I want to put custom border around zxing capture screen (camera screen). What modification would I need to make for this? Which activity and layouts would I need to change to have this effect?
You don't need to edit layouts at all.
In ViewfinderView
find onDraw
method. It's the core that draws the "scanning rectangle". You can modify it the way you want.
The code that actually draws the rectangle can be found here:
// Draw the exterior (i.e. outside the framing rect) darkened
paint.setColor(resultBitmap != null ? resultColor : maskColor);
canvas.drawRect(0, 0, width, frame.top, paint);
canvas.drawRect(0, frame.top, frame.left, frame.bottom + 1, paint);
canvas.drawRect(frame.right + 1, frame.top, width, frame.bottom + 1, paint);
canvas.drawRect(0, frame.bottom + 1, width, height, paint);