Source Code: ImageView Flipper + SD Card Scanner

This is a little project I have been working on that is based on code that I found at codeshogun.com for working with the ViewFlipper. If you are looking for a sample project that incorporates the ViewFlipper to scroll through images or if you are looking for a sample project for how to recursively search the SD Card for files based on type (or any other type of file searching for that matter) than this project might help. This is open source with no license whatsoever… so you can use it however you like. This project also features something I haven’t seen in other projects and that is how to save an array object to a file and read it back in. It works very quickly and it is a fast way to save data instances without messing with a database or serialization. The reason I used it was to save the data so that the application wouldn’t attempt to rescan the SD Card whenever the screen orientation changed (something I hate about Android). This also shows you how to save variable state using SharedPreferences. You can download a zip of the Eclipse project at the bottom of the post.

The layout – /res/layout/main.xml

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A string array /res/values/mimetypes.xml

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<?xml version="1.0" encoding="utf-8"?>
<resources>
<string-array name="image">
<item>bmp</item>
<item>cmx</item>
<item>cod</item>
<item>gif</item>
<item>ico</item>
<item>ief</item>
<item>jpe</item>
<item>jpeg</item>
<item>jpg</item>
<item>jfif</item>
<item>pbm</item>
<item>pgm</item>
<item>png</item>
<item>pnm</item>
<item>ppm</item>
<item>ras</item>
<item>rgb</item>
<item>svg</item>
<item>tif</item>
<item>tiff</item>
<item>xbm</item>
<item>xpm</item>
<item>xwd</item>
</string-array>
</resources>

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package com.androidworkz.imageviewflipper;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FilenameFilter;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Vector;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;

import android.app.Activity;
import android.content.SharedPreferences;
import android.content.res.Resources;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.os.SystemClock;
import android.util.Log;
import android.view.GestureDetector;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.view.GestureDetector.SimpleOnGestureListener;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.ImageView;
import android.widget.Toast;
import android.widget.ViewFlipper;

public class ImageViewFlipper extends Activity {

private static final int EXIT = 0;
private static final int SWIPE_MIN_DISTANCE = 120;
private static final int SWIPE_MAX_OFF_PATH = 250;
private static final int SWIPE_THRESHOLD_VELOCITY = 200;
private static final String DIRECTORY = "/sdcard/";
private static final String DATA_DIRECTORY = "/sdcard/.ImageViewFlipper/";
private static final String DATA_FILE = "/sdcard/.ImageViewFlipper/imagelist.dat";
private GestureDetector gestureDetector;
View.OnTouchListener gestureListener;
private Animation slideLeftIn;
private Animation slideLeftOut;
private Animation slideRightIn;
private Animation slideRightOut;
private ViewFlipper viewFlipper;
private int currentView = 0;
List<String> ImageList;
private int currentIndex = 0;
private int maxIndex = 0;

FileOutputStream output = null;
OutputStreamWriter writer = null;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);

setContentView(R.layout.main);
ImageView iv = (ImageView) findViewById(R.id.zero);

File data_directory = new File(DATA_DIRECTORY);
if (!data_directory.exists()) {
if (data_directory.mkdir()) {
FileUtils savedata = new FileUtils();
Toast toast = Toast.makeText(ImageViewFlipper.this,
"Please wait while we search your SD Card for images...", Toast.LENGTH_SHORT);
toast.show();
SystemClock.sleep(100);
ImageList = FindFiles();
savedata.saveArray(DATA_FILE, ImageList);

} else {
ImageList = FindFiles();
}

}
else {
File data_file= new File(DATA_FILE);
if (!data_file.exists()) {
FileUtils savedata = new FileUtils();
Toast toast = Toast.makeText(ImageViewFlipper.this,
"Please wait while we search your SD Card for images...", Toast.LENGTH_SHORT);
toast.show();
SystemClock.sleep(100);
ImageList = FindFiles();
savedata.saveArray(DATA_FILE, ImageList);
} else {
FileUtils readdata = new FileUtils();
ImageList = readdata.loadArray(DATA_FILE);
}
}

if (ImageList == null) {
quit();
}

SharedPreferences indexPrefs = getSharedPreferences("currentIndex",
MODE_PRIVATE);
if (indexPrefs.contains("currentIndex")) {
currentIndex = indexPrefs.getInt("currentIndex", 0);
}

maxIndex = ImageList.size() - 1;

