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.launcher3.util;
18
19import android.annotation.TargetApi;
20import android.app.WallpaperManager;
21import android.content.SharedPreferences;
22import android.content.res.Resources;
23import android.graphics.Point;
24import android.os.Build;
25import android.view.WindowManager;
26
27import com.android.launcher3.Utilities;
28
29/**
30 * Utility methods for wallpaper management.
31 */
32public final class WallpaperUtils {
33
34    public static final String WALLPAPER_WIDTH_KEY = "wallpaper.width";
35    public static final String WALLPAPER_HEIGHT_KEY = "wallpaper.height";
36    public static final float WALLPAPER_SCREENS_SPAN = 2f;
37
38    public static void suggestWallpaperDimension(Resources res,
39            final SharedPreferences sharedPrefs,
40            WindowManager windowManager,
41            final WallpaperManager wallpaperManager, boolean fallBackToDefaults) {
42        final Point defaultWallpaperSize = WallpaperUtils.getDefaultWallpaperSize(res, windowManager);
43        // If we have saved a wallpaper width/height, use that instead
44
45        int savedWidth = sharedPrefs.getInt(WALLPAPER_WIDTH_KEY, -1);
46        int savedHeight = sharedPrefs.getInt(WALLPAPER_HEIGHT_KEY, -1);
47
48        if (savedWidth == -1 || savedHeight == -1) {
49            if (!fallBackToDefaults) {
50                return;
51            } else {
52                savedWidth = defaultWallpaperSize.x;
53                savedHeight = defaultWallpaperSize.y;
54            }
55        }
56
57        if (savedWidth != wallpaperManager.getDesiredMinimumWidth() ||
58                savedHeight != wallpaperManager.getDesiredMinimumHeight()) {
59            wallpaperManager.suggestDesiredDimensions(savedWidth, savedHeight);
60        }
61    }
62
63    /**
64     * As a ratio of screen height, the total distance we want the parallax effect to span
65     * horizontally
66     */
67    public static float wallpaperTravelToScreenWidthRatio(int width, int height) {
68        float aspectRatio = width / (float) height;
69
70        // At an aspect ratio of 16/10, the wallpaper parallax effect should span 1.5 * screen width
71        // At an aspect ratio of 10/16, the wallpaper parallax effect should span 1.2 * screen width
72        // We will use these two data points to extrapolate how much the wallpaper parallax effect
73        // to span (ie travel) at any aspect ratio:
74
75        final float ASPECT_RATIO_LANDSCAPE = 16/10f;
76        final float ASPECT_RATIO_PORTRAIT = 10/16f;
77        final float WALLPAPER_WIDTH_TO_SCREEN_RATIO_LANDSCAPE = 1.5f;
78        final float WALLPAPER_WIDTH_TO_SCREEN_RATIO_PORTRAIT = 1.2f;
79
80        // To find out the desired width at different aspect ratios, we use the following two
81        // formulas, where the coefficient on x is the aspect ratio (width/height):
82        //   (16/10)x + y = 1.5
83        //   (10/16)x + y = 1.2
84        // We solve for x and y and end up with a final formula:
85        final float x =
86            (WALLPAPER_WIDTH_TO_SCREEN_RATIO_LANDSCAPE - WALLPAPER_WIDTH_TO_SCREEN_RATIO_PORTRAIT) /
87            (ASPECT_RATIO_LANDSCAPE - ASPECT_RATIO_PORTRAIT);
88        final float y = WALLPAPER_WIDTH_TO_SCREEN_RATIO_PORTRAIT - x * ASPECT_RATIO_PORTRAIT;
89        return x * aspectRatio + y;
90    }
91
92    private static Point sDefaultWallpaperSize;
93
94    @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
95    public static Point getDefaultWallpaperSize(Resources res, WindowManager windowManager) {
96        if (sDefaultWallpaperSize == null) {
97            Point minDims = new Point();
98            Point maxDims = new Point();
99            windowManager.getDefaultDisplay().getCurrentSizeRange(minDims, maxDims);
100
101            int maxDim = Math.max(maxDims.x, maxDims.y);
102            int minDim = Math.max(minDims.x, minDims.y);
103
104            if (Utilities.ATLEAST_JB_MR1) {
105                Point realSize = new Point();
106                windowManager.getDefaultDisplay().getRealSize(realSize);
107                maxDim = Math.max(realSize.x, realSize.y);
108                minDim = Math.min(realSize.x, realSize.y);
109            }
110
111            // We need to ensure that there is enough extra space in the wallpaper
112            // for the intended parallax effects
113            final int defaultWidth, defaultHeight;
114            if (res.getConfiguration().smallestScreenWidthDp >= 720) {
115                defaultWidth = (int) (maxDim * wallpaperTravelToScreenWidthRatio(maxDim, minDim));
116                defaultHeight = maxDim;
117            } else {
118                defaultWidth = Math.max((int) (minDim * WALLPAPER_SCREENS_SPAN), maxDim);
119                defaultHeight = maxDim;
120            }
121            sDefaultWallpaperSize = new Point(defaultWidth, defaultHeight);
122        }
123        return sDefaultWallpaperSize;
124    }
125}
126