How to convert Bitmap to Byte Array

Question

I want to convert a URL to Bitmap image.i am also trying to compress and saving this bitmap on SD Card but when i run code, no image is displayed in Web Image-view. i have following code:

Logger.d(LOG_TAG, "Enter retrieveImageData()");
    URL url = new URL(imageUrl);
    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
    connection.setReadTimeout(CONNECTTION_TIMEOUT);
    // determine the image size and allocate a buffer
    int fileSize = connection.getContentLength();
    if (fileSize < 0) {
        Logger.d(LOG_TAG, "retrieveImageData()->file size less than 0");
        return null;
    }
    byte[] imageData = null;

    byte[] buffer = new byte[BUFFER_SIZE];

    // download the file
    // if(Global.show_logs) Log.d(LOG_TAG, "fetching image " + imageUrl +
    // " (" + fileSize + ")");
    BufferedInputStream istream = new BufferedInputStream(connection.getInputStream());

    if ((!(height == -1)) && (!(width == -1))) {
        Logger.d(LOG_TAG, "Enter retrieveImageData() :width="+width+" height"+height);
        File tmpFile = GlobalFunctions.getTmpFile();

        if (tmpFile == null)
            throw new IOException("DroidFu::ImageLoader: Could not create temp file!");

        BufferedOutputStream ostream = new BufferedOutputStream(new FileOutputStream(tmpFile));

        Logger.d(LOG_TAG, "before call of IOUtils.copy");
        IOUtils.copy(istream, ostream);
        Logger.d(LOG_TAG, "after call of IOUtils.copy");
        // First decode with inJustDecodeBounds=true to check dimensions
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeFile(tmpFile.getAbsolutePath(), options);

        // Calculate inSampleSize
        Logger.d(LOG_TAG, "before call of calculateInSampleSize()");
        options.inSampleSize = calculateInSampleSize(options, width, height);
        Logger.d(LOG_TAG, "after call of calculateInSampleSize()");

        // Decode bitmap with inSampleSize set
        options.inJustDecodeBounds = false;
        Logger.d(LOG_TAG, "Absolute path of tmp file is: "+tmpFile.getAbsolutePath());
        Bitmap b=BitmapFactory.decodeFile(tmpFile.getAbsolutePath(), options);
        ByteArrayOutputStream stream = new ByteArrayOutputStream();
        b.compress(Bitmap.CompressFormat.PNG, 100, stream);

        byte[] byteArray = stream.toByteArray();

        b.recycle();
        //imageData = stream.toByteArray();

        istream.close();
        ostream.close();
        stream.close();
        Logger.d(LOG_TAG, "Exit retrieveImageData() after resizing to imageview");
        return byteArray;
    }

But this code throw exception (Throwable e) at this line and also " e " is null.:

b.compress(Bitmap.CompressFormat.PNG, 100, stream);
byte[] byteArray = stream.toByteArray();

StackTrace is not helpful(not informative), that's why ,i haven't share. Any how,if you can help me,i'll share. — Mohammad Imran
– Mohammad Imran, Commented Feb 22, 2013 at 6:14
@MohammadImran should we debug the code on the screen ? :-) You should share your stacktrace. — stoilkov
– stoilkov, Commented Feb 22, 2013 at 21:51
Is b null? Was it an IOException? These are all questions answered by posting your stack trace. No one will help you if you don't post relevant information. — Jason Robinson
– Jason Robinson, Commented Feb 24, 2013 at 2:32
Without the stack trace we have no idea what caused the error. It may be as simple as a NPE, but it could be something like networking on main thread. Where do you call the above code from? Why not post your stack trace? If you are voted up to +5, you will get all the reputation you posted back (you don't get it back if you simply don't select a correct answer). — Phil
– Phil, Commented Feb 26, 2013 at 21:14

Dipak Keshariya · Accepted Answer · 2013-01-04 08:35:27Z

10

Try this.

Convert Bitmap to Byte Array:-

Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bmp.compress(Bitmap.CompressFormat.PNG, 100, stream);
byte[] byteArray = stream.toByteArray();

Convert Byte Array into Bitmap Image:-

Bitmap bmp = BitmapFactory.decodeByteArray(byteArray, 0, byteArray.length);

answered Jan 4, 2013 at 8:35

Dipak Keshariya

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1 Comment

Phil Over a year ago

@AliImran have a look at the dates. This was the first answer.

Scarecrow · Accepted Answer · 2013-02-24 19:05:48Z

6

to convert bitmap into byte array you can use

        final int lnth=bitmap.getByteCount();

        ByteBuffer dst= ByteBuffer.allocate(lnth);
        bitmap.copyPixelsToBuffer( dst);
        byte[] barray=dst.array();

And to get bitmap from byte array use

Bitmap bitmap = new BitmapFactory().decodeByteArray(byte_array, 0/* starting index*/, byte_array.length/*no of byte to read*/)

edited Feb 24, 2013 at 19:05

answered Feb 21, 2013 at 23:10

Scarecrow

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Comments

Ali Imran · Accepted Answer · 2013-02-27 05:46:46Z

Here is the link for more advanced image Loader library

the usage is as below:

first put this code in your main activity.

DisplayImageOptions defaultOptions = new DisplayImageOptions.Builder().showStubImage(R.drawable.ic_stub).showImageOnFail(R.drawable.ic_error).showImageForEmptyUri(R.drawable.ic_empty_url).cacheInMemory().cacheOnDisc().build();
    // Create global configuration and initialize ImageLoader with this
    // configuration
    ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(getApplicationContext()).defaultDisplayImageOptions(defaultOptions).build();
    ImageLoader.getInstance().init(config);

then use it in your class like this:

private ImageLoader imageLoader;

inside your onCreate() method

imageLoader = ImageLoader.getInstance();

then load image like this

imageLoader.displayImage(IMG_URL, imageView);

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