Wiedermal ein Thumbnailproblem...

package de.unicate.android.thumbnailtest;

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.database.Cursor;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;

public class ThumbnailTestActivity extends Activity {
    
    private ImageView _image;
    private long _id;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        _image = ((ImageView)findViewById(R.id.imageTest));
        
        _image.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View v) {
                _image.setImageBitmap(BitmapFactory.decodeFile("/mnt/sdcard/tmp/srgg.jpg"));
                _image.invalidate();
            }
        });
        
        _id = getIdByPath("/mnt/sdcard/tmp/srgg.jpg");
        
        ((Button)findViewById(R.id.buttonUpdate)).setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View v) {
                // we want to receive if the mediascanner finished scanning the sdcard
                IntentFilter intentFilter = new IntentFilter(Intent.ACTION_MEDIA_SCANNER_FINISHED);
                // after the mediascanner finished scanning files
                intentFilter.addDataScheme("file");
                // registering the receiver
                registerReceiver(_receiver, intentFilter);
                //
                sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://" + Environment.getExternalStorageDirectory())));
                
            }
        });
        
        showImage(_id);
        
    }
    
    public long getIdByPath(String path) {
        String[] projection = { MediaStore.Images.ImageColumns._ID,
                                MediaStore.Images.ImageColumns.DATA
                };

        long id = -1;
        Cursor cursor = getContentResolver().query(
                MediaStore.Images.Media.EXTERNAL_CONTENT_URI, 
                projection, 
                MediaStore.Images.ImageColumns.DATA + " = ?", 
                new String[]{path}, null);
        if(null != cursor && cursor.getCount() > 0) {
            if(cursor.moveToFirst()) {
                id = cursor.getLong(cursor.getColumnIndex(MediaStore.Images.ImageColumns._ID));
            }
            cursor.close();
        }
        return id;
    }
    
    
    public void showImage(long id) {
        if(id > 0) {
                _image.setImageBitmap(MediaStore.Images.Thumbnails.getThumbnail(getContentResolver(),id ,MediaStore.Images.Thumbnails.MICRO_KIND,null));
            _image.invalidate();
        }
    }
    private BroadcastReceiver _receiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            showImage(_id);
            unregisterReceiver(this);
            
        }
        
    };
}

package de.unicate.android.thumbnailtest;
/*
 * 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.
 */
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileLock;
import java.util.Hashtable;

import android.graphics.Bitmap;
import android.net.Uri;
import android.os.Environment;
import android.util.Log;

/**
 * This class handles the mini-thumb file. A mini-thumb file consists
 * of blocks, indexed by id. Each block has BYTES_PER_MINTHUMB bytes in the
 * following format:
 *
 * 1 byte status (0 = empty, 1 = mini-thumb available)
 * 8 bytes magic (a magic number to match what's in the database)
 * 4 bytes data length (LEN)
 * LEN bytes jpeg data
 * (the remaining bytes are unused)
 *
 * @hide This file is shared between MediaStore and MediaProvider and should remained internal use
 *       only.
 */
public class MiniThumbFile {
    private static final String TAG = "MiniThumbFile";
    private static final int MINI_THUMB_DATA_FILE_VERSION = 3;
    public static final int BYTES_PER_MINTHUMB = 10000;
    private static final int HEADER_SIZE = 1 + 8 + 4;
    private Uri mUri;
    private RandomAccessFile mMiniThumbFile;
    private FileChannel mChannel;
    private ByteBuffer mBuffer;
    private static Hashtable<String, MiniThumbFile> sThumbFiles =
        new Hashtable<String, MiniThumbFile>();

    /**
     * We store different types of thumbnails in different files. To remain backward compatibility,
     * we should hashcode of content://media/external/images/media remains the same.
     */
    public static synchronized void reset() {
        for (MiniThumbFile file : sThumbFiles.values()) {
            file.deactivate();
        }
        sThumbFiles.clear();
    }

    public static synchronized MiniThumbFile instance(Uri uri) {
        String type = uri.getPathSegments().get(1);
        MiniThumbFile file = sThumbFiles.get(type);
        // Log.v(TAG, "get minithumbfile for type: "+type);
        if (file == null) {
            file = new MiniThumbFile(
                    Uri.parse("content://media/external/" + type + "/media"));
            sThumbFiles.put(type, file);
        }

        return file;
    }

    private String randomAccessFilePath(int version) {
        String directoryName =
                Environment.getExternalStorageDirectory().toString()
                + "/DCIM/.thumbnails";
        return directoryName + "/.thumbdata" + version + "-" + mUri.hashCode();
    }

