media/java/android/media/ThumbnailUtils.java - platform/frameworks/base - Git at Google

 /*
  * Copyright (C) 2009 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package android.media;

 import android.content.ContentResolver;
 import android.content.ContentUris;
 import android.content.ContentValues;
 import android.database.Cursor;
 import android.graphics.Bitmap;
 import android.graphics.BitmapFactory;
 import android.graphics.Canvas;
 import android.graphics.Matrix;
 import android.graphics.Rect;
 import android.media.MediaMetadataRetriever;
 import android.media.MediaFile.MediaFileType;
 import android.net.Uri;
 import android.os.ParcelFileDescriptor;
 import android.provider.BaseColumns;
 import android.provider.MediaStore.Images;
 import android.provider.MediaStore.Images.Thumbnails;
 import android.util.Log;

 import java.io.FileDescriptor;
 import java.io.IOException;
 import java.io.OutputStream;

 /**
  * Thumbnail generation routines for media provider.
  */

 public class ThumbnailUtils {
     private static final String TAG = "ThumbnailUtils";

     /* Maximum pixels size for created bitmap. */
     private static final int THUMBNAIL_MAX_NUM_PIXELS = 512 * 384;
     private static final int MINI_THUMB_MAX_NUM_PIXELS = 128 * 128;
     private static final int UNCONSTRAINED = -1;

     /* Whether we should rotate the resulting bitmap. */
     private static final boolean ROTATE_AS_NEEDED = true;
     private static final boolean NO_ROTATE = false;

     /* Whether we should create bitmap in native memory. */
     private static final boolean USE_NATIVE = true;
     private static final boolean NO_NATIVE = false;

     /**
      * Constant used to indicate we should recycle the input in
      * {@link #extractMiniThumb(Bitmap, int, int, boolean)} unless the output is the input.
      */
     public static final boolean RECYCLE_INPUT = true;

     /**
      * Constant used to indicate we should not recycle the input in
      * {@link #extractMiniThumb(Bitmap, int, int, boolean)}.
      */
     public static final boolean NO_RECYCLE_INPUT = false;

     /**
      * Constant used to indicate the dimension of normal thumbnail in
      * {@link #extractMiniThumb(Bitmap, int, int, boolean)}.
      */
     public static final int THUMBNAIL_TARGET_SIZE = 320;

     /**
      * Constant used to indicate the dimension of mini thumbnail in
      * {@link #extractMiniThumb(Bitmap, int, int, boolean)}.
      */
     public static final int MINI_THUMB_TARGET_SIZE = 96;

     /**
      * This method first examines if the thumbnail embedded in EXIF is bigger than our target
      * size. If not, then it'll create a thumbnail from original image. Due to efficiency
      * consideration, we want to let MediaThumbRequest avoid calling this method twice for
      * both kinds, so it only requests for MICRO_KIND and set saveImage to true.
      *
      * This method always returns a "square thumbnail" for MICRO_KIND thumbnail.
      *
      * @param cr ContentResolver
      * @param filePath file path needed by EXIF interface
      * @param uri URI of original image
      * @param origId image id
      * @param kind either MINI_KIND or MICRO_KIND
      * @param saveMini Whether to save MINI_KIND thumbnail obtained in this method.
      * @return Bitmap
      */
     public static Bitmap createImageThumbnail(ContentResolver cr, String filePath, Uri uri,
             long origId, int kind, boolean saveMini) {
         boolean wantMini = (kind == Images.Thumbnails.MINI_KIND || saveMini);
         int targetSize = wantMini ?
                 THUMBNAIL_TARGET_SIZE : MINI_THUMB_TARGET_SIZE;
         int maxPixels = wantMini ?
                 THUMBNAIL_MAX_NUM_PIXELS : MINI_THUMB_MAX_NUM_PIXELS;
         SizedThumbnailBitmap sizedThumbnailBitmap = new SizedThumbnailBitmap();
         Bitmap bitmap = null;
         MediaFileType fileType = MediaFile.getFileType(filePath);
         if (fileType != null && fileType.fileType == MediaFile.FILE_TYPE_JPEG) {
             createThumbnailFromEXIF(filePath, targetSize, maxPixels, sizedThumbnailBitmap);
             bitmap = sizedThumbnailBitmap.mBitmap;
         }

         if (bitmap == null) {
             bitmap = makeBitmap(targetSize, maxPixels, uri, cr);
         }

         if (bitmap == null) {
             return null;
         }

         if (saveMini) {
             if (sizedThumbnailBitmap.mThumbnailData != null) {
                 storeThumbnail(cr, origId,
                         sizedThumbnailBitmap.mThumbnailData,
                         sizedThumbnailBitmap.mThumbnailWidth,
                         sizedThumbnailBitmap.mThumbnailHeight);
             } else {
                 storeThumbnail(cr, origId, bitmap);
             }
         }

         if (kind == Images.Thumbnails.MICRO_KIND) {
             // now we make it a "square thumbnail" for MICRO_KIND thumbnail
             bitmap = extractMiniThumb(bitmap,
                     MINI_THUMB_TARGET_SIZE,
                     MINI_THUMB_TARGET_SIZE, RECYCLE_INPUT);
         }
         return bitmap;
     }

