Add Pale Moon

application/palemoon/base/content/newtab/dropTargetShim.js

@@ -0,0 +1,188 @@
+#ifdef 0
+/* 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/. */
+#endif
+
+/**
+ * This singleton provides a custom drop target detection. We need this because
+ * the default DnD target detection relies on the cursor's position. We want
+ * to pick a drop target based on the dragged site's position.
+ */
+let gDropTargetShim = {
+  /**
+   * Cache for the position of all cells, cleaned after drag finished.
+   */
+  _cellPositions: null,
+
+  /**
+   * The last drop target that was hovered.
+   */
+  _lastDropTarget: null,
+
+  /**
+   * Initializes the drop target shim.
+   */
+  init: function DropTargetShim_init() {
+    let node = gGrid.node;
+
+    // Add drag event handlers.
+    node.addEventListener("dragstart", this, true);
+    node.addEventListener("dragend", this, true);
+  },
+
+  /**
+   * Handles all shim events.
+   */
+  handleEvent: function DropTargetShim_handleEvent(aEvent) {
+    switch (aEvent.type) {
+      case "dragstart":
+        this._start(aEvent);
+        break;
+      case "dragover":
+        this._dragover(aEvent);
+        break;
+      case "dragend":
+        this._end(aEvent);
+        break;
+    }
+  },
+
+  /**
+   * Handles the 'dragstart' event.
+   * @param aEvent The 'dragstart' event.
+   */
+  _start: function DropTargetShim_start(aEvent) {
+    if (aEvent.target.classList.contains("newtab-link")) {
+      gGrid.lock();
+
+      // XXX bug 505521 - Listen for dragover on the document.
+      document.documentElement.addEventListener("dragover", this, false);
+    }
+  },
+
+  /**
+   * Handles the 'drag' event and determines the current drop target.
+   * @param aEvent The 'drag' event.
+   */
+  _drag: function DropTargetShim_drag(aEvent) {
+    // Let's see if we find a drop target.
+    let target = this._findDropTarget(aEvent);
+
+    if (target != this._lastDropTarget) {
+      if (this._lastDropTarget)
+        // We left the last drop target.
+        this._dispatchEvent(aEvent, "dragexit", this._lastDropTarget);
+
+      if (target)
+        // We're now hovering a (new) drop target.
+        this._dispatchEvent(aEvent, "dragenter", target);
+
+      if (this._lastDropTarget)
+        // We left the last drop target.
+        this._dispatchEvent(aEvent, "dragleave", this._lastDropTarget);
+
+      this._lastDropTarget = target;
+    }
+  },
+
+  /**
+   * Handles the 'dragover' event as long as bug 505521 isn't fixed to get
+   * current mouse cursor coordinates while dragging.
+   * @param aEvent The 'dragover' event.
+   */
+  _dragover: function DropTargetShim_dragover(aEvent) {
+    let sourceNode = aEvent.dataTransfer.mozSourceNode.parentNode;
+    gDrag.drag(sourceNode._newtabSite, aEvent);
+
+    this._drag(aEvent);
+  },
+
+  /**
+   * Handles the 'dragend' event.
+   * @param aEvent The 'dragend' event.
+   */
+  _end: function DropTargetShim_end(aEvent) {
+    // Make sure to determine the current drop target in case the dragenter
+    // event hasn't been fired.
+    this._drag(aEvent);
+
+    if (this._lastDropTarget) {
+      if (aEvent.dataTransfer.mozUserCancelled) {
+        // The drag operation was cancelled.
+        this._dispatchEvent(aEvent, "dragexit", this._lastDropTarget);
+        this._dispatchEvent(aEvent, "dragleave", this._lastDropTarget);
+      } else {
+        // A site was successfully dropped.
+        this._dispatchEvent(aEvent, "drop", this._lastDropTarget);
+      }
+
+      // Clean up.
+      this._lastDropTarget = null;
+      this._cellPositions = null;
+    }
+
+    gGrid.unlock();
+
+    // XXX bug 505521 - Remove the document's dragover listener.
+    document.documentElement.removeEventListener("dragover", this, false);
+  },
+
+  /**
+   * Determines the current drop target by matching the dragged site's position
+   * against all cells in the grid.
+   * @return The currently hovered drop target or null.
+   */
+  _findDropTarget: function DropTargetShim_findDropTarget() {
+    // These are the minimum intersection values - we want to use the cell if
+    // the site is >= 50% hovering its position.
+    let minWidth = gDrag.cellWidth / 2;
+    let minHeight = gDrag.cellHeight / 2;
+
+    let cellPositions = this._getCellPositions();
+    let rect = gTransformation.getNodePosition(gDrag.draggedSite.node);
+
+    // Compare each cell's position to the dragged site's position.
+    for (let i = 0; i < cellPositions.length; i++) {
+      let inter = rect.intersect(cellPositions[i].rect);
+
+      // If the intersection is big enough we found a drop target.
+      if (inter.width >= minWidth && inter.height >= minHeight)
+        return cellPositions[i].cell;
+    }
+
+    // No drop target found.
+    return null;
+  },
+
+  /**
+   * Gets the positions of all cell nodes.
+   * @return The (cached) cell positions.
+   */
+  _getCellPositions: function DropTargetShim_getCellPositions() {
+    if (this._cellPositions)
+      return this._cellPositions;
+
+    return this._cellPositions = gGrid.cells.map(function (cell) {
+      return {cell: cell, rect: gTransformation.getNodePosition(cell.node)};
+    });
+  },
+
+  /**
+   * Dispatches a custom DragEvent on the given target node.
+   * @param aEvent The source event.
+   * @param aType The event type.
+   * @param aTarget The target node that receives the event.
+   */
+  _dispatchEvent:
+    function DropTargetShim_dispatchEvent(aEvent, aType, aTarget) {
+
+    let node = aTarget.node;
+    let event = document.createEvent("DragEvents");
+
+    event.initDragEvent(aType, true, true, window, 0, 0, 0, 0, 0, false, false,
+                        false, false, 0, node, aEvent.dataTransfer);
+
+    node.dispatchEvent(event);
+  }
+};