    private void removeOldFile() {
        String oldPath = randomAccessFilePath(MINI_THUMB_DATA_FILE_VERSION - 1);
        File oldFile = new File(oldPath);
        if (oldFile.exists()) {
            try {
                oldFile.delete();
            } catch (SecurityException ex) {
                // ignore
            }
        }
    }

    private RandomAccessFile miniThumbDataFile() {
        if (mMiniThumbFile == null) {
            removeOldFile();
            String path = randomAccessFilePath(MINI_THUMB_DATA_FILE_VERSION);
            File directory = new File(path).getParentFile();
            if (!directory.isDirectory()) {
                if (!directory.mkdirs()) {
                    Log.e(TAG, "Unable to create .thumbnails directory "
                            + directory.toString());
                }
            }
            File f = new File(path);
            try {
                mMiniThumbFile = new RandomAccessFile(f, "rw");
            } catch (IOException ex) {
                // Open as read-only so we can at least read the existing
                // thumbnails.
                ex.printStackTrace();
                try {
                    mMiniThumbFile = new RandomAccessFile(f, "r");
                } catch (IOException ex2) {
                    // ignore exception
                }
            }
            if (mMiniThumbFile != null) {
                mChannel = mMiniThumbFile.getChannel();
            }
        }
        return mMiniThumbFile;
    }

    public MiniThumbFile(Uri uri) {
        mUri = uri;
        mBuffer = ByteBuffer.allocateDirect(BYTES_PER_MINTHUMB);
    }

    public synchronized void deactivate() {
        if (mMiniThumbFile != null) {
            try {
                mMiniThumbFile.close();
                mMiniThumbFile = null;
            } catch (IOException ex) {
                // ignore exception
            }
        }
    }

    // Get the magic number for the specified id in the mini-thumb file.
    // Returns 0 if the magic is not available.
    public synchronized long getMagic(long id) {
        // check the mini thumb file for the right data.  Right is
        // defined as having the right magic number at the offset
        // reserved for this "id".
        RandomAccessFile r = miniThumbDataFile();
        if (r != null) {
            long pos = id * BYTES_PER_MINTHUMB;
            FileLock lock = null;
            try {
                mBuffer.clear();
                mBuffer.limit(1 + 8);

                lock = mChannel.lock(pos, 1 + 8, true);
                // check that we can read the following 9 bytes
                // (1 for the "status" and 8 for the long)
                if (mChannel.read(mBuffer, pos) == 9) {
                    mBuffer.position(0);
                    if (mBuffer.get() == 1) {
                        return mBuffer.getLong();
                    }
                }
            } catch (IOException ex) {
                Log.v(TAG, "Got exception checking file magic: ", ex);
            } catch (RuntimeException ex) {
                // Other NIO related exception like disk full, read only channel..etc
                Log.e(TAG, "Got exception when reading magic, id = " + id +
                        ", disk full or mount read-only? " + ex.getClass());
            } finally {
                try {
                    if (lock != null) lock.release();
                }
                catch (IOException ex) {
                    // ignore it.
                }
            }
        }
        return 0;
    }

    public synchronized void saveMiniThumbToFile(byte[] data, long id, long magic)
            throws IOException {
        RandomAccessFile r = miniThumbDataFile();
        if (r == null) return;

        long pos = id * BYTES_PER_MINTHUMB;
        FileLock lock = null;
        try {
            if (data != null) {
                if (data.length > BYTES_PER_MINTHUMB - HEADER_SIZE) {
                    // not enough space to store it.
                    return;
                }
                mBuffer.clear();
                mBuffer.put((byte) 1);
                mBuffer.putLong(magic);
                mBuffer.putInt(data.length);
                mBuffer.put(data);
                mBuffer.flip();

                lock = mChannel.lock(pos, BYTES_PER_MINTHUMB, false);
                mChannel.write(mBuffer, pos);
            }
        } catch (IOException ex) {
            Log.e(TAG, "couldn't save mini thumbnail data for "
                    + id + "; ", ex);
            throw ex;
        } catch (RuntimeException ex) {
            // Other NIO related exception like disk full, read only channel..etc
            Log.e(TAG, "couldn't save mini thumbnail data for "
                    + id + "; disk full or mount read-only? " + ex.getClass());
        } finally {
            try {
                if (lock != null) lock.release();
            }
            catch (IOException ex) {
                // ignore it.
            }
        }
    }