     /**
      * Create a video thumbnail for a video. May return null if the video is
      * corrupt.
      *
      * @param filePath
      */
     public static Bitmap createVideoThumbnail(String filePath) {
         Bitmap bitmap = null;
         MediaMetadataRetriever retriever = new MediaMetadataRetriever();
         try {
             retriever.setMode(MediaMetadataRetriever.MODE_CAPTURE_FRAME_ONLY);
             retriever.setDataSource(filePath);
             bitmap = retriever.captureFrame();
         } catch (IllegalArgumentException ex) {
             // Assume this is a corrupt video file
         } catch (RuntimeException ex) {
             // Assume this is a corrupt video file.
         } finally {
             try {
                 retriever.release();
             } catch (RuntimeException ex) {
                 // Ignore failures while cleaning up.
             }
         }
         return bitmap;
     }

     /**
      * Creates a centered bitmap of the desired size.
      *
      * @param source original bitmap source
      * @param width targeted width
      * @param height targeted height
      * @param recycle whether we want to recycle the input
      */
     public static Bitmap extractMiniThumb(
             Bitmap source, int width, int height, boolean recycle) {
         if (source == null) {
             return null;
         }

         float scale;
         if (source.getWidth() < source.getHeight()) {
             scale = width / (float) source.getWidth();
         } else {
             scale = height / (float) source.getHeight();
         }
         Matrix matrix = new Matrix();
         matrix.setScale(scale, scale);
         Bitmap miniThumbnail = transform(matrix, source, width, height, true, recycle);
         return miniThumbnail;
     }

     /*
      * Compute the sample size as a function of minSideLength
      * and maxNumOfPixels.
      * minSideLength is used to specify that minimal width or height of a
      * bitmap.
      * maxNumOfPixels is used to specify the maximal size in pixels that is
      * tolerable in terms of memory usage.
      *
      * The function returns a sample size based on the constraints.
      * Both size and minSideLength can be passed in as IImage.UNCONSTRAINED,
      * which indicates no care of the corresponding constraint.
      * The functions prefers returning a sample size that
      * generates a smaller bitmap, unless minSideLength = IImage.UNCONSTRAINED.
      *
      * Also, the function rounds up the sample size to a power of 2 or multiple
      * of 8 because BitmapFactory only honors sample size this way.
      * For example, BitmapFactory downsamples an image by 2 even though the
      * request is 3. So we round up the sample size to avoid OOM.
      */
     private static int computeSampleSize(BitmapFactory.Options options,
             int minSideLength, int maxNumOfPixels) {
         int initialSize = computeInitialSampleSize(options, minSideLength,
                 maxNumOfPixels);

         int roundedSize;
         if (initialSize <= 8 ) {
             roundedSize = 1;
             while (roundedSize < initialSize) {
                 roundedSize <<= 1;
             }
         } else {
             roundedSize = (initialSize + 7) / 8 * 8;
         }

         return roundedSize;
     }

     private static int computeInitialSampleSize(BitmapFactory.Options options,
             int minSideLength, int maxNumOfPixels) {
         double w = options.outWidth;
         double h = options.outHeight;

         int lowerBound = (maxNumOfPixels == UNCONSTRAINED) ? 1 :
                 (int) Math.ceil(Math.sqrt(w * h / maxNumOfPixels));
         int upperBound = (minSideLength == UNCONSTRAINED) ? 128 :
                 (int) Math.min(Math.floor(w / minSideLength),
                 Math.floor(h / minSideLength));

         if (upperBound < lowerBound) {
             // return the larger one when there is no overlapping zone.
             return lowerBound;
         }

         if ((maxNumOfPixels == UNCONSTRAINED) &&
                 (minSideLength == UNCONSTRAINED)) {
             return 1;
         } else if (minSideLength == UNCONSTRAINED) {
             return lowerBound;
         } else {
             return upperBound;
         }
     }

     /**
      *  Returns Options that set the native alloc flag for Bitmap decode.
      */
     private static BitmapFactory.Options createNativeAllocOptions() {
         BitmapFactory.Options options = new BitmapFactory.Options();
         options.inNativeAlloc = true;
         return options;
     }

     /**
      * Make a bitmap from a given Uri, minimal side length, and maximum number of pixels.
      */
     private static Bitmap makeBitmap(int minSideLength, int maxNumOfPixels,
             Uri uri, ContentResolver cr) {
         return makeBitmap(minSideLength, maxNumOfPixels, uri, cr,
                 NO_NATIVE);
     }

     /**
      * Make a bitmap from a given Uri, minimal side length, and maximum number of pixels.
      * The image data will be read from specified ContentResolver and clients are allowed to specify
      * whether they want the Bitmap be created in native memory.
      */
     private static Bitmap makeBitmap(int minSideLength, int maxNumOfPixels,
             Uri uri, ContentResolver cr, boolean useNative) {
         ParcelFileDescriptor input = null;
         try {
             input = cr.openFileDescriptor(uri, "r");
             BitmapFactory.Options options = null;
             if (useNative) {
                 options = createNativeAllocOptions();
             }
             return makeBitmap(minSideLength, maxNumOfPixels, uri, cr, input,
                     options);
         } catch (IOException ex) {
             Log.e(TAG, "", ex);
             return null;
         } finally {
             closeSilently(input);
         }
     }

     /**
      * Make a bitmap from a given Uri, minimal side length, and maximum number of pixels.
      * The image data will be read from specified pfd if it's not null, otherwise
      * a new input stream will be created using specified ContentResolver.
      *
      * Clients are allowed to pass their own BitmapFactory.Options used for bitmap decoding. A
      * new BitmapFactory.Options will be created if options is null.
      */
     private static Bitmap makeBitmap(int minSideLength, int maxNumOfPixels,
             Uri uri, ContentResolver cr, ParcelFileDescriptor pfd,
             BitmapFactory.Options options) {
             Bitmap b = null;
         try {
             if (pfd == null) pfd = makeInputStream(uri, cr);
             if (pfd == null) return null;
             if (options == null) options = new BitmapFactory.Options();

