在Android中对大图片进行缩放真的很不尽如人意，不知道是不是我的方法不对。下面我列出3种对图片缩放的方法，并给出相应速度。请高人指教。

第一种是BitmapFactory和BitmapFactory.Options。

首先，BitmapFactory.Options有几个Fields很有用：

inJustDecodeBounds：If set to true, the decoder will return null (no bitmap), but the out...

也就是说，当inJustDecodeBounds设成true时，bitmap并不加载到内存，这样效率很高哦。而这时，你可以获得bitmap的高、宽等信息。

outHeight：The resulting height of the bitmap, set independent of the state of inJustDecodeBounds.

outWidth：The resulting width of the bitmap, set independent of the state of inJustDecodeBounds.

看到了吧，上面3个变量是相关联的哦。

inSampleSize ： If set to a value > 1, requests the decoder to subsample the original p_w_picpath, returning a smaller p_w_picpath to save memory.

这就是用来做缩放比的。这里有个技巧：

inSampleSize=(outHeight/Height+outWidth/Width)/2

实践证明，这样缩放出来的图片还是很好的。

最后用BitmapFactory.decodeFile(path, options)生成。

由于只是对bitmap加载到内存一次，所以效率比较高。解析速度快。

第二种是使用Bitmap加Matrix来缩放。

首先要获得原bitmap，再从原bitmap的基础上生成新图片。这样效率很低。

第三种是用2.2新加的类ThumbnailUtils来做。

让我们新看看这个类，从API中来看，此类就三个静态方法：createVideoThumbnail、extractThumbnail(Bitmap source, int width, int height, int options)、extractThumbnail(Bitmap source, int width, int height)。

我这里使用了第三个方法。再看看它的源码，下面会附上。是上面我们用到的BitmapFactory.Options和Matrix等经过人家一阵加工而成。

效率好像比第二种方法高一点点。

下面是我的例子：

1. <?xml version="1.0" encoding="utf-8"?>

2.

3. android:orientation="vertical"

4. android:layout_;fill_parent"

5. android:layout_height="fill_parent"

6. >

7.

8.

9. android:id="@+id/p_w_picpathShow"

10. android:layout_;wrap_content"

11. android:layout_height="wrap_content"

12. />

13.

14. android:id="@+id/p_w_picpath2"

15. android:layout_;wrap_content"

16. android:layout_height="wrap_content"

17. />

18.

19. android:id="@+id/text"

20. android:layout_;fill_parent"

21. android:layout_height="wrap_content"

22. android:text="@string/hello"

23. />

24.

1. package com.linc.ResolvePicture;

2.

3. import java.io.File;

4. import java.io.FileNotFoundException;

5. import java.io.FileOutputStream;

6. import java.io.IOException;

7.

8. import android.app.Activity;

9. import android.graphics.Bitmap;

10. import android.graphics.BitmapFactory;

11. import android.graphics.Matrix;

12. import android.graphics.drawable.BitmapDrawable;

13. import android.graphics.drawable.Drawable;

14. import android.media.ThumbnailUtils;

15. import android.os.Bundle;

16. import android.util.Log;

17. import android.widget.ImageView;

18. import android.widget.TextView;

19.

20. public class ResolvePicture extends Activity {

21. private static String tag="ResolvePicture";

22.     Drawable bmImg;

23.     ImageView imView;

24.     ImageView imView2;

25.     TextView text;

26.     String theTime;

27. long start, stop;

28. /** Called when the activity is first created. */

29. @Override

30. public void onCreate(Bundle savedInstanceState) {

31. super.onCreate(savedInstanceState);

32.         setContentView(R.layout.main);

33.

34.         text=(TextView)findViewById(R.id.text);

35.

36.         imView=(ImageView) findViewById(R.id.p_w_picpathShow);

37.         imView2=(ImageView) findViewById(R.id.p_w_picpath2);

38.

39.         Bitmap bitmap = BitmapFactory.decodeResource(getResources(),

40.                 R.drawable.pic);

41.

