在Android中對(duì)大圖片進(jìn)行縮放真的很不盡如人意，不知道是不是我的方法不對(duì)。下面我列出3種對(duì)圖片縮放的方法，并給出相應(yīng)速度。請(qǐng)高人指教。

第一種是BitmapFactory和BitmapFactory.Options。

首先，BitmapFactory.Options有幾個(gè)Fields很有用：

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

也就是說(shuō)，當(dāng)inJustDecodeBounds設(shè)成true時(shí)，bitmap并不加載到內(nèi)存，這樣效率很高哦。而這時(shí)，你可以獲得bitmap的高、寬等信息。

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個(gè)變量是相關(guān)聯(lián)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.

這就是用來(lái)做縮放比的。這里有個(gè)技巧：

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

實(shí)踐證明，這樣縮放出來(lái)的圖片還是很好的。

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

由于只是對(duì)bitmap加載到內(nèi)存一次，所以效率比較高。解析速度快。

第二種是使用Bitmap加Matrix來(lái)縮放。

首先要獲得原bitmap，再?gòu)脑璪itmap的基礎(chǔ)上生成新圖片。這樣效率很低。

第三種是用2.2新加的類(lèi)ThumbnailUtils來(lái)做。

讓我們新看看這個(gè)類(lèi)，從API中來(lái)看，此類(lèi)就三個(gè)靜態(tài)方法：createVideoThumbnail、extractThumbnail(Bitmap source, int width, int height, int options)、extractThumbnail(Bitmap source, int width, int height)。

我這里使用了第三個(gè)方法。再看看它的源碼，下面會(huì)附上。是上面我們用到的BitmapFactory.Options和Matrix等經(jīng)過(guò)人家一陣加工而成。

效率好像比第二種方法高一點(diǎn)點(diǎn)。

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才加進(jìn)來(lái)的新類(lèi)，簡(jiǎn)單易用

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來(lái)縮放

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參數(shù)來(lái)縮放

86. public static Drawable resizeImage2(String path,

87. int width,int height)

88.???? {

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

90.???????? options.inJustDecodeBounds = true;//不加載bitmap到內(nèi)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. //圖片保存

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源碼：

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. }

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