Question

I would try to develop an application in which I can draw a planimetry. So, each room has got its own ID or name and, if I touch a room, I want to show a Toast Message with that ID or name. The problem is how check if and which path is touched!!

I saw a lot of topic discussions that talked about this problem. Someone says to use the getBounds method and, after, contains method for checking if touched point is in Rect. But, I guess getBounds returns the smallest Rect that contains path, right?

So, rooms have different custom geometric forms and, for this reason, if I get bounds about 2 close rooms, method could return a shared set of points. Bad! Each room has got only their area points. How can I solve this problem?

In iOS i could use PathContainsPoint method, but, unfortunaly, Android Path doesn’t have something similar.

Answer 1

Ok i solved my problem. I post the example code:

Path p;
Region r;

@Override
public void onDraw(Canvas canvas) {

    p = new Path();

    p.moveTo(50, 50);
    p.lineTo(100, 50);
    p.lineTo(100, 100);
    p.lineTo(80, 100);
    p.close();      

    canvas.drawPath(p, paint);

    RectF rectF = new RectF();
    p.computeBounds(rectF, true);
    r = new Region();
    r.setPath(p, new Region((int) rectF.left, (int) rectF.top, (int) rectF.right, (int) rectF.bottom));

}   

public boolean onTouch(View view, MotionEvent event) {

    Point point = new Point();
    point.x = event.getX();
    point.y = event.getY();
    points.add(point);
    invalidate();
    Log.d(TAG, "point: " + point);

    if(r.contains((int)point.x,(int) point.y))
        Log.d(TAG, "Touch IN");
    else
        Log.d(TAG, "Touch OUT");

    return true;
}