Develop Reference

Using muPDF with curl/flip effect

I'm using muPDF for reading PDFs in my application. I don't like its default animation (Switching horizontally). In other side i found this brilliant library for curl effect on images, and this project for flip-flap effect on layouts.
In curl sample project, in CurlActivity, all of data are images and set in PageProvider like this:
private class PageProvider implements CurlView.PageProvider {
// Bitmap resources.
private int[] mBitmapIds = { R.drawable.image1, R.drawable.image2,
R.drawable.image3, R.drawable.image4};
And use it like this:
private CurlView mCurlView;
mCurlView = (CurlView) findViewById(R.id.curl);
mCurlView.setPageProvider(new PageProvider());
And CurlView extends from GLSurfaceView and implements View.OnTouchListener, CurlRenderer.Observer
But in muPDF if i'm not mistaken, data are in core object. core is instance of MuPDFCore. And using it like this:
MuPDFReaderView mDocView;
MuPDFView pageView = (MuPDFView) mDocView.getDisplayedView();
mDocView.setAdapter(new MuPDFPageAdapter(this, this, core));
MuPDFReaderView extends ReaderView and ReaderView extends AdapterView<Adapter> and implements GestureDetector.OnGestureListener, ScaleGestureDetector.OnScaleGestureListener, Runnable.
My question is where how can I using curl effect in muPDF? Where should I get pages one by one and converting them to bitmaps? and then changing aspects of the Adapter in muPDF to CurlView.
In flip-flap sample project, in FlipHorizontalLayoutActivity (I like this effect too), we have these:
private FlipViewController flipView;
flipView = new FlipViewController(this, FlipViewController.HORIZONTAL);
flipView.setAdapter(new TravelAdapter(this));
setContentView(flipView);
And FlipViewController extends AdapterView<Adapter>, and data set in TravelAdapter that extends BaseAdapter.
No one has done this before? Or can help me to do that?!
EDIT:
I found another good open source PDF reader with curl effect called fbreaderJ. its developer says "An additional module that allows to open PDF files in FBReader. Based on radaee pdf library."
I got confused! cause radaeepdf is closed source and downloadable project is just for demo and inserted username and password is for this package.
People want to change whole fbreader project such as package name.
Another issue for make me confused is where is this additional module source code?!
Anyway, if someone wants to help me, fbreader has done it very well.
EDIT:
I talked to Robin Watts, who developed muPDF (or one of developers), and he said:
Have you read platform/android/ClassStructure.txt ? MuPDF is
primarily a C library. The standard api is therefore a C one. Rather
than exposing that api exactly as is to Java (which would be the
nicest solution, and something that I've done some work on, but have
not completed due to lack of time), we've implemented MuPDFCore to
wrap up just the bits we needed. MuPDFCore handles opening a PDF file,
and getting bitmaps from it to be used in views. or rather, MuPDFCore
returns 'views', not 'bitmaps'. If you need bitmaps, then you're going
to need to make changes in MuPDFCore.
There are too many errors when changing a little part of MuPDFReaderView class. I get confused! These are related to each other.
Please answer more precisely.
EDIT:
And bounty has expired.

If the muPDF does not support rendering to a bitmap, you have no other choice than rendering to a regular view and take a screen dump to a bitmap like this:
View content = findViewById(R.id.yourPdfView);
Bitmap bitmap = content.getDrawingCache();
Then use this bitmap as input to your other library.