42.         start=System.currentTimeMillis();

43.

44. //        imView.setImageDrawable(resizeImage(bitmap, 300, 100));

45.

46.         imView2.setImageDrawable(resizeImage2("/sdcard/2.jpeg", 200, 100));

47.

48.         stop=System.currentTimeMillis();

49.

50.         String theTime= String.format("\n1 iterative: (%d msec)",

51.                 stop - start);

52.

53.         start=System.currentTimeMillis();

54.         imView.setImageBitmap(ThumbnailUtils.extractThumbnail(bitmap,200,100));//2.2才加进来的新类，简单易用

55. //        imView.setImageDrawable(resizeImage(bitmap, 30, 30));

56.         stop=System.currentTimeMillis();

57.

58.          theTime+= String.format("\n2 iterative: (%d msec)",

59.                 stop - start);

60.

61.         text.setText(theTime);

62.     }

63.

64. //使用Bitmap加Matrix来缩放

65. public static Drawable resizeImage(Bitmap bitmap, int w, int h)

66.     {

67.         Bitmap BitmapOrg = bitmap;

68. int width = BitmapOrg.getWidth();

69. int height = BitmapOrg.getHeight();

70. int newWidth = w;

71. int newHeight = h;

72.

73. float scaleWidth = ((float) newWidth) / width;

74. float scaleHeight = ((float) newHeight) / height;

75.

76.         Matrix matrix = new Matrix();

77.         matrix.postScale(scaleWidth, scaleHeight);

78. // if you want to rotate the Bitmap

79. // matrix.postRotate(45);

80.         Bitmap resizedBitmap = Bitmap.createBitmap(BitmapOrg, 0, 0, width,

81.                         height, matrix, true);

82. return new BitmapDrawable(resizedBitmap);

83.     }

84.

85. //使用BitmapFactory.Options的inSampleSize参数来缩放

86. public static Drawable resizeImage2(String path,

87. int width,int height)

88.     {

89.         BitmapFactory.Options options = new BitmapFactory.Options();

90.         options.inJustDecodeBounds = true;//不加载bitmap到内存中

91.         BitmapFactory.decodeFile(path,options);

92. int outWidth = options.outWidth;

93. int outHeight = options.outHeight;

94.         options.inDither = false;

95.         options.inPreferredConfig = Bitmap.Config.ARGB_8888;

96.         options.inSampleSize = 1;

97.

98. if (outWidth != 0 && outHeight != 0 && width != 0 && height != 0)

99.         {

100. int sampleSize=(outWidth/width+outHeight/height)/2;

101.             Log.d(tag, "sampleSize = " + sampleSize);

102.             options.inSampleSize = sampleSize;

103.         }

104.

105.         options.inJustDecodeBounds = false;

106. return new BitmapDrawable(BitmapFactory.decodeFile(path, options));

107.     }

108.

109. //图片保存

110. private void saveThePicture(Bitmap bitmap)

111.     {

112.         File file=new File("/sdcard/2.jpeg");

113. try

114.         {

115.             FileOutputStream fos=new FileOutputStream(file);

116. if(bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos))

117.             {

118.                 fos.flush();

119.                 fos.close();

120.             }

121.         }

122. catch(FileNotFoundException e1)

123.         {

124.             e1.printStackTrace();

125.         }

126. catch(IOException e2)

127.         {

128.             e2.printStackTrace();

129.         }

130.     }

131. }

ThumbnailUtils源码：

1. /*

2.  * Copyright (C) 2009 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.

17. package android.media;

18.

19. import android.content.ContentResolver;

20. import android.content.ContentUris;

21. import android.content.ContentValues;

22. import android.database.Cursor;

23. import android.graphics.Bitmap;

24. import android.graphics.BitmapFactory;

25. import android.graphics.Canvas;

26. import android.graphics.Matrix;

27. import android.graphics.Rect;

28. import android.media.MediaMetadataRetriever;

29. import android.media.MediaFile.MediaFileType;

30. import android.net.Uri;

31. import android.os.ParcelFileDescriptor;

32. import android.provider.BaseColumns;

33. import android.provider.MediaStore.Images;

34. import android.provider.MediaStore.Images.Thumbnails;

35. import android.util.Log;

36.

