PersistentFocusWrapper.java revision d30b6d18e1c6b988f75d76c50dbec7199386ce9b 
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 android.support.v17.leanback.widget;
18
19import android.content.Context;
20import android.graphics.Rect;
21import android.os.Parcel;
22import android.os.Parcelable;
23import android.util.AttributeSet;
24import android.util.Log;
25import android.view.View;
26import android.view.ViewGroup;
27import android.widget.FrameLayout;
28
29import java.util.ArrayList;
30
31/**
32 * Saves the focused grandchild position.
33 * Helps add persistent focus feature to various ViewGroups.
34 * @hide
35 */
36class PersistentFocusWrapper extends FrameLayout {
37
38    private static final String TAG = "PersistentFocusWrapper";
39    private static final boolean DEBUG = false;
40
41    private int mSelectedPosition = -1;
42
43    /**
44     * By default, focus is persisted when searching vertically
45     * but not horizontally.
46     */
47    private boolean mPersistFocusVertical = true;
48
49    public PersistentFocusWrapper(Context context, AttributeSet attrs) {
50        super(context, attrs);
51    }
52
53    public PersistentFocusWrapper(Context context, AttributeSet attrs, int defStyle) {
54        super(context, attrs, defStyle);
55    }
56
57    int getGrandChildCount() {
58        ViewGroup wrapper = (ViewGroup) getChildAt(0);
59        return wrapper == null ? 0 : wrapper.getChildCount();
60    }
61
62    /**
63     * Clears the selected position and clears focus.
64     */
65    public void clearSelection() {
66        mSelectedPosition = -1;
67        if (hasFocus()) {
68            clearFocus();
69        }
70    }
71
72    /**
73     * Persist focus when focus search direction is up or down.
74     */
75    public void persistFocusVertical() {
76        mPersistFocusVertical = true;
77    }
78
79    /**
80     * Persist focus when focus search direction is left or right.
81     */
82    public void persistFocusHorizontal() {
83        mPersistFocusVertical = false;
84    }
85
86    private boolean shouldPersistFocusFromDirection(int direction) {
87        return ((mPersistFocusVertical && (direction == FOCUS_UP || direction == FOCUS_DOWN)) ||
88                (!mPersistFocusVertical && (direction == FOCUS_LEFT || direction == FOCUS_RIGHT)));
89    }
90
91    @Override
92    public void addFocusables(ArrayList<View> views, int direction, int focusableMode) {
93        if (DEBUG) Log.v(TAG, "addFocusables");
94        if (hasFocus() || getGrandChildCount() == 0 ||
95                !shouldPersistFocusFromDirection(direction)) {
96            super.addFocusables(views, direction, focusableMode);
97        } else {
98            // Select a child in requestFocus
99            views.add(this);
100        }
101    }
102
103    @Override
104    public void requestChildFocus(View child, View focused) {
105        super.requestChildFocus(child, focused);
106        View view = focused;
107        while (view != null && view.getParent() != child) {
108            view = (View) view.getParent();
109        }
110        mSelectedPosition = view == null ? -1 : ((ViewGroup) child).indexOfChild(view);
111        if (DEBUG) Log.v(TAG, "requestChildFocus focused " + focused + " mSelectedPosition " + mSelectedPosition);
112    }
113
114    @Override
115    public boolean requestFocus(int direction, Rect previouslyFocusedRect) {
116        if (DEBUG) Log.v(TAG, "requestFocus mSelectedPosition " + mSelectedPosition);
117        ViewGroup wrapper = (ViewGroup) getChildAt(0);
118        if (wrapper != null && mSelectedPosition >= 0 && mSelectedPosition < getGrandChildCount()) {
119            if (wrapper.getChildAt(mSelectedPosition).requestFocus(
120                    direction, previouslyFocusedRect)) {
121                return true;
122            }
123        }
124        return super.requestFocus(direction, previouslyFocusedRect);
125    }
126
127    static class SavedState extends View.BaseSavedState {
128
129        int mSelectedPosition;
130
131        SavedState(Parcel in) {
132            super(in);
133            mSelectedPosition = in.readInt();
134        }
135
136        SavedState(Parcelable superState) {
137            super(superState);
138        }
139
140        @Override
141        public void writeToParcel(Parcel dest, int flags) {
142            super.writeToParcel(dest, flags);
143            dest.writeInt(mSelectedPosition);
144        }
145
146        public static final Parcelable.Creator<SavedState> CREATOR
147                = new Parcelable.Creator<SavedState>() {
148            @Override
149            public SavedState createFromParcel(Parcel in) {
150                return new SavedState(in);
151            }
152
153            @Override
154            public SavedState[] newArray(int size) {
155                return new SavedState[size];
156            }
157        };
158    }
159
160    @Override
161    protected Parcelable onSaveInstanceState() {
162        if (DEBUG) Log.v(TAG, "onSaveInstanceState");
163        SavedState savedState = new SavedState(super.onSaveInstanceState());
164        savedState.mSelectedPosition = mSelectedPosition;
165        return savedState;
166    }
167
168    @Override
169    protected void onRestoreInstanceState(Parcelable state) {
170        SavedState savedState = (SavedState) state;
171        mSelectedPosition = ((SavedState) state).mSelectedPosition;
172        if (DEBUG) Log.v(TAG, "onRestoreInstanceState mSelectedPosition " + mSelectedPosition);
173        super.onRestoreInstanceState(savedState.getSuperState());
174    }
175}
176