1/* 2 * Copyright (C) 2012 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 17package com.android.contacts.common.util; 18 19import android.graphics.Bitmap; 20import android.graphics.BitmapFactory; 21import android.graphics.Canvas; 22import android.graphics.drawable.Drawable; 23import android.graphics.drawable.BitmapDrawable; 24 25/** 26 * Provides static functions to decode bitmaps at the optimal size 27 */ 28public class BitmapUtil { 29 private BitmapUtil() {} 30 31 /** 32 * Returns Width or Height of the picture, depending on which size is smaller. Doesn't actually 33 * decode the picture, so it is pretty efficient to run. 34 */ 35 public static int getSmallerExtentFromBytes(byte[] bytes) { 36 final BitmapFactory.Options options = new BitmapFactory.Options(); 37 38 // don't actually decode the picture, just return its bounds 39 options.inJustDecodeBounds = true; 40 BitmapFactory.decodeByteArray(bytes, 0, bytes.length, options); 41 42 // test what the best sample size is 43 return Math.min(options.outWidth, options.outHeight); 44 } 45 46 /** 47 * Finds the optimal sampleSize for loading the picture 48 * @param originalSmallerExtent Width or height of the picture, whichever is smaller 49 * @param targetExtent Width or height of the target view, whichever is bigger. 50 * 51 * If either one of the parameters is 0 or smaller, no sampling is applied 52 */ 53 public static int findOptimalSampleSize(int originalSmallerExtent, int targetExtent) { 54 // If we don't know sizes, we can't do sampling. 55 if (targetExtent < 1) return 1; 56 if (originalSmallerExtent < 1) return 1; 57 58 // Test what the best sample size is. To do that, we find the sample size that gives us 59 // the best trade-off between resulting image size and memory requirement. We allow 60 // the down-sampled image to be 20% smaller than the target size. That way we can get around 61 // unfortunate cases where e.g. a 720 picture is requested for 362 and not down-sampled at 62 // all. Why 20%? Why not. Prove me wrong. 63 int extent = originalSmallerExtent; 64 int sampleSize = 1; 65 while ((extent >> 1) >= targetExtent * 0.8f) { 66 sampleSize <<= 1; 67 extent >>= 1; 68 } 69 70 return sampleSize; 71 } 72 73 /** 74 * Decodes the bitmap with the given sample size 75 */ 76 public static Bitmap decodeBitmapFromBytes(byte[] bytes, int sampleSize) { 77 final BitmapFactory.Options options; 78 if (sampleSize <= 1) { 79 options = null; 80 } else { 81 options = new BitmapFactory.Options(); 82 options.inSampleSize = sampleSize; 83 } 84 return BitmapFactory.decodeByteArray(bytes, 0, bytes.length, options); 85 } 86 87 /** 88 * Retrieves a copy of the specified drawable resource, rotated by a specified angle. 89 * 90 * @param resources The current resources. 91 * @param resourceId The resource ID of the drawable to rotate. 92 * @param angle The angle of rotation. 93 * @return Rotated drawable. 94 */ 95 public static Drawable getRotatedDrawable( 96 android.content.res.Resources resources, int resourceId, float angle) { 97 98 // Get the original drawable and make a copy which will be rotated. 99 Bitmap original = BitmapFactory.decodeResource(resources, resourceId); 100 Bitmap rotated = Bitmap.createBitmap( 101 original.getWidth(), original.getHeight(), Bitmap.Config.ARGB_8888); 102 103 // Perform the rotation. 104 Canvas tempCanvas = new Canvas(rotated); 105 tempCanvas.rotate(angle, original.getWidth()/2, original.getHeight()/2); 106 tempCanvas.drawBitmap(original, 0, 0, null); 107 108 return new BitmapDrawable(resources,rotated); 109 } 110} 111