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.launcher2; 18 19 import android.content.Context; 20 import android.graphics.PointF; 21 import android.graphics.Rect; 22 import android.util.Log; 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 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 /** Post drag animation runnable */ 58 public Runnable postAnimationRunnable = null; 59 60 /** Indicates that the drag operation was cancelled */ 61 public boolean cancelled = false; 62 63 /** Defers removing the DragView from the DragLayer until after the drop animation. */ 64 public boolean deferDragViewCleanupPostAnimation = true; 65 DragObject()66 public DragObject() { 67 } 68 } 69 70 public static class DragEnforcer implements DragController.DragListener { 71 int dragParity = 0; 72 DragEnforcer(Context context)73 public DragEnforcer(Context context) { 74 Launcher launcher = (Launcher) context; 75 launcher.getDragController().addDragListener(this); 76 } 77 onDragEnter()78 void onDragEnter() { 79 dragParity++; 80 if (dragParity != 1) { 81 Log.e(TAG, "onDragEnter: Drag contract violated: " + dragParity); 82 } 83 } 84 onDragExit()85 void onDragExit() { 86 dragParity--; 87 if (dragParity != 0) { 88 Log.e(TAG, "onDragExit: Drag contract violated: " + dragParity); 89 } 90 } 91 92 @Override onDragStart(DragSource source, Object info, int dragAction)93 public void onDragStart(DragSource source, Object info, int dragAction) { 94 if (dragParity != 0) { 95 Log.e(TAG, "onDragEnter: Drag contract violated: " + dragParity); 96 } 97 } 98 99 @Override onDragEnd()100 public void onDragEnd() { 101 if (dragParity != 0) { 102 Log.e(TAG, "onDragExit: Drag contract violated: " + dragParity); 103 } 104 } 105 } 106 107 /** 108 * Used to temporarily disable certain drop targets 109 * 110 * @return boolean specifying whether this drop target is currently enabled 111 */ isDropEnabled()112 boolean isDropEnabled(); 113 114 /** 115 * Handle an object being dropped on the DropTarget 116 * 117 * @param source DragSource where the drag started 118 * @param x X coordinate of the drop location 119 * @param y Y coordinate of the drop location 120 * @param xOffset Horizontal offset with the object being dragged where the original 121 * touch happened 122 * @param yOffset Vertical offset with the object being dragged where the original 123 * touch happened 124 * @param dragView The DragView that's being dragged around on screen. 125 * @param dragInfo Data associated with the object being dragged 126 * 127 */ onDrop(DragObject dragObject)128 void onDrop(DragObject dragObject); 129 onDragEnter(DragObject dragObject)130 void onDragEnter(DragObject dragObject); 131 onDragOver(DragObject dragObject)132 void onDragOver(DragObject dragObject); 133 onDragExit(DragObject dragObject)134 void onDragExit(DragObject dragObject); 135 136 /** 137 * Handle an object being dropped as a result of flinging to delete and will be called in place 138 * of onDrop(). (This is only called on objects that are set as the DragController's 139 * fling-to-delete target. 140 */ onFlingToDelete(DragObject dragObject, int x, int y, PointF vec)141 void onFlingToDelete(DragObject dragObject, int x, int y, PointF vec); 142 143 /** 144 * Allows a DropTarget to delegate drag and drop events to another object. 145 * 146 * Most subclasses will should just return null from this method. 147 * 148 * @param source DragSource where the drag started 149 * @param x X coordinate of the drop location 150 * @param y Y coordinate of the drop location 151 * @param xOffset Horizontal offset with the object being dragged where the original 152 * touch happened 153 * @param yOffset Vertical offset with the object being dragged where the original 154 * touch happened 155 * @param dragView The DragView that's being dragged around on screen. 156 * @param dragInfo Data associated with the object being dragged 157 * 158 * @return The DropTarget to delegate to, or null to not delegate to another object. 159 */ getDropTargetDelegate(DragObject dragObject)160 DropTarget getDropTargetDelegate(DragObject dragObject); 161 162 /** 163 * Check if a drop action can occur at, or near, the requested location. 164 * This will be called just before onDrop. 165 * 166 * @param source DragSource where the drag started 167 * @param x X coordinate of the drop location 168 * @param y Y coordinate of the drop location 169 * @param xOffset Horizontal offset with the object being dragged where the 170 * original touch happened 171 * @param yOffset Vertical offset with the object being dragged where the 172 * original touch happened 173 * @param dragView The DragView that's being dragged around on screen. 174 * @param dragInfo Data associated with the object being dragged 175 * @return True if the drop will be accepted, false otherwise. 176 */ acceptDrop(DragObject dragObject)177 boolean acceptDrop(DragObject dragObject); 178 179 // These methods are implemented in Views getHitRect(Rect outRect)180 void getHitRect(Rect outRect); getLocationInDragLayer(int[] loc)181 void getLocationInDragLayer(int[] loc); getLeft()182 int getLeft(); getTop()183 int getTop(); 184 } 185