ViewCompat.java revision 9648c538bac4f04145c118cc41168d1d7a536312 
1/*
2 * Copyright (C) 2011 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 android.support.v4.view;
18
19import android.support.v4.view.accessibility.AccessibilityNodeInfoCompat;
20import android.view.View;
21import android.view.accessibility.AccessibilityEvent;
22
23/**
24 * Helper for accessing newer features in View.
25 */
26public class ViewCompat {
27    /**
28     * Always allow a user to over-scroll this view, provided it is a
29     * view that can scroll.
30     */
31    public static final int OVER_SCROLL_ALWAYS = 0;
32
33    /**
34     * Allow a user to over-scroll this view only if the content is large
35     * enough to meaningfully scroll, provided it is a view that can scroll.
36     */
37    public static final int OVER_SCROLL_IF_CONTENT_SCROLLS = 1;
38
39    /**
40     * Never allow a user to over-scroll this view.
41     */
42    public static final int OVER_SCROLL_NEVER = 2;
43
44    interface ViewCompatImpl {
45        public boolean canScrollHorizontally(View v, int direction);
46        public boolean canScrollVertically(View v, int direction);
47        public int getOverScrollMode(View v);
48        public void setOverScrollMode(View v, int mode);
49        public void onInitializeAccessibilityEvent(View v, AccessibilityEvent event);
50        public void onPopulateAccessibilityEvent(View v, AccessibilityEvent event);
51        public void onInitializeAccessibilityNodeInfo(View v, AccessibilityNodeInfoCompat info);
52        public void setAccessibilityDelegate(View v, AccessibilityDelegateCompat delegate);
53    }
54
55    static class BaseViewCompatImpl implements ViewCompatImpl {
56        public boolean canScrollHorizontally(View v, int direction) {
57            return false;
58        }
59        public boolean canScrollVertically(View v, int direction) {
60            return false;
61        }
62        public int getOverScrollMode(View v) {
63            return OVER_SCROLL_NEVER;
64        }
65        public void setOverScrollMode(View v, int mode) {
66            // Do nothing; API doesn't exist
67        }
68        public void setAccessibilityDelegate(View v, AccessibilityDelegateCompat delegate) {
69            // Do nothing; API doesn't exist
70        }
71        public void onPopulateAccessibilityEvent(View v, AccessibilityEvent event) {
72            // Do nothing; API doesn't exist
73        }
74        public void onInitializeAccessibilityEvent(View v, AccessibilityEvent event) {
75         // Do nothing; API doesn't exist
76        }
77        public void onInitializeAccessibilityNodeInfo(View v, AccessibilityNodeInfoCompat info) {
78            // Do nothing; API doesn't exist
79        }
80    }
81
82    static class GBViewCompatImpl extends BaseViewCompatImpl {
83        @Override
84        public int getOverScrollMode(View v) {
85            return ViewCompatGingerbread.getOverScrollMode(v);
86        }
87        @Override
88        public void setOverScrollMode(View v, int mode) {
89            ViewCompatGingerbread.setOverScrollMode(v, mode);
90        }
91    }
92
93    static class ICSViewCompatImpl extends GBViewCompatImpl {
94        @Override
95        public boolean canScrollHorizontally(View v, int direction) {
96            return ViewCompatICS.canScrollHorizontally(v, direction);
97        }
98        @Override
99        public boolean canScrollVertically(View v, int direction) {
100            return ViewCompatICS.canScrollVertically(v, direction);
101        }
102        @Override
103        public void onPopulateAccessibilityEvent(View v, AccessibilityEvent event) {
104            ViewCompatICS.onPopulateAccessibilityEvent(v, event);
105        }
106        @Override
107        public void onInitializeAccessibilityEvent(View v, AccessibilityEvent event) {
108            ViewCompatICS.onInitializeAccessibilityEvent(v, event);
109        }
110        @Override
111        public void onInitializeAccessibilityNodeInfo(View v, AccessibilityNodeInfoCompat info) {
112            ViewCompatICS.onInitializeAccessibilityNodeInfo(v, info.getImpl());
113        }
114        @Override
115        public void setAccessibilityDelegate(View v, AccessibilityDelegateCompat delegate) {
116            ViewCompatICS.setAccessibilityDelegate(v, delegate.getBridge());
117        }
118    }
119
120    static final ViewCompatImpl IMPL;
121    static {
122        final int version = android.os.Build.VERSION.SDK_INT;
123        if (version >= 14) {
124            IMPL = new ICSViewCompatImpl();
125        } else if (version >= 9) {
126            IMPL = new GBViewCompatImpl();
127        } else {
128            IMPL = new BaseViewCompatImpl();
129        }
130    }
131
132    public static boolean canScrollHorizontally(View v, int direction) {
133        return IMPL.canScrollHorizontally(v, direction);
134    }
135
136    public static boolean canScrollVertically(View v, int direction) {
137        return IMPL.canScrollVertically(v, direction);
138    }
139
140    public static int getOverScrollMode(View v) {
141        return IMPL.getOverScrollMode(v);
142    }
143
144    public static void setOverScrollMode(View v, int mode) {
145        IMPL.setOverScrollMode(v, mode);
146    }
147
148    public static void onPopulateAccessibilityEvent(View v, AccessibilityEvent event) {
149        IMPL.onPopulateAccessibilityEvent(v, event);
150    }
151
152    public static void onInitializeAccessibilityEvent(View v, AccessibilityEvent event) {
153        IMPL.onInitializeAccessibilityEvent(v, event);
154    }
155
156    public static void onInitializeAccessibilityNodeInfo(View v, AccessibilityNodeInfoCompat info) {
157        IMPL.onInitializeAccessibilityNodeInfo(v, info);
158    }
159
160    public static void setAccessibilityDelegate(View v, AccessibilityDelegateCompat delegate) {
161        IMPL.setAccessibilityDelegate(v, delegate);
162    }
163}
164