Drawable to byte[]

Question

I have an image from the web in an ImageView. It is very small (a favicon) and I'd like to store it in my SQLite database. I can get a Drawable from mImageView.getDrawable() but then I don't know what to do next. I don't fully understand the Drawable class in Android.

I know I can get a byte array from a Bitmap like:

Bitmap defaultIcon = BitmapFactory.decodeStream(in);

ByteArrayOutputStream stream = new ByteArrayOutputStream();
defaultIcon.compress(Bitmap.CompressFormat.JPEG, 100, stream);

byte[] bitmapdata = stream.toByteArray();

But how do I get a byte array from a Drawable?

score 147 · Accepted Answer · edited Apr 10 '12 at 06:57

147

Drawable d; // the drawable (Captain Obvious, to the rescue!!!)
Bitmap bitmap = ((BitmapDrawable)d).getBitmap();
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, stream);
byte[] bitmapdata = stream.toByteArray();

edited Apr 10 '12 at 06:57

Ilya Saunkin

18,934
9
36
50

answered Dec 14 '10 at 04:19

Cristian

198,401
62
356
264

Thank you for the obvious!! Didn't think about casting it. – David Shellabarger Dec 15 '10 at 00:01
9

It should be: bitmap.compress(Bitmap.CompressFormat.JPEG, 100, stream); Otherwise the stream contains no data... – Entreco Sep 07 '11 at 09:54
@Cristian i saved bitmapdata in database as BLOB, again when i regain my drawable from BLOB, background becomes black. Can u help me? i want background transparent as it was before saving to database. – Sazzad Hissain Khan Sep 12 '14 at 10:29
1

@Hissain because JPG does not store transparency, you need PNG for that – EpicPandaForce Dec 10 '15 at 07:58
Note: in most of the cases compressing JPEG with 90 (instead of 100) will be the best way to go! – Kirill Karmazin Nov 01 '18 at 20:31
why 90 or even 100? what is the meaning of either choices – Ryhan Jan 24 '22 at 09:15

score 22 · Answer 2 · answered Apr 01 '12 at 18:03

22

Thanks all and this solved my problem.

Resources res = getResources();
Drawable drawable = res.getDrawable(R.drawable.my_pic);
Bitmap bitmap = ((BitmapDrawable)drawable).getBitmap();
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, stream);
byte[] bitMapData = stream.toByteArray();

answered Apr 01 '12 at 18:03

Randula

1,537
15
11

i saved bitMapData in database as BLOB, again when i regain my drawable from BLOB, background becomes black. Can u help me? i want background transparent as it was before saving to database. – Sazzad Hissain Khan Sep 12 '14 at 10:30
I think its a different issue that occur parallel to that process. Its great if you can provide more details to reproduce and check. – Randula Sep 20 '14 at 18:42
1

it was happening when saving with JPEG format, but i changed to PNG its working fine... – Sazzad Hissain Khan Sep 21 '14 at 04:47

Kalpesh · Answer 3 · 2016-04-23T13:23:01.940

10

Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.tester);
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, stream);
byte[] bitMapData = stream.toByteArray();

edited Apr 23 '16 at 13:23

answered Jul 16 '12 at 10:05

Kalpesh

1,767
19
29

This is a better answer, since it doesn't require casting to BitmapDrawable, which the drawable may not actually be an instance of. – matt snider Apr 29 '16 at 21:11
@mattsnider Thanks – Kalpesh May 09 '16 at 09:54

score 2 · Answer 4 · answered Dec 21 '22 at 14:00

Here is my Utility function which can be copy-pasted

/**
 * @param ctx the context
 * @param res the resource id
 * @return the byte[] data of the fiven drawable identified with the resId
 */
public static byte[] getDrawableFromRes(Context ctx, @DrawableRes int res) {
    Bitmap bitmap = BitmapFactory.decodeResource(ctx.getResources(), res);
    ByteArrayOutputStream stream = new ByteArrayOutputStream();
    bitmap.compress(Bitmap.CompressFormat.JPEG, 100, stream);
    return stream.toByteArray();
}

Favas Kv · Answer 5 · 2014-06-16T05:40:26.817

0

If Drawable is an BitmapDrawable you can try this one.

long getSizeInBytes(Drawable drawable) {
    if (drawable == null)
        return 0;

    Bitmap bitmap = ((BitmapDrawable) drawable).getBitmap();
    return bitmap.getRowBytes() * bitmap.getHeight();
}

Bitmap.getRowBytes() returns the number of bytes between rows in the bitmap's pixels.

For more refer this project: LazyList

edited Jun 16 '14 at 05:40

answered Jun 13 '14 at 14:36

Favas Kv

2,961
2
28
38

1

This post is being automatically flagged as low quality because it is only code. Would you mind expanding it by adding some text to explain how it solves the problem? – gung - Reinstate Monica Jun 13 '14 at 15:04

score -2 · Answer 6 · edited Mar 08 '12 at 01:00

-2

File myFile = new File(selectedImagePath);

byte [] mybytearray  = new byte [filelenghth];

BufferedInputStream bis1 = new BufferedInputStream(new FileInputStream(myFile));

bis1.read(mybytearray,0,mybytearray.length);

now the image is stored in the bytearray..

edited Mar 08 '12 at 01:00

Samet Atdag

982
6
21

answered Dec 14 '10 at 06:09

Abhishek Susarla

578
1
6
12

Drawable to byte[]

6 Answers6

Linked