RecyclerViewUtil.java revision ccbc11770397888cf7780925bb4c7cf1d2f2f80e 
1/*
2 * Copyright (C) 2015 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.layoutlib.bridge.android.support;
18
19import com.android.ide.common.rendering.api.LayoutLog;
20import com.android.ide.common.rendering.api.LayoutlibCallback;
21import com.android.layoutlib.bridge.Bridge;
22import com.android.layoutlib.bridge.android.BridgeContext;
23import com.android.layoutlib.bridge.android.RenderParamsFlags;
24import com.android.layoutlib.bridge.util.ReflectionUtils;
25
26import android.annotation.NonNull;
27import android.annotation.Nullable;
28import android.content.Context;
29import android.view.View;
30
31import java.lang.reflect.Method;
32
33import static com.android.layoutlib.bridge.util.ReflectionUtils.ReflectionException;
34import static com.android.layoutlib.bridge.util.ReflectionUtils.getCause;
35import static com.android.layoutlib.bridge.util.ReflectionUtils.getMethod;
36import static com.android.layoutlib.bridge.util.ReflectionUtils.invoke;
37
38/**
39 * Utility class for working with android.support.v7.widget.RecyclerView
40 */
41public class RecyclerViewUtil {
42
43    private static final String RV_PKG_PREFIX = "android.support.v7.widget.";
44    public static final String CN_RECYCLER_VIEW = RV_PKG_PREFIX + "RecyclerView";
45    private static final String CN_LAYOUT_MANAGER = CN_RECYCLER_VIEW + "$LayoutManager";
46    private static final String CN_ADAPTER = CN_RECYCLER_VIEW + "$Adapter";
47
48    // LinearLayoutManager related constants.
49    private static final String CN_LINEAR_LAYOUT_MANAGER = RV_PKG_PREFIX + "LinearLayoutManager";
50    private static final Class<?>[] LLM_CONSTRUCTOR_SIGNATURE = new Class<?>[]{Context.class};
51
52    /**
53     * Tries to create an Adapter ({@code android.support.v7.widget.RecyclerView.Adapter} and a
54     * LayoutManager {@code RecyclerView.LayoutManager} and assign these to the {@code RecyclerView}
55     * that is passed.
56     * <p/>
57     * Any exceptions thrown during the process are logged in {@link Bridge#getLog()}
58     */
59    public static void setAdapter(@NonNull View recyclerView, @NonNull BridgeContext context,
60            @NonNull LayoutlibCallback layoutlibCallback, int adapterLayout) {
61        try {
62            setLayoutManager(recyclerView, context, layoutlibCallback);
63            Object adapter = createAdapter(layoutlibCallback);
64            if (adapter != null) {
65                setProperty(recyclerView, CN_ADAPTER, adapter, "setAdapter");
66                setProperty(adapter, int.class, adapterLayout, "setLayoutId");
67            }
68        } catch (ReflectionException e) {
69            Throwable cause = getCause(e);
70            Bridge.getLog().error(LayoutLog.TAG_BROKEN,
71                    "Error occurred while trying to setup RecyclerView.", cause, null);
72        }
73    }
74
75    private static void setLayoutManager(@NonNull View recyclerView, @NonNull BridgeContext context,
76            @NonNull LayoutlibCallback callback) throws ReflectionException {
77        if (getLayoutManager(recyclerView) == null) {
78            // Only set the layout manager if not already set by the recycler view.
79            Object layoutManager = createLayoutManager(context, callback);
80            if (layoutManager != null) {
81                setProperty(recyclerView, CN_LAYOUT_MANAGER, layoutManager, "setLayoutManager");
82            }
83        }
84    }
85
86    /** Creates a LinearLayoutManager using the provided context. */
87    @Nullable
88    private static Object createLayoutManager(@NonNull Context context,
89            @NonNull LayoutlibCallback callback)
90            throws ReflectionException {
91        try {
92            return callback.loadView(CN_LINEAR_LAYOUT_MANAGER, LLM_CONSTRUCTOR_SIGNATURE,
93                    new Object[]{context});
94        } catch (Exception e) {
95            throw new ReflectionException(e);
96        }
97    }
98
99    @Nullable
100    private static Object getLayoutManager(View recyclerView) throws ReflectionException {
101        Method getLayoutManager = getMethod(recyclerView.getClass(), "getLayoutManager");
102        return getLayoutManager != null ? invoke(getLayoutManager, recyclerView) : null;
103    }
104
105    @Nullable
106    private static Object createAdapter(@NonNull LayoutlibCallback layoutlibCallback)
107            throws ReflectionException {
108        Boolean ideSupport =
109                layoutlibCallback.getFlag(RenderParamsFlags.FLAG_KEY_RECYCLER_VIEW_SUPPORT);
110        if (ideSupport != Boolean.TRUE) {
111            return null;
112        }
113        try {
114            return layoutlibCallback.loadClass(CN_ADAPTER, new Class[0], new Object[0]);
115        } catch (Exception e) {
116            throw new ReflectionException(e);
117        }
118    }
119
120    private static void setProperty(@NonNull Object object, @NonNull String propertyClassName,
121      @NonNull Object propertyValue, @NonNull String propertySetter)
122            throws ReflectionException {
123        Class<?> propertyClass = getClassInstance(propertyValue, propertyClassName);
124        setProperty(object, propertyClass, propertyValue, propertySetter);
125    }
126
127    private static void setProperty(@NonNull Object object, @NonNull Class<?> propertyClass,
128            @Nullable Object propertyValue, @NonNull String propertySetter)
129            throws ReflectionException {
130        Method setter = getMethod(object.getClass(), propertySetter, propertyClass);
131        if (setter != null) {
132            invoke(setter, object, propertyValue);
133        }
134    }
135
136    /**
137     * Looks through the class hierarchy of {@code object} at runtime and returns the class matching
138     * the name {@code className}.
139     * <p/>
140     * This is used when we cannot use Class.forName() since the class we want was loaded from a
141     * different ClassLoader.
142     */
143    @NonNull
144    private static Class<?> getClassInstance(@NonNull Object object, @NonNull String className) {
145        Class<?> superClass = object.getClass();
146        while (superClass != null) {
147            if (className.equals(superClass.getName())) {
148                return superClass;
149            }
150            superClass = superClass.getSuperclass();
151        }
152        throw new RuntimeException("invalid object/classname combination.");
153    }
154}
155