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ThumbnailUtils.javaAPI DocAndroid 5.1 API19576Thu Mar 12 22:22:30 GMT 2015android.media

ThumbnailUtils

public class ThumbnailUtils extends Object
Thumbnail generation routines for media provider.

Fields Summary
private static final String
TAG
private static final int
MAX_NUM_PIXELS_THUMBNAIL
private static final int
MAX_NUM_PIXELS_MICRO_THUMBNAIL
private static final int
UNCONSTRAINED
private static final int
OPTIONS_NONE
private static final int
OPTIONS_SCALE_UP
public static final int
OPTIONS_RECYCLE_INPUT
Constant used to indicate we should recycle the input in {@link #extractThumbnail(Bitmap, int, int, int)} unless the output is the input.
public static final int
TARGET_SIZE_MINI_THUMBNAIL
Constant used to indicate the dimension of mini thumbnail.
public static final int
TARGET_SIZE_MICRO_THUMBNAIL
Constant used to indicate the dimension of micro thumbnail.
Constructors Summary
Methods Summary
private static voidcloseSilently(android.os.ParcelFileDescriptor c)

      if (c == null) return;
      try {
          c.close();
      } catch (Throwable t) {
          // do nothing
      }
private static intcomputeInitialSampleSize(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;
        }
private static intcomputeSampleSize(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;
public static android.graphics.BitmapcreateImageThumbnail(java.lang.String filePath, int kind)
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
filePath the path of image file
param
kind could be MINI_KIND or MICRO_KIND
return
Bitmap, or null on failures
hide
This method is only used by media framework and media provider internally.


                                                                                                          
           
        boolean wantMini = (kind == Images.Thumbnails.MINI_KIND);
        int targetSize = wantMini
                ? TARGET_SIZE_MINI_THUMBNAIL
                : TARGET_SIZE_MICRO_THUMBNAIL;
        int maxPixels = wantMini
                ? MAX_NUM_PIXELS_THUMBNAIL
                : MAX_NUM_PIXELS_MICRO_THUMBNAIL;
        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) {
            FileInputStream stream = null;
            try {
                stream = new FileInputStream(filePath);
                FileDescriptor fd = stream.getFD();
                BitmapFactory.Options options = new BitmapFactory.Options();
                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, targetSize, maxPixels);
                options.inJustDecodeBounds = false;

                options.inDither = false;
                options.inPreferredConfig = Bitmap.Config.ARGB_8888;
                bitmap = BitmapFactory.decodeFileDescriptor(fd, null, options);
            } catch (IOException ex) {
                Log.e(TAG, "", ex);
            } catch (OutOfMemoryError oom) {
                Log.e(TAG, "Unable to decode file " + filePath + ". OutOfMemoryError.", oom);
            } finally {
                try {
                    if (stream != null) {
                        stream.close();
                    }
                } catch (IOException ex) {
                    Log.e(TAG, "", ex);
                }
            }

        }

        if (kind == Images.Thumbnails.MICRO_KIND) {
            // now we make it a "square thumbnail" for MICRO_KIND thumbnail
            bitmap = extractThumbnail(bitmap,
                    TARGET_SIZE_MICRO_THUMBNAIL,
                    TARGET_SIZE_MICRO_THUMBNAIL, OPTIONS_RECYCLE_INPUT);
        }
        return bitmap;
private static voidcreateThumbnailFromEXIF(java.lang.String filePath, int targetSize, int maxPixels, android.media.ThumbnailUtils$SizedThumbnailBitmap sizedThumbBitmap)
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.

        if (filePath == null) return;

        ExifInterface exif = null;
        byte [] thumbData = null;
        try {
            exif = new ExifInterface(filePath);
            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 (thumbData != null && 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);
        }
public static android.graphics.BitmapcreateVideoThumbnail(java.lang.String filePath, int kind)
Create a video thumbnail for a video. May return null if the video is corrupt or the format is not supported.

param
filePath the path of video file
param
kind could be MINI_KIND or MICRO_KIND

        Bitmap bitmap = null;
        MediaMetadataRetriever retriever = new MediaMetadataRetriever();
        try {
            retriever.setDataSource(filePath);
            bitmap = retriever.getFrameAtTime(-1);
        } 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.
            }
        }

        if (bitmap == null) return null;

        if (kind == Images.Thumbnails.MINI_KIND) {
            // Scale down the bitmap if it's too large.
            int width = bitmap.getWidth();
            int height = bitmap.getHeight();
            int max = Math.max(width, height);
            if (max > 512) {
                float scale = 512f / max;
                int w = Math.round(scale * width);
                int h = Math.round(scale * height);
                bitmap = Bitmap.createScaledBitmap(bitmap, w, h, true);
            }
        } else if (kind == Images.Thumbnails.MICRO_KIND) {
            bitmap = extractThumbnail(bitmap,
                    TARGET_SIZE_MICRO_THUMBNAIL,
                    TARGET_SIZE_MICRO_THUMBNAIL,
                    OPTIONS_RECYCLE_INPUT);
        }
        return bitmap;
public static android.graphics.BitmapextractThumbnail(android.graphics.Bitmap source, int width, int height)
Creates a centered bitmap of the desired size.

param
source original bitmap source
param
width targeted width
param
height targeted height

        return extractThumbnail(source, width, height, OPTIONS_NONE);
public static android.graphics.BitmapextractThumbnail(android.graphics.Bitmap source, int width, int height, int options)
Creates a centered bitmap of the desired size.

param
source original bitmap source
param
width targeted width
param
height targeted height
param
options options used during thumbnail extraction

        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 thumbnail = transform(matrix, source, width, height,
                OPTIONS_SCALE_UP | options);
        return thumbnail;
private static android.graphics.BitmapmakeBitmap(int minSideLength, int maxNumOfPixels, android.net.Uri uri, android.content.ContentResolver cr, android.os.ParcelFileDescriptor pfd, BitmapFactory.Options options)
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.

        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;
private static android.os.ParcelFileDescriptormakeInputStream(android.net.Uri uri, android.content.ContentResolver cr)

        try {
            return cr.openFileDescriptor(uri, "r");
        } catch (IOException ex) {
            return null;
        }
private static android.graphics.Bitmaptransform(android.graphics.Matrix scaler, android.graphics.Bitmap source, int targetWidth, int targetHeight, int options)
Transform source Bitmap to targeted width and height.

        boolean scaleUp = (options & OPTIONS_SCALE_UP) != 0;
        boolean recycle = (options & OPTIONS_RECYCLE_INPUT) != 0;

        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();
            }
            c.setBitmap(null);
            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;