怎样建设一个购物网站,石家庄城乡建设部网站首页,做一家新闻媒体网站多少钱,营销云在Android中对大图片进行缩放真的很不尽如人意#xff0c;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#xff0c;并给出相应速度。请高人指教。第一种是BitmapFactory和BitmapFactory.Options。首先#xff0c;BitmapFactory.Options有几个Fields很有用…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inJustDecodeBoundsIf 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。outHeightThe resulting height of the bitmap, set independent of the state of inJustDecodeBounds.outWidthThe 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/HeightoutWidth/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 version1.0 encodingutf-8?2. 3. android:orientationvertical4. android:layout_;fill_parent5. android:layout_heightfill_parent6. 7.8. 9. android:idid/p_w_picpathShow10. android:layout_;wrap_content11. android:layout_heightwrap_content12. /13. 14. android:idid/p_w_picpath215. android:layout_;wrap_content16. android:layout_heightwrap_content17. /18. 19. android:idid/text20. android:layout_;fill_parent21. android:layout_heightwrap_content22. android:textstring/hello23. /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 tagResolvePicture;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. Override30. 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. startSystem.currentTimeMillis();43.44. // imView.setImageDrawable(resizeImage(bitmap, 300, 100));45.46. imView2.setImageDrawable(resizeImage2(/sdcard/2.jpeg, 200, 100));47.48. stopSystem.currentTimeMillis();49.50. String theTime String.format(\n1 iterative: (%d msec),51. stop - start);52.53. startSystem.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. stopSystem.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 Bitmap79. // 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/widthoutHeight/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 filenew File(/sdcard/2.jpeg);113. try114. {115. FileOutputStream fosnew 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 Project3. *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 at7. *8. * http://www.apache.org/licenses/LICENSE-2.09. *10. * Unless required by applicable law or agreed to in writing, software11. * 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 and14. * 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 in60. * {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 target78. * size. If not, then itll create a thumbnail from original p_w_picpath. Due to efficiency79. * consideration, we want to let MediaThumbRequest avoid calling this method twice for80. * 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 file85. * param kind could be MINI_KIND or MICRO_KIND86. * return Bitmap87. *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 wantMini93. ? TARGET_SIZE_MINI_THUMBNAIL94. : TARGET_SIZE_MICRO_THUMBNAIL;95. int maxPixels wantMini96. ? MAX_NUM_PIXELS_THUMBNAIL97. : 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 -1114. || 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 thumbnail131. 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 is140. * corrupt or the format is not supported.141. *142. * param filePath the path of video file143. * param kind could be MINI_KIND or MICRO_KIND144. */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 file154. } 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 source176. * param width targeted width177. * param height targeted height178. */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 source188. * param width targeted width189. * param height targeted height190. * param options options used during thumbnail extraction191. */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 minSideLength213. * and maxNumOfPixels.214. * minSideLength is used to specify that minimal width or height of a215. * bitmap.216. * maxNumOfPixels is used to specify the maximal size in pixels that is217. * 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 that223. * generates a smaller bitmap, unless minSideLength IImage.UNCONSTRAINED.224. *225. * Also, the function rounds up the sample size to a power of 2 or multiple226. * of 8 because BitmapFactory only honors sample size this way.227. * For example, BitmapFactory downsamples an p_w_picpath by 2 even though the228. * 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 its not null, otherwise277. * 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. A280. * 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 -1296. || 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 nothing321. }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_picpath350. * as possible into the target and leaving the top/bottom or351. * 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 from433. * the thumbnail in exif or the full p_w_picpath.434. * mThumbnailData, mThumbnailWidth and mThumbnailHeight are set together only if mThumbnail435. * 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. }
