#  BallQt.py  Copyright (c) Kari Laitinen

#  http://www.naturalprogramming.com

#  2010-09-27  File created.
#  2010-09-27  Last modification.

#  The Ball class represents a graphical ball that can be drawn
#  onto the screen.

#  The Ball class is used in programs MovingBallOOQt.py and
#  MovingBallWithMouseQt.py

from PyQt4.QtCore import *
from PyQt4.QtGui import *

import math

class Ball :

   def __init__( self, given_center_point_x,
                       given_center_point_y,
                       given_color )  :

      self.ball_center_point_x  =  given_center_point_x
      self.ball_center_point_y  =  given_center_point_y
      self.ball_color           =  given_color

      self.ball_diameter  =  100
      self.this_ball_is_activated  =  False


   def activate_ball( self ) : 

      self.this_ball_is_activated  =  True


   def deactivate_ball( self ) :

      self.this_ball_is_activated  =  False



   def get_ball_center_point_x( self ) :

      return self.ball_center_point_x


   def get_ball_center_point_y( self ) :

      return self.ball_center_point_y


   def get_ball_diameter( self ) :

      return self.ball_diameter

   def get_ball_color( self ) :

      return self.ball_color


   def move_right( self ) :

      self.ball_center_point_x  +=  3


   def move_left( self ) :

      self.ball_center_point_x  -=  3


   def move_up( self ) :

      self.ball_center_point_y  -=  3


   def move_down( self ) :

      self.ball_center_point_y  +=  3



   def move_this_ball( self, movement_in_direction_x,
                             movement_in_direction_y ) :

      self.ball_center_point_x  +=  movement_in_direction_x
      self.ball_center_point_y  +=  movement_in_direction_y


   def move_to_position( self, new_center_point_x,
                               new_center_point_y ) :

      self.ball_center_point_x  =  new_center_point_x
      self.ball_center_point_y  =  new_center_point_y


   def shrink( self ) :

      #  The if-construct ensures that the ball does not become
      #  too small.

      if  self.ball_diameter  > 10  :

         self.ball_diameter  -=  6


   def enlarge( self ) :

      self.ball_diameter  +=  6


   def set_diameter( self, new_diameter ) :

      if  new_diameter  >  5  :

         self.ball_diameter  =  new_diameter


   def set_color( self, new_color ) :

      self.ball_color  =  new_color


   def contains_point( self, given_point_x, given_point_y ) :

      ball_radius  =  self.ball_diameter / 2

      #  Here we use the Pythagorean theorem to calculate the distance
      #  from the given point to the center point of the ball.
      #  See the note at the end of this file.

      distance_from_given_point_to_ball_center  =   \
          int( math.sqrt(
                 math.pow( self.ball_center_point_x  -  given_point_x, 2 )  +
                 math.pow( self.ball_center_point_y  -  given_point_y, 2 )  ) )

      return  distance_from_given_point_to_ball_center  <=  ball_radius 


#   def intersects_rectangle( self, given_rectangle ) :

#   This method to be written later.

#      Area  this_ball_area  =  new  Area(

#                   new  Ellipse2D.Float( self.ball_center_point_x,
#                                         self.ball_center_point_y,
#                                         self.ball_diameter,
#                                         self.ball_diameter ) )

#      return this_ball_area.intersects( given_rectangle  )


   def draw( self, painter ) :

      painter.setBrush( self.ball_color )

      ball_radius  =  self.ball_diameter / 2

      painter.drawEllipse( self.ball_center_point_x - ball_radius,
                           self.ball_center_point_y - ball_radius,
                           self.ball_diameter, self.ball_diameter )

      #  If this ball is activated, it will have a thick black edge

      if  self.this_ball_is_activated  ==  True :

         painter.drawEllipse( self.ball_center_point_x - ball_radius + 1,
                              self.ball_center_point_y - ball_radius + 1,
                              self.ball_diameter - 2, self.ball_diameter - 2 )

         painter.drawEllipse( self.ball_center_point_x - ball_radius + 2,
                              self.ball_center_point_y - ball_radius + 2,
                              self.ball_diameter - 4, self.ball_diameter - 4 )