Where should i get pages one by one and converting them to bitmaps?
In our application (newspaper app) we use MuPDF to render PDFs.
The workflow goes like this:
Download PDF file (we have one PDF per newspaper page)
Render it with MuPDF
Save the bitmap to the filesystem
Load the Bitmap from filesystem as background image to a view
So, finally, what we use is MuPDFCore.java and its methods drawPage(...) and onDestroy()
Is this what you want to know or do i miss the point?
EDIT
1.) I think it is not necessary to post code how to download a file. But after downloading i add a RenderTask (extends from Runnable) to a Renderqueue and trigger that queue. The RenderTask needs some information for rendering:
/**
* constructs a new RenderTask instance
* #param context: you need Context for MuPdfCore instance
* #param pageNumber
* #param pathToPdf
* #param renderCallback: callback to set bitmap to the view after
* rendering
* #param heightOfRenderedBitmap: this is the target height
* #param widthOfRenderedBitmap: this is the target width
*/
public RenderTask (Context context, Integer pageNumber, String pathToPdf, IRenderCallback,
renderCallback, int heightOfRenderedBitmap,
int widthOfRenderedBitmap) {
//store things in fields
}
2.) + 3.) The Renderqueue wraps the RenderTask in a new Thread and starts it. So the run-method of the RenderTask will be invoked:
#Override
public void run () {
//do not render it if file exists
if (exists () == true) {
finish();
return;
}
Bitmap bitmap = render();
//if something went wrong, we can't store the bitmap
if (bitmap == null) {
finish();
return;
}
//now save the bitmap
// in my case i save the destination path in a String field
imagePath = save(bitmap, new File("path/to/your/destination/folder/" + pageNumber + ".jpg"));
bitmap.recycle();
finish();
}
/**
* let's trigger the callback
*/
private void finish () {
if (renderCallback != null) {
// i send the whole Rendertask to callback
// maybe in your case it is enough to send the pageNumber or path to
// renderend bitmap
renderCallback.finished(this);
}
}
/**
* renders a bitmap
* #return
*/
private Bitmap render() {
MuPDFCore core = null;
try {
core = new MuPDFCore(context, pathToPdf);
} catch (Exception e) {
return null;
}
Bitmap bm = Bitmap.createBitmap(widthOfRenderedBitmap, heightOfRenderedBitmap, Config.ARGB_8888);
// here you render the WHOLE pdf cause patch-x/-y == 0
core.drawPage(bm, 0, widthOfRenderedBitmap, heightOfRenderedBitmap, 0, 0, widthOfRenderedBitmap, heightOfRenderedBitmap, core.new Cookie());
core.onDestroy();
core = null;
return bm;
}
/**
* saves bitmap to filesystem
* #param bitmap
* #param image
* #return
*/
private String save(Bitmap bitmap, File image) {
FileOutputStream out = null;
try {
out = new FileOutputStream(image.getAbsolutePath());
bitmap.compress(Bitmap.CompressFormat.JPEG, 80, out);
return image.getAbsolutePath();
} catch (Exception e) {
return null;
}
finally {
try {
if (out != null) {
out.close();
}
} catch(Throwable ignore) {}
}
}
}
4.) I think it is not necessary to post code how to set a bitmap as background of a view

Android ImageManager Google Game Services

We are trying to download avatars from Google Play Game Services at URIs like content :/ / ... through android-class ImageManager, but for unknown reasons, the class stops loading on same avatars, simply ceases to come in response OnImageLoadedListener. Each picture is a separate instance of the manager.
All avatars are valid (for the tests, each at least once loaded) no exceptions catch, the context in create manager is valid, tried everything, from the current Activity to getApplicationContext().
Tried to make loading and asynchronously and synchronously.
What is remarkable: after the last loader's action is always line in log with garbage collector and then do not continue to load (the application continues its work), although all references to objects are stored.
More often than not finish loading the last avatar.
Has anyone encountered a similar problem? Appears on versions from 2.3 to 4.2
Code in the alternate boot:
static ImageManager imageManager = null;
static int id = 0;
static Uri uri = null;
...
// ...
// change id & uri
// ...
imageManager = ImageManager.create(context);
Log.v("app", "LoadImageFromGoogle Manager created for Image #" + id);
imageManager.loadImage(new OnImageLoadedListener() {
#Override
public void onImageLoaded(Uri arg0, Drawable arg1) {
try {
Log.v("app", "LoadImageFromGoogle Image loaded #" + id);
Bitmap bm = ((BitmapDrawable)arg1).getBitmap();
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.PNG, 100, stream);
byte[] byteArray = stream.toByteArray();
// ... some code
Log.v("app", "LoadImageFromGoogle Image added #" + id);
} catch (Exception e) {
Log.v("app", "LoadImageFromGoogle after loading Exception = " + e.toString());
}
}
}, uri, android.R.drawable.btn_star);
the last line in the log is always the case:
Log.v("app", "LoadImageFromGoogle Manager created for Image #" + id);
and the following message GC.