             FileDescriptor fd = pfd.getFileDescriptor();
             options.inSampleSize = 1;
             options.inJustDecodeBounds = true;
             BitmapFactory.decodeFileDescriptor(fd, null, options);
             if (options.mCancel || options.outWidth == -1
                     || options.outHeight == -1) {
                 return null;
             }
             options.inSampleSize = computeSampleSize(
                     options, minSideLength, maxNumOfPixels);
             options.inJustDecodeBounds = false;

             options.inDither = false;
             options.inPreferredConfig = Bitmap.Config.ARGB_8888;
             b = BitmapFactory.decodeFileDescriptor(fd, null, options);
         } catch (OutOfMemoryError ex) {
             Log.e(TAG, "Got oom exception ", ex);
             return null;
         } finally {
             closeSilently(pfd);
         }
         return b;
     }

     /**
      * Rotates the bitmap by the specified degree.
      * If a new bitmap is created, the original bitmap is recycled.
      */
     private static Bitmap rotate(Bitmap b, int degrees) {
         if (degrees != 0 && b != null) {
             Matrix m = new Matrix();
             m.setRotate(degrees,
                     (float) b.getWidth() / 2, (float) b.getHeight() / 2);
             try {
                 Bitmap b2 = Bitmap.createBitmap(
                         b, 0, 0, b.getWidth(), b.getHeight(), m, true);
                 if (b != b2) {
                     b.recycle();
                     b = b2;
                 }
             } catch (OutOfMemoryError ex) {
                 // We have no memory to rotate. Return the original bitmap.
             }
         }
         return b;
     }

     private static void closeSilently(ParcelFileDescriptor c) {
       if (c == null) return;
       try {
           c.close();
       } catch (Throwable t) {
           // do nothing
       }
     }

     private static ParcelFileDescriptor makeInputStream(
             Uri uri, ContentResolver cr) {
         try {
             return cr.openFileDescriptor(uri, "r");
         } catch (IOException ex) {
             return null;
         }
     }

     /**
      * Transform source Bitmap to targeted width and height.
      */
     private static Bitmap transform(Matrix scaler,
             Bitmap source,
             int targetWidth,
             int targetHeight,
             boolean scaleUp,
             boolean recycle) {

         int deltaX = source.getWidth() - targetWidth;
         int deltaY = source.getHeight() - targetHeight;
         if (!scaleUp && (deltaX < 0 || deltaY < 0)) {
             /*
             * In this case the bitmap is smaller, at least in one dimension,
             * than the target.  Transform it by placing as much of the image
             * as possible into the target and leaving the top/bottom or
             * left/right (or both) black.
             */
             Bitmap b2 = Bitmap.createBitmap(targetWidth, targetHeight,
             Bitmap.Config.ARGB_8888);
             Canvas c = new Canvas(b2);

             int deltaXHalf = Math.max(0, deltaX / 2);
             int deltaYHalf = Math.max(0, deltaY / 2);
             Rect src = new Rect(
             deltaXHalf,
             deltaYHalf,
             deltaXHalf + Math.min(targetWidth, source.getWidth()),
             deltaYHalf + Math.min(targetHeight, source.getHeight()));
             int dstX = (targetWidth  - src.width())  / 2;
             int dstY = (targetHeight - src.height()) / 2;
             Rect dst = new Rect(
                     dstX,
                     dstY,
                     targetWidth - dstX,
                     targetHeight - dstY);
             c.drawBitmap(source, src, dst, null);
             if (recycle) {
                 source.recycle();
             }
             return b2;
         }
         float bitmapWidthF = source.getWidth();
         float bitmapHeightF = source.getHeight();

         float bitmapAspect = bitmapWidthF / bitmapHeightF;
         float viewAspect   = (float) targetWidth / targetHeight;

         if (bitmapAspect > viewAspect) {
             float scale = targetHeight / bitmapHeightF;
             if (scale < .9F || scale > 1F) {
                 scaler.setScale(scale, scale);
             } else {
                 scaler = null;
             }
         } else {
             float scale = targetWidth / bitmapWidthF;
             if (scale < .9F || scale > 1F) {
                 scaler.setScale(scale, scale);
             } else {
                 scaler = null;
             }
         }

         Bitmap b1;
         if (scaler != null) {
             // this is used for minithumb and crop, so we want to filter here.
             b1 = Bitmap.createBitmap(source, 0, 0,
             source.getWidth(), source.getHeight(), scaler, true);
         } else {
             b1 = source;
         }

         if (recycle && b1 != source) {
             source.recycle();
         }

         int dx1 = Math.max(0, b1.getWidth() - targetWidth);
         int dy1 = Math.max(0, b1.getHeight() - targetHeight);

         Bitmap b2 = Bitmap.createBitmap(
                 b1,
                 dx1 / 2,
                 dy1 / 2,
                 targetWidth,
                 targetHeight);

         if (b2 != b1) {
             if (recycle || b1 != source) {
                 b1.recycle();
             }
         }

         return b2;
     }

     private static final String[] THUMB_PROJECTION = new String[] {
         BaseColumns._ID // 0
     };

