1/*
2 * Copyright 2018 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 androidx.core.view;
18
19import android.content.Context;
20import android.os.Build;
21import android.util.AttributeSet;
22import android.util.Log;
23import android.view.LayoutInflater;
24import android.view.View;
25
26import androidx.annotation.NonNull;
27
28import java.lang.reflect.Field;
29
30/**
31 * Helper for accessing features in {@link LayoutInflater}.
32 */
33public final class LayoutInflaterCompat {
34    private static final String TAG = "LayoutInflaterCompatHC";
35
36    private static Field sLayoutInflaterFactory2Field;
37    private static boolean sCheckedField;
38
39    @SuppressWarnings("deprecation")
40    static class Factory2Wrapper implements LayoutInflater.Factory2 {
41        final LayoutInflaterFactory mDelegateFactory;
42
43        Factory2Wrapper(LayoutInflaterFactory delegateFactory) {
44            mDelegateFactory = delegateFactory;
45        }
46
47        @Override
48        public View onCreateView(String name, Context context, AttributeSet attrs) {
49            return mDelegateFactory.onCreateView(null, name, context, attrs);
50        }
51
52        @Override
53        public View onCreateView(View parent, String name, Context context,
54                AttributeSet attributeSet) {
55            return mDelegateFactory.onCreateView(parent, name, context, attributeSet);
56        }
57
58        @Override
59        public String toString() {
60            return getClass().getName() + "{" + mDelegateFactory + "}";
61        }
62    }
63
64    /**
65     * For APIs < 21, there was a framework bug that prevented a LayoutInflater's
66     * Factory2 from being merged properly if set after a cloneInContext from a LayoutInflater
67     * that already had a Factory2 registered. We work around that bug here. If we can't we
68     * log an error.
69     */
70    private static void forceSetFactory2(LayoutInflater inflater, LayoutInflater.Factory2 factory) {
71        if (!sCheckedField) {
72            try {
73                sLayoutInflaterFactory2Field = LayoutInflater.class.getDeclaredField("mFactory2");
74                sLayoutInflaterFactory2Field.setAccessible(true);
75            } catch (NoSuchFieldException e) {
76                Log.e(TAG, "forceSetFactory2 Could not find field 'mFactory2' on class "
77                        + LayoutInflater.class.getName()
78                        + "; inflation may have unexpected results.", e);
79            }
80            sCheckedField = true;
81        }
82        if (sLayoutInflaterFactory2Field != null) {
83            try {
84                sLayoutInflaterFactory2Field.set(inflater, factory);
85            } catch (IllegalAccessException e) {
86                Log.e(TAG, "forceSetFactory2 could not set the Factory2 on LayoutInflater "
87                        + inflater + "; inflation may have unexpected results.", e);
88            }
89        }
90    }
91
92    /*
93     * Hide the constructor.
94     */
95    private LayoutInflaterCompat() {
96    }
97
98    /**
99     * Attach a custom Factory interface for creating views while using
100     * this LayoutInflater. This must not be null, and can only be set once;
101     * after setting, you can not change the factory.
102     *
103     * @see LayoutInflater#setFactory(android.view.LayoutInflater.Factory)
104     *
105     * @deprecated Use {@link #setFactory2(LayoutInflater, LayoutInflater.Factory2)} instead to set
106     * and {@link LayoutInflater#getFactory2()} to get the factory.
107     */
108    @Deprecated
109    public static void setFactory(
110            @NonNull LayoutInflater inflater, @NonNull LayoutInflaterFactory factory) {
111        if (Build.VERSION.SDK_INT >= 21) {
112            inflater.setFactory2(factory != null ? new Factory2Wrapper(factory) : null);
113        } else {
114            final LayoutInflater.Factory2 factory2 = factory != null
115                    ? new Factory2Wrapper(factory) : null;
116            inflater.setFactory2(factory2);
117
118            final LayoutInflater.Factory f = inflater.getFactory();
119            if (f instanceof LayoutInflater.Factory2) {
120                // The merged factory is now set to getFactory(), but not getFactory2() (pre-v21).
121                // We will now try and force set the merged factory to mFactory2
122                forceSetFactory2(inflater, (LayoutInflater.Factory2) f);
123            } else {
124                // Else, we will force set the original wrapped Factory2
125                forceSetFactory2(inflater, factory2);
126            }
127        }
128    }
129
130    /**
131     * Attach a custom {@link LayoutInflater.Factory2} for creating views while using
132     * this {@link LayoutInflater}. This must not be null, and can only be set once;
133     * after setting, you can not change the factory.
134     *
135     * @see LayoutInflater#setFactory2(android.view.LayoutInflater.Factory2)
136     */
137    public static void setFactory2(
138            @NonNull LayoutInflater inflater, @NonNull LayoutInflater.Factory2 factory) {
139        inflater.setFactory2(factory);
140
141        if (Build.VERSION.SDK_INT < 21) {
142            final LayoutInflater.Factory f = inflater.getFactory();
143            if (f instanceof LayoutInflater.Factory2) {
144                // The merged factory is now set to getFactory(), but not getFactory2() (pre-v21).
145                // We will now try and force set the merged factory to mFactory2
146                forceSetFactory2(inflater, (LayoutInflater.Factory2) f);
147            } else {
148                // Else, we will force set the original wrapped Factory2
149                forceSetFactory2(inflater, factory);
150            }
151        }
152    }
153
154    /**
155     * Return the current {@link LayoutInflaterFactory} (or null). This is
156     * called on each element name. If the factory returns a View, add that
157     * to the hierarchy. If it returns null, proceed to call onCreateView(name).
158     *
159     * @return The {@link LayoutInflaterFactory} associated with the
160     * {@link LayoutInflater}. Will be {@code null} if the inflater does not
161     * have a {@link LayoutInflaterFactory} but a raw {@link LayoutInflater.Factory}.
162     * @see LayoutInflater#getFactory()
163     *
164     * @deprecated Use {@link #setFactory2(LayoutInflater, LayoutInflater.Factory2)} to set and
165     * {@link LayoutInflater#getFactory2()} to get the factory.
166     */
167    @Deprecated
168    public static LayoutInflaterFactory getFactory(LayoutInflater inflater) {
169        LayoutInflater.Factory factory = inflater.getFactory();
170        if (factory instanceof Factory2Wrapper) {
171            return ((Factory2Wrapper) factory).mDelegateFactory;
172        }
173        return null;
174    }
175}
176