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Diffstat (limited to 'src/com/android/camera/gallery/MiniThumbFile.java')
| -rw-r--r-- | src/com/android/camera/gallery/MiniThumbFile.java | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/src/com/android/camera/gallery/MiniThumbFile.java b/src/com/android/camera/gallery/MiniThumbFile.java new file mode 100644 index 0000000..e2c825c --- /dev/null +++ b/src/com/android/camera/gallery/MiniThumbFile.java @@ -0,0 +1,196 @@ +/* + * 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 com.android.camera.gallery; + +import android.graphics.Bitmap; +import android.net.Uri; +import android.os.Environment; +import android.util.Log; + +import java.io.File; +import java.io.IOException; +import java.io.RandomAccessFile; + +// 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) +// +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 static final byte [] sMiniThumbData = new byte[BYTES_PER_MINTHUMB]; + private Uri mUri; + private RandomAccessFile mMiniThumbFile; + + 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) { + // ignore exception + } + } + return mMiniThumbFile; + } + + public MiniThumbFile(Uri uri) { + mUri = uri; + } + + public 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 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) { + synchronized (r) { + long pos = id * BYTES_PER_MINTHUMB; + try { + // check that we can read the following 9 bytes + // (1 for the "status" and 8 for the long) + if (r.length() >= pos + 1 + 8) { + r.seek(pos); + if (r.readByte() == 1) { + long fileMagic = r.readLong(); + return fileMagic; + } + } + } catch (IOException ex) { + Log.v(TAG, "Got exception checking file magic: ", ex); + } + } + } + return 0; + } + + public void saveMiniThumbToFile(Bitmap bitmap, long id, long magic) + throws IOException { + byte[] data = Util.miniThumbData(bitmap); + saveMiniThumbToFile(data, id, magic); + } + + public void saveMiniThumbToFile(byte[] data, long id, long magic) + throws IOException { + RandomAccessFile r = miniThumbDataFile(); + if (r == null) return; + + long pos = id * BYTES_PER_MINTHUMB; + long t0 = System.currentTimeMillis(); + synchronized (r) { + try { + if (data != null) { + if (data.length > BYTES_PER_MINTHUMB - HEADER_SIZE) { + // not enough space to store it. + return; + } + r.seek(pos); + r.writeByte(0); // we have no data in this slot + + // if magic is 0 then leave it alone + if (magic == 0) { + r.skipBytes(8); + } else { + r.writeLong(magic); + } + r.writeInt(data.length); + r.write(data); + r.seek(pos); + r.writeByte(1); // we have data in this slot + } + } catch (IOException ex) { + Log.e(TAG, "couldn't save mini thumbnail data for " + + id + "; ", ex); + throw ex; + } + } + } + + byte [] getMiniThumbFromFile(long id, byte [] data, long magicCheck) { + RandomAccessFile r = miniThumbDataFile(); + if (r == null) return null; + + long pos = id * BYTES_PER_MINTHUMB; + synchronized (r) { + try { + r.seek(pos); + if (r.readByte() == 1) { + long magic = r.readLong(); + if (magic != magicCheck) { + return null; + } + int length = r.readInt(); + r.read(data, 0, length); + return data; + } else { + return null; + } + } catch (IOException ex) { + return null; + } + } + } +} |