37. import java.io.FileInputStream;

38. import java.io.FileDescriptor;

39. import java.io.IOException;

40. import java.io.OutputStream;

41.

42. /**

43.  * Thumbnail generation routines for media provider.

44.  */

45.

46. public class ThumbnailUtils {

47. private static final String TAG = "ThumbnailUtils";

48.

49. /* Maximum pixels size for created bitmap. */

50. private static final int MAX_NUM_PIXELS_THUMBNAIL = 512 * 384;

51. private static final int MAX_NUM_PIXELS_MICRO_THUMBNAIL = 128 * 128;

52. private static final int UNCONSTRAINED = -1;

53.

54. /* Options used internally. */

55. private static final int OPTIONS_NONE = 0x0;

56. private static final int OPTIONS_SCALE_UP = 0x1;

57.

58. /**

59.      * Constant used to indicate we should recycle the input in

60.      * {@link #extractThumbnail(Bitmap, int, int, int)} unless the output is the input.

61.      */

62. public static final int OPTIONS_RECYCLE_INPUT = 0x2;

63.

64. /**

65.      * Constant used to indicate the dimension of mini thumbnail.

66.      * @hide Only used by media framework and media provider internally.

67.      */

68. public static final int TARGET_SIZE_MINI_THUMBNAIL = 320;

69.

70. /**

71.      * Constant used to indicate the dimension of micro thumbnail.

72.      * @hide Only used by media framework and media provider internally.

73.      */

74. public static final int TARGET_SIZE_MICRO_THUMBNAIL = 96;

75.

76. /**

77.      * This method first examines if the thumbnail embedded in EXIF is bigger than our target

78.      * size. If not, then it'll create a thumbnail from original p_w_picpath. Due to efficiency

79.      * consideration, we want to let MediaThumbRequest avoid calling this method twice for

80.      * both kinds, so it only requests for MICRO_KIND and set saveImage to true.

81.      *

82.      * This method always returns a "square thumbnail" for MICRO_KIND thumbnail.

83.      *

84.      * @param filePath the path of p_w_picpath file

85.      * @param kind could be MINI_KIND or MICRO_KIND

86.      * @return Bitmap

87.      *

88.      * @hide This method is only used by media framework and media provider internally.

89.      */

90. public static Bitmap createImageThumbnail(String filePath, int kind) {

91. boolean wantMini = (kind == Images.Thumbnails.MINI_KIND);

92. int targetSize = wantMini

93.                 ? TARGET_SIZE_MINI_THUMBNAIL

94.                 : TARGET_SIZE_MICRO_THUMBNAIL;

95. int maxPixels = wantMini

96.                 ? MAX_NUM_PIXELS_THUMBNAIL

97.                 : MAX_NUM_PIXELS_MICRO_THUMBNAIL;

98.         SizedThumbnailBitmap sizedThumbnailBitmap = new SizedThumbnailBitmap();

99.         Bitmap bitmap = null;

100.         MediaFileType fileType = MediaFile.getFileType(filePath);

101. if (fileType != null && fileType.fileType == MediaFile.FILE_TYPE_JPEG) {

102.             createThumbnailFromEXIF(filePath, targetSize, maxPixels, sizedThumbnailBitmap);

103.             bitmap = sizedThumbnailBitmap.mBitmap;

104.         }

105.