Hmm.... I've never seen this issue. Are you sure you are feeding it a valid URI? My first guess would be that it might be an off-by-one error somewhere in your code where you're passing an invalid URI the last time you call imageManager.loadImage(). I'd try making the above code print the URIs it's trying to load as well as the image numbers, to see if something weird comes up.
If not, can you make a simple repro case and post it to our public bug tracker?
http://code.google.com/p/play-games-platform
Thanks!

I had the same problem. It looks like garbage collector can "clean" the listener before it can retrieve the image. The way to solve the problem is to implement the ImageManager.OnImageLoadedListener directly on your activity and not creating a new object on the moment.
Here you can find a related issue on google code:
https://code.google.com/p/play-games-platform/issues/detail?id=14&can=1&sort=-status&colspec=ID%20Type%20Status%20Priority%20Platform%20Summary%20Stars
Never is to late ;)

Android: Bitmap Decode java.lang.OutofMemoryError error

My current android applications main functionality is to pull the frames (10fps) from a recorded video using the built in camera. Whenever the user selects the video I call my class "FrameCollector" which loops through the video and pulls the frames out and stores them into an ArrayList of Bitmaps. Having this work well for a number of days had me thinking that I was on the right track, but now I'm getting the dreaded "java.lang.OutofMemoryError"
My code is as follows:
Here it is setting the MediaMetaDataRetriever to select 10 frames per second from the video path which was passed from the main class
public class FrameCollector {
MediaMetadataRetriever _mmr;
double _fps;
double _duration;
long _counter = 0;
long _incrementer;
public FrameCollector(String path, Context context)
{
try
{
_mmr = new MediaMetadataRetriever();
_mmr.setDataSource(path);
SharedPreferences pref = PreferenceManager.getDefaultSharedPreferences(context);
String fpsString = pref.getString("prefFPS", "10");
_fps = Double.parseDouble(fpsString);
_incrementer = (long) (1000000 / _fps);
String stringDuration = _mmr.extractMetadata(MediaMetadataRetriever.METADATA_KEY_DURATION);
_duration = Double.parseDouble(stringDuration) * 1000;
}
catch(Exception ex)
{
ex.printStackTrace();
}
}
The below method is then adding the frame at that time to a bitmap and adding the bitmap to an arraylist of bitmaps "bitFrames"
public ArrayList<Bitmap> getBitmaps()
{
try
{
ArrayList<Bitmap> bitFrames = new ArrayList<Bitmap>();
Bitmap b = _mmr.getFrameAtTime(_counter);
while (_counter < _duration && b != null)
{
bitFrames.add(b);
_counter += _incrementer;
b = _mmr.getFrameAtTime(_counter);
}
return bitFrames;
}
catch (Exception ex)
{
ex.printStackTrace();
return null;
}
}
I'm thinking my issue lies with in this method. I believe I need to decode the bitmaps before I store them into the ArrayList but I'm unsure how as
Bitmap b = BitmapFactory.decode____(_mmr.getFrameAtTime(_counter));
-- Whether it be decodeStream, decodeResource, decodeFile all bring errors.
Any help would be much appreciated
Many Thanks,

Never store Bitmaps in an ArrayList unless the number of bitmaps are very small. Bitmaps take up large amounts of memory.
I've not worked with video recording before, but I would suggest you try to get a native codec library like ffmpeg to do it for you.
If you have to grab the frames yourself, however, I suggest storing them in a fixed size buffer in memory from the camera and have a background thread which pulls bitmaps from the buffer and stores it to the disk in parallel.

It's not good to store ArrayList of Bitmaps in RAM.
Anyway if you need more than default heap size to store bitmaps in ArrayList, you can try this hack.
http://habrahabr.ru/post/139717/
It's in Russian, but I guess code is quite clear to understand.

