FocusHighlightHelper.java revision b9e89a1544f8cf582f191184fb9b2a4f24e1fa5b 
1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
5 * in compliance with the License. You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software distributed under the License
10 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
11 * or implied. See the License for the specific language governing permissions and limitations under
12 * the License.
13 */
14package android.support.v17.leanback.widget;
15
16import android.support.v17.leanback.R;
17import android.view.View;
18import android.content.res.Resources;
19
20/**
21 * Setup the behavior how to highlight when a item gains focus.
22 */
23public class FocusHighlightHelper {
24
25    static class BrowseItemFocusHighlight implements FocusHighlight {
26        private static final int DURATION_MS = 150;
27
28        public static int ZOOM_FACTOR_NONE = 0;
29        public static int ZOOM_FACTOR_SMALL = 1;
30        public static int ZOOM_FACTOR_MEDIUM = 2;
31        public static int ZOOM_FACTOR_LARGE = 3;
32
33        private static float[] sScaleFactor = new float[4];
34
35        private int mScaleIndex;
36
37        BrowseItemFocusHighlight(int zoomIndex) {
38            mScaleIndex = (zoomIndex >= 0 && zoomIndex < sScaleFactor.length) ?
39                    zoomIndex : ZOOM_FACTOR_MEDIUM;
40        }
41
42        private void lazyInit(Resources resources) {
43            if (sScaleFactor[ZOOM_FACTOR_NONE] == 0f) {
44                sScaleFactor[ZOOM_FACTOR_NONE] = 1f;
45                sScaleFactor[ZOOM_FACTOR_SMALL] =
46                        resources.getFraction(R.fraction.lb_focus_zoom_factor_small, 1, 1);
47                sScaleFactor[ZOOM_FACTOR_MEDIUM] =
48                        resources.getFraction(R.fraction.lb_focus_zoom_factor_medium, 1, 1);
49                sScaleFactor[ZOOM_FACTOR_LARGE] =
50                        resources.getFraction(R.fraction.lb_focus_zoom_factor_large, 1, 1);
51            }
52        }
53
54        private float getScale(View view) {
55            lazyInit(view.getResources());
56            return sScaleFactor[mScaleIndex];
57        }
58
59        private void viewFocused(View view, boolean hasFocus) {
60            if (hasFocus) {
61                final float scale = getScale(view);
62                view.animate().scaleX(scale).scaleY(scale).setDuration(DURATION_MS);
63            } else {
64                view.animate().scaleX(1f).scaleY(1f).setDuration(DURATION_MS);
65            }
66        }
67
68        @Override
69        public void onItemFocused(View view, Object item, boolean hasFocus) {
70            viewFocused(view, hasFocus);
71        }
72    }
73
74    private static HeaderItemFocusHighlight sHeaderItemFocusHighlight =
75            new HeaderItemFocusHighlight();
76
77    /**
78     * Setup the focus highlight behavior of a focused item in browse list row.
79     * @param adapter  adapter of the list row.
80     */
81    public static void setupBrowseItemFocusHighlight(ItemBridgeAdapter adapter, int zoomIndex) {
82        adapter.setFocusHighlight(new BrowseItemFocusHighlight(zoomIndex));
83    }
84
85    /**
86     * Setup the focus highlight behavior of a focused item in header list.
87     * @param adapter  adapter of the header list.
88     */
89    public static void setupHeaderItemFocusHighlight(ItemBridgeAdapter adapter) {
90        adapter.setFocusHighlight(sHeaderItemFocusHighlight);
91    }
92
93    static class HeaderItemFocusHighlight implements FocusHighlight {
94        private boolean mInitialized;
95        private float mSelectScale;
96        private float mUnselectAlpha;
97        private int mDuration;
98
99        private void initializeDimensions(Resources res) {
100            if (!mInitialized) {
101                mSelectScale =
102                        Float.parseFloat(res.getString(R.dimen.lb_browse_header_select_scale));
103                mUnselectAlpha =
104                        Float.parseFloat(res.getString(R.dimen.lb_browse_header_unselect_alpha));
105                mDuration =
106                        Integer.parseInt(res.getString(R.dimen.lb_browse_header_select_duration));
107                mInitialized = true;
108            }
109        }
110
111        private void viewFocused(View view, boolean hasFocus) {
112            initializeDimensions(view.getResources());
113            if (hasFocus) {
114                view.animate().scaleX(mSelectScale).scaleY(mSelectScale)
115                        .alpha(1f)
116                        .setDuration(mDuration);
117            } else {
118                view.animate().scaleX(1f).scaleY(1f)
119                        .alpha(mUnselectAlpha)
120                        .setDuration(mDuration);
121            }
122        }
123
124        @Override
125        public void onItemFocused(View view, Object item, boolean hasFocus) {
126            viewFocused(view, hasFocus);
127        }
128    }
129}
130