1 /* 2 * Copyright (C) 2010 The Android Open Source Project 3 * 4 * Licensed under the Eclipse Public License, Version 1.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.eclipse.org/org/documents/epl-v10.php 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.ide.eclipse.adt.internal.editors.layout.gle2; 18 19 import com.android.ide.common.api.IViewRule; 20 import com.android.ide.common.api.Rect; 21 22 23 /** 24 * This singleton is used to keep track of drag'n'drops initiated within this 25 * session of Eclipse. A drag can be initiated from a palette or from a canvas 26 * and its content is an Android View fully-qualified class name. 27 * <p/> 28 * Overall this is a workaround: the issue is that the drag'n'drop SWT API does not 29 * allow us to know the transfered data during the initial drag -- only when the 30 * data is dropped do we know what it is about (and to be more exact there is a workaround 31 * to do just that which works on Windows but not on Linux/Mac SWT). 32 * <p/> 33 * In the GLE we'd like to adjust drag feedback to the data being actually dropped. 34 * The singleton instance of this class will be used to track the data currently dragged 35 * off a canvas or its palette and then set back to null when the drag'n'drop is finished. 36 * <p/> 37 * Note that when a drag starts in one instance of Eclipse and the dragOver/drop is done 38 * in a <em>separate</em> instance of Eclipse, the dragged FQCN won't be registered here 39 * and will be null. 40 */ 41 final class GlobalCanvasDragInfo { 42 43 private static final GlobalCanvasDragInfo sInstance = new GlobalCanvasDragInfo(); 44 45 private SimpleElement[] mCurrentElements = null; 46 private SelectionItem[] mCurrentSelection; 47 private Object mSourceCanvas = null; 48 private Runnable mRemoveSourceHandler; 49 private Rect mDragBounds; 50 private int mDragBaseline = -1; 51 52 /** Private constructor. Use {@link #getInstance()} to retrieve the singleton. */ GlobalCanvasDragInfo()53 private GlobalCanvasDragInfo() { 54 // pass 55 } 56 57 /** Returns the singleton instance. */ getInstance()58 public static GlobalCanvasDragInfo getInstance() { 59 return sInstance; 60 } 61 62 /** 63 * Registers the XML elements being dragged. 64 * 65 * @param elements The elements being dragged 66 * @param selection The selection (which can be null, for example when the 67 * user drags from the palette) 68 * @param sourceCanvas An object representing the source we are dragging 69 * from (used for identity comparisons only) 70 * @param removeSourceHandler A runnable (or null) which can clean up the 71 * source. It should only be invoked if the drag operation is a 72 * move, not a copy. 73 */ startDrag(SimpleElement[] elements, SelectionItem[] selection, Object sourceCanvas, Runnable removeSourceHandler)74 public void startDrag(SimpleElement[] elements, SelectionItem[] selection, 75 Object sourceCanvas, Runnable removeSourceHandler) { 76 mCurrentElements = elements; 77 mCurrentSelection = selection; 78 mSourceCanvas = sourceCanvas; 79 mRemoveSourceHandler = removeSourceHandler; 80 } 81 82 /** Unregisters elements being dragged. */ stopDrag()83 public void stopDrag() { 84 mCurrentElements = null; 85 mCurrentSelection = null; 86 mSourceCanvas = null; 87 mRemoveSourceHandler = null; 88 mDragBounds = null; 89 } 90 isDragging()91 public boolean isDragging() { 92 return mCurrentElements != null; 93 } 94 95 /** Returns the elements being dragged. */ getCurrentElements()96 public SimpleElement[] getCurrentElements() { 97 return mCurrentElements; 98 } 99 100 /** Returns the selection originally dragged. 101 * Can be null if the drag did not start in a canvas. 102 */ getCurrentSelection()103 public SelectionItem[] getCurrentSelection() { 104 return mCurrentSelection; 105 } 106 107 /** 108 * Returns the object that call {@link #startDrag(SimpleElement[], SelectionItem[], Object)}. 109 * Can be null. 110 * This is not meant to access the object indirectly, it is just meant to compare if the 111 * source and the destination of the drag'n'drop are the same, so object identity 112 * is all what matters. 113 */ getSourceCanvas()114 public Object getSourceCanvas() { 115 return mSourceCanvas; 116 } 117 118 /** 119 * Removes source of the drag. This should only be called when the drag and 120 * drop operation is a move (not a copy). 121 */ removeSource()122 public void removeSource() { 123 if (mRemoveSourceHandler != null) { 124 mRemoveSourceHandler.run(); 125 mRemoveSourceHandler = null; 126 } 127 } 128 129 /** 130 * Get the bounds of the drag, relative to the starting mouse position. For example, 131 * if you have a rectangular view of size 100x80, and you start dragging at position 132 * (15,20) from the top left corner of this rectangle, then the drag bounds would be 133 * (-15,-20, 100x80). 134 * <p> 135 * NOTE: The coordinate units will be in SWT/control pixels, not Android view pixels. 136 * In other words, they are affected by the canvas zoom: If you zoom the view and the 137 * bounds of a view grow, the drag bounds will be larger. 138 * 139 * @return the drag bounds, or null if there are no bounds for the current drag 140 */ getDragBounds()141 public Rect getDragBounds() { 142 return mDragBounds; 143 } 144 145 /** 146 * Set the bounds of the drag, relative to the starting mouse position. See 147 * {@link #getDragBounds()} for details on the semantics of the drag bounds. 148 * 149 * @param dragBounds the new drag bounds, or null if there are no drag bounds 150 */ setDragBounds(Rect dragBounds)151 public void setDragBounds(Rect dragBounds) { 152 mDragBounds = dragBounds; 153 } 154 155 /** 156 * Returns the baseline of the drag, or -1 if not applicable 157 * 158 * @return the current SWT modifier key mask as an {@link IViewRule} modifier mask 159 */ getDragBaseline()160 public int getDragBaseline() { 161 return mDragBaseline; 162 } 163 164 /** 165 * Sets the baseline of the drag 166 * 167 * @param baseline the new baseline 168 */ setDragBaseline(int baseline)169 public void setDragBaseline(int baseline) { 170 mDragBaseline = baseline; 171 } 172 } 173