The Tor Browser: browser/components/customizableui/src/DragPositionManager.jsm@8bccb770b82d (annotated)

browser/components/customizableui/src/DragPositionManager.jsm@8bccb770b82d (annotated)

browser/components/customizableui/src/DragPositionManager.jsm

Wed, 31 Dec 2014 13:27:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 13:27:57 +0100
branch: TOR_BUG_3246
changeset 6: 8bccb770b82d
permissions: -rw-r--r--

Ignore runtime configuration files generated during quality assurance.

 /* 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/. */
 "use strict";
 Components.utils.import("resource:///modules/CustomizableUI.jsm");
 let gManagers = new WeakMap();
 const kPaletteId = "customization-palette";
 const kPlaceholderClass = "panel-customization-placeholder";
 this.EXPORTED_SYMBOLS = ["DragPositionManager"];
 function AreaPositionManager(aContainer) {
   // Caching the direction and bounds of the container for quick access later:
   let window = aContainer.ownerDocument.defaultView;
   this._dir = window.getComputedStyle(aContainer).direction;
   let containerRect = aContainer.getBoundingClientRect();
   this._containerInfo = {
     left: containerRect.left,
     right: containerRect.right,
     top: containerRect.top,
     width: containerRect.width
   };
   this._inPanel = aContainer.id == CustomizableUI.AREA_PANEL;
   this._horizontalDistance = null;
   this.update(aContainer);
 }
 AreaPositionManager.prototype = {
   _nodePositionStore: null,
   _wideCache: null,
   update: function(aContainer) {
     let window = aContainer.ownerDocument.defaultView;
     this._nodePositionStore = new WeakMap();
     this._wideCache = new Set();
     let last = null;
     let singleItemHeight;
     for (let child of aContainer.children) {
       if (child.hidden) {
         continue;
       }
       let isNodeWide = this._checkIfWide(child);
       if (isNodeWide) {
         this._wideCache.add(child.id);
       }
       let coordinates = this._lazyStoreGet(child);
       // We keep a baseline horizontal distance between non-wide nodes around
       // for use when we can't compare with previous/next nodes
       if (!this._horizontalDistance && last && !isNodeWide) {
         this._horizontalDistance = coordinates.left - last.left;
       }
       // We also keep the basic height of non-wide items for use below:
       if (!isNodeWide && !singleItemHeight) {
         singleItemHeight = coordinates.height;
       }
       last = !isNodeWide ? coordinates : null;
     }
     if (this._inPanel) {
       this._heightToWidthFactor = CustomizableUI.PANEL_COLUMN_COUNT;
     } else {
       this._heightToWidthFactor = this._containerInfo.width / singleItemHeight;
     }
   },
   /**
    * Find the closest node in the container given the coordinates.
    * "Closest" is defined in a somewhat strange manner: we prefer nodes
    * which are in the same row over nodes that are in a different row.
    * In order to implement this, we use a weighted cartesian distance
    * where dy is more heavily weighted by a factor corresponding to the
    * ratio between the container's width and the height of its elements.
    */
   find: function(aContainer, aX, aY, aDraggedItemId) {
     let closest = null;
     let minCartesian = Number.MAX_VALUE;
     let containerX = this._containerInfo.left;
     let containerY = this._containerInfo.top;
     for (let node of aContainer.children) {
       let coordinates = this._lazyStoreGet(node);
       let offsetX = coordinates.x - containerX;
       let offsetY = coordinates.y - containerY;
       let hDiff = offsetX - aX;
       let vDiff = offsetY - aY;
       // For wide widgets, we're always going to be further from the center
       // horizontally. Compensate:
       if (this.isWide(node)) {
         hDiff /= CustomizableUI.PANEL_COLUMN_COUNT;
       }
       // Then compensate for the height/width ratio so that we prefer items
       // which are in the same row:
       hDiff /= this._heightToWidthFactor;
       let cartesianDiff = hDiff * hDiff + vDiff * vDiff;
       if (cartesianDiff < minCartesian) {
         minCartesian = cartesianDiff;
         closest = node;
       }
     }
     // Now correct this node based on what we're dragging