106. if (bitmap == null) {

107. try {

108.                 FileDescriptor fd = new FileInputStream(filePath).getFD();

109.                 BitmapFactory.Options options = new BitmapFactory.Options();

110.                 options.inSampleSize = 1;

111.                 options.inJustDecodeBounds = true;

112.                 BitmapFactory.decodeFileDescriptor(fd, null, options);

113. if (options.mCancel || options.outWidth == -1

114.                         || options.outHeight == -1) {

115. return null;

116.                 }

117.                 options.inSampleSize = computeSampleSize(

118.                         options, targetSize, maxPixels);

119.                 options.inJustDecodeBounds = false;

120.

121.                 options.inDither = false;

122.                 options.inPreferredConfig = Bitmap.Config.ARGB_8888;

123.                 bitmap = BitmapFactory.decodeFileDescriptor(fd, null, options);

124.             } catch (IOException ex) {

125.                 Log.e(TAG, "", ex);

126.             }

127.         }

128.

129. if (kind == Images.Thumbnails.MICRO_KIND) {

130. // now we make it a "square thumbnail" for MICRO_KIND thumbnail

131.             bitmap = extractThumbnail(bitmap,

132.                     TARGET_SIZE_MICRO_THUMBNAIL,

133.                     TARGET_SIZE_MICRO_THUMBNAIL, OPTIONS_RECYCLE_INPUT);

134.         }

135. return bitmap;

136.     }

137.

138. /**

139.      * Create a video thumbnail for a video. May return null if the video is

140.      * corrupt or the format is not supported.

141.      *

142.      * @param filePath the path of video file

143.      * @param kind could be MINI_KIND or MICRO_KIND

144.      */

145. public static Bitmap createVideoThumbnail(String filePath, int kind) {

146.         Bitmap bitmap = null;

147.         MediaMetadataRetriever retriever = new MediaMetadataRetriever();

148. try {

149.             retriever.setMode(MediaMetadataRetriever.MODE_CAPTURE_FRAME_ONLY);

150.             retriever.setDataSource(filePath);

151.             bitmap = retriever.captureFrame();

152.         } catch (IllegalArgumentException ex) {

153. // Assume this is a corrupt video file

154.         } catch (RuntimeException ex) {

155. // Assume this is a corrupt video file.

156.         } finally {

157. try {

158.                 retriever.release();

159.             } catch (RuntimeException ex) {

160. // Ignore failures while cleaning up.

161.             }

162.         }

163. if (kind == Images.Thumbnails.MICRO_KIND && bitmap != null) {

164.             bitmap = extractThumbnail(bitmap,

165.                     TARGET_SIZE_MICRO_THUMBNAIL,

166.                     TARGET_SIZE_MICRO_THUMBNAIL,

167.                     OPTIONS_RECYCLE_INPUT);

168.         }

169. return bitmap;

170.     }

171.

172. /**

173.      * Creates a centered bitmap of the desired size.

174.      *

175.      * @param source original bitmap source

176.      * @param width targeted width

177.      * @param height targeted height

178.      */

179. public static Bitmap extractThumbnail(

180.             Bitmap source, int width, int height) {

181. return extractThumbnail(source, width, height, OPTIONS_NONE);

182.     }

183.

184. /**

185.      * Creates a centered bitmap of the desired size.

186.      *

187.      * @param source original bitmap source

188.      * @param width targeted width

189.      * @param height targeted height

190.      * @param options options used during thumbnail extraction

191.      */

192. public static Bitmap extractThumbnail(

193.             Bitmap source, int width, int height, int options) {

194. if (source == null) {

195. return null;

196.         }

197.

198. float scale;

199. if (source.getWidth() < source.getHeight()) {

200.             scale = width / (float) source.getWidth();

201.         } else {

202.             scale = height / (float) source.getHeight();

203.         }

204.         Matrix matrix = new Matrix();

205.         matrix.setScale(scale, scale);

206.         Bitmap thumbnail = transform(matrix, source, width, height,

207.                 OPTIONS_SCALE_UP | options);

208. return thumbnail;

209.     }

210.

211. /*

212.      * Compute the sample size as a function of minSideLength

213.      * and maxNumOfPixels.

214.      * minSideLength is used to specify that minimal width or height of a

215.      * bitmap.

