ColorFilterCache.java revision cf94c5fa8ae8edb7e26a623133207415ceeed187 
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.graphics;
15
16import android.graphics.Color;
17import android.graphics.ColorFilter;
18import android.graphics.PorterDuff;
19import android.graphics.PorterDuffColorFilter;
20import android.util.SparseArray;
21
22/**
23 * Helper class of mapping ColorFilter from a color with different alpha levels.
24 */
25public final class ColorFilterCache {
26
27    private static final SparseArray<ColorFilterCache> sColorToFiltersMap =
28            new SparseArray<ColorFilterCache>();
29
30    private final PorterDuffColorFilter[] mFilters = new PorterDuffColorFilter[0x100];
31
32    /**
33     * Get ColorDimmer for a given color.  Only r/g/b are used, alpha channel is ignored
34     * from parameter dimColor.
35     */
36    public static ColorFilterCache getColorFilterCache(int dimColor) {
37        final int r = Color.red(dimColor);
38        final int g = Color.green(dimColor);
39        final int b = Color.blue(dimColor);
40        dimColor = Color.rgb(r, g, b);
41        ColorFilterCache colorDimmer = sColorToFiltersMap.get(dimColor);
42        if (colorDimmer == null) {
43            colorDimmer = new ColorFilterCache(r, g, b);
44            sColorToFiltersMap.put(dimColor, colorDimmer);
45        }
46        return colorDimmer;
47    }
48
49    private ColorFilterCache(int r, int g, int b) {
50        // Pre cache all Dim filter levels
51        for (int i = 0x00; i <= 0xFF; i++) {
52            int color = Color.argb(i, r, g, b);
53            mFilters[i] = new PorterDuffColorFilter(color, PorterDuff.Mode.SRC_ATOP);
54        }
55    }
56
57    /**
58     * Returns ColorFilter for a given level between 0 and 1.
59     */
60    public ColorFilter getFilterForLevel(float level) {
61        if (level >= 0 && level <= 1.0) {
62            int filterIndex = (int) (0xFF * level);
63            return mFilters[filterIndex];
64        } else {
65            return null;
66        }
67    }
68}