     if (closest) {
       let doc = aContainer.ownerDocument;
       let draggedItem = doc.getElementById(aDraggedItemId);
       // If dragging a wide item, always pick the first item in a row:
       if (this._inPanel && draggedItem &&
           draggedItem.classList.contains(CustomizableUI.WIDE_PANEL_CLASS)) {
         return this._firstInRow(closest);
       }
       let targetBounds = this._lazyStoreGet(closest);
       let farSide = this._dir == "ltr" ? "right" : "left";
       let outsideX = targetBounds[farSide];
       // Check if we're closer to the next target than to this one:
       // Only move if we're not targeting a node in a different row:
       if (aY > targetBounds.top && aY < targetBounds.bottom) {
         if ((this._dir == "ltr" && aX > outsideX) ||
             (this._dir == "rtl" && aX < outsideX)) {
           return closest.nextSibling || aContainer;
         }
       }
     }
     return closest;
   },
   /**
    * "Insert" a "placeholder" by shifting the subsequent children out of the
    * way. We go through all the children, and shift them based on the position
    * they would have if we had inserted something before aBefore. We use CSS
    * transforms for this, which are CSS transitioned.
    */
   insertPlaceholder: function(aContainer, aBefore, aWide, aSize, aIsFromThisArea) {
     let isShifted = false;
     let shiftDown = aWide;
     for (let child of aContainer.children) {
       // Don't need to shift hidden nodes:
       if (child.getAttribute("hidden") == "true") {
         continue;
       }
       // If this is the node before which we're inserting, start shifting
       // everything that comes after. One exception is inserting at the end
       // of the menupanel, in which case we do not shift the placeholders:
       if (child == aBefore && !child.classList.contains(kPlaceholderClass)) {
         isShifted = true;
         // If the node before which we're inserting is wide, we should
         // shift everything one row down:
         if (!shiftDown && this.isWide(child)) {
           shiftDown = true;
         }
       }
       // If we're moving items before a wide node that were already there,
       // it's possible it's not necessary to shift nodes
       // including & after the wide node.
       if (this.__undoShift) {
         isShifted = false;
       }
       if (isShifted) {
         // Conversely, if we're adding something before a wide node, for
         // simplicity's sake we move everything including the wide node down:
         if (this.__moveDown) {
           shiftDown = true;
         }
         if (aIsFromThisArea && !this._lastPlaceholderInsertion) {
           child.setAttribute("notransition", "true");
         }
         // Determine the CSS transform based on the next node:
         child.style.transform = this._getNextPos(child, shiftDown, aSize);
       } else {
         // If we're not shifting this node, reset the transform
         child.style.transform = "";
       }
     }
     if (aContainer.lastChild && aIsFromThisArea &&
         !this._lastPlaceholderInsertion) {
       // Flush layout:
       aContainer.lastChild.getBoundingClientRect();
       // then remove all the [notransition]
       for (let child of aContainer.children) {
         child.removeAttribute("notransition");
       }
     }
     delete this.__moveDown;
     delete this.__undoShift;
     this._lastPlaceholderInsertion = aBefore;
   },
   isWide: function(aNode) {
     return this._wideCache.has(aNode.id);
   },
   _checkIfWide: function(aNode) {
     return this._inPanel && aNode && aNode.firstChild &&
            aNode.firstChild.classList.contains(CustomizableUI.WIDE_PANEL_CLASS);
   },
   /**
    * Reset all the transforms in this container, optionally without
    * transitioning them.
    * @param aContainer    the container in which to reset transforms
    * @param aNoTransition if truthy, adds a notransition attribute to the node
    *                      while resetting the transform.
    */
   clearPlaceholders: function(aContainer, aNoTransition) {
     for (let child of aContainer.children) {
       if (aNoTransition) {
         child.setAttribute("notransition", true);
       }
