    * @param {!options.DisplayPosition} point The point to check the position.
    * @return {options.DisplayLayoutType} The position of the calculated point.
    */
   function getPositionToRectangle(rect, point) {
     // Separates the area into four (LEFT/RIGHT/TOP/BOTTOM) by the diagonals of
     // the rect, and decides which area the display should reside.
@@ skipping 35 matching lines @@
     // Prefer the closer one if both edges are close enough.
     if (startDiff < SNAP_DISTANCE_PX && startDiff < endDiff)
       return basePoint;
     else if (endDiff < SNAP_DISTANCE_PX)
       return basePoint + baseWidth - width;
 
     return point;
   }
 
   /**
-   * Encapsulated handling of the 'Display' page.
+   * @param {number} visualScale
    * @constructor
-   * @extends {cr.ui.pageManager.Page}
    */
-  function DisplayOptions() {
-    Page.call(this, 'display',
-              loadTimeData.getString('displayOptionsPageTabTitle'),
-              'display-options-page');
+  function DisplayLayoutManager(visualScale) {
+    this.visualScale_ = visualScale;
   }
 
-  cr.addSingletonGetter(DisplayOptions);
-
-  DisplayOptions.prototype = {
-    __proto__: Page.prototype,
-
+  // Helper class for display layout management. Implements logic for laying
+  // out two displays.
+  DisplayLayoutManager.prototype = {
     /**
-     * Whether the current output status is mirroring displays or not.
-     * @type {boolean}
-     * @private
-     */
-    mirroring_: false,
-
-    /**
-     * Whether the unified desktop is enable or not.
-     * @type {boolean}
-     * @private
-     */
-    unifiedDesktopEnabled_: false,
-
-    /**
-     * Whether the unified desktop option should be present.
-     * @type {boolean}
-     * @private
-     */
-    showUnifiedDesktopOption_: false,
-
-    /**
-     * The array of current output displays.  It also contains the display
-     * rectangles currently rendered on screen.
-     * @type {!Array<!options.DisplayInfo>}
-     * @private
-     */
-    displays_: [],
-
-    /**
-     * An object containing DisplayLayout objects for each entry in |displays_|.
+     * An object containing DisplayLayout objects for each entry in
+     * |displays_|.
      * @type {!Object<!options.DisplayLayout>}
      * @private
      */
     displayLayoutMap_: {},
 
     /**
-     * The id of the currently focused display, or empty for none.
-     * @type {string}
-     * @private
-     */
-    focusedId_: '',
-
-    /**
-     * The primary display id.
-     * @type {string}
-     * @private
-     */
-    primaryDisplayId_: '',
-
-    /**
-     * The secondary display id.
-     * @type {string}
-     * @private
-     */
-    secondaryDisplayId_: '',
-
-    /**
-     * Drag info.
-     * @type {?{displayId: string,
-     *          originalLocation: !options.DisplayPosition,
-     *          eventLocation: !options.DisplayPosition}}
-     * @private
-     */
-    dragInfo_: null,
-
-    /**
-     * The container div element which contains all of the display rectangles.
-     * @type {?Element}
-     * @private
-     */
-    displaysView_: null,
-
-    /**
      * The scale factor of the actual display size to the drawn display
-     * rectangle size.
+     * rectangle size. Set to the correct value for the UI in the constructor.
      * @type {number}
      * @private
      */
-    visualScale_: VISUAL_SCALE,
+    visualScale_: 1,
 
     /**
-     * The location where the last touch event happened.  This is used to
-     * prevent unnecessary dragging events happen.  Set to null unless it's
-     * during touch events.
-     * @type {?options.DisplayPosition}
-     * @private
+     * Adds a display to the layout map.
+     * @param {options.DisplayLayout} displayLayout
      */
-    lastTouchLocation_: null,
-
-    /**
-     * Whether the display settings can be shown.
-     * @type {boolean}
-     * @private
-     */
-    enabled_: true,
-
-    /** @override */
-    initializePage: function() {
-      Page.prototype.initializePage.call(this);
-
-      $('display-options-select-mirroring').onchange = (function() {
-        this.mirroring_ =
-            $('display-options-select-mirroring').value == 'mirroring';
-        chrome.send('setMirroring', [this.mirroring_]);
-      }).bind(this);
-
-      var container = $('display-options-displays-view-host');
-      container.onmousemove = this.onMouseMove_.bind(this);
-      window.addEventListener('mouseup', this.endDragging_.bind(this), true);
-      container.ontouchmove = this.onTouchMove_.bind(this);
-      container.ontouchend = this.endDragging_.bind(this);
-
-      $('display-options-set-primary').onclick = (function() {
-        chrome.send('setPrimary', [this.focusedId_]);
-      }).bind(this);
-      $('display-options-resolution-selection').onchange = (function(ev) {
-        var display = this.getDisplayInfoFromId(this.focusedId_);
-        var resolution = display.resolutions[ev.target.value];
-        chrome.send('setDisplayMode', [this.focusedId_, resolution]);
-      }).bind(this);
-      $('display-options-orientation-selection').onchange = (function(ev) {
-        var rotation = parseInt(ev.target.value, 10);
-        chrome.send('setRotation', [this.focusedId_, rotation]);
-      }).bind(this);
-      $('display-options-color-profile-selection').onchange = (function(ev) {
-        chrome.send('setColorProfile', [this.focusedId_, ev.target.value]);
-      }).bind(this);
-      $('selected-display-start-calibrating-overscan').onclick = (function() {
-        // Passes the target display ID. Do not specify it through URL hash,
-        // we do not care back/forward.
-        var displayOverscan = options.DisplayOverscan.getInstance();
-        displayOverscan.setDisplayId(this.focusedId_);
-        PageManager.showPageByName('displayOverscan');
-        chrome.send('coreOptionsUserMetricsAction',
-                    ['Options_DisplaySetOverscan']);
-      }).bind(this);
-
-      $('display-options-done').onclick = function() {
-        PageManager.closeOverlay();
-      };
-
-      $('display-options-toggle-unified-desktop').onclick = (function() {
-        this.unifiedDesktopEnabled_ = !this.unifiedDesktopEnabled_;
-        chrome.send('setUnifiedDesktopEnabled',
-                    [this.unifiedDesktopEnabled_]);
-      }).bind(this);
-    },
-
-    /** @override */
-    didShowPage: function() {
-      var optionTitles = document.getElementsByClassName(
-          'selected-display-option-title');
-      var maxSize = 0;
-      for (var i = 0; i < optionTitles.length; i++)
-        maxSize = Math.max(maxSize, optionTitles[i].clientWidth);
-      for (var i = 0; i < optionTitles.length; i++)
-        optionTitles[i].style.width = maxSize + 'px';
-      chrome.send('getDisplayInfo');
-    },
-
-    /** @override */
-    canShowPage: function() { return this.enabled_; },
-
-    /**
-     * Enables or disables the page. When disabled, the page will not be able to
-     * open, and will close if currently opened.
-     * @param {boolean} enabled Whether the page should be enabled.
-     * @param {boolean} showUnifiedDesktop Whether the unified desktop option
-     *     should be present.
-     */
-    setEnabled: function(enabled, showUnifiedDesktop) {
-      if (this.enabled_ == enabled &&
-          this.showUnifiedDesktopOption_ == showUnifiedDesktop) {
-        return;
-      }
-      this.enabled_ = enabled;
-      this.showUnifiedDesktopOption_ = showUnifiedDesktop;
-      if (!enabled && this.visible)
-        PageManager.closeOverlay();
+    addDisplayLayout: function(displayLayout) {
+      this.displayLayoutMap_[displayLayout.id] = displayLayout;
     },
 
