| 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 | |
| 5 | package org.chromium.ui.gfx; |
| 6 | |
| 7 | import android.content.res.Resources; |
| 8 | import android.graphics.Bitmap; |
| 9 | import android.graphics.BitmapFactory; |
| 10 | import org.chromium.base.CalledByNative; |
| 11 | import org.chromium.base.JNINamespace; |
| 12 | |
| 13 | @JNINamespace("ui") |
| 14 | public 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 | } |