Implement the new Photo picker, part two.

chrome/android/java/src/org/chromium/chrome/browser/photo_picker/BitmapUtils.java

Index: chrome/android/java/src/org/chromium/chrome/browser/photo_picker/BitmapUtils.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/photo_picker/BitmapUtils.java b/chrome/android/java/src/org/chromium/chrome/browser/photo_picker/BitmapUtils.java
new file mode 100644
index 0000000000000000000000000000000000000000..cb557800130028486f3d357fb66f49315bdb6ed1
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/photo_picker/BitmapUtils.java
@@ -0,0 +1,145 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.photo_picker;
+
+import android.graphics.Bitmap;
+import android.graphics.BitmapFactory;
+
+import java.io.FileDescriptor;
+
+class BitmapUtils {
+    /**
+     * Takes a |bitmap| and returns a square thumbnail of |width| from the center of the bitmap
+     * specified.
+     * @param bitmap The bitmap to adjust.
+     * @param width The desired width.
+     * @return The new bitmap thumbnail.
+     */
+    public static Bitmap sizeBitmap(Bitmap bitmap, int width) {
+        bitmap = ensureMinSize(bitmap, width);
+        bitmap = cropToSquare(bitmap, width);
+        return bitmap;
+    }
+
+    /**
+     * Given a FileDescriptor, decodes the contents and returns a bitmap of size |width|x|width|.
+     * @param descriptor The FileDescriptor for the file to read.
+     * @param width The width of the bitmap to return.
+     * @return The resulting bitmap.
+     */
+    public static Bitmap decodeBitmapFromFileDescriptor(FileDescriptor descriptor, int width) {
+        BitmapFactory.Options options = new BitmapFactory.Options();
+        options.inJustDecodeBounds = true;
+        BitmapFactory.decodeFileDescriptor(descriptor, null, options);
+        options.inSampleSize = calculateInSampleSize(options, width, width);
+        options.inJustDecodeBounds = false;
+        Bitmap bitmap = BitmapFactory.decodeFileDescriptor(descriptor, null, options);
+        if (bitmap == null) {
+            return null;
+        }
+        return sizeBitmap(bitmap, width);
+    }
+
+    /**
+     * Given a file path, decodes the contents of the file and returns a bitmap of size
+     * |width|x|width|.
+     * @param filePath The path to the file to read.
+     * @param width The width of the bitmap to return.
+     * @return The resulting bitmap.
+     */
+    public static Bitmap decodeBitmapFromDisk(String filePath, int width) {
+        BitmapFactory.Options options = new BitmapFactory.Options();
+        options.inJustDecodeBounds = true;
+        BitmapFactory.decodeFile(filePath, options);
+        options.inSampleSize = calculateInSampleSize(options, width, width);
+        options.inJustDecodeBounds = false;
+        Bitmap bitmap = BitmapFactory.decodeFile(filePath, options);
+        if (bitmap == null) {
+            return null;
+        }
+        return sizeBitmap(bitmap, width);
+    }
+
+    /**
+     * Calculates the sub-sampling factor (inSampleSize option from the BitmapFactory) for a given
+     * bitmap option, which will be used to create a bitmap of a pre-determined size (no larger than
+     * |width| and |height|).
+     * @param options The bitmap options to consider.
+     * @param width The requested width.
+     * @param height The requested height.
+     * @return The sub-sampling factor (1 = no change, 2 = half-size, etc).
+     */
+    private static int calculateInSampleSize(BitmapFactory.Options options, int width, int height) {
+        int inSampleSize = 1;
+
+        if (options.outHeight > height || options.outWidth > width) {
+            final int halfHeight = options.outHeight / 2;
+            final int halfWidth = options.outWidth / 2;
+
+            while ((halfHeight / inSampleSize) >= height || (halfWidth / inSampleSize) >= width) {
+                inSampleSize *= 2;
+            }
+        }
+
+        return inSampleSize;
+    }
+
+    /**
+     * Scales a |bitmap| to a certain size.
+     * @param bitmap The bitmap to scale.
+     * @param scaleMaxSize What to scale it to.
+     * @param filter true if the source should be filtered.
+     * @return The resulting scaled bitmap.
+     */
+    public static Bitmap scale(Bitmap bitmap, float scaleMaxSize, boolean filter) {
+        float ratio = Math.min((float) scaleMaxSize / bitmap.getWidth(),
+                (float) scaleMaxSize / bitmap.getHeight());
+        int height = Math.round(ratio * bitmap.getHeight());
+        int width = Math.round(ratio * bitmap.getWidth());
+
+        return Bitmap.createScaledBitmap(bitmap, width, height, filter);
+    }
+
+    /**
+     * Ensures a |bitmap| is at least |size| in both width and height.
+     * @param bitmap The bitmap to modify.
+     * @param size The minimum size (width and height).
+     * @return The resulting (scaled) bitmap.
+     */
+    private static Bitmap ensureMinSize(Bitmap bitmap, int size) {
+        int width = bitmap.getWidth();
+        int height = bitmap.getHeight();
+        if (width < size) {
+            float scale = (float) size / width;
+            width = size;
+            height *= scale;
+        }
+
+        if (height < size) {
+            float scale = (float) size / height;
+            height = size;
+            width *= scale;
+        }
+
+        return Bitmap.createScaledBitmap(bitmap, width, height, true);
+    }
+
+    /**
+     * Crops a |bitmap| to a certain square |size|
+     * @param bitmap The bitmap to crop.
+     * @param size The size desired (width and height).
+     * @return The resulting (square) bitmap.
+     */
+    private static Bitmap cropToSquare(Bitmap bitmap, int size) {
+        int x = 0;
+        int y = 0;
+        int width = bitmap.getWidth();
+        int height = bitmap.getHeight();
+
+        if (width > size) x = (width - size) / 2;
+        if (height > size) y = (height - size) / 2;
+        return Bitmap.createBitmap(bitmap, x, y, size, size);
+    }
+}