Monday 22 October 2012

Android - how to add padding or a border to a Bitmap

Here's a neat (I'd like to think) method (which you can tinker with) for adding padding or a border to a Bitmap:
 
 
/** Creates and returns a new bitmap which is the same as the provided bitmap
 * but with horizontal or vertical padding (if necessary)
 * either side of the original bitmap
 * so that the resulting bitmap is a square.
 * @param bitmap is the bitmap to pad.
 * @return the padded bitmap.*/
public static Bitmap padBitmap(Bitmap bitmap)
{
  int paddingX;
  int paddingY;

  if (bitmap.getWidth() == bitmap.getHeight())
  {
    paddingX = 0;
    paddingY = 0;
  }
  else if (bitmap.getWidth() > bitmap.getHeight())
  {
    paddingX = 0;
    paddingY = bitmap.getWidth() - bitmap.getHeight();
  }
  else
  {
    paddingX = bitmap.getHeight() - bitmap.getWidth();
    paddingY = 0;
  }

  Bitmap paddedBitmap = Bitmap.createBitmap(
      bitmap.getWidth() + paddingX,
      bitmap.getHeight() + paddingY,
      Bitmap.Config.ARGB_8888);

  Canvas canvas = new Canvas(paddedBitmap);
  canvas.drawARGB(0xFF, 0xFF, 0xFF, 0xFF); // this represents white color
  canvas.drawBitmap(
      bitmap,
      paddingX / 2,
      paddingY / 2,
      new Paint(Paint.FILTER_BITMAP_FLAG));

  return paddedBitmap;
}
 

1 comment:

Anonymous said...

I found this useful, thanks.