Get byte[] of image

[yash wardhan]

Hi All,
I am working on an app. in which I set some images in gridview.
What I want to do is take the byte[] of any image clicked and store it in DB.
Currently I have stored those images in drawable of the application. I tried "Bitmap bitmap = view.getDrawingCache();", but it is giving bitmap as null.


Can anyone please help me in getting byte[] of the image?


Thanks,
Yash

[yash wardhan]

Any replies on this please.

[Monu Tripathi]

[I am not sure I understood your question fully..]

If you have a handle on a android.graphics.Bitmap, you can write it to a java.lang.ByteArrayOutputStream using the compress method of android.graphics.BitmapFactory class. You can then get the byte array from java.lang.ByteArrayOutputStream object using toByteArray() method.

Something like,

ByteArrayOutputStream baos = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.PNG, 100, baos); //bm is the bitmap object 
byte[] b = baos.toByteArray();

Hope that helps..

[yash wardhan]

Thanks Monu,

I tried this but the problem is my bm object is null.
Actually I have my images in drawable and I want to get the Bitmap (or byte[]) of the user selected image.
Don't know why object of bitmap is null.
I used getDrawingCache() of view, and I have one more doubt even if this method gives me bitmap, what if any user disables the cache(don't know how to do it though).

Please reply

[Monu Tripathi]

I'd imagine you can get selected bitmap by having a onItemClickListener on your grid view and overriding the onItemClick method(atleast if you have setup your adapter for grid view like this one here).

[yash wardhan]

Monu,
I tries that solution but may be doing something wrong, can you please post the code.
I tried the same code that you pointed to. I want to convert that byte[] into string and save in DB.


Thanks,
Yash

[Monu Tripathi]

Sorry, I haven't coded anything in this regard. I was just making some general suggestions..

Why dont you go ahead and post your code-maybe that would help?

[yash wardhan]

Hi Monu,

I tried following code which is not working.
The adapter is same as given in sample code here

  

class TestGridImages extends Activity implements
		android.widget.AdapterView.OnItemClickListener {
	
	ByteArrayOutputStream bos;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
    	 super.onCreate(savedInstanceState);
    	    setContentView(R.layout.gridlayout);

    	    GridView gridview = (GridView) findViewById(R.id.gridview);
    	     
    	    gridview.setAdapter(new ImageAdapter(this));
    	    gridview.setOnItemClickListener(this);
    	   
    }
    
    
    public void onItemClick(AdapterView<?> adapterView, View view, int position, long rowId) {
    	Log.i("PatternGrid ","Image clicked");
    	
    	Bitmap bitmap = view.getDrawingCache();
    	bos = new ByteArrayOutputStream();
    	bitmap.compress(CompressFormat.JPEG,100,bos);
    	//TODO furthere processing to convert byte[] into string and save to DB.    	
    }
}

In onItemClick() method bitmap is remaining null.

[Monu Tripathi]

Yash,

If you understand the purpose of all the functions in your ImageAdapter class and the way Adapters and views work, your problem is solved.
Here's what you can do:

Override the getItem(int position) method of the ImageAdapter class to return the resource Id.

public Object getItem(int position) {
        return mThumbIds[position];
    }

In the onItemClick(..) of your TestGridImages do a getItem on the adapter, this will return the resource Id(remember we did so earlier).Use this resource Id to create a bitmap, then write the bitmap to your ByteArrayOutputStream.

 Integer imageId = (Integer)((ImageAdapter)adapterView.getAdapter()).getItem(position);
 Bitmap bitmap = BitmapFactory.decodeResource(getResources(), imageId.intValue());   
 bos = new ByteArrayOutputStream();   
 bitmap.compress(CompressFormat.JPEG,100,bos);