    /**
     * Gallery app can use this method to retrieve mini-thumbnail. Full size
     * images share the same IDs with their corresponding thumbnails.
     *
     * @param id the ID of the image (same of full size image).
     * @param data the buffer to store mini-thumbnail.
     */
    public synchronized byte [] getMiniThumbFromFile(long id, byte [] data) {
        RandomAccessFile r = miniThumbDataFile();
        if (r == null) return null;

        long pos = id * BYTES_PER_MINTHUMB;
        FileLock lock = null;
        try {
            mBuffer.clear();
            lock = mChannel.lock(pos, BYTES_PER_MINTHUMB, true);
            int size = mChannel.read(mBuffer, pos);
            if (size > 1 + 8 + 4) { // flag, magic, length
                mBuffer.position(0);
                byte flag = mBuffer.get();
                long magic = mBuffer.getLong();
                int length = mBuffer.getInt();

                if (size >= 1 + 8 + 4 + length && data.length >= length) {
                    mBuffer.get(data, 0, length);
                    return data;
                }
            }
        } catch (IOException ex) {
            Log.w(TAG, "got exception when reading thumbnail id=" + id + ", exception: " + ex);
        } catch (RuntimeException ex) {
            // Other NIO related exception like disk full, read only channel..etc
            Log.e(TAG, "Got exception when reading thumbnail, id = " + id +
                    ", disk full or mount read-only? " + ex.getClass());
        } finally {
            try {
                if (lock != null) lock.release();
            }
            catch (IOException ex) {
                // ignore it.
            }
        }
        return null;
    }

    public void createNewMicroThumbnail(Bitmap bitmap, long origId) throws IOException {
        long magic = getMagic(origId);
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.PNG, 100, baos); //bm is the bitmap object 
        byte[] b = baos.toByteArray();
        saveMiniThumbToFile(b, origId, magic);
    }
}

package de.unicate.android.thumbnailtest;

import java.io.FileDescriptor;
import java.io.FileInputStream;
import java.io.IOException;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.provider.MediaStore.Images;
import android.util.Log;

public class ThumbnailUtils extends android.media.ThumbnailUtils {
    
    private static final String TAG = "ThumbnailUtils";

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


    /**
     * 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 OPTIONS_RECYCLE_INPUT = 0x2;

    /**
     * Constant used to indicate the dimension of mini thumbnail.
     * @hide Only used by media framework and media provider internally.
     */
    public static final int TARGET_SIZE_MINI_THUMBNAIL = 320;

    /**
     * Constant used to indicate the dimension of micro thumbnail.
     * @hide Only used by media framework and media provider internally.
     */
    public static final int TARGET_SIZE_MICRO_THUMBNAIL = 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 filePath the path of image file
     * @param kind could be MINI_KIND or MICRO_KIND
     * @return Bitmap
     *
     * @hide This method is only used by media framework and media provider internally.
     */
    public static Bitmap createImageThumbnail(String filePath, int kind) {
        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;
        Bitmap bitmap = null;
        if (bitmap == null) {
            try {
                FileDescriptor fd = new FileInputStream(filePath).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);
            }
        }

        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;
    }




    /*
     * 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;
        }
    }


}

package de.unicate.android.thumbnailtest;

import android.content.ContentResolver;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.net.Uri;
import android.provider.MediaStore;
import android.util.Log;

public class BitmapUtilities {
    
    private static final String TAG = BitmapUtilities.class.getSimpleName();
    
    public static void refreshMicroThumbnails(ContentResolver cr, long[] thumbnails2Refresh) {
        final String[] PROJECTION = new String[] {MediaStore.Images.Media._ID, MediaStore.Images.Media.DATA};        
        MiniThumbFile thumbFile = MiniThumbFile.instance(MediaStore.Images.Thumbnails.EXTERNAL_CONTENT_URI);
        for(long origId : thumbnails2Refresh) {
            Cursor c = null;
            try {
                Uri uri = Uri.parse(
                        MediaStore.Images.Thumbnails.EXTERNAL_CONTENT_URI.buildUpon().appendPath(String.valueOf(origId))
                                .toString().replaceFirst("thumbnails", "media"));
                c = cr.query(uri, PROJECTION, null, null, null);
                if (c == null || !c.moveToFirst()) {
                    Log.e(TAG, "cannot find thumbnailpath!");
                    return;
                }
                String filePath = c.getString(1);
                Bitmap bitmap = ThumbnailUtils.createImageThumbnail(filePath, MediaStore.Images.Thumbnails.MICRO_KIND);
                thumbFile.createNewMicroThumbnail(bitmap, origId);
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                if(c!=null)c.close();
            }            
        }
    }
}

private Bitmap getThumbnail(long id, int kind, boolean forceRefresh) {
        if(forceRefresh)
            BitmapUtilities.refreshMicroThumbnails(getContentResolver(), new long[]{id});
        return MediaStore.Images.Thumbnails.getThumbnail(this.getContentResolver(), id, kind, null);
    }