Custom image viewing slows down

The problem
Hi there,
I'm developing an application where the user specifies some pictures and how long they are going to be on the screen.So sometimes he wants to create something like a small animation or viewing the images for a small amount of time.The problem is that after some time the images are not previewed when they should and we have a few ms of error.In the application that i'm developing time matters so I would like some help on what the problem might be.
The code
So let me explain how it works.I take the pictures from my web app and then I save them in a HashMap
Bitmap image = ImageOperations(url,String.valueOf(frameNum) + ".jpg");
ImageMap.put(String.valueOf(frameNum), image);
where the mathod ImageOperations is like that:
private Bitmap ImageOperations(String url, String saveFilename) {
try {
Display display = getWindowManager().getDefaultDisplay();
InputStream is = (InputStream) this.fetch(url);
Bitmap theImage = BitmapFactory.decodeStream(is);
if (theImage.getHeight() >= 700 || theImage.getWidth() >= 700) {
theImage = Bitmap.createScaledBitmap(theImage,
display.getWidth(), display.getHeight() - 140, true);
}
return theImage;
} catch (MalformedURLException e) {
e.printStackTrace();
return null;
} catch (IOException e) {
e.printStackTrace();
return null;
}
}
So later I run a thread that updates the UI when the user specified.The method that updates it is this one.
public void setPictures(int NumOfFrame) {
if (frameArray.get(NumOfFrame - 1).frame_pic.contains("n/a") != true) {
ImagePlace.setImageBitmap(ImageMap.get(String.valueOf(NumOfFrame)));
} else {
ImagePlace.setImageDrawable(null);
}
}
After we update the image we put the thread for sleep and when runs again it updates the thread.Is there something that creates the problem?Does it have to do with Garbage collection?
Thank you in advance

Probably the issue is in increasing heap size when it loads additional images. I would suggest You to do some profiling so things will be much clearer and You'll get full picture of timings for the app.

First you are missing a null check at here:
ImageMap.get(String.valueOf(NumOfFrame))
And you do not recycle the old bitmap at here:
theImage.recycle(); // missing line
theImage = Bitmap.createScaledBitmap(theImage,
display.getWidth(), display.getHeight() - 140, true);
It may lead to outofmemory exceptions, with is most likely from your description of the problem.
Also I am not sure if BitmapFactory.decodeStream throw exception when he fails. You need to add a null point check there too.

Obfuscate JPG by bit-toggle - reading performance on Android

Abstract:
reading images from file
with toggled bits to make unusable for preview tools
cant use encryption, to much power needed
can I either optimize the code below, or is there a better approach
Longer description:
I am trying to improve my code, maybe you got some ideas or improvements for the following situation. Please be aware that I neither try to beat the CIA, nor care much if somebody "brakes" the encryption.
The background is simple: My app loads a bunch of images from a server into a folder on the SD card. I do NOT want the images to be simple JPG files, because in this case the media indexer would list them in the library, and a user could simply copy the whole folder to his harddrive.
The obvious way to go is encryption. But a full blown AES or other encryption does not make sense, for two reasons: I would have to store the passkey in the app, so anyone could get the key with some effort anyway. And the price for decrypting images on the fly is way too high (we are talking about e.g. a gallery with 30 200kB pictures).
So I decided to toggle some bits in the image. This makes the format unreadable for image tools (or previews), but is pretty easy undone when reading the images. For "encrypting" I use some C# tool, the "decrypt" lines are the following ones:
public class CustomInputStream extends InputStream {
private String _fileName;
private BufferedInputStream _stream;
public CustomInputStream(String fileName) {
_fileName = fileName;
}
public void Open() throws IOException {
int len = (int) new File(_fileName).length();
_stream = new BufferedInputStream(new FileInputStream(_fileName), len);
}
#Override
public int read() throws IOException {
int value = _stream.read() ^ (1 << 7);
return value;
}
#Override
public void close() throws IOException {
_stream.close();
}
}
I tried overwriting the other methods (read with more then one byte) too, but this kills the BitmapFactory - not sure why, maybe I did something wrong. Here is the code for the image bitmap creation:
Bitmap bitmap = null;
try {
InputStream i = CryptoProvider.GetInstance().GetDecoderStream(path);
bitmap = BitmapFactory.decodeStream(i);
i.close();
} catch (Exception e1) {
_logger.Error("Cant load image " + path + " ERROR " + e1);
}
if (bitmap == null) {
_logger.Error("Image is NULL for path " + path);
}
return bitmap;
Do you have any feedback on the chosen approach? Any way to optimize it, or a completely different approach for Android devices?

You could try XORing the bytestream with the output of a fast PRNG. Just use a different seed for each file and you're done.
note: As already noted in the question, such methods are trivial to bypass.