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 
17 package com.android.launcher3.util;
18 
19 import android.annotation.TargetApi;
20 import android.app.WallpaperManager;
21 import android.content.SharedPreferences;
22 import android.content.res.Resources;
23 import android.graphics.Point;
24 import android.os.Build;
25 import android.view.WindowManager;
26 
27 import com.android.launcher3.Utilities;
28 
29 /**
30  * Utility methods for wallpaper management.
31  */
32 public 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 
suggestWallpaperDimension(Resources res, final SharedPreferences sharedPrefs, WindowManager windowManager, final WallpaperManager wallpaperManager, boolean fallBackToDefaults)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      */
wallpaperTravelToScreenWidthRatio(int width, int height)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)
getDefaultWallpaperSize(Resources res, WindowManager windowManager)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