     /**
-     * Mouse move handler for dragging display rectangle.
-     * @param {Event} e The mouse move event.
-     * @private
+     * Returns the layout type for |id|.
+     * @param {string} id
+     * @return {options.DisplayLayout}
      */
-    onMouseMove_: function(e) {
-      return this.processDragging_(e, {x: e.pageX, y: e.pageY});
+    getDisplayLayout: function(id) { return this.displayLayoutMap_[id]; },
+
+    /**
+     * Creates a div for each entry in displayLayoutMap_.
+     * @param {!Element} parentElement The parent element to contain the div.
+     * @param {!options.DisplayPosition} offset The offset to the center of
+     *     the display area.
+     */
+    createDisplayLayoutDivs: function(parentElement, offset) {
+      for (var id in this.displayLayoutMap_) {
+        var layout = this.displayLayoutMap_[id];
+        if (layout.div)
+          continue;  // May have already been created by its child.
+        this.createDisplayLayoutDiv_(id, parentElement, offset);
+      }
     },
 
     /**
-     * Touch move handler for dragging display rectangle.
-     * @param {Event} e The touch move event.
+     * Update the location of display |id| to |newPosition|.
+     * @param {string} id
+     * @param {options.DisplayPosition} newPosition
      * @private
      */
-    onTouchMove_: function(e) {
-      if (e.touches.length != 1)
-        return true;
-
-      var touchLocation = {x: e.touches[0].pageX, y: e.touches[0].pageY};
-      // Touch move events happen even if the touch location doesn't change, but
-      // it doesn't need to process the dragging.  Since sometimes the touch
-      // position changes slightly even though the user doesn't think to move
-      // the finger, very small move is just ignored.
-      /** @const */ var IGNORABLE_TOUCH_MOVE_PX = 1;
-      var xDiff = Math.abs(touchLocation.x - this.lastTouchLocation_.x);
-      var yDiff = Math.abs(touchLocation.y - this.lastTouchLocation_.y);
-      if (xDiff <= IGNORABLE_TOUCH_MOVE_PX &&
-          yDiff <= IGNORABLE_TOUCH_MOVE_PX) {
-        return true;
-      }
-
-      this.lastTouchLocation_ = touchLocation;
-      return this.processDragging_(e, touchLocation);
-    },
-
-    /**
-     * Mouse down handler for dragging display rectangle.
-     * @param {Event} e The mouse down event.
-     * @private
-     */
-    onMouseDown_: function(e) {
-      if (this.mirroring_)
-        return true;
-
-      if (e.button != 0)
-        return true;
-
-      e.preventDefault();
-      var target = assertInstanceof(e.target, HTMLElement);
-      return this.startDragging_(target, {x: e.pageX, y: e.pageY});
-    },
-
-    /**
-     * Touch start handler for dragging display rectangle.
-     * @param {Event} e The touch start event.
-     * @private
-     */
-    onTouchStart_: function(e) {
-      if (this.mirroring_)
-        return true;
-
-      if (e.touches.length != 1)
-        return false;
-
-      e.preventDefault();
-      var touch = e.touches[0];
-      this.lastTouchLocation_ = {x: touch.pageX, y: touch.pageY};
-      var target = assertInstanceof(e.target, HTMLElement);
-      return this.startDragging_(target, this.lastTouchLocation_);
-    },
-
-    /**
-     * @param {string} id
-     * @return {options.DisplayInfo}
-     */
-    getDisplayInfoFromId(id) {
-      return this.displays_.find(function(display) {
-        return display.id == id;
-      });
-    },
-
-    /**
-     * Collects the current data and sends it to Chrome.
-     * @private
-     */
-    sendDragResult_: function() {
-      // Offset is calculated from top or left edge.
-      var primary = this.displayLayoutMap_[this.primaryDisplayId_];
-      var secondary = this.displayLayoutMap_[this.secondaryDisplayId_];
-      var layoutType = secondary.layoutType;
-      var offset;
-      if (layoutType == options.DisplayLayoutType.LEFT ||
-          layoutType == options.DisplayLayoutType.RIGHT) {
-        offset = secondary.div.offsetTop - primary.div.offsetTop;
-      } else {
-        offset = secondary.div.offsetLeft - primary.div.offsetLeft;
-      }
-      offset = Math.floor(offset / this.visualScale_);
-      chrome.send('setDisplayLayout', [secondary.id, layoutType, offset]);
-    },
-
-    /**
-     * Processes the actual dragging of display rectangle.
-     * @param {Event} e The event which triggers this drag.
-     * @param {options.DisplayPosition} eventLocation The location where the
-     *     event happens.
-     * @private
-     */
-    processDragging_: function(e, eventLocation) {
-      if (!this.dragInfo_)
-        return true;
-
-      e.preventDefault();
-
-      // Note that current code of moving display-rectangles doesn't work
-      // if there are >=3 displays.  This is our assumption for M21.
-      // TODO(mukai): Fix the code to allow >=3 displays.
-      var dragInfo = this.dragInfo_;
-      /** @type {options.DisplayPosition} */ var newPosition = {
-        x: dragInfo.originalLocation.x +
-            (eventLocation.x - dragInfo.eventLocation.x),
-        y: dragInfo.originalLocation.y +
-            (eventLocation.y - dragInfo.eventLocation.y)
-      };
-
-      var dragLayout = this.displayLayoutMap_[dragInfo.displayId];
-      var draggingDiv = dragLayout.div;
-
-      var baseDisplayId = dragLayout.isPrimary ? this.secondaryDisplayId_ :
-                                                 this.primaryDisplayId_;
-      var baseLayout = this.displayLayoutMap_[baseDisplayId];
+    updatePosition: function(id, newPosition) {
+      var displayLayout = this.displayLayoutMap_[id];
+      var div = displayLayout.div;
+      var baseLayout = this.getBaseLayout_(displayLayout);
       var baseDiv = baseLayout.div;
 
