converting Java bitmap to byte array

Question

  Bitmap bmp   = intent.getExtras().get("data");   int size     = bmp.getRowBytes() * bmp.getHeight();   ByteBuffer b = ByteBuffer.allocate(size);    bmp.copyPixelsToBuffer(b);    byte[] bytes = new byte[size];    try {      b.get(bytes, 0, bytes.length);   } catch (BufferUnderflowException e) {      // always happens   }   // do something with byte[] 

When I look at the buffer after the call to copyPixelsToBuffer the bytes are all 0... The bitmap returned from the camera is immutable... but that shouldn't matter since it's doing a copy.

What could be wrong with this code?

Answer 1

Try something like this:

Bitmap bmp = intent.getExtras().get("data"); ByteArrayOutputStream stream = new ByteArrayOutputStream(); bmp.compress(Bitmap.CompressFormat.PNG, 100, stream); byte[] byteArray = stream.toByteArray(); bmp.recycle(); 

Answer 2

CompressFormat is too slow...

Try ByteBuffer.

※※※Bitmap to byte※※※

width = bitmap.getWidth(); height = bitmap.getHeight();  int size = bitmap.getRowBytes() * bitmap.getHeight(); ByteBuffer byteBuffer = ByteBuffer.allocate(size); bitmap.copyPixelsToBuffer(byteBuffer); byteArray = byteBuffer.array(); 

※※※byte to bitmap※※※

Bitmap.Config configBmp = Bitmap.Config.valueOf(bitmap.getConfig().name()); Bitmap bitmap_tmp = Bitmap.createBitmap(width, height, configBmp); ByteBuffer buffer = ByteBuffer.wrap(byteArray); bitmap_tmp.copyPixelsFromBuffer(buffer);