216.      * maxNumOfPixels is used to specify the maximal size in pixels that is

217.      * tolerable in terms of memory usage.

218.      *

219.      * The function returns a sample size based on the constraints.

220.      * Both size and minSideLength can be passed in as IImage.UNCONSTRAINED,

221.      * which indicates no care of the corresponding constraint.

222.      * The functions prefers returning a sample size that

223.      * generates a smaller bitmap, unless minSideLength = IImage.UNCONSTRAINED.

224.      *

225.      * Also, the function rounds up the sample size to a power of 2 or multiple

226.      * of 8 because BitmapFactory only honors sample size this way.

227.      * For example, BitmapFactory downsamples an p_w_picpath by 2 even though the

228.      * request is 3. So we round up the sample size to avoid OOM.

229.      */

230. private static int computeSampleSize(BitmapFactory.Options options,

231. int minSideLength, int maxNumOfPixels) {

232. int initialSize = computeInitialSampleSize(options, minSideLength,

233.                 maxNumOfPixels);

234.

235. int roundedSize;

236. if (initialSize <= 8 ) {

237.             roundedSize = 1;

238. while (roundedSize < initialSize) {

239.                 roundedSize <<= 1;

240.             }

241.         } else {

242.             roundedSize = (initialSize + 7) / 8 * 8;

243.         }

244.

245. return roundedSize;

246.     }

247.

248. private static int computeInitialSampleSize(BitmapFactory.Options options,

249. int minSideLength, int maxNumOfPixels) {

250. double w = options.outWidth;

251. double h = options.outHeight;

252.

253. int lowerBound = (maxNumOfPixels == UNCONSTRAINED) ? 1 :

254.                 (int) Math.ceil(Math.sqrt(w * h / maxNumOfPixels));

255. int upperBound = (minSideLength == UNCONSTRAINED) ? 128 :

256.                 (int) Math.min(Math.floor(w / minSideLength),

257.                 Math.floor(h / minSideLength));

258.

259. if (upperBound < lowerBound) {

260. // return the larger one when there is no overlapping zone.

261. return lowerBound;

262.         }

263.

264. if ((maxNumOfPixels == UNCONSTRAINED) &&

265.                 (minSideLength == UNCONSTRAINED)) {

266. return 1;

267.         } else if (minSideLength == UNCONSTRAINED) {

268. return lowerBound;

269.         } else {

270. return upperBound;

271.         }

272.     }

273.

274. /**

275.      * Make a bitmap from a given Uri, minimal side length, and maximum number of pixels.

276.      * The p_w_picpath data will be read from specified pfd if it's not null, otherwise

277.      * a new input stream will be created using specified ContentResolver.

278.      *

279.      * Clients are allowed to pass their own BitmapFactory.Options used for bitmap decoding. A

280.      * new BitmapFactory.Options will be created if options is null.

281.      */

282. private static Bitmap makeBitmap(int minSideLength, int maxNumOfPixels,

283.             Uri uri, ContentResolver cr, ParcelFileDescriptor pfd,

284.             BitmapFactory.Options options) {

285.             Bitmap b = null;

286. try {

287. if (pfd == null) pfd = makeInputStream(uri, cr);

288. if (pfd == null) return null;

289. if (options == null) options = new BitmapFactory.Options();

290.

291.             FileDescriptor fd = pfd.getFileDescriptor();

292.             options.inSampleSize = 1;

293.             options.inJustDecodeBounds = true;

294.             BitmapFactory.decodeFileDescriptor(fd, null, options);

295. if (options.mCancel || options.outWidth == -1

296.                     || options.outHeight == -1) {

297. return null;

298.             }

299.             options.inSampleSize = computeSampleSize(

300.                     options, minSideLength, maxNumOfPixels);

301.             options.inJustDecodeBounds = false;

302.

