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 /* -*- Mode: Javascript; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

 /* vim: set ft=javascript ts=2 et sw=2 tw=80: */

 /* This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this

  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

 const Cu = Components.utils;

 const Ci = Components.interfaces;

 const Cr = Components.results;

 Cu.import("resource://gre/modules/XPCOMUtils.jsm");

 XPCOMUtils.defineLazyModuleGetter(this, "Services",

   "resource://gre/modules/Services.jsm");

 this.EXPORTED_SYMBOLS = ["LayoutHelpers"];

 this.LayoutHelpers = LayoutHelpers = function(aTopLevelWindow) {

   this._topDocShell = aTopLevelWindow.QueryInterface(Ci.nsIInterfaceRequestor)

                                      .getInterface(Ci.nsIWebNavigation)

                                      .QueryInterface(Ci.nsIDocShell);

 };

 LayoutHelpers.prototype = {

   /**

    * Get box quads adjusted for iframes and zoom level.

    *

    * @param {DOMNode} node

    *        The node for which we are to get the box model region quads

    * @param  {String} region

    *         The box model region to return:

    *         "content", "padding", "border" or "margin"

    */

   getAdjustedQuads: function(node, region) {

     if (!node) {

       return;

     }

     let [quads] = node.getBoxQuads({

       box: region

     });

     if (!quads) {

       return;

     }

     let [xOffset, yOffset] = this._getNodeOffsets(node);

     let scale = this.calculateScale(node);

     return {

       p1: {

         w: quads.p1.w * scale,

         x: quads.p1.x * scale + xOffset,

         y: quads.p1.y * scale + yOffset,

         z: quads.p1.z * scale

       },

       p2: {

         w: quads.p2.w * scale,

         x: quads.p2.x * scale + xOffset,

         y: quads.p2.y * scale + yOffset,

         z: quads.p2.z * scale

       },

       p3: {

         w: quads.p3.w * scale,

         x: quads.p3.x * scale + xOffset,

         y: quads.p3.y * scale + yOffset,

         z: quads.p3.z * scale

       },

       p4: {

         w: quads.p4.w * scale,

         x: quads.p4.x * scale + xOffset,

         y: quads.p4.y * scale + yOffset,

         z: quads.p4.z * scale

       },

       bounds: {

         bottom: quads.bounds.bottom * scale + yOffset,

         height: quads.bounds.height * scale,

         left: quads.bounds.left * scale + xOffset,

         right: quads.bounds.right * scale + xOffset,

         top: quads.bounds.top * scale + yOffset,

         width: quads.bounds.width * scale,

         x: quads.bounds.x * scale + xOffset,

         y: quads.bounds.y * scale + yOffset

       }

     };

   },

   calculateScale: function(node) {

     let win = node.ownerDocument.defaultView;

     let winUtils = win.QueryInterface(Ci.nsIInterfaceRequestor)

                       .getInterface(Ci.nsIDOMWindowUtils);

     return winUtils.fullZoom;

   },

   /**

    * Compute the absolute position and the dimensions of a node, relativalely

    * to the root window.

    *

    * @param nsIDOMNode aNode

    *        a DOM element to get the bounds for

    * @param nsIWindow aContentWindow

    *        the content window holding the node

    */

   getRect: function LH_getRect(aNode, aContentWindow) {

     let frameWin = aNode.ownerDocument.defaultView;

     let clientRect = aNode.getBoundingClientRect();

     // Go up in the tree of frames to determine the correct rectangle.

     // clientRect is read-only, we need to be able to change properties.

     let rect = {top: clientRect.top + aContentWindow.pageYOffset,

             left: clientRect.left + aContentWindow.pageXOffset,

             width: clientRect.width,

             height: clientRect.height};

     // We iterate through all the parent windows.

     while (true) {

       // Are we in the top-level window?

       if (this.isTopLevelWindow(frameWin)) {

         break;

       }

       let frameElement = this.getFrameElement(frameWin);

       if (!frameElement) {

         break;

       }

       // We are in an iframe.