     /**
      * Look up thumbnail uri by given imageId, it will be automatically created if it's not created
      * yet. Most of the time imageId is identical to thumbId, but it's not always true.
      */
     private static Uri getImageThumbnailUri(ContentResolver cr, long origId, int width, int height) {
         Uri thumbUri = Images.Thumbnails.EXTERNAL_CONTENT_URI;
         Cursor c = cr.query(thumbUri, THUMB_PROJECTION,
               Thumbnails.IMAGE_ID + "=?",
               new String[]{String.valueOf(origId)}, null);
         if (c == null) return null;
         try {
             if (c.moveToNext()) {
                 return ContentUris.withAppendedId(thumbUri, c.getLong(0));
             }
         } finally {
             if (c != null) c.close();
         }

         ContentValues values = new ContentValues(4);
         values.put(Thumbnails.KIND, Thumbnails.MINI_KIND);
         values.put(Thumbnails.IMAGE_ID, origId);
         values.put(Thumbnails.HEIGHT, height);
         values.put(Thumbnails.WIDTH, width);
         try {
             return cr.insert(thumbUri, values);
         } catch (Exception ex) {
             Log.w(TAG, ex);
             return null;
         }
     }

     /**
      * Store a given thumbnail in the database. (Bitmap)
      */
     private static boolean storeThumbnail(ContentResolver cr, long origId, Bitmap thumb) {
         if (thumb == null) return false;
         try {
             Uri uri = getImageThumbnailUri(cr, origId, thumb.getWidth(), thumb.getHeight());
             if (uri == null) return false;
             OutputStream thumbOut = cr.openOutputStream(uri);
             thumb.compress(Bitmap.CompressFormat.JPEG, 85, thumbOut);
             thumbOut.close();
             return true;
         } catch (Throwable t) {
             Log.e(TAG, "Unable to store thumbnail", t);
             return false;
         }
     }

     /**
      * Store a given thumbnail in the database. (byte array)
      */
     private static boolean storeThumbnail(ContentResolver cr, long origId, byte[] jpegThumbnail,
             int width, int height) {
         if (jpegThumbnail == null) return false;

         Uri uri = getImageThumbnailUri(cr, origId, width, height);
         if (uri == null) {
             return false;
         }
         try {
             OutputStream thumbOut = cr.openOutputStream(uri);
             thumbOut.write(jpegThumbnail);
             thumbOut.close();
             return true;
         } catch (Throwable t) {
             Log.e(TAG, "Unable to store thumbnail", t);
             return false;
         }
     }

     /**
      * SizedThumbnailBitmap contains the bitmap, which is downsampled either from
      * the thumbnail in exif or the full image.
      * mThumbnailData, mThumbnailWidth and mThumbnailHeight are set together only if mThumbnail
      * is not null.
      *
      * The width/height of the sized bitmap may be different from mThumbnailWidth/mThumbnailHeight.
      */
     private static class SizedThumbnailBitmap {
         public byte[] mThumbnailData;
         public Bitmap mBitmap;
         public int mThumbnailWidth;
         public int mThumbnailHeight;
     }

     /**
      * Creates a bitmap by either downsampling from the thumbnail in EXIF or the full image.
      * The functions returns a SizedThumbnailBitmap,
      * which contains a downsampled bitmap and the thumbnail data in EXIF if exists.
      */
     private static void createThumbnailFromEXIF(String filePath, int targetSize,
             int maxPixels, SizedThumbnailBitmap sizedThumbBitmap) {
         if (filePath == null) return;

         ExifInterface exif = null;
         byte [] thumbData = null;
         try {
             exif = new ExifInterface(filePath);
             if (exif != null) {
                 thumbData = exif.getThumbnail();
             }
         } catch (IOException ex) {
             Log.w(TAG, ex);
         }

         BitmapFactory.Options fullOptions = new BitmapFactory.Options();
         BitmapFactory.Options exifOptions = new BitmapFactory.Options();
         int exifThumbWidth = 0;
         int fullThumbWidth = 0;

         // Compute exifThumbWidth.
         if (thumbData != null) {
             exifOptions.inJustDecodeBounds = true;
             BitmapFactory.decodeByteArray(thumbData, 0, thumbData.length, exifOptions);
             exifOptions.inSampleSize = computeSampleSize(exifOptions, targetSize, maxPixels);
             exifThumbWidth = exifOptions.outWidth / exifOptions.inSampleSize;
         }

         // Compute fullThumbWidth.
         fullOptions.inJustDecodeBounds = true;
         BitmapFactory.decodeFile(filePath, fullOptions);
         fullOptions.inSampleSize = computeSampleSize(fullOptions, targetSize, maxPixels);
         fullThumbWidth = fullOptions.outWidth / fullOptions.inSampleSize;