       child.style.transform = "";
       if (aNoTransition) {
         // Need to force a reflow otherwise this won't work.
         child.getBoundingClientRect();
         child.removeAttribute("notransition");
       }
     }
     // We snapped back, so we can assume there's no more
     // "last" placeholder insertion point to keep track of.
     if (aNoTransition) {
       this._lastPlaceholderInsertion = null;
     }
   },
   _getNextPos: function(aNode, aShiftDown, aSize) {
     // Shifting down is easy:
     if (this._inPanel && aShiftDown) {
       return "translate(0, " + aSize.height + "px)";
     }
     return this._diffWithNext(aNode, aSize);
   },
   _diffWithNext: function(aNode, aSize) {
     let xDiff;
     let yDiff = null;
     let nodeBounds = this._lazyStoreGet(aNode);
     let side = this._dir == "ltr" ? "left" : "right";
     let next = this._getVisibleSiblingForDirection(aNode, "next");
     // First we determine the transform along the x axis.
     // Usually, there will be a next node to base this on:
     if (next) {
       let otherBounds = this._lazyStoreGet(next);
       xDiff = otherBounds[side] - nodeBounds[side];
       // If the next node is a wide item in the panel, check if we could maybe
       // just move further out in the same row, without snapping to the next
       // one. This happens, for example, if moving an item that's before a wide
       // node within its own row of items. There will be space to drop this
       // item within the row, and the rest of the items do not need to shift.
       if (this.isWide(next)) {
         let otherXDiff = this._moveNextBasedOnPrevious(aNode, nodeBounds,
                                                        this._firstInRow(aNode));
         // If this has the same sign as our original shift, we're still
         // snapping to the start of the row. In this case, we should move
         // everything after us a row down, so as not to display two nodes on
         // top of each other:
         // (we would be able to get away with checking for equality instead of
         //  equal signs here, but one of these is based on the x coordinate of
         //  the first item in row N and one on that for row N - 1, so this is
         //  safer, as their margins might differ)
         if ((otherXDiff < 0) == (xDiff < 0)) {
           this.__moveDown = true;
         } else {
           // Otherwise, we succeeded and can move further out. This also means
           // we can stop shifting the rest of the content:
           xDiff = otherXDiff;
           this.__undoShift = true;
         }
       } else {
         // We set this explicitly because otherwise some strange difference
         // between the height and the actual difference between line creeps in
         // and messes with alignments
         yDiff = otherBounds.top - nodeBounds.top;
       }
     } else {
       // We don't have a sibling whose position we can use. First, let's see
       // if we're also the first item (which complicates things):
       let firstNode = this._firstInRow(aNode);
       if (aNode == firstNode) {
         // Maybe we stored the horizontal distance between non-wide nodes,
         // if not, we'll use the width of the incoming node as a proxy:
         xDiff = this._horizontalDistance || aSize.width;
       } else {
         // If not, we should be able to get the distance to the previous node
         // and use the inverse, unless there's no room for another node (ie we
         // are the last node and there's no room for another one)
         xDiff = this._moveNextBasedOnPrevious(aNode, nodeBounds, firstNode);
       }
     }
     // If we've not determined the vertical difference yet, check it here
     if (yDiff === null) {
       // If the next node is behind rather than in front, we must have moved
       // vertically:
       if ((xDiff > 0 && this._dir == "rtl") || (xDiff < 0 && this._dir == "ltr")) {
         yDiff = aSize.height;
       } else {
         // Otherwise, we haven't
         yDiff = 0;
       }
     }
     return "translate(" + xDiff + "px, " + yDiff + "px)";
   },
   /**
    * Helper function to find the transform a node if there isn't a next node
    * to base that on.
