1 /* 2 * Copyright (C) 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.android.documentsui; 18 19 import static com.android.documentsui.base.Shared.DEBUG; 20 21 import android.util.Log; 22 23 import com.android.documentsui.base.DocumentInfo; 24 25 import java.util.List; 26 27 /** 28 * A helper class for drag and drop operations 29 */ 30 public final class DragAndDropHelper { 31 32 private static final String TAG = "DragAndDropHelper"; 33 DragAndDropHelper()34 private DragAndDropHelper() {} 35 36 /** 37 * Helper method to see whether an item can be dropped/copied into a particular destination. 38 * Don't copy from the cwd into a provided list of prohibited directories. (ie. into cwd, into a 39 * selected directory). Note: this currently doesn't work for multi-window drag, because 40 * localState isn't carried over from one process to another. 41 */ canCopyTo(Object dragLocalState, DocumentInfo dst)42 public static boolean canCopyTo(Object dragLocalState, DocumentInfo dst) { 43 if (dst == null) { 44 if (DEBUG) Log.d(TAG, "Invalid destination. Ignoring."); 45 return false; 46 } 47 48 if (dragLocalState == null || !(dragLocalState instanceof List<?>)) { 49 if (DEBUG) Log.d(TAG, "Invalid local state object. Will allow copy."); 50 return true; 51 } 52 53 List<?> src = (List<?>) dragLocalState; 54 if (src.contains(dst)) { 55 if (DEBUG) Log.d(TAG, "Drop target same as source. Ignoring."); 56 return false; 57 } 58 return true; 59 } 60 } 61