ActionBarDrawerToggleHoneycomb.java revision 79f95ce3e660d267831067e514ff455156c4381f 
1/*
2 * Copyright (C) 2013 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
18package android.support.v4.app;
19
20import android.R;
21import android.app.ActionBar;
22import android.app.Activity;
23import android.content.res.TypedArray;
24import android.graphics.drawable.Drawable;
25import android.util.Log;
26import android.view.View;
27import android.view.ViewGroup;
28import android.widget.ImageView;
29
30import java.lang.reflect.Method;
31
32/**
33 * This class encapsulates some awful hacks.
34 *
35 * Before JB-MR2 (API 18) it was not possible to change the home-as-up indicator glyph
36 * in an action bar without some really gross hacks. Since the MR2 SDK is not published as of
37 * this writing, the new API is accessed via reflection here if available.
38 */
39class ActionBarDrawerToggleHoneycomb {
40    private static final String TAG = "ActionBarDrawerToggleHoneycomb";
41
42    private static final int[] THEME_ATTRS = new int[] {
43            R.attr.homeAsUpIndicator
44    };
45
46    public static Object setActionBarUpIndicator(Object info, Activity activity,
47            Drawable drawable, int contentDescRes) {
48        if (info == null) {
49            info = new SetIndicatorInfo(activity);
50        }
51        final SetIndicatorInfo sii = (SetIndicatorInfo) info;
52        if (sii.setHomeAsUpIndicator != null) {
53            try {
54                final ActionBar actionBar = activity.getActionBar();
55                sii.setHomeAsUpIndicator.invoke(actionBar, drawable);
56                sii.setHomeActionContentDescription.invoke(actionBar, contentDescRes);
57            } catch (Exception e) {
58                Log.w(TAG, "Couldn't set home-as-up indicator via JB-MR2 API", e);
59            }
60        } else if (sii.upIndicatorView != null) {
61            sii.upIndicatorView.setImageDrawable(drawable);
62        } else {
63            Log.w(TAG, "Couldn't set home-as-up indicator");
64        }
65        return info;
66    }
67
68    public static Object setActionBarDescription(Object info, Activity activity,
69            int contentDescRes) {
70        if (info == null) {
71            info = new SetIndicatorInfo(activity);
72        }
73        final SetIndicatorInfo sii = (SetIndicatorInfo) info;
74        if (sii.setHomeAsUpIndicator != null) {
75            try {
76                final ActionBar actionBar = activity.getActionBar();
77                sii.setHomeActionContentDescription.invoke(actionBar, contentDescRes);
78            } catch (Exception e) {
79                Log.w(TAG, "Couldn't set content description via JB-MR2 API", e);
80            }
81        }
82        return info;
83    }
84
85    public static Drawable getThemeUpIndicator(Activity activity) {
86        final TypedArray a = activity.obtainStyledAttributes(THEME_ATTRS);
87        final Drawable result = a.getDrawable(0);
88        a.recycle();
89        return result;
90    }
91
92    private static class SetIndicatorInfo {
93        public Method setHomeAsUpIndicator;
94        public Method setHomeActionContentDescription;
95        public ImageView upIndicatorView;
96
97        SetIndicatorInfo(Activity activity) {
98            try {
99                setHomeAsUpIndicator = ActionBar.class.getDeclaredMethod("setHomeAsUpIndicator",
100                        Drawable.class);
101                setHomeActionContentDescription = ActionBar.class.getDeclaredMethod(
102                        "setHomeActionContentDescription", Integer.TYPE);
103
104                // If we got the method we won't need the stuff below.
105                return;
106            } catch (NoSuchMethodException e) {
107                // Oh well. We'll use the other mechanism below instead.
108            }
109
110            final View home = activity.findViewById(android.R.id.home);
111            if (home == null) {
112                // Action bar doesn't have a known configuration, an OEM messed with things.
113                return;
114            }
115
116            final ViewGroup parent = (ViewGroup) home.getParent();
117            final int childCount = parent.getChildCount();
118            if (childCount != 2) {
119                // No idea which one will be the right one, an OEM messed with things.
120                return;
121            }
122
123            final View first = parent.getChildAt(0);
124            final View second = parent.getChildAt(1);
125            final View up = first.getId() == android.R.id.home ? second : first;
126
127            if (up instanceof ImageView) {
128                // Jackpot! (Probably...)
129                upIndicatorView = (ImageView) up;
130            }
131        }
132    }
133}
134