       newPosition.x = snapToEdge(
-          newPosition.x, draggingDiv.offsetWidth, baseDiv.offsetLeft,
+          newPosition.x, div.offsetWidth, baseDiv.offsetLeft,
           baseDiv.offsetWidth);
       newPosition.y = snapToEdge(
-          newPosition.y, draggingDiv.offsetHeight, baseDiv.offsetTop,
+          newPosition.y, div.offsetHeight, baseDiv.offsetTop,
           baseDiv.offsetHeight);
 
       /** @type {!options.DisplayPosition} */ var newCenter = {
-        x: newPosition.x + draggingDiv.offsetWidth / 2,
-        y: newPosition.y + draggingDiv.offsetHeight / 2
+        x: newPosition.x + div.offsetWidth / 2,
+        y: newPosition.y + div.offsetHeight / 2
       };
 
       /** @type {!options.DisplayBounds} */ var baseBounds = {
         left: baseDiv.offsetLeft,
         top: baseDiv.offsetTop,
         width: baseDiv.offsetWidth,
         height: baseDiv.offsetHeight
       };
 
-      var isPrimary = dragLayout.isPrimary;
-      // layoutType is always stored in the secondary layout.
+      // This implementation considers only the case of two displays, i.e
+      // a single parent with one child.
+      var isPrimary = displayLayout.parentId == '';
+
+      // layoutType is always stored in the child layout.
       var layoutType =
-          isPrimary ? baseLayout.layoutType : dragLayout.layoutType;
+          isPrimary ? baseLayout.layoutType : displayLayout.layoutType;
 
       switch (getPositionToRectangle(baseBounds, newCenter)) {
         case options.DisplayLayoutType.RIGHT:
           layoutType = isPrimary ? options.DisplayLayoutType.LEFT :
                                    options.DisplayLayoutType.RIGHT;
           break;
         case options.DisplayLayoutType.LEFT:
           layoutType = isPrimary ? options.DisplayLayoutType.RIGHT :
                                    options.DisplayLayoutType.LEFT;
           break;
         case options.DisplayLayoutType.TOP:
           layoutType = isPrimary ? options.DisplayLayoutType.BOTTOM :
                                    options.DisplayLayoutType.TOP;
           break;
         case options.DisplayLayoutType.BOTTOM:
           layoutType = isPrimary ? options.DisplayLayoutType.TOP :
                                    options.DisplayLayoutType.BOTTOM;
           break;
       }
 
       if (layoutType == options.DisplayLayoutType.LEFT ||
           layoutType == options.DisplayLayoutType.RIGHT) {
         if (newPosition.y > baseDiv.offsetTop + baseDiv.offsetHeight)
           layoutType = isPrimary ? options.DisplayLayoutType.TOP :
                                    options.DisplayLayoutType.BOTTOM;
-        else if (newPosition.y + draggingDiv.offsetHeight < baseDiv.offsetTop)
+        else if (newPosition.y + div.offsetHeight < baseDiv.offsetTop)
           layoutType = isPrimary ? options.DisplayLayoutType.BOTTOM :
                                    options.DisplayLayoutType.TOP;
       } else {
         if (newPosition.x > baseDiv.offsetLeft + baseDiv.offsetWidth)
           layoutType = isPrimary ? options.DisplayLayoutType.LEFT :
                                    options.DisplayLayoutType.RIGHT;
-        else if (newPosition.x + draggingDiv.offsetWidth < baseDiv.offsetLeft)
+        else if (newPosition.x + div.offsetWidth < baseDiv.offsetLeft)
           layoutType = isPrimary ? options.DisplayLayoutType.RIGHT :
                                    options.DisplayLayoutType.LEFT;
       }
 
