1 /* 2 * Copyright (C) 2008 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0 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.launcher3; 18 19 import android.content.Context; 20 import android.graphics.Rect; 21 22 import com.android.launcher3.accessibility.DragViewStateAnnouncer; 23 import com.android.launcher3.dragndrop.DragOptions; 24 import com.android.launcher3.dragndrop.DragView; 25 import com.android.launcher3.dragndrop.DraggableView; 26 import com.android.launcher3.folder.FolderNameProvider; 27 import com.android.launcher3.logging.InstanceId; 28 import com.android.launcher3.logging.InstanceIdSequence; 29 import com.android.launcher3.model.data.ItemInfo; 30 import com.android.launcher3.util.Executors; 31 32 /** 33 * Interface defining an object that can receive a drag. 34 * 35 */ 36 public interface DropTarget { 37 38 class DragObject { 39 public int x = -1; 40 public int y = -1; 41 42 /** X offset from the upper-left corner of the cell to where we touched. */ 43 public int xOffset = -1; 44 45 /** Y offset from the upper-left corner of the cell to where we touched. */ 46 public int yOffset = -1; 47 48 /** This indicates whether a drag is in final stages, either drop or cancel. It 49 * differentiates onDragExit, since this is called when the drag is ending, above 50 * the current drag target, or when the drag moves off the current drag object. 51 */ 52 public boolean dragComplete = false; 53 54 /** The view that moves around while you drag. */ 55 public DragView dragView = null; 56 57 /** The data associated with the object, after item is dropped. */ 58 public ItemInfo dragInfo = null; 59 60 /** The data associated with the object being dragged */ 61 public ItemInfo originalDragInfo = null; 62 63 /** Where the drag originated */ 64 public DragSource dragSource = null; 65 66 /** Indicates that the drag operation was cancelled */ 67 public boolean cancelled = false; 68 69 /** Defers removing the DragView from the DragLayer until after the drop animation. */ 70 public boolean deferDragViewCleanupPostAnimation = true; 71 72 public DragViewStateAnnouncer stateAnnouncer; 73 74 public FolderNameProvider folderNameProvider; 75 76 /** The source view (ie. icon, widget etc.) that is being dragged and which the 77 * DragView represents. May be an actual View class or a virtual stand-in */ 78 public DraggableView originalView = null; 79 80 /** Used for matching DROP event with its corresponding DRAG event on the server side. */ 81 public final InstanceId logInstanceId = new InstanceIdSequence().newInstanceId(); 82 DragObject(Context context)83 public DragObject(Context context) { 84 Executors.MODEL_EXECUTOR.post(() -> 85 folderNameProvider = FolderNameProvider.newInstance(context)); 86 } 87 88 /** 89 * This is used to compute the visual center of the dragView. This point is then 90 * used to visualize drop locations and determine where to drop an item. The idea is that 91 * the visual center represents the user's interpretation of where the item is, and hence 92 * is the appropriate point to use when determining drop location. 93 */ getVisualCenter(float[] recycle)94 public final float[] getVisualCenter(float[] recycle) { 95 final float res[] = (recycle == null) ? new float[2] : recycle; 96 Rect dragRegion = dragView.getDragRegion(); 97 98 // These represent the visual top and left of drag view if a dragRect was provided. 99 // If a dragRect was not provided, then they correspond to the actual view left and 100 // top, as the dragRect is in that case taken to be the entire dragView. 101 int left = x - xOffset - dragRegion.left; 102 int top = y - yOffset - dragRegion.top; 103 104 // In order to find the visual center, we shift by half the dragRect 105 res[0] = left + dragRegion.width() / 2; 106 res[1] = top + dragRegion.height() / 2; 107 108 return res; 109 } 110 } 111 112 /** 113 * Used to temporarily disable certain drop targets 114 * 115 * @return boolean specifying whether this drop target is currently enabled 116 */ isDropEnabled()117 boolean isDropEnabled(); 118 119 /** 120 * Handle an object being dropped on the DropTarget. 121 * 122 * This will be called only if this target previously returned true for {@link #acceptDrop}. It 123 * is the responsibility of this target to exit out of the spring loaded mode (either 124 * immediately or after any pending animations). 125 * 126 * If the drop was cancelled for some reason, onDrop will never get called, the UI will 127 * automatically exit out of this mode. 128 */ onDrop(DragObject dragObject, DragOptions options)129 void onDrop(DragObject dragObject, DragOptions options); 130 onDragEnter(DragObject dragObject)131 void onDragEnter(DragObject dragObject); 132 onDragOver(DragObject dragObject)133 void onDragOver(DragObject dragObject); 134 onDragExit(DragObject dragObject)135 void onDragExit(DragObject dragObject); 136 137 /** 138 * Check if a drop action can occur at, or near, the requested location. 139 * This will be called just before onDrop. 140 * @return True if the drop will be accepted, false otherwise. 141 */ acceptDrop(DragObject dragObject)142 boolean acceptDrop(DragObject dragObject); 143 prepareAccessibilityDrop()144 void prepareAccessibilityDrop(); 145 146 // These methods are implemented in Views getHitRectRelativeToDragLayer(Rect outRect)147 void getHitRectRelativeToDragLayer(Rect outRect); 148 } 149