         // Choose the larger thumbnail as the returning sizedThumbBitmap.
         if (exifThumbWidth >= fullThumbWidth) {
             int width = exifOptions.outWidth;
             int height = exifOptions.outHeight;
             exifOptions.inJustDecodeBounds = false;
             sizedThumbBitmap.mBitmap = BitmapFactory.decodeByteArray(thumbData, 0,
                     thumbData.length, exifOptions);
             if (sizedThumbBitmap.mBitmap != null) {
                 sizedThumbBitmap.mThumbnailData = thumbData;
                 sizedThumbBitmap.mThumbnailWidth = width;
                 sizedThumbBitmap.mThumbnailHeight = height;
             }
         } else {
             fullOptions.inJustDecodeBounds = false;
             sizedThumbBitmap.mBitmap = BitmapFactory.decodeFile(filePath, fullOptions);
         }
     }
 }
	/*
	* Copyright (C) 2009 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package android.media;

	import android.content.ContentResolver;
	import android.content.ContentUris;
	import android.content.ContentValues;
	import android.database.Cursor;
	import android.graphics.Bitmap;
	import android.graphics.BitmapFactory;
	import android.graphics.Canvas;
	import android.graphics.Matrix;
	import android.graphics.Rect;
	import android.media.MediaMetadataRetriever;
	import android.media.MediaFile.MediaFileType;
	import android.net.Uri;
	import android.os.ParcelFileDescriptor;
	import android.provider.BaseColumns;
	import android.provider.MediaStore.Images;
	import android.provider.MediaStore.Images.Thumbnails;
	import android.util.Log;

	import java.io.FileDescriptor;
	import java.io.IOException;
	import java.io.OutputStream;

	/**
	* Thumbnail generation routines for media provider.
	*/

	public class ThumbnailUtils {
	private static final String TAG = "ThumbnailUtils";

	/* Maximum pixels size for created bitmap. */
	private static final int THUMBNAIL_MAX_NUM_PIXELS = 512 * 384;
	private static final int MINI_THUMB_MAX_NUM_PIXELS = 128 * 128;
	private static final int UNCONSTRAINED = -1;

	/* Whether we should rotate the resulting bitmap. */
	private static final boolean ROTATE_AS_NEEDED = true;
	private static final boolean NO_ROTATE = false;

	/* Whether we should create bitmap in native memory. */
	private static final boolean USE_NATIVE = true;
	private static final boolean NO_NATIVE = false;

	/**
	* Constant used to indicate we should recycle the input in
	* {@link #extractMiniThumb(Bitmap, int, int, boolean)} unless the output is the input.
	*/
	public static final boolean RECYCLE_INPUT = true;

	/**
	* Constant used to indicate we should not recycle the input in
	* {@link #extractMiniThumb(Bitmap, int, int, boolean)}.
	*/
	public static final boolean NO_RECYCLE_INPUT = false;

	/**
	* Constant used to indicate the dimension of normal thumbnail in
	* {@link #extractMiniThumb(Bitmap, int, int, boolean)}.
	*/
	public static final int THUMBNAIL_TARGET_SIZE = 320;

	/**
	* Constant used to indicate the dimension of mini thumbnail in
	* {@link #extractMiniThumb(Bitmap, int, int, boolean)}.
	*/
	public static final int MINI_THUMB_TARGET_SIZE = 96;

	/**
	* This method first examines if the thumbnail embedded in EXIF is bigger than our target
	* size. If not, then it'll create a thumbnail from original image. Due to efficiency
	* consideration, we want to let MediaThumbRequest avoid calling this method twice for
	* both kinds, so it only requests for MICRO_KIND and set saveImage to true.
	*
	* This method always returns a "square thumbnail" for MICRO_KIND thumbnail.
	*
	* @param cr ContentResolver
	* @param filePath file path needed by EXIF interface
	* @param uri URI of original image
	* @param origId image id
	* @param kind either MINI_KIND or MICRO_KIND
	* @param saveMini Whether to save MINI_KIND thumbnail obtained in this method.
	* @return Bitmap
	*/
	public static Bitmap createImageThumbnail(ContentResolver cr, String filePath, Uri uri,
	long origId, int kind, boolean saveMini) {
	boolean wantMini = (kind == Images.Thumbnails.MINI_KIND \|\| saveMini);
	int targetSize = wantMini ?
	THUMBNAIL_TARGET_SIZE : MINI_THUMB_TARGET_SIZE;
	int maxPixels = wantMini ?
	THUMBNAIL_MAX_NUM_PIXELS : MINI_THUMB_MAX_NUM_PIXELS;
	SizedThumbnailBitmap sizedThumbnailBitmap = new SizedThumbnailBitmap();
	Bitmap bitmap = null;
	MediaFileType fileType = MediaFile.getFileType(filePath);
	if (fileType != null && fileType.fileType == MediaFile.FILE_TYPE_JPEG) {
	createThumbnailFromEXIF(filePath, targetSize, maxPixels, sizedThumbnailBitmap);
	bitmap = sizedThumbnailBitmap.mBitmap;
	}

	if (bitmap == null) {
	bitmap = makeBitmap(targetSize, maxPixels, uri, cr);
	}

	if (bitmap == null) {
	return null;
	}

	if (saveMini) {
	if (sizedThumbnailBitmap.mThumbnailData != null) {
	storeThumbnail(cr, origId,
	sizedThumbnailBitmap.mThumbnailData,
	sizedThumbnailBitmap.mThumbnailWidth,
	sizedThumbnailBitmap.mThumbnailHeight);
	} else {
	storeThumbnail(cr, origId, bitmap);
	}
	}

	if (kind == Images.Thumbnails.MICRO_KIND) {
	// now we make it a "square thumbnail" for MICRO_KIND thumbnail
	bitmap = extractMiniThumb(bitmap,
	MINI_THUMB_TARGET_SIZE,
	MINI_THUMB_TARGET_SIZE, RECYCLE_INPUT);
	}
	return bitmap;
	}