       var layoutToBase;
       if (!isPrimary) {
-        dragLayout.layoutType = layoutType;
+        displayLayout.layoutType = layoutType;
         layoutToBase = layoutType;
       } else {
         baseLayout.layoutType = layoutType;
         switch (layoutType) {
           case options.DisplayLayoutType.RIGHT:
             layoutToBase = options.DisplayLayoutType.LEFT;
             break;
           case options.DisplayLayoutType.LEFT:
             layoutToBase = options.DisplayLayoutType.RIGHT;
             break;
           case options.DisplayLayoutType.TOP:
             layoutToBase = options.DisplayLayoutType.BOTTOM;
             break;
           case options.DisplayLayoutType.BOTTOM:
             layoutToBase = options.DisplayLayoutType.TOP;
             break;
         }
       }
 
       switch (layoutToBase) {
         case options.DisplayLayoutType.RIGHT:
-          draggingDiv.style.left =
-              baseDiv.offsetLeft + baseDiv.offsetWidth + 'px';
-          draggingDiv.style.top = newPosition.y + 'px';
+          div.style.left = baseDiv.offsetLeft + baseDiv.offsetWidth + 'px';
+          div.style.top = newPosition.y + 'px';
           break;
         case options.DisplayLayoutType.LEFT:
-          draggingDiv.style.left =
-              baseDiv.offsetLeft - draggingDiv.offsetWidth + 'px';
-          draggingDiv.style.top = newPosition.y + 'px';
+          div.style.left = baseDiv.offsetLeft - div.offsetWidth + 'px';
+          div.style.top = newPosition.y + 'px';
           break;
         case options.DisplayLayoutType.TOP:
-          draggingDiv.style.top =
-              baseDiv.offsetTop - draggingDiv.offsetHeight + 'px';
-          draggingDiv.style.left = newPosition.x + 'px';
+          div.style.top = baseDiv.offsetTop - div.offsetHeight + 'px';
+          div.style.left = newPosition.x + 'px';
           break;
         case options.DisplayLayoutType.BOTTOM:
-          draggingDiv.style.top =
-              baseDiv.offsetTop + baseDiv.offsetHeight + 'px';
-          draggingDiv.style.left = newPosition.x + 'px';
+          div.style.top = baseDiv.offsetTop + baseDiv.offsetHeight + 'px';
+          div.style.left = newPosition.x + 'px';
           break;
       }
-
-      return false;
     },
 
     /**
-     * Start dragging of a display rectangle.
-     * @param {!HTMLElement} target The event target.
-     * @param {!options.DisplayPosition} eventLocation The event location.
-     * @private
+     * Finalize the location of display |id| after updates are complete
+     * (e.g. draging has ended).
+     * @param {string} id
+     * @return {boolean} True if the final position differs from the original.
      */
-    startDragging_: function(target, eventLocation) {
-      var oldFocusedId = this.focusedId_;
-      var newFocusedId;
-      var willUpdateDisplayDescription = false;
-      for (var i = 0; i < this.displays_.length; i++) {
-        var displayLayout = this.displayLayoutMap_[this.displays_[i].id];
-        if (displayLayout.div == target ||
-            (target.offsetParent && target.offsetParent == displayLayout.div)) {
-          newFocusedId = displayLayout.id;
-          break;
-        }
-      }
-      if (!newFocusedId)
-        return false;
+    finalizePosition: function(id) {
+      // Make sure the dragging location is connected.
+      var displayLayout = this.displayLayoutMap_[id];
+      var div = displayLayout.div;
+      var baseLayout = this.getBaseLayout_(displayLayout);
+      var baseDiv = baseLayout.div;
 
-      this.focusedId_ = newFocusedId;
-      willUpdateDisplayDescription = newFocusedId != oldFocusedId;
+      var isPrimary = displayLayout.parentId == '';
+      var layoutType =
+          isPrimary ? baseLayout.layoutType : displayLayout.layoutType;
 
-      for (var i = 0; i < this.displays_.length; i++) {
-        var displayLayout = this.displayLayoutMap_[this.displays_[i].id];
-        displayLayout.div.className = 'displays-display';
-        if (displayLayout.id != this.focusedId_)
-          continue;
-
-        displayLayout.div.classList.add('displays-focused');
-        if (this.displays_.length > 1) {
-          this.dragInfo_ = {
-            displayId: displayLayout.id,
-            originalLocation: {
-              x: displayLayout.div.offsetLeft,
-              y: displayLayout.div.offsetTop
-            },
-            eventLocation: {x: eventLocation.x, y: eventLocation.y}
-          };
-        }
-      }
-
-      if (willUpdateDisplayDescription)
-        this.updateSelectedDisplayDescription_();
-      return false;
-    },
-
-    /**
-     * finish the current dragging of displays.
-     * @param {Event} e The event which triggers this.
-     * @private
-     */
-    endDragging_: function(e) {
-      this.lastTouchLocation_ = null;
-      if (!this.dragInfo_)
-        return false;
-
-      // Make sure the dragging location is connected.
-      var dragLayout = this.displayLayoutMap_[this.dragInfo_.displayId];
-      var baseDisplayId = dragLayout.isPrimary ? this.secondaryDisplayId_ :
-                                                 this.primaryDisplayId_;
-
-      var baseLayout = this.displayLayoutMap_[baseDisplayId];
-      var baseDiv = baseLayout.div;
-      var draggingDiv = dragLayout.div;
-
-      // layoutType is always stored in the secondary layout.
-      var layoutType =
-          dragLayout.isPrimary ? baseLayout.layoutType : dragLayout.layoutType;
+      // The number of pixels to share the edges between displays.
+      /** @const */ var MIN_OFFSET_OVERLAP = 5;
 
