1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5package org.chromium.ui.gfx;
6
7import android.content.res.Resources;
8import android.graphics.Bitmap;
9import android.graphics.BitmapFactory;
10import org.chromium.base.CalledByNative;
11import org.chromium.base.JNINamespace;
12
13@JNINamespace("ui")
14public class BitmapHelper {
15    @CalledByNative
16    public static Bitmap createBitmap(int width, int height) {
17        return Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
18    }
19
20    /**
21     * Decode and sample down a bitmap resource to the requested width and height.
22     *
23     * @param name The resource name of the bitmap to decode.
24     * @param reqWidth The requested width of the resulting bitmap.
25     * @param reqHeight The requested height of the resulting bitmap.
26     * @return A bitmap sampled down from the original with the same aspect ratio and dimensions.
27     *         that are equal to or greater than the requested width and height.
28     */
29    @CalledByNative
30    private static Bitmap decodeDrawableResource(String name,
31                                                 int reqWidth,
32                                                 int reqHeight) {
33        Resources res = Resources.getSystem();
34        int resId = res.getIdentifier(name, null, null);
35
36        final BitmapFactory.Options options = new BitmapFactory.Options();
37        options.inJustDecodeBounds = true;
38        BitmapFactory.decodeResource(res, resId, options);
39
40        options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
41
42        options.inJustDecodeBounds = false;
43        return BitmapFactory.decodeResource(res, resId, options);
44    }
45
46    // http://developer.android.com/training/displaying-bitmaps/load-bitmap.html
47    private static int calculateInSampleSize(BitmapFactory.Options options,
48                                             int reqWidth,
49                                             int reqHeight) {
50        // Raw height and width of image
51        final int height = options.outHeight;
52        final int width = options.outWidth;
53        int inSampleSize = 1;
54
55        if (height > reqHeight || width > reqWidth) {
56
57            // Calculate ratios of height and width to requested height and width
58            final int heightRatio = Math.round((float) height / (float) reqHeight);
59            final int widthRatio = Math.round((float) width / (float) reqWidth);
60
61            // Choose the smallest ratio as inSampleSize value, this will guarantee
62            // a final image with both dimensions larger than or equal to the
63            // requested height and width.
64            inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
65        }
66
67        return inSampleSize;
68    }
69}
70