	/**
	* Create a video thumbnail for a video. May return null if the video is
	* corrupt.
	*
	* @param filePath
	*/
	public static Bitmap createVideoThumbnail(String filePath) {
	Bitmap bitmap = null;
	MediaMetadataRetriever retriever = new MediaMetadataRetriever();
	try {
	retriever.setMode(MediaMetadataRetriever.MODE_CAPTURE_FRAME_ONLY);
	retriever.setDataSource(filePath);
	bitmap = retriever.captureFrame();
	} catch (IllegalArgumentException ex) {
	// Assume this is a corrupt video file
	} catch (RuntimeException ex) {
	// Assume this is a corrupt video file.
	} finally {
	try {
	retriever.release();
	} catch (RuntimeException ex) {
	// Ignore failures while cleaning up.
	}
	}
	return bitmap;
	}

	/**
	* Creates a centered bitmap of the desired size.
	*
	* @param source original bitmap source
	* @param width targeted width
	* @param height targeted height
	* @param recycle whether we want to recycle the input
	*/
	public static Bitmap extractMiniThumb(
	Bitmap source, int width, int height, boolean recycle) {
	if (source == null) {
	return null;
	}

	float scale;
	if (source.getWidth() < source.getHeight()) {
	scale = width / (float) source.getWidth();
	} else {
	scale = height / (float) source.getHeight();
	}
	Matrix matrix = new Matrix();
	matrix.setScale(scale, scale);
	Bitmap miniThumbnail = transform(matrix, source, width, height, true, recycle);
	return miniThumbnail;
	}

	/*
	* Compute the sample size as a function of minSideLength
	* and maxNumOfPixels.
	* minSideLength is used to specify that minimal width or height of a
	* bitmap.
	* maxNumOfPixels is used to specify the maximal size in pixels that is
	* tolerable in terms of memory usage.
	*
	* The function returns a sample size based on the constraints.
	* Both size and minSideLength can be passed in as IImage.UNCONSTRAINED,
	* which indicates no care of the corresponding constraint.
	* The functions prefers returning a sample size that
	* generates a smaller bitmap, unless minSideLength = IImage.UNCONSTRAINED.
	*
	* Also, the function rounds up the sample size to a power of 2 or multiple
	* of 8 because BitmapFactory only honors sample size this way.
	* For example, BitmapFactory downsamples an image by 2 even though the
	* request is 3. So we round up the sample size to avoid OOM.
	*/
	private static int computeSampleSize(BitmapFactory.Options options,
	int minSideLength, int maxNumOfPixels) {
	int initialSize = computeInitialSampleSize(options, minSideLength,
	maxNumOfPixels);

	int roundedSize;
	if (initialSize <= 8 ) {
	roundedSize = 1;
	while (roundedSize < initialSize) {
	roundedSize <<= 1;
	}
	} else {
	roundedSize = (initialSize + 7) / 8 * 8;
	}

	return roundedSize;
	}

	private static int computeInitialSampleSize(BitmapFactory.Options options,
	int minSideLength, int maxNumOfPixels) {
	double w = options.outWidth;
	double h = options.outHeight;

	int lowerBound = (maxNumOfPixels == UNCONSTRAINED) ? 1 :
	(int) Math.ceil(Math.sqrt(w * h / maxNumOfPixels));
	int upperBound = (minSideLength == UNCONSTRAINED) ? 128 :
	(int) Math.min(Math.floor(w / minSideLength),
	Math.floor(h / minSideLength));

	if (upperBound < lowerBound) {
	// return the larger one when there is no overlapping zone.
	return lowerBound;
	}

	if ((maxNumOfPixels == UNCONSTRAINED) &&
	(minSideLength == UNCONSTRAINED)) {
	return 1;
	} else if (minSideLength == UNCONSTRAINED) {
	return lowerBound;
	} else {
	return upperBound;
	}
	}

	/**
	* Returns Options that set the native alloc flag for Bitmap decode.
	*/
	private static BitmapFactory.Options createNativeAllocOptions() {
	BitmapFactory.Options options = new BitmapFactory.Options();
	options.inNativeAlloc = true;
	return options;
	}

	/**
	* Make a bitmap from a given Uri, minimal side length, and maximum number of pixels.
	*/
	private static Bitmap makeBitmap(int minSideLength, int maxNumOfPixels,
	Uri uri, ContentResolver cr) {
	return makeBitmap(minSideLength, maxNumOfPixels, uri, cr,
	NO_NATIVE);
	}

	/**
	* Make a bitmap from a given Uri, minimal side length, and maximum number of pixels.
	* The image data will be read from specified ContentResolver and clients are allowed to specify
	* whether they want the Bitmap be created in native memory.
	*/
	private static Bitmap makeBitmap(int minSideLength, int maxNumOfPixels,
	Uri uri, ContentResolver cr, boolean useNative) {
	ParcelFileDescriptor input = null;
	try {
	input = cr.openFileDescriptor(uri, "r");
	BitmapFactory.Options options = null;
	if (useNative) {
	options = createNativeAllocOptions();
	}
	return makeBitmap(minSideLength, maxNumOfPixels, uri, cr, input,
	options);
	} catch (IOException ex) {
	Log.e(TAG, "", ex);
	return null;
	} finally {
	closeSilently(input);
	}
	}

	/**
	* Make a bitmap from a given Uri, minimal side length, and maximum number of pixels.
	* The image data will be read from specified pfd if it's not null, otherwise
	* a new input stream will be created using specified ContentResolver.
	*
	* Clients are allowed to pass their own BitmapFactory.Options used for bitmap decoding. A
	* new BitmapFactory.Options will be created if options is null.
	*/
	private static Bitmap makeBitmap(int minSideLength, int maxNumOfPixels,
	Uri uri, ContentResolver cr, ParcelFileDescriptor pfd,
	BitmapFactory.Options options) {
	Bitmap b = null;
	try {
	if (pfd == null) pfd = makeInputStream(uri, cr);
	if (pfd == null) return null;
	if (options == null) options = new BitmapFactory.Options();