Log.v("currentIndex", "Index: "+currentIndex);

viewFlipper = (ViewFlipper) findViewById(R.id.flipper);

slideLeftIn = AnimationUtils.loadAnimation(this, R.anim.slide_left_in);
slideLeftOut = AnimationUtils
.loadAnimation(this, R.anim.slide_left_out);
slideRightIn = AnimationUtils
.loadAnimation(this, R.anim.slide_right_in);
slideRightOut = AnimationUtils.loadAnimation(this,
R.anim.slide_right_out);

viewFlipper.setInAnimation(AnimationUtils.loadAnimation(this,
android.R.anim.fade_in));
viewFlipper.setOutAnimation(AnimationUtils.loadAnimation(this,
android.R.anim.fade_out));

iv.setImageDrawable(Drawable.createFromPath(ImageList
.get(currentIndex)));
System.gc();

gestureDetector = new GestureDetector(new MyGestureDetector());
gestureListener = new View.OnTouchListener() {
public boolean onTouch(View v, MotionEvent event) {
if (gestureDetector.onTouchEvent(event)) {
return true;
}
return false;
}
};

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);

int NONE = Menu.NONE;
menu.add(NONE, EXIT, NONE, "Exit");
return true;
}

public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case EXIT:
quit();
break;
}

return super.onOptionsItemSelected(item);
}

protected void onPause() {
super.onPause();

SharedPreferences indexPrefs = getSharedPreferences("currentIndex",
MODE_PRIVATE);

SharedPreferences.Editor indexEditor = indexPrefs.edit();
indexEditor.putInt("currentIndex", currentIndex);
indexEditor.commit();
}

protected void onResume() {
super.onResume();
SharedPreferences indexPrefs = getSharedPreferences("currentIndex",
MODE_PRIVATE);
if (indexPrefs.contains("currentIndex")) {
currentIndex = indexPrefs.getInt("currentIndex", 0);
}
}

private List<String> FindFiles() {
final List<String> tFileList = new ArrayList<String>();
Resources resources = getResources();
// array of valid image file extensions
String[] imageTypes = resources.getStringArray(R.array.image);
FilenameFilter[] filter = new FilenameFilter[imageTypes.length];

int i = 0;
for (final String type : imageTypes) {
filter[i] = new FilenameFilter() {
public boolean accept(File dir, String name) {
return name.endsWith("." + type);
}
};
i++;
}

FileUtils fileUtils = new FileUtils();
File[] allMatchingFiles = fileUtils.listFilesAsArray(
new File(DIRECTORY), filter, -1);
for (File f : allMatchingFiles) {
tFileList.add(f.getAbsolutePath());
}
return tFileList;
}

public class FileUtils {

public void saveArray(String filename, List<String> output_field) {
try {
FileOutputStream fos = new FileOutputStream(filename);
GZIPOutputStream gzos = new GZIPOutputStream(fos);
ObjectOutputStream out = new ObjectOutputStream(gzos);
out.writeObject(output_field);
out.flush();
out.close();
}
catch (IOException e) {
e.getStackTrace();
}
}

@SuppressWarnings("unchecked")
public List<String> loadArray(String filename) {
try {
FileInputStream fis = new FileInputStream(filename);
GZIPInputStream gzis = new GZIPInputStream(fis);
ObjectInputStream in = new ObjectInputStream(gzis);
List<String> read_field = (List<String>)in.readObject();
in.close();
return read_field;
}
catch (Exception e) {
e.getStackTrace();
}
return null;
}

public File[] listFilesAsArray(File directory, FilenameFilter[] filter,
int recurse) {
Collection<File> files = listFiles(directory, filter, recurse);