       // We take into account the parent iframe position and its

       // offset (borders and padding).

       let frameRect = frameElement.getBoundingClientRect();

       let [offsetTop, offsetLeft] =

         this.getIframeContentOffset(frameElement);

       rect.top += frameRect.top + offsetTop;

       rect.left += frameRect.left + offsetLeft;

       frameWin = this.getParentWindow(frameWin);

     }

     return rect;

   },

   /**

    * Returns iframe content offset (iframe border + padding).

    * Note: this function shouldn't need to exist, had the platform provided a

    * suitable API for determining the offset between the iframe's content and

    * its bounding client rect. Bug 626359 should provide us with such an API.

    *

    * @param aIframe

    *        The iframe.

    * @returns array [offsetTop, offsetLeft]

    *          offsetTop is the distance from the top of the iframe and the

    *            top of the content document.

    *          offsetLeft is the distance from the left of the iframe and the

    *            left of the content document.

    */

   getIframeContentOffset: function LH_getIframeContentOffset(aIframe) {

     let style = aIframe.contentWindow.getComputedStyle(aIframe, null);

     // In some cases, the computed style is null

     if (!style) {

       return [0, 0];

     }

     let paddingTop = parseInt(style.getPropertyValue("padding-top"));

     let paddingLeft = parseInt(style.getPropertyValue("padding-left"));

     let borderTop = parseInt(style.getPropertyValue("border-top-width"));

     let borderLeft = parseInt(style.getPropertyValue("border-left-width"));

     return [borderTop + paddingTop, borderLeft + paddingLeft];

   },

   /**

    * Find an element from the given coordinates. This method descends through

    * frames to find the element the user clicked inside frames.

    *

    * @param DOMDocument aDocument the document to look into.

    * @param integer aX

    * @param integer aY

    * @returns Node|null the element node found at the given coordinates.

    */

   getElementFromPoint: function LH_elementFromPoint(aDocument, aX, aY) {

     let node = aDocument.elementFromPoint(aX, aY);

     if (node && node.contentDocument) {

       if (node instanceof Ci.nsIDOMHTMLIFrameElement) {

         let rect = node.getBoundingClientRect();

         // Gap between the iframe and its content window.

         let [offsetTop, offsetLeft] = this.getIframeContentOffset(node);

         aX -= rect.left + offsetLeft;

         aY -= rect.top + offsetTop;

         if (aX < 0 || aY < 0) {

           // Didn't reach the content document, still over the iframe.

           return node;

         }

       }

       if (node instanceof Ci.nsIDOMHTMLIFrameElement ||

           node instanceof Ci.nsIDOMHTMLFrameElement) {

         let subnode = this.getElementFromPoint(node.contentDocument, aX, aY);

         if (subnode) {

           node = subnode;

         }

       }

     }

     return node;

   },

   /**

    * Scroll the document so that the element "elem" appears in the viewport.

    *

    * @param Element elem the element that needs to appear in the viewport.

    * @param bool centered true if you want it centered, false if you want it to

    * appear on the top of the viewport. It is true by default, and that is

    * usually what you want.

    */

   scrollIntoViewIfNeeded: function(elem, centered) {

     // We want to default to centering the element in the page,

     // so as to keep the context of the element.

     centered = centered === undefined? true: !!centered;

     let win = elem.ownerDocument.defaultView;

     let clientRect = elem.getBoundingClientRect();

     // The following are always from the {top, bottom, left, right}

     // of the viewport, to the {top, …} of the box.

     // Think of them as geometrical vectors, it helps.

     // The origin is at the top left.

     let topToBottom = clientRect.bottom;

     let bottomToTop = clientRect.top - win.innerHeight;

     let leftToRight = clientRect.right;

     let rightToLeft = clientRect.left - win.innerWidth;

     let xAllowed = true;  // We allow one translation on the x axis,

     let yAllowed = true;  // and one on the y axis.

