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
17package com.android.launcher2;
18
19import android.content.Context;
20import android.graphics.PointF;
21import android.graphics.Rect;
22import android.util.Log;
23
24/**
25 * Interface defining an object that can receive a drag.
26 *
27 */
28public 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
66        public DragObject() {
67        }
68    }
69
70    public static class DragEnforcer implements DragController.DragListener {
71        int dragParity = 0;
72
73        public DragEnforcer(Context context) {
74            Launcher launcher = (Launcher) context;
75            launcher.getDragController().addDragListener(this);
76        }
77
78        void onDragEnter() {
79            dragParity++;
80            if (dragParity != 1) {
81                Log.e(TAG, "onDragEnter: Drag contract violated: " + dragParity);
82            }
83        }
84
85        void onDragExit() {
86            dragParity--;
87            if (dragParity != 0) {
88                Log.e(TAG, "onDragExit: Drag contract violated: " + dragParity);
89            }
90        }
91
92        @Override
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
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     */
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     */
128    void onDrop(DragObject dragObject);
129
130    void onDragEnter(DragObject dragObject);
131
132    void onDragOver(DragObject dragObject);
133
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     */
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     */
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     */
177    boolean acceptDrop(DragObject dragObject);
178
179    // These methods are implemented in Views
180    void getHitRect(Rect outRect);
181    void getLocationInDragLayer(int[] loc);
182    int getLeft();
183    int getTop();
184}
185