       if (layoutType == options.DisplayLayoutType.LEFT ||
           layoutType == options.DisplayLayoutType.RIGHT) {
         var top = Math.max(
-            draggingDiv.offsetTop,
-            baseDiv.offsetTop - draggingDiv.offsetHeight + MIN_OFFSET_OVERLAP);
+            div.offsetTop,
+            baseDiv.offsetTop - div.offsetHeight + MIN_OFFSET_OVERLAP);
         top = Math.min(
             top, baseDiv.offsetTop + baseDiv.offsetHeight - MIN_OFFSET_OVERLAP);
-        draggingDiv.style.top = top + 'px';
+        div.style.top = top + 'px';
       } else {
         var left = Math.max(
-            draggingDiv.offsetLeft,
-            baseDiv.offsetLeft - draggingDiv.offsetWidth + MIN_OFFSET_OVERLAP);
+            div.offsetLeft,
+            baseDiv.offsetLeft - div.offsetWidth + MIN_OFFSET_OVERLAP);
         left = Math.min(
             left,
             baseDiv.offsetLeft + baseDiv.offsetWidth - MIN_OFFSET_OVERLAP);
-        draggingDiv.style.left = left + 'px';
-      }
-      if (dragLayout.originalPosition.x != draggingDiv.offsetLeft ||
-          dragLayout.originalPosition.y != draggingDiv.offsetTop) {
-        this.sendDragResult_();
+        div.style.left = left + 'px';
       }
 
-      this.dragInfo_ = null;
+      // Calculate the offset of the child display.
+      this.calculateOffset_(isPrimary ? baseLayout : displayLayout);
 
-      return false;
+      return displayLayout.originalPosition.x != div.offsetLeft ||
+          displayLayout.originalPosition.y != div.offsetTop;
     },
 
     /**
-     * Updates the description of selected display section for mirroring mode.
-     * @private
+     * Creates a div element and assigns it to |displayLayout|. Returns the
+     * created div for additional decoration.
+     * @param {string} id
+     * @param {!Element} parentElement The parent element to contain the div.
+     * @param {!options.DisplayPosition} offset The offset to the center of
+     *     the display area.
      */
-    updateSelectedDisplaySectionMirroring_: function() {
-      $('display-configuration-arrow').hidden = true;
-      $('display-options-set-primary').disabled = true;
-      $('display-options-select-mirroring').disabled = false;
-      $('selected-display-start-calibrating-overscan').disabled = true;
-      var display = this.displays_[0];
-      var orientation = $('display-options-orientation-selection');
-      orientation.disabled = false;
-      var orientationOptions = orientation.getElementsByTagName('option');
-      var orientationIndex = Math.floor(display.rotation / 90);
-      orientationOptions[orientationIndex].selected = true;
-      $('selected-display-name').textContent =
-          loadTimeData.getString('mirroringDisplay');
-      var resolution = $('display-options-resolution-selection');
-      var option = document.createElement('option');
-      option.value = 'default';
-      option.textContent = display.bounds.width + 'x' + display.bounds.height;
-      resolution.appendChild(option);
-      resolution.disabled = true;
-    },
-
-    /**
-     * Updates the description of selected display section when no display is
-     * selected.
-     * @private
-     */
-    updateSelectedDisplaySectionNoSelected_: function() {
-      $('display-configuration-arrow').hidden = true;
-      $('display-options-set-primary').disabled = true;
-      $('display-options-select-mirroring').disabled = true;
-      $('selected-display-start-calibrating-overscan').disabled = true;
-      $('display-options-orientation-selection').disabled = true;
-      $('selected-display-name').textContent = '';
-      var resolution = $('display-options-resolution-selection');
-      resolution.appendChild(document.createElement('option'));
-      resolution.disabled = true;
-    },
-
-    /**
-     * Updates the description of selected display section for the selected
-     * display.
-     * @param {options.DisplayInfo} display The selected display object.
-     * @private
-     */
-    updateSelectedDisplaySectionForDisplay_: function(display) {
-      var displayLayout = this.displayLayoutMap_[display.id];
-      var arrow = $('display-configuration-arrow');
-      arrow.hidden = false;
-      // Adding 1 px to the position to fit the border line and the border in
-      // arrow precisely.
-      arrow.style.top = $('display-configurations').offsetTop -
-          arrow.offsetHeight / 2 + 'px';
-      arrow.style.left = displayLayout.div.offsetLeft +
-          displayLayout.div.offsetWidth / 2 - arrow.offsetWidth / 2 + 'px';
-
-      $('display-options-set-primary').disabled = display.isPrimary;
-      $('display-options-select-mirroring').disabled =
-          (this.displays_.length <= 1 && !this.unifiedDesktopEnabled_);
-      $('selected-display-start-calibrating-overscan').disabled =
-          display.isInternal;
-
-      var orientation = $('display-options-orientation-selection');
-      orientation.disabled = this.unifiedDesktopEnabled_;
-
-      var orientationOptions = orientation.getElementsByTagName('option');
-      var orientationIndex = Math.floor(display.rotation / 90);
-      orientationOptions[orientationIndex].selected = true;
-
-      $('selected-display-name').textContent = display.name;
-
-      var resolution = $('display-options-resolution-selection');
-      if (display.resolutions.length <= 1) {
-        var option = document.createElement('option');
-        option.value = 'default';
-        option.textContent = display.bounds.width + 'x' + display.bounds.height;
-        option.selected = true;
-        resolution.appendChild(option);
-        resolution.disabled = true;
-      } else {
-        var previousOption;
-        for (var i = 0; i < display.resolutions.length; i++) {
-          var option = document.createElement('option');
-          option.value = i;
-          option.textContent = display.resolutions[i].width + 'x' +
-              display.resolutions[i].height;
-          if (display.resolutions[i].isBest) {
-            option.textContent += ' ' +
-                loadTimeData.getString('annotateBest');
-          } else if (display.resolutions[i].isNative) {
-            option.textContent += ' ' +
-                loadTimeData.getString('annotateNative');
-          }
-          if (display.resolutions[i].deviceScaleFactor && previousOption &&
-              previousOption.textContent == option.textContent) {
-            option.textContent +=
-                ' (' + display.resolutions[i].deviceScaleFactor + 'x)';
-          }
-          option.selected = display.resolutions[i].selected;
-          resolution.appendChild(option);
-          previousOption = option;
-        }
-        resolution.disabled = (display.resolutions.length <= 1);
+    createDisplayLayoutDiv_: function(id, parentElement, offset) {
+      var displayLayout = this.displayLayoutMap_[id];
+      var parentId = displayLayout.parentId;
+      if (parentId) {
+        // Ensure the parent div is created first.
+        var parentLayout = this.displayLayoutMap_[parentId];
+        if (!parentLayout.div)
+          this.createDisplayLayoutDiv_(parentId, parentElement, offset);
       }
 
