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.graphics.PointF; 20 import android.graphics.Rect; 21 22 import com.android.launcher3.accessibility.DragViewStateAnnouncer; 23 24 /** 25 * Interface defining an object that can receive a drag. 26 * 27 */ 28 public interface DropTarget { 29 30 public static final String TAG = "DropTarget"; 31 32 public static class DragObject { 33 public int x = -1; 34 public int y = -1; 35 36 /** X offset from the upper-left corner of the cell to where we touched. */ 37 public int xOffset = -1; 38 39 /** Y offset from the upper-left corner of the cell to where we touched. */ 40 public int yOffset = -1; 41 42 /** This indicates whether a drag is in final stages, either drop or cancel. It 43 * differentiates onDragExit, since this is called when the drag is ending, above 44 * the current drag target, or when the drag moves off the current drag object. 45 */ 46 public boolean dragComplete = false; 47 48 /** The view that moves around while you drag. */ 49 public DragView dragView = null; 50 51 /** The data associated with the object being dragged */ 52 public Object dragInfo = null; 53 54 /** Where the drag originated */ 55 public DragSource dragSource = null; 56 57 /** The object is part of an accessible drag operation */ 58 public boolean accessibleDrag; 59 60 /** Post drag animation runnable */ 61 public Runnable postAnimationRunnable = null; 62 63 /** Indicates that the drag operation was cancelled */ 64 public boolean cancelled = false; 65 66 /** Defers removing the DragView from the DragLayer until after the drop animation. */ 67 public boolean deferDragViewCleanupPostAnimation = true; 68 69 public DragViewStateAnnouncer stateAnnouncer; 70 DragObject()71 public DragObject() { 72 } 73 74 /** 75 * This is used to compute the visual center of the dragView. This point is then 76 * used to visualize drop locations and determine where to drop an item. The idea is that 77 * the visual center represents the user's interpretation of where the item is, and hence 78 * is the appropriate point to use when determining drop location. 79 */ getVisualCenter(float[] recycle)80 public final float[] getVisualCenter(float[] recycle) { 81 final float res[] = (recycle == null) ? new float[2] : recycle; 82 83 // These represent the visual top and left of drag view if a dragRect was provided. 84 // If a dragRect was not provided, then they correspond to the actual view left and 85 // top, as the dragRect is in that case taken to be the entire dragView. 86 // R.dimen.dragViewOffsetY. 87 int left = x - xOffset; 88 int top = y - yOffset; 89 90 // In order to find the visual center, we shift by half the dragRect 91 res[0] = left + dragView.getDragRegion().width() / 2; 92 res[1] = top + dragView.getDragRegion().height() / 2; 93 94 return res; 95 } 96 } 97 98 /** 99 * Used to temporarily disable certain drop targets 100 * 101 * @return boolean specifying whether this drop target is currently enabled 102 */ isDropEnabled()103 boolean isDropEnabled(); 104 105 /** 106 * Handle an object being dropped on the DropTarget 107 * 108 * @param source DragSource where the drag started 109 * @param x X coordinate of the drop location 110 * @param y Y coordinate of the drop location 111 * @param xOffset Horizontal offset with the object being dragged where the original 112 * touch happened 113 * @param yOffset Vertical offset with the object being dragged where the original 114 * touch happened 115 * @param dragView The DragView that's being dragged around on screen. 116 * @param dragInfo Data associated with the object being dragged 117 * 118 */ onDrop(DragObject dragObject)119 void onDrop(DragObject dragObject); 120 onDragEnter(DragObject dragObject)121 void onDragEnter(DragObject dragObject); 122 onDragOver(DragObject dragObject)123 void onDragOver(DragObject dragObject); 124 onDragExit(DragObject dragObject)125 void onDragExit(DragObject dragObject); 126 127 /** 128 * Handle an object being dropped as a result of flinging to delete and will be called in place 129 * of onDrop(). (This is only called on objects that are set as the DragController's 130 * fling-to-delete target. 131 */ onFlingToDelete(DragObject dragObject, PointF vec)132 void onFlingToDelete(DragObject dragObject, PointF vec); 133 134 /** 135 * Check if a drop action can occur at, or near, the requested location. 136 * This will be called just before onDrop. 137 * 138 * @param source DragSource where the drag started 139 * @param x X coordinate of the drop location 140 * @param y Y coordinate of the drop location 141 * @param xOffset Horizontal offset with the object being dragged where the 142 * original touch happened 143 * @param yOffset Vertical offset with the object being dragged where the 144 * original touch happened 145 * @param dragView The DragView that's being dragged around on screen. 146 * @param dragInfo Data associated with the object being dragged 147 * @return True if the drop will be accepted, false otherwise. 148 */ acceptDrop(DragObject dragObject)149 boolean acceptDrop(DragObject dragObject); 150 prepareAccessibilityDrop()151 void prepareAccessibilityDrop(); 152 153 // These methods are implemented in Views getHitRectRelativeToDragLayer(Rect outRect)154 void getHitRectRelativeToDragLayer(Rect outRect); getLocationInDragLayer(int[] loc)155 void getLocationInDragLayer(int[] loc); getLeft()156 int getLeft(); getTop()157 int getTop(); 158 } 159