	FileDescriptor fd = pfd.getFileDescriptor();
	options.inSampleSize = 1;
	options.inJustDecodeBounds = true;
	BitmapFactory.decodeFileDescriptor(fd, null, options);
	if (options.mCancel \|\| options.outWidth == -1
	\|\| options.outHeight == -1) {
	return null;
	}
	options.inSampleSize = computeSampleSize(
	options, minSideLength, maxNumOfPixels);
	options.inJustDecodeBounds = false;

	options.inDither = false;
	options.inPreferredConfig = Bitmap.Config.ARGB_8888;
	b = BitmapFactory.decodeFileDescriptor(fd, null, options);
	} catch (OutOfMemoryError ex) {
	Log.e(TAG, "Got oom exception ", ex);
	return null;
	} finally {
	closeSilently(pfd);
	}
	return b;
	}

	/**
	* Rotates the bitmap by the specified degree.
	* If a new bitmap is created, the original bitmap is recycled.
	*/
	private static Bitmap rotate(Bitmap b, int degrees) {
	if (degrees != 0 && b != null) {
	Matrix m = new Matrix();
	m.setRotate(degrees,
	(float) b.getWidth() / 2, (float) b.getHeight() / 2);
	try {
	Bitmap b2 = Bitmap.createBitmap(
	b, 0, 0, b.getWidth(), b.getHeight(), m, true);
	if (b != b2) {
	b.recycle();
	b = b2;
	}
	} catch (OutOfMemoryError ex) {
	// We have no memory to rotate. Return the original bitmap.
	}
	}
	return b;
	}

	private static void closeSilently(ParcelFileDescriptor c) {
	if (c == null) return;
	try {
	c.close();
	} catch (Throwable t) {
	// do nothing
	}
	}

	private static ParcelFileDescriptor makeInputStream(
	Uri uri, ContentResolver cr) {
	try {
	return cr.openFileDescriptor(uri, "r");
	} catch (IOException ex) {
	return null;
	}
	}

	/**
	* Transform source Bitmap to targeted width and height.
	*/
	private static Bitmap transform(Matrix scaler,
	Bitmap source,
	int targetWidth,
	int targetHeight,
	boolean scaleUp,
	boolean recycle) {

	int deltaX = source.getWidth() - targetWidth;
	int deltaY = source.getHeight() - targetHeight;
	if (!scaleUp && (deltaX < 0 \|\| deltaY < 0)) {
	/*
	* In this case the bitmap is smaller, at least in one dimension,
	* than the target. Transform it by placing as much of the image
	* as possible into the target and leaving the top/bottom or
	* left/right (or both) black.
	*/
	Bitmap b2 = Bitmap.createBitmap(targetWidth, targetHeight,
	Bitmap.Config.ARGB_8888);
	Canvas c = new Canvas(b2);

	int deltaXHalf = Math.max(0, deltaX / 2);
	int deltaYHalf = Math.max(0, deltaY / 2);
	Rect src = new Rect(
	deltaXHalf,
	deltaYHalf,
	deltaXHalf + Math.min(targetWidth, source.getWidth()),
	deltaYHalf + Math.min(targetHeight, source.getHeight()));
	int dstX = (targetWidth - src.width()) / 2;
	int dstY = (targetHeight - src.height()) / 2;
	Rect dst = new Rect(
	dstX,
	dstY,
	targetWidth - dstX,
	targetHeight - dstY);
	c.drawBitmap(source, src, dst, null);
	if (recycle) {
	source.recycle();
	}
	return b2;
	}
	float bitmapWidthF = source.getWidth();
	float bitmapHeightF = source.getHeight();

	float bitmapAspect = bitmapWidthF / bitmapHeightF;
	float viewAspect = (float) targetWidth / targetHeight;

	if (bitmapAspect > viewAspect) {
	float scale = targetHeight / bitmapHeightF;
	if (scale < .9F \|\| scale > 1F) {
	scaler.setScale(scale, scale);
	} else {
	scaler = null;
	}
	} else {
	float scale = targetWidth / bitmapWidthF;
	if (scale < .9F \|\| scale > 1F) {
	scaler.setScale(scale, scale);
	} else {
	scaler = null;
	}
	}

	Bitmap b1;
	if (scaler != null) {
	// this is used for minithumb and crop, so we want to filter here.
	b1 = Bitmap.createBitmap(source, 0, 0,
	source.getWidth(), source.getHeight(), scaler, true);
	} else {
	b1 = source;
	}

	if (recycle && b1 != source) {
	source.recycle();
	}

	int dx1 = Math.max(0, b1.getWidth() - targetWidth);
	int dy1 = Math.max(0, b1.getHeight() - targetHeight);

	Bitmap b2 = Bitmap.createBitmap(
	b1,
	dx1 / 2,
	dy1 / 2,
	targetWidth,
	targetHeight);

	if (b2 != b1) {
	if (recycle \|\| b1 != source) {
	b1.recycle();
	}
	}

	return b2;
	}

	private static final String[] THUMB_PROJECTION = new String[] {
	BaseColumns._ID // 0
	};