-      if (display.availableColorProfiles.length <= 1) {
-        $('selected-display-color-profile-row').hidden = true;
-      } else {
-        $('selected-display-color-profile-row').hidden = false;
-        var profiles = $('display-options-color-profile-selection');
-        profiles.innerHTML = '';
-        for (var i = 0; i < display.availableColorProfiles.length; i++) {
-          var option = document.createElement('option');
-          var colorProfile = display.availableColorProfiles[i];
-          option.value = colorProfile.profileId;
-          option.textContent = colorProfile.name;
-          option.selected = (display.colorProfileId == colorProfile.profileId);
-          profiles.appendChild(option);
-        }
-      }
-    },
-
-    /**
-     * Updates the description of the selected display section.
-     * @private
-     */
-    updateSelectedDisplayDescription_: function() {
-      var resolution = $('display-options-resolution-selection');
-      resolution.textContent = '';
-      var orientation = $('display-options-orientation-selection');
-      var orientationOptions = orientation.getElementsByTagName('option');
-      for (var i = 0; i < orientationOptions.length; i++)
-        orientationOptions[i].selected = false;
-
-      if (this.mirroring_) {
-        this.updateSelectedDisplaySectionMirroring_();
-      } else if (this.focusedId_ == '') {
-        this.updateSelectedDisplaySectionNoSelected_();
-      } else {
-        this.updateSelectedDisplaySectionForDisplay_(
-            this.getDisplayInfoFromId(this.focusedId_));
-      }
-    },
-
-    /**
-     * Clears the drawing area for display rectangles.
-     * @private
-     */
-    resetDisplaysView_: function() {
-      var displaysViewHost = $('display-options-displays-view-host');
-      displaysViewHost.removeChild(displaysViewHost.firstChild);
-      this.displaysView_ = document.createElement('div');
-      this.displaysView_.id = 'display-options-displays-view';
-      displaysViewHost.appendChild(this.displaysView_);
-    },
-
-    /**
-     * Lays out the display rectangles for mirroring.
-     * @private
-     */
-    layoutMirroringDisplays_: function() {
-      // Offset pixels for secondary display rectangles. The offset includes the
-      // border width.
-      /** @const */ var MIRRORING_OFFSET_PIXELS = 3;
-      // Always show two displays because there must be two displays when
-      // the display_options is enabled.  Don't rely on displays_.length because
-      // there is only one display from chrome's perspective in mirror mode.
-      /** @const */ var MIN_NUM_DISPLAYS = 2;
-      /** @const */ var MIRRORING_VERTICAL_MARGIN = 20;
-
-      // The width/height should be same as the first display:
-      var width = Math.ceil(this.displays_[0].bounds.width * this.visualScale_);
-      var height =
-          Math.ceil(this.displays_[0].bounds.height * this.visualScale_);
-
-      var numDisplays = Math.max(MIN_NUM_DISPLAYS, this.displays_.length);
-
-      var totalWidth = width + numDisplays * MIRRORING_OFFSET_PIXELS;
-      var totalHeight = height + numDisplays * MIRRORING_OFFSET_PIXELS;
-
-      this.displaysView_.style.height = totalHeight + 'px';
-
-      // The displays should be centered.
-      var offsetX =
-          $('display-options-displays-view').offsetWidth / 2 - totalWidth / 2;
-
-      for (var i = 0; i < numDisplays; i++) {
-        var div = /** @type {HTMLElement} */ (document.createElement('div'));
-        div.className = 'displays-display';
-        div.style.top = i * MIRRORING_OFFSET_PIXELS + 'px';
-        div.style.left = i * MIRRORING_OFFSET_PIXELS + offsetX + 'px';
-        div.style.width = width + 'px';
-        div.style.height = height + 'px';
-        div.style.zIndex = i;
-        // set 'display-mirrored' class for the background display rectangles.
-        if (i != numDisplays - 1)
-          div.classList.add('display-mirrored');
-        this.displaysView_.appendChild(div);
-      }
-    },
-
-    /**
-     * Creates a DisplayLayout object representing the display.
-     * @param {!options.DisplayInfo} display
-     * @param {!options.DisplayLayoutType} layoutType
-     * @return {!options.DisplayLayout}
-     * @private
-     */
-    createDisplayLayout_: function(display, layoutType) {
-      return {
-        bounds: display.bounds,
-        div: null,
-        id: display.id,
-        isPrimary: display.isPrimary,
-        layoutType: layoutType,
-        name: display.name,
-        originalPosition: {x: 0, y: 0}
-      };
-    },
-
-    /**
-     * Creates a div element representing the specified display.
-     * @param {!options.DisplayLayout} displayLayout
-     * @param {options.DisplayLayoutType} layoutType The layout type for the
-     *     secondary display.
-     * @param {!options.DisplayPosition} offset The offset to the center of the
-     *     display area.
-     * @private
-     */
-    createDisplayLayoutDiv_: function(displayLayout, layoutType, offset) {
       var div = /** @type {!HTMLElement} */ (document.createElement('div'));
       div.className = 'displays-display';
-      div.classList.toggle(
-          'displays-focused', displayLayout.id == this.focusedId_);
 