303.             options.inDither = false;

304.             options.inPreferredConfig = Bitmap.Config.ARGB_8888;

305.             b = BitmapFactory.decodeFileDescriptor(fd, null, options);

306.         } catch (OutOfMemoryError ex) {

307.             Log.e(TAG, "Got oom exception ", ex);

308. return null;

309.         } finally {

310.             closeSilently(pfd);

311.         }

312. return b;

313.     }

314.

315. private static void closeSilently(ParcelFileDescriptor c) {

316. if (c == null) return;

317. try {

318.           c.close();

319.       } catch (Throwable t) {

320. // do nothing

321.       }

322.     }

323.

324. private static ParcelFileDescriptor makeInputStream(

325.             Uri uri, ContentResolver cr) {

326. try {

327. return cr.openFileDescriptor(uri, "r");

328.         } catch (IOException ex) {

329. return null;

330.         }

331.     }

332.

333. /**

334.      * Transform source Bitmap to targeted width and height.

335.      */

336. private static Bitmap transform(Matrix scaler,

337.             Bitmap source,

338. int targetWidth,

339. int targetHeight,

340. int options) {

341. boolean scaleUp = (options & OPTIONS_SCALE_UP) != 0;

342. boolean recycle = (options & OPTIONS_RECYCLE_INPUT) != 0;

343.

344. int deltaX = source.getWidth() - targetWidth;

345. int deltaY = source.getHeight() - targetHeight;

346. if (!scaleUp && (deltaX < 0 || deltaY < 0)) {

347. /*

348.             * In this case the bitmap is smaller, at least in one dimension,

349.             * than the target.  Transform it by placing as much of the p_w_picpath

350.             * as possible into the target and leaving the top/bottom or

351.             * left/right (or both) black.

352.             */

353.             Bitmap b2 = Bitmap.createBitmap(targetWidth, targetHeight,

354.             Bitmap.Config.ARGB_8888);

355.             Canvas c = new Canvas(b2);

356.

357. int deltaXHalf = Math.max(0, deltaX / 2);

358. int deltaYHalf = Math.max(0, deltaY / 2);

359.             Rect src = new Rect(

360.             deltaXHalf,

361.             deltaYHalf,

362.             deltaXHalf + Math.min(targetWidth, source.getWidth()),

363.             deltaYHalf + Math.min(targetHeight, source.getHeight()));

364. int dstX = (targetWidth  - src.width())  / 2;

365. int dstY = (targetHeight - src.height()) / 2;

366.             Rect dst = new Rect(

367.                     dstX,

368.                     dstY,

369.                     targetWidth - dstX,

370.                     targetHeight - dstY);

371.             c.drawBitmap(source, src, dst, null);

372. if (recycle) {

373.                 source.recycle();

374.             }

375. return b2;

376.         }

377. float bitmapWidthF = source.getWidth();

378. float bitmapHeightF = source.getHeight();

379.

380. float bitmapAspect = bitmapWidthF / bitmapHeightF;

381. float viewAspect   = (float) targetWidth / targetHeight;

382.

383. if (bitmapAspect > viewAspect) {

384. float scale = targetHeight / bitmapHeightF;

385. if (scale < .9F || scale > 1F) {

386.                 scaler.setScale(scale, scale);

387.             } else {

388.                 scaler = null;

389.             }

390.         } else {

391. float scale = targetWidth / bitmapWidthF;

392. if (scale < .9F || scale > 1F) {

393.                 scaler.setScale(scale, scale);

394.             } else {

395.                 scaler = null;

396.             }

397.         }

398.

399.         Bitmap b1;

400. if (scaler != null) {

401. // this is used for minithumb and crop, so we want to filter here.

402.             b1 = Bitmap.createBitmap(source, 0, 0,

403.             source.getWidth(), source.getHeight(), scaler, true);

404.         } else {

405.             b1 = source;

406.         }

407.

408. if (recycle && b1 != source) {

409.             source.recycle();

410.         }

411.

412. int dx1 = Math.max(0, b1.getWidth() - targetWidth);

413. int dy1 = Math.max(0, b1.getHeight() - targetHeight);

414.

