CODEWITHSUNDEEP
androidbitmap
Mohammad Imran
Mohammad Imran

Reputation: 3273

How to convert Bitmap to Byte Array

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();

Upvotes: 2

Views: 20366

Answers (3)

Ali Imran
Ali Imran

Reputation: 9217

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);

Upvotes: 4

Scarecrow
Scarecrow

Reputation: 4137

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*/)

Upvotes: 6

Dipak Keshariya
Dipak Keshariya

Reputation: 22291

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);

Upvotes: 10

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