       // div needs to be added to the DOM tree first, otherwise offsetHeight for
       // nameContainer below cannot be computed.
-      this.displaysView_.appendChild(div);
+      parentElement.appendChild(div);
 
       var nameContainer = document.createElement('div');
       nameContainer.textContent = displayLayout.name;
       div.appendChild(nameContainer);
 
       var bounds = displayLayout.bounds;
       div.style.width = Math.floor(bounds.width * this.visualScale_) + 'px';
       var newHeight = Math.floor(bounds.height * this.visualScale_);
       div.style.height = newHeight + 'px';
       nameContainer.style.marginTop =
           (newHeight - nameContainer.offsetHeight) / 2 + 'px';
 
-      div.onmousedown = this.onMouseDown_.bind(this);
-      div.ontouchstart = this.onTouchStart_.bind(this);
-
-      if (displayLayout.isPrimary) {
+      if (displayLayout.parentId == '') {
         div.style.left =
             Math.floor(bounds.left * this.visualScale_) + offset.x + 'px';
         div.style.top =
             Math.floor(bounds.top * this.visualScale_) + offset.y + 'px';
       } else {
-        // Don't trust the secondary display's x or y, because it may cause a
+        // Don't trust the child display's x or y, because it may cause a
         // 1px gap due to rounding, which will create a fake update on end
         // dragging. See crbug.com/386401
-        var primaryDiv = this.displayLayoutMap_[this.primaryDisplayId_].div;
-        switch (layoutType) {
+        var parentDiv = this.displayLayoutMap_[displayLayout.parentId].div;
+        switch (displayLayout.layoutType) {
           case options.DisplayLayoutType.TOP:
             div.style.left =
                 Math.floor(bounds.left * this.visualScale_) + offset.x + 'px';
-            div.style.top = primaryDiv.offsetTop - div.offsetHeight + 'px';
+            div.style.top = parentDiv.offsetTop - div.offsetHeight + 'px';
             break;
           case options.DisplayLayoutType.RIGHT:
             div.style.left =
-                primaryDiv.offsetLeft + primaryDiv.offsetWidth + 'px';
+                parentDiv.offsetLeft + parentDiv.offsetWidth + 'px';
             div.style.top =
                 Math.floor(bounds.top * this.visualScale_) + offset.y + 'px';
             break;
           case options.DisplayLayoutType.BOTTOM:
             div.style.left =
                 Math.floor(bounds.left * this.visualScale_) + offset.x + 'px';
-            div.style.top =
-                primaryDiv.offsetTop + primaryDiv.offsetHeight + 'px';
+            div.style.top = parentDiv.offsetTop + parentDiv.offsetHeight + 'px';
             break;
           case options.DisplayLayoutType.LEFT:
-            div.style.left = primaryDiv.offsetLeft - div.offsetWidth + 'px';
+            div.style.left = parentDiv.offsetLeft - div.offsetWidth + 'px';
             div.style.top =
                 Math.floor(bounds.top * this.visualScale_) + offset.y + 'px';
             break;
         }
       }
 
       displayLayout.div = div;
       displayLayout.originalPosition.x = div.offsetLeft;
       displayLayout.originalPosition.y = div.offsetTop;
+
+      this.calculateOffset_(displayLayout);
     },
 