    * @param aNode           the node to transform
    * @param aNodeBounds     the bounding rect info of this node
    * @param aFirstNodeInRow the first node in aNode's row
    */
   _moveNextBasedOnPrevious: function(aNode, aNodeBounds, aFirstNodeInRow) {
     let next = this._getVisibleSiblingForDirection(aNode, "previous");
     let otherBounds = this._lazyStoreGet(next);
     let side = this._dir == "ltr" ? "left" : "right";
     let xDiff = aNodeBounds[side] - otherBounds[side];
     // If, however, this means we move outside the container's box
     // (i.e. the row in which this item is placed is full)
     // we should move it to align with the first item in the next row instead
     let bound = this._containerInfo[this._dir == "ltr" ? "right" : "left"];
     if ((this._dir == "ltr" && xDiff + aNodeBounds.right > bound) ||
         (this._dir == "rtl" && xDiff + aNodeBounds.left < bound)) {
       xDiff = this._lazyStoreGet(aFirstNodeInRow)[side] - aNodeBounds[side];
     }
     return xDiff;
   },
   /**
    * Get position details from our cache. If the node is not yet cached, get its position
    * information and cache it now.
    * @param aNode  the node whose position info we want
    * @return the position info
    */
   _lazyStoreGet: function(aNode) {
     let rect = this._nodePositionStore.get(aNode);
     if (!rect) {
       // getBoundingClientRect() returns a DOMRect that is live, meaning that
       // as the element moves around, the rects values change. We don't want
       // that - we want a snapshot of what the rect values are right at this
       // moment, and nothing else. So we have to clone the values.
       let clientRect = aNode.getBoundingClientRect();
       rect = {
         left: clientRect.left,
         right: clientRect.right,
         width: clientRect.width,
         height: clientRect.height,
         top: clientRect.top,
         bottom: clientRect.bottom,
       };
       rect.x = rect.left + rect.width / 2;
       rect.y = rect.top + rect.height / 2;
       Object.freeze(rect);
       this._nodePositionStore.set(aNode, rect);
     }
     return rect;
   },
   _firstInRow: function(aNode) {
     // XXXmconley: I'm not entirely sure why we need to take the floor of these
     // values - it looks like, periodically, we're getting fractional pixels back
     //from lazyStoreGet. I've filed bug 994247 to investigate.
     let bound = Math.floor(this._lazyStoreGet(aNode).top);
     let rv = aNode;
     let prev;
     while (rv && (prev = this._getVisibleSiblingForDirection(rv, "previous"))) {
       if (Math.floor(this._lazyStoreGet(prev).bottom) <= bound) {
         return rv;
       }
       rv = prev;
     }
     return rv;
   },
   _getVisibleSiblingForDirection: function(aNode, aDirection) {
     let rv = aNode;
     do {
       rv = rv[aDirection + "Sibling"];
     } while (rv && rv.getAttribute("hidden") == "true")
     return rv;
   }
 }
 let DragPositionManager = {
   start: function(aWindow) {
     let areas = CustomizableUI.areas.filter((area) => CustomizableUI.getAreaType(area) != "toolbar");
     areas = areas.map((area) => CustomizableUI.getCustomizeTargetForArea(area, aWindow));
     areas.push(aWindow.document.getElementById(kPaletteId));
     for (let areaNode of areas) {
       let positionManager = gManagers.get(areaNode);
       if (positionManager) {
         positionManager.update(areaNode);
       } else {
         gManagers.set(areaNode, new AreaPositionManager(areaNode));
       }
     }
   },
   add: function(aWindow, aArea, aContainer) {
     if (CustomizableUI.getAreaType(aArea) != "toolbar") {
       return;
     }
     gManagers.set(aContainer, new AreaPositionManager(aContainer));
   },
   remove: function(aWindow, aArea, aContainer) {
     if (CustomizableUI.getAreaType(aArea) != "toolbar") {
       return;
     }
     gManagers.delete(aContainer);
   },
   stop: function() {
     gManagers.clear();
   },
   getManagerForArea: function(aArea) {
     return gManagers.get(aArea);
   }
 };
 Object.freeze(DragPositionManager);

The Tor Browser / annotate

browser/components/customizableui/src/DragPositionManager.jsm@8bccb770b82d (annotated)

browser/components/customizableui/src/DragPositionManager.jsm