     // Whatever `centered` is, the behavior is the same if the box is

     // (even partially) visible.

     if ((topToBottom > 0 || !centered) && topToBottom <= elem.offsetHeight) {

       win.scrollBy(0, topToBottom - elem.offsetHeight);

       yAllowed = false;

     } else

     if ((bottomToTop < 0 || !centered) && bottomToTop >= -elem.offsetHeight) {

       win.scrollBy(0, bottomToTop + elem.offsetHeight);

       yAllowed = false;

     }

     if ((leftToRight > 0 || !centered) && leftToRight <= elem.offsetWidth) {

       if (xAllowed) {

         win.scrollBy(leftToRight - elem.offsetWidth, 0);

         xAllowed = false;

       }

     } else

     if ((rightToLeft < 0 || !centered) && rightToLeft >= -elem.offsetWidth) {

       if (xAllowed) {

         win.scrollBy(rightToLeft + elem.offsetWidth, 0);

         xAllowed = false;

       }

     }

     // If we want it centered, and the box is completely hidden,

     // then we center it explicitly.

     if (centered) {

       if (yAllowed && (topToBottom <= 0 || bottomToTop >= 0)) {

         win.scroll(win.scrollX,

                    win.scrollY + clientRect.top

                    - (win.innerHeight - elem.offsetHeight) / 2);

       }

       if (xAllowed && (leftToRight <= 0 || rightToLeft <= 0)) {

         win.scroll(win.scrollX + clientRect.left

                    - (win.innerWidth - elem.offsetWidth) / 2,

                    win.scrollY);

       }

     }

     if (!this.isTopLevelWindow(win)) {

       // We are inside an iframe.

       let frameElement = this.getFrameElement(win);

       this.scrollIntoViewIfNeeded(frameElement, centered);

     }

   },

   /**

    * Check if a node and its document are still alive

    * and attached to the window.

    *

    * @param aNode

    */

   isNodeConnected: function LH_isNodeConnected(aNode)

   {

     try {

       let connected = (aNode.ownerDocument && aNode.ownerDocument.defaultView &&

                       !(aNode.compareDocumentPosition(aNode.ownerDocument.documentElement) &

                       aNode.DOCUMENT_POSITION_DISCONNECTED));

       return connected;

     } catch (e) {

       // "can't access dead object" error

       return false;

     }

   },

   /**

    * like win.parent === win, but goes through mozbrowsers and mozapps iframes.

    */

   isTopLevelWindow: function LH_isTopLevelWindow(win) {

     let docShell = win.QueryInterface(Ci.nsIInterfaceRequestor)

                    .getInterface(Ci.nsIWebNavigation)

                    .QueryInterface(Ci.nsIDocShell);

     return docShell === this._topDocShell;

   },

   /**

    * Check a window is part of the top level window.

    */

   isIncludedInTopLevelWindow: function LH_isIncludedInTopLevelWindow(win) {

     if (this.isTopLevelWindow(win)) {

       return true;

     }

     let parent = this.getParentWindow(win);

     if (!parent || parent === win) {

       return false;

     }

     return this.isIncludedInTopLevelWindow(parent);

   },

   /**

    * like win.parent, but goes through mozbrowsers and mozapps iframes.

    */

   getParentWindow: function LH_getParentWindow(win) {

     if (this.isTopLevelWindow(win)) {

       return null;

     }

     let docShell = win.QueryInterface(Ci.nsIInterfaceRequestor)

                    .getInterface(Ci.nsIWebNavigation)

                    .QueryInterface(Ci.nsIDocShell);

     if (docShell.isBrowserOrApp) {

       let parentDocShell = docShell.getSameTypeParentIgnoreBrowserAndAppBoundaries();

       return parentDocShell ? parentDocShell.contentViewer.DOMDocument.defaultView : null;

     } else {

       return win.parent;

     }

   },

   /**

    * like win.frameElement, but goes through mozbrowsers and mozapps iframes.

    *

    * @param DOMWindow win The window to get the frame for

    * @return DOMElement The element in which the window is embedded.

    */

   getFrameElement: function LH_getFrameElement(win) {

     if (this.isTopLevelWindow(win)) {

       return null;

     }

     let winUtils = win.

       QueryInterface(Components.interfaces.nsIInterfaceRequestor).

       getInterface(Components.interfaces.nsIDOMWindowUtils);

     return winUtils.containerElement;

   },

   /**

    * Get the x and y offsets for a node taking iframes into account.

