// the method that draws the balls @Override protected void onDraw(Canvas canvas) { // canvas.drawColor(0xFFCCCCCC); //if you want another background color // draw the balls on the canvas for (ColorBall ball : colorballs) { canvas.drawBitmap(ball.getBitmap(), ball.getX(), ball.getY(), null); } }
// events when touching the screen public boolean onTouchEvent(MotionEvent event) { int eventaction = event.getAction(); int X = (int) event.getX(); int Y = (int) event.getY(); switch (eventaction) { case MotionEvent.ACTION_DOWN: // touch down so check if the finger is on a ball balID = 0; for (ColorBall ball : colorballs) { // check if inside the bounds of the ball (circle) // get the center for the ball int centerX = ball.getX() + 25; int centerY = ball.getY() + 25; // calculate the radius from the touch to the center of the ball double radCircle = Math.sqrt((double) (((centerX - X) * (centerX - X)) + (centerY - Y) * (centerY - Y))); // if the radius is smaller then 23 (radius of a ball is 22), then it must be on the ball if (radCircle < 23) { balID = ball.getID(); break; } // check all the bounds of the ball (square) // if (X > ball.getX() && X < ball.getX()+50 && Y > ball.getY() && Y < ball.getY()+50){ // balID = ball.getID(); // break; // } } break; case MotionEvent.ACTION_MOVE: // touch drag with the ball // move the balls the same as the finger if (balID > 0) { colorballs[balID - 1].setX(X - 25); colorballs[balID - 1].setY(Y - 25); } break; case MotionEvent.ACTION_UP: // touch drop - just do things here after dropping break; } // redraw the canvas invalidate(); return true; }