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diff --git a/src/com/android/launcher3/util/WallpaperUtils.java b/src/com/android/launcher3/util/WallpaperUtils.java
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+++ b/src/com/android/launcher3/util/WallpaperUtils.java
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+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.launcher3.util;
+
+import android.annotation.TargetApi;
+import android.app.WallpaperManager;
+import android.content.SharedPreferences;
+import android.content.res.Resources;
+import android.graphics.Point;
+import android.os.Build;
+import android.view.WindowManager;
+
+/**
+ * Utility methods for wallpaper management.
+ */
+public final class WallpaperUtils {
+
+    public static final String WALLPAPER_WIDTH_KEY = "wallpaper.width";
+    public static final String WALLPAPER_HEIGHT_KEY = "wallpaper.height";
+    public static final float WALLPAPER_SCREENS_SPAN = 2f;
+
+    public static void suggestWallpaperDimension(Resources res,
+            final SharedPreferences sharedPrefs,
+            WindowManager windowManager,
+            final WallpaperManager wallpaperManager, boolean fallBackToDefaults) {
+        final Point defaultWallpaperSize = WallpaperUtils.getDefaultWallpaperSize(res, windowManager);
+        // If we have saved a wallpaper width/height, use that instead
+
+        int savedWidth = sharedPrefs.getInt(WALLPAPER_WIDTH_KEY, -1);
+        int savedHeight = sharedPrefs.getInt(WALLPAPER_HEIGHT_KEY, -1);
+
+        if (savedWidth == -1 || savedHeight == -1) {
+            if (!fallBackToDefaults) {
+                return;
+            } else {
+                savedWidth = defaultWallpaperSize.x;
+                savedHeight = defaultWallpaperSize.y;
+            }
+        }
+
+        if (savedWidth != wallpaperManager.getDesiredMinimumWidth() ||
+                savedHeight != wallpaperManager.getDesiredMinimumHeight()) {
+            wallpaperManager.suggestDesiredDimensions(savedWidth, savedHeight);
+        }
+    }
+
+    /**
+     * As a ratio of screen height, the total distance we want the parallax effect to span
+     * horizontally
+     */
+    public static float wallpaperTravelToScreenWidthRatio(int width, int height) {
+        float aspectRatio = width / (float) height;
+
+        // At an aspect ratio of 16/10, the wallpaper parallax effect should span 1.5 * screen width
+        // At an aspect ratio of 10/16, the wallpaper parallax effect should span 1.2 * screen width
+        // We will use these two data points to extrapolate how much the wallpaper parallax effect
+        // to span (ie travel) at any aspect ratio:
+
+        final float ASPECT_RATIO_LANDSCAPE = 16/10f;
+        final float ASPECT_RATIO_PORTRAIT = 10/16f;
+        final float WALLPAPER_WIDTH_TO_SCREEN_RATIO_LANDSCAPE = 1.5f;
+        final float WALLPAPER_WIDTH_TO_SCREEN_RATIO_PORTRAIT = 1.2f;
+
+        // To find out the desired width at different aspect ratios, we use the following two
+        // formulas, where the coefficient on x is the aspect ratio (width/height):
+        //   (16/10)x + y = 1.5
+        //   (10/16)x + y = 1.2
+        // We solve for x and y and end up with a final formula:
+        final float x =
+            (WALLPAPER_WIDTH_TO_SCREEN_RATIO_LANDSCAPE - WALLPAPER_WIDTH_TO_SCREEN_RATIO_PORTRAIT) /
+            (ASPECT_RATIO_LANDSCAPE - ASPECT_RATIO_PORTRAIT);
+        final float y = WALLPAPER_WIDTH_TO_SCREEN_RATIO_PORTRAIT - x * ASPECT_RATIO_PORTRAIT;
+        return x * aspectRatio + y;
+    }
+
+    private static Point sDefaultWallpaperSize;
+
+    @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
+    public static Point getDefaultWallpaperSize(Resources res, WindowManager windowManager) {
+        if (sDefaultWallpaperSize == null) {
+            Point minDims = new Point();
+            Point maxDims = new Point();
+            windowManager.getDefaultDisplay().getCurrentSizeRange(minDims, maxDims);
+
+            int maxDim = Math.max(maxDims.x, maxDims.y);
+            int minDim = Math.max(minDims.x, minDims.y);
+
+            if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.JELLY_BEAN_MR1) {
+                Point realSize = new Point();
+                windowManager.getDefaultDisplay().getRealSize(realSize);
+                maxDim = Math.max(realSize.x, realSize.y);
+                minDim = Math.min(realSize.x, realSize.y);
+            }
+
+            // We need to ensure that there is enough extra space in the wallpaper
+            // for the intended parallax effects
+            final int defaultWidth, defaultHeight;
+            if (res.getConfiguration().smallestScreenWidthDp >= 720) {
+                defaultWidth = (int) (maxDim * wallpaperTravelToScreenWidthRatio(maxDim, minDim));
+                defaultHeight = maxDim;
+            } else {
+                defaultWidth = Math.max((int) (minDim * WALLPAPER_SCREENS_SPAN), maxDim);
+                defaultHeight = maxDim;
+            }
+            sDefaultWallpaperSize = new Point(defaultWidth, defaultHeight);
+        }
+        return sDefaultWallpaperSize;
+    }
+}