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/*
* 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 com.android.camera.Util;
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 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;
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();
int got = r.read(data, 0, length);
if (got != length) return null;
return data;
} else {
return null;
}
} catch (IOException ex) {
return null;
}
}
}
}
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