1 /* 2 * Copyright 2016, 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.example.android.droptarget; 18 19 import android.content.ClipData; 20 import android.net.Uri; 21 import android.view.DragEvent; 22 import android.view.View; 23 import android.widget.ImageView; 24 25 public class ImageDragListener implements View.OnDragListener { 26 27 private static final int COLOR_INACTIVE = 0xFF888888; 28 29 private static final int COLOR_ACTIVE = 0xFFCCCCCC; 30 31 private static final int COLOR_HOVER = 0xFFEEEEEE; 32 33 @Override 34 public boolean onDrag(View view, DragEvent event) { 35 switch (event.getAction()) { 36 case DragEvent.ACTION_DRAG_STARTED: 37 setTargetColor(view, COLOR_ACTIVE); 38 return true; 39 40 case DragEvent.ACTION_DRAG_ENTERED: 41 setTargetColor(view, COLOR_HOVER); 42 return true; 43 44 case DragEvent.ACTION_DRAG_LOCATION: 45 processLocation(event.getX(), event.getY()); 46 return true; 47 48 case DragEvent.ACTION_DRAG_EXITED: 49 setTargetColor(view, COLOR_ACTIVE); 50 return true; 51 52 case DragEvent.ACTION_DROP: 53 return processDrop(view, event); 54 55 case DragEvent.ACTION_DRAG_ENDED: 56 setTargetColor(view, COLOR_INACTIVE); 57 return true; 58 59 default: 60 break; 61 } 62 63 return false; 64 } 65 66 private void setTargetColor(View view, int color) { 67 view.setBackgroundColor(color); 68 } 69 70 private boolean processDrop(View view, DragEvent event) { 71 ClipData clipData = event.getClipData(); 72 if (clipData == null || clipData.getItemCount() == 0) { 73 return false; 74 } 75 ClipData.Item item = clipData.getItemAt(0); 76 if (item == null) { 77 return false; 78 } 79 Uri uri = item.getUri(); 80 if (uri == null) { 81 return false; 82 } 83 return setImageUri(view, event, uri); 84 } 85 86 protected void processLocation(float x, float y) { 87 } 88 89 protected boolean setImageUri(View view, DragEvent event, Uri uri) { 90 if (!(view instanceof ImageView)) { 91 return false; 92 } 93 ((ImageView) view).setImageURI(uri); 94 return true; 95 } 96 } 97