	/**
	* Look up thumbnail uri by given imageId, it will be automatically created if it's not created
	* yet. Most of the time imageId is identical to thumbId, but it's not always true.
	*/
	private static Uri getImageThumbnailUri(ContentResolver cr, long origId, int width, int height) {
	Uri thumbUri = Images.Thumbnails.EXTERNAL_CONTENT_URI;
	Cursor c = cr.query(thumbUri, THUMB_PROJECTION,
	Thumbnails.IMAGE_ID + "=?",
	new String[]{String.valueOf(origId)}, null);
	if (c == null) return null;
	try {
	if (c.moveToNext()) {
	return ContentUris.withAppendedId(thumbUri, c.getLong(0));
	}
	} finally {
	if (c != null) c.close();
	}

	ContentValues values = new ContentValues(4);
	values.put(Thumbnails.KIND, Thumbnails.MINI_KIND);
	values.put(Thumbnails.IMAGE_ID, origId);
	values.put(Thumbnails.HEIGHT, height);
	values.put(Thumbnails.WIDTH, width);
	try {
	return cr.insert(thumbUri, values);
	} catch (Exception ex) {
	Log.w(TAG, ex);
	return null;
	}
	}

	/**
	* Store a given thumbnail in the database. (Bitmap)
	*/
	private static boolean storeThumbnail(ContentResolver cr, long origId, Bitmap thumb) {
	if (thumb == null) return false;
	try {
	Uri uri = getImageThumbnailUri(cr, origId, thumb.getWidth(), thumb.getHeight());
	if (uri == null) return false;
	OutputStream thumbOut = cr.openOutputStream(uri);
	thumb.compress(Bitmap.CompressFormat.JPEG, 85, thumbOut);
	thumbOut.close();
	return true;
	} catch (Throwable t) {
	Log.e(TAG, "Unable to store thumbnail", t);
	return false;
	}
	}

	/**
	* Store a given thumbnail in the database. (byte array)
	*/
	private static boolean storeThumbnail(ContentResolver cr, long origId, byte[] jpegThumbnail,
	int width, int height) {
	if (jpegThumbnail == null) return false;

	Uri uri = getImageThumbnailUri(cr, origId, width, height);
	if (uri == null) {
	return false;
	}
	try {
	OutputStream thumbOut = cr.openOutputStream(uri);
	thumbOut.write(jpegThumbnail);
	thumbOut.close();
	return true;
	} catch (Throwable t) {
	Log.e(TAG, "Unable to store thumbnail", t);
	return false;
	}
	}

	/**
	* SizedThumbnailBitmap contains the bitmap, which is downsampled either from
	* the thumbnail in exif or the full image.
	* mThumbnailData, mThumbnailWidth and mThumbnailHeight are set together only if mThumbnail
	* is not null.
	*
	* The width/height of the sized bitmap may be different from mThumbnailWidth/mThumbnailHeight.
	*/
	private static class SizedThumbnailBitmap {
	public byte[] mThumbnailData;
	public Bitmap mBitmap;
	public int mThumbnailWidth;
	public int mThumbnailHeight;
	}

	/**
	* Creates a bitmap by either downsampling from the thumbnail in EXIF or the full image.
	* The functions returns a SizedThumbnailBitmap,
	* which contains a downsampled bitmap and the thumbnail data in EXIF if exists.
	*/
	private static void createThumbnailFromEXIF(String filePath, int targetSize,
	int maxPixels, SizedThumbnailBitmap sizedThumbBitmap) {
	if (filePath == null) return;

	ExifInterface exif = null;
	byte [] thumbData = null;
	try {
	exif = new ExifInterface(filePath);
	if (exif != null) {
	thumbData = exif.getThumbnail();
	}
	} catch (IOException ex) {
	Log.w(TAG, ex);
	}

	BitmapFactory.Options fullOptions = new BitmapFactory.Options();
	BitmapFactory.Options exifOptions = new BitmapFactory.Options();
	int exifThumbWidth = 0;
	int fullThumbWidth = 0;

	// Compute exifThumbWidth.
	if (thumbData != null) {
	exifOptions.inJustDecodeBounds = true;
	BitmapFactory.decodeByteArray(thumbData, 0, thumbData.length, exifOptions);
	exifOptions.inSampleSize = computeSampleSize(exifOptions, targetSize, maxPixels);
	exifThumbWidth = exifOptions.outWidth / exifOptions.inSampleSize;
	}

	// Compute fullThumbWidth.
	fullOptions.inJustDecodeBounds = true;
	BitmapFactory.decodeFile(filePath, fullOptions);
	fullOptions.inSampleSize = computeSampleSize(fullOptions, targetSize, maxPixels);
	fullThumbWidth = fullOptions.outWidth / fullOptions.inSampleSize;

	// Choose the larger thumbnail as the returning sizedThumbBitmap.
	if (exifThumbWidth >= fullThumbWidth) {
	int width = exifOptions.outWidth;
	int height = exifOptions.outHeight;
	exifOptions.inJustDecodeBounds = false;
	sizedThumbBitmap.mBitmap = BitmapFactory.decodeByteArray(thumbData, 0,
	thumbData.length, exifOptions);
	if (sizedThumbBitmap.mBitmap != null) {
	sizedThumbBitmap.mThumbnailData = thumbData;
	sizedThumbBitmap.mThumbnailWidth = width;
	sizedThumbBitmap.mThumbnailHeight = height;
	}
	} else {
	fullOptions.inJustDecodeBounds = false;
	sizedThumbBitmap.mBitmap = BitmapFactory.decodeFile(filePath, fullOptions);
	}
	}
	}