File[] arr = new File[files.size()];
return files.toArray(arr);
}

public Collection<File> listFiles(File directory,
FilenameFilter[] filter, int recurse) {

Vector<File> files = new Vector<File>();

File[] entries = directory.listFiles();

if (entries != null) {
for (File entry : entries) {
for (FilenameFilter filefilter : filter) {
if (filter == null
|| filefilter
.accept(directory, entry.getName())) {
files.add(entry);
Log.v("ImageViewFlipper", "Added: "
+ entry.getName());
}
}
if ((recurse <= -1) || (recurse > 0 && entry.isDirectory())) {
recurse--;
files.addAll(listFiles(entry, filter, recurse));
recurse++;
}
}
}
return files;
}
}

class MyGestureDetector extends SimpleOnGestureListener {
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
float velocityY) {
try {
if (Math.abs(e1.getY() - e2.getY()) > SWIPE_MAX_OFF_PATH)
return false;
// right to left swipe
if (e1.getX() - e2.getX() > SWIPE_MIN_DISTANCE
&& Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
viewFlipper.setInAnimation(slideLeftIn);
viewFlipper.setOutAnimation(slideLeftOut);

if (currentIndex == maxIndex) {
currentIndex = 0;
} else {
currentIndex = currentIndex + 1;
}
if (currentView == 0) {
currentView = 1;
ImageView iv = (ImageView) findViewById(R.id.one);
iv.setImageDrawable(Drawable.createFromPath(ImageList
.get(currentIndex)));
System.gc();
} else if (currentView == 1) {
currentView = 2;
ImageView iv = (ImageView) findViewById(R.id.two);
iv.setImageDrawable(Drawable.createFromPath(ImageList
.get(currentIndex)));
System.gc();
} else {
currentView = 0;
ImageView iv = (ImageView) findViewById(R.id.zero);
iv.setImageDrawable(Drawable.createFromPath(ImageList
.get(currentIndex)));
System.gc();
}
Log.v("ImageViewFlipper", "Current View: " + currentView);
viewFlipper.showNext();
} else if (e2.getX() - e1.getX() > SWIPE_MIN_DISTANCE
&& Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
viewFlipper.setInAnimation(slideRightIn);
viewFlipper.setOutAnimation(slideRightOut);
if (currentIndex == 0) {
currentIndex = maxIndex;
} else {
currentIndex = currentIndex - 1;
}
if (currentView == 0) {
currentView = 2;
ImageView iv = (ImageView) findViewById(R.id.two);
iv.setImageDrawable(Drawable.createFromPath(ImageList
.get(currentIndex)));
} else if (currentView == 2) {
currentView = 1;
ImageView iv = (ImageView) findViewById(R.id.one);
iv.setImageDrawable(Drawable.createFromPath(ImageList
.get(currentIndex)));
} else {
currentView = 0;
ImageView iv = (ImageView) findViewById(R.id.zero);
iv.setImageDrawable(Drawable.createFromPath(ImageList
.get(currentIndex)));
}
Log.v("ImageViewFlipper", "Current View: " + currentView);
viewFlipper.showPrevious();
}
} catch (Exception e) {
// nothing
}
return false;
}
}

@Override
public boolean onTouchEvent(MotionEvent event) {
if (gestureDetector.onTouchEvent(event))
return true;
else
return false;
}

public void quit() {
SharedPreferences indexPrefs = getSharedPreferences("currentIndex",
MODE_PRIVATE);

SharedPreferences.Editor indexEditor = indexPrefs.edit();
indexEditor.putInt("currentIndex", 0);
indexEditor.commit();

File settings = new File(DATA_FILE);
settings.delete();
finish();
int pid = android.os.Process.myPid();
android.os.Process.killProcess(pid);
System.exit(0);
}
}

You can download the Eclipse Project Here: Download ImageViewFlipper.zip

Android Workz