     /**
-     * Layouts the display rectangles according to the current layout_.
-     * @param {options.DisplayLayoutType} layoutType
-     * @private
+     * Calculates the offset for display |id| relative to its parent.
+     * @param {options.DisplayLayout} displayLayout
      */
-    layoutDisplays_: function(layoutType) {
-      var maxWidth = 0;
-      var maxHeight = 0;
-      var boundingBox = {left: 0, right: 0, top: 0, bottom: 0};
-      this.primaryDisplayId_ = '';
-      this.secondaryDisplayId_ = '';
-      for (var i = 0; i < this.displays_.length; i++) {
-        var display = this.displays_[i];
-        if (display.isPrimary)
-          this.primaryDisplayId_ = display.id;
-        else if (this.secondaryDisplayId_ == '')
-          this.secondaryDisplayId_ = display.id;
-
-        var bounds = display.bounds;
-        boundingBox.left = Math.min(boundingBox.left, bounds.left);
-        boundingBox.right =
-            Math.max(boundingBox.right, bounds.left + bounds.width);
-        boundingBox.top = Math.min(boundingBox.top, bounds.top);
-        boundingBox.bottom =
-            Math.max(boundingBox.bottom, bounds.top + bounds.height);
-        maxWidth = Math.max(maxWidth, bounds.width);
-        maxHeight = Math.max(maxHeight, bounds.height);
+    calculateOffset_: function(displayLayout) {
+      // Offset is calculated from top or left edge.
+      var parent = this.displayLayoutMap_[displayLayout.parentId];
+      if (!parent) {
+        displayLayout.offset = 0;
+        return;
       }
-      if (this.primaryDisplayId_ == '')
-        return;
-
-      // Make the margin around the bounding box.
-      var areaWidth = boundingBox.right - boundingBox.left + maxWidth;
-      var areaHeight = boundingBox.bottom - boundingBox.top + maxHeight;
-
-      // Calculates the scale by the width since horizontal size is more strict.
-      // TODO(mukai): Adds the check of vertical size in case.
-      this.visualScale_ = Math.min(
-          VISUAL_SCALE, this.displaysView_.offsetWidth / areaWidth);
-
-      // Prepare enough area for thisplays_view by adding the maximum height.
-      this.displaysView_.style.height =
-          Math.ceil(areaHeight * this.visualScale_) + 'px';
-
-      // Centering the bounding box of the display rectangles.
-      var offset = {
-        x: Math.floor(
-            this.displaysView_.offsetWidth / 2 -
-            (boundingBox.right + boundingBox.left) * this.visualScale_ / 2),
-        y: Math.floor(
-            this.displaysView_.offsetHeight / 2 -
-            (boundingBox.bottom + boundingBox.top) * this.visualScale_ / 2)
-      };
-
-      // Layout the display rectangles. First layout the primary display and
-      // then layout any secondary displays.
-      this.createDisplayLayoutDiv_(
-          this.displayLayoutMap_[this.primaryDisplayId_], layoutType, offset);
-      for (var i = 0; i < this.displays_.length; i++) {
-        if (!this.displays_[i].isPrimary) {
-          this.createDisplayLayoutDiv_(
-              this.displayLayoutMap_[this.displays_[i].id], layoutType, offset);
-        }
+      var offset;
+      if (displayLayout.layoutType == options.DisplayLayoutType.LEFT ||
+          displayLayout.layoutType == options.DisplayLayoutType.RIGHT) {
+        offset = displayLayout.div.offsetTop - parent.div.offsetTop;
+      } else {
+        offset = displayLayout.div.offsetLeft - parent.div.offsetLeft;
       }
+      displayLayout.offset = Math.floor(offset / this.visualScale_);
     },
 
     /**
-     * Called when the display arrangement has changed.
-     * @param {options.MultiDisplayMode} mode multi display mode.
-     * @param {!Array<!options.DisplayInfo>} displays The list of the display
-     *     information.
-     * @param {options.DisplayLayoutType} layoutType The layout strategy.
-     * @param {number} offset The offset of the secondary display.
+     * Returns the display paired with |displayLayout|, either the parent
+     * or a matching child (currently there will only be one).
+     * @param {options.DisplayLayout} displayLayout
+     * @return {?options.DisplayLayout}
      * @private
      */
-    onDisplayChanged_: function(mode, displays, layoutType, offset) {
-      if (!this.visible)
-        return;
-
-      this.displays_ = displays;
-      this.displayLayoutMap_ = {};
-      for (var i = 0; i < displays.length; i++) {
-        var display = displays[i];
-        this.displayLayoutMap_[display.id] =
-            this.createDisplayLayout_(display, layoutType);
+    getBaseLayout_(displayLayout) {
+      if (displayLayout.parentId != '')
+        return this.displayLayoutMap_[displayLayout.parentId];
+      for (var childId in this.displayLayoutMap_) {
+        var child = this.displayLayoutMap_[childId];
+        if (child.parentId == displayLayout.id)
+          return child;
       }
-
-      var mirroring = mode == options.MultiDisplayMode.MIRRORING;
-      var unifiedDesktopEnabled = mode == options.MultiDisplayMode.UNIFIED;
-
-      // Focus to the first display next to the primary one when |displays_|
-      // is updated.
-      if (mirroring) {
-        this.focusedId_ = '';
-      } else if (
-          this.focusedId_ == '' || this.mirroring_ != mirroring ||
-          this.unifiedDesktopEnabled_ != unifiedDesktopEnabled ||
-          this.displays_.length != displays.length) {
-        this.focusedId_ = displays.length > 0 ? displays[0].id : '';
-      }
-
-      this.mirroring_ = mirroring;
-      this.unifiedDesktopEnabled_ = unifiedDesktopEnabled;
-
-      this.resetDisplaysView_();
-      if (this.mirroring_)
-        this.layoutMirroringDisplays_();
-      else
-        this.layoutDisplays_(layoutType);
-
-      $('display-options-select-mirroring').value =
-          mirroring ? 'mirroring' : 'extended';
-
-      $('display-options-unified-desktop').hidden =
-          !this.showUnifiedDesktopOption_;
-
-      $('display-options-toggle-unified-desktop').checked =
-          this.unifiedDesktopEnabled_;
-
-      var disableUnifiedDesktopOption =
-           (this.mirroring_ ||
-            (!this.unifiedDesktopEnabled_ &&
-              this.displays_.length == 1));
-
-      $('display-options-toggle-unified-desktop').disabled =
-          disableUnifiedDesktopOption;
-
-      this.updateSelectedDisplayDescription_();
+      assertNotReached();
+      return null;
     }
   };
 
-  DisplayOptions.setDisplayInfo = function(
-      mode, displays, layoutType, offset) {
-    DisplayOptions.getInstance().onDisplayChanged_(
-        mode, displays, layoutType, offset);
-  };
-
   // Export
-  return {
-    DisplayOptions: DisplayOptions
-  };
+  return {DisplayLayoutManager: DisplayLayoutManager};
 });