415.         Bitmap b2 = Bitmap.createBitmap(

416.                 b1,

417.                 dx1 / 2,

418.                 dy1 / 2,

419.                 targetWidth,

420.                 targetHeight);

421.

422. if (b2 != b1) {

423. if (recycle || b1 != source) {

424.                 b1.recycle();

425.             }

426.         }

427.

428. return b2;

429.     }

430.

431. /**

432.      * SizedThumbnailBitmap contains the bitmap, which is downsampled either from

433.      * the thumbnail in exif or the full p_w_picpath.

434.      * mThumbnailData, mThumbnailWidth and mThumbnailHeight are set together only if mThumbnail

435.      * is not null.

436.      *

437.      * The width/height of the sized bitmap may be different from mThumbnailWidth/mThumbnailHeight.

438.      */

439. private static class SizedThumbnailBitmap {

440. public byte[] mThumbnailData;

441. public Bitmap mBitmap;

442. public int mThumbnailWidth;

443. public int mThumbnailHeight;

444.     }

445.

446. /**

447.      * Creates a bitmap by either downsampling from the thumbnail in EXIF or the full p_w_picpath.

448.      * The functions returns a SizedThumbnailBitmap,

449.      * which contains a downsampled bitmap and the thumbnail data in EXIF if exists.

450.      */

451. private static void createThumbnailFromEXIF(String filePath, int targetSize,

452. int maxPixels, SizedThumbnailBitmap sizedThumbBitmap) {

453. if (filePath == null) return;

454.

455.         ExifInterface exif = null;

456. byte [] thumbData = null;

457. try {

458.             exif = new ExifInterface(filePath);

459. if (exif != null) {

460.                 thumbData = exif.getThumbnail();

461.             }

462.         } catch (IOException ex) {

463.             Log.w(TAG, ex);

464.         }

465.

466.         BitmapFactory.Options fullOptions = new BitmapFactory.Options();

467.         BitmapFactory.Options exifOptions = new BitmapFactory.Options();

468. int exifThumbWidth = 0;

469. int fullThumbWidth = 0;

470.

471. // Compute exifThumbWidth.

472. if (thumbData != null) {

473.             exifOptions.inJustDecodeBounds = true;

474.             BitmapFactory.decodeByteArray(thumbData, 0, thumbData.length, exifOptions);

475.             exifOptions.inSampleSize = computeSampleSize(exifOptions, targetSize, maxPixels);

476.             exifThumbWidth = exifOptions.outWidth / exifOptions.inSampleSize;

477.         }

478.

479. // Compute fullThumbWidth.

480.         fullOptions.inJustDecodeBounds = true;

481.         BitmapFactory.decodeFile(filePath, fullOptions);

482.         fullOptions.inSampleSize = computeSampleSize(fullOptions, targetSize, maxPixels);

483.         fullThumbWidth = fullOptions.outWidth / fullOptions.inSampleSize;

484.

485. // Choose the larger thumbnail as the returning sizedThumbBitmap.

486. if (thumbData != null && exifThumbWidth >= fullThumbWidth) {

487. int width = exifOptions.outWidth;

488. int height = exifOptions.outHeight;

489.             exifOptions.inJustDecodeBounds = false;

490.             sizedThumbBitmap.mBitmap = BitmapFactory.decodeByteArray(thumbData, 0,

491.                     thumbData.length, exifOptions);

492. if (sizedThumbBitmap.mBitmap != null) {

493.                 sizedThumbBitmap.mThumbnailData = thumbData;

494.                 sizedThumbBitmap.mThumbnailWidth = width;

495.                 sizedThumbBitmap.mThumbnailHeight = height;

496.             }

497.         } else {

498.             fullOptions.inJustDecodeBounds = false;

499.             sizedThumbBitmap.mBitmap = BitmapFactory.decodeFile(filePath, fullOptions);

500.         }

501.     }

502. }