    *

    * @param {DOMNode} node

    *        The node for which we are to get the offset

    */

   _getNodeOffsets: function(node) {

     let xOffset = 0;

     let yOffset = 0;

     let frameWin = node.ownerDocument.defaultView;

     let scale = this.calculateScale(node);

     while (true) {

       // Are we in the top-level window?

       if (this.isTopLevelWindow(frameWin)) {

         break;

       }

       let frameElement = this.getFrameElement(frameWin);

       if (!frameElement) {

         break;

       }

       // We are in an iframe.

       // We take into account the parent iframe position and its

       // offset (borders and padding).

       let frameRect = frameElement.getBoundingClientRect();

       let [offsetTop, offsetLeft] =

         this.getIframeContentOffset(frameElement);

       xOffset += frameRect.left + offsetLeft;

       yOffset += frameRect.top + offsetTop;

       frameWin = this.getParentWindow(frameWin);

     }

     return [xOffset * scale, yOffset * scale];

   },

   /********************************************************************

    * GetBoxQuads POLYFILL START TODO: Remove this when bug 917755 is fixed.

    ********************************************************************/

   _getBoxQuadsFromRect: function(rect, node) {

     let scale = this.calculateScale(node);

     let [xOffset, yOffset] = this._getNodeOffsets(node);

     let out = {

       p1: {

         x: rect.left * scale + xOffset,

         y: rect.top * scale + yOffset

       },

       p2: {

         x: (rect.left + rect.width) * scale + xOffset,

         y: rect.top * scale + yOffset

       },

       p3: {

         x: (rect.left + rect.width) * scale + xOffset,

         y: (rect.top + rect.height) * scale + yOffset

       },

       p4: {

         x: rect.left * scale + xOffset,

         y: (rect.top + rect.height) * scale + yOffset

       }

     };

     out.bounds = {

       bottom: out.p4.y,

       height: out.p4.y - out.p1.y,

       left: out.p1.x,

       right: out.p2.x,

       top: out.p1.y,

       width: out.p2.x - out.p1.x,

       x: out.p1.x,

       y: out.p1.y

     };

     return out;

   },

   _parseNb: function(distance) {

     let nb = parseFloat(distance, 10);

     return isNaN(nb) ? 0 : nb;

   },

   getAdjustedQuadsPolyfill: function(node, region) {

     // Get the border-box rect

     // Note that this is relative to the node's viewport, so before we can use

     // it, will need to go back up the frames like getRect

     let borderRect = node.getBoundingClientRect();

     // If the boxType is border, no need to go any further, we're done

     if (region === "border") {

       return this._getBoxQuadsFromRect(borderRect, node);

     }

     // Else, need to get margin/padding/border distances

     let style = node.ownerDocument.defaultView.getComputedStyle(node);

     let camel = s => s.substring(0, 1).toUpperCase() + s.substring(1);

     let distances = {border:{}, padding:{}, margin: {}};

     for (let side of ["top", "right", "bottom", "left"]) {

       distances.border[side] = this._parseNb(style["border" + camel(side) + "Width"]);

       distances.padding[side] = this._parseNb(style["padding" + camel(side)]);

       distances.margin[side] = this._parseNb(style["margin" + camel(side)]);

     }

     // From the border-box rect, calculate the content-box, padding-box and

     // margin-box rects

     function offsetRect(rect, offsetType, dir=1) {

       return {

         top: rect.top + (dir * distances[offsetType].top),

         left: rect.left + (dir * distances[offsetType].left),

         width: rect.width - (dir * (distances[offsetType].left + distances[offsetType].right)),

         height: rect.height - (dir * (distances[offsetType].top + distances[offsetType].bottom))

       };

     }

     if (region === "margin") {

       return this._getBoxQuadsFromRect(offsetRect(borderRect, "margin", -1), node);

     } else if (region === "padding") {

       return this._getBoxQuadsFromRect(offsetRect(borderRect, "border"), node);

     } else if (region === "content") {

       let paddingRect = offsetRect(borderRect, "border");

       return this._getBoxQuadsFromRect(offsetRect(paddingRect, "padding"), node);

     }

   },

   /********************************************************************

    * GetBoxQuads POLYFILL END

    ********************************************************************/

 };