How to add a rectangular overlay in a camera application?

Question

How do I add a rectangular overlay (which should be more like a rectangular frame) in the camera preview? My application consists of a button that opens the camera upon clicking

Answer 1

First, create a public Class that extends View. Inside its onDraw() method, draw your rectangle. For example:

public class Box extends View {
  private Paint paint = new Paint();
  Box(Context context) {
    super(context);
  }

  @Override
  protected void onDraw(Canvas canvas) { // Override the onDraw() Method
    super.onDraw(canvas);

    paint.setStyle(Paint.Style.STROKE);
    paint.setColor(Color.GREEN);
    paint.setStrokeWidth(10);

    //center
    int x0 = canvas.getWidth()/2;
    int y0 = canvas.getHeight()/2;
    int dx = canvas.getHeight()/3;
    int dy = canvas.getHeight()/3;
    //draw guide box
    canvas.drawRect(x0-dx, y0-dy, x0+dx, y0+dy, paint);
  }
}

Then, in your camera preview Activity, have an instance to your Box class:

Box box = new Box(this);

Finally:

addContentView(box, new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));

A green rectangle will be drawn onto your camera preview.