/*
   DrawingRectanglesFX.java Copyright (c) Kari Laitinen

   http://www.naturalprogramming.com/

   2014-12-21 File created.
   2014-12-29 Last modification.


   With this program the user can draw rectangles to the screen.

   This program demonstrates how to react to mouse events.Lambda expressions
   are used to specify the mouse-related activities.
       
   This program is able to draw a rectangle "in a correct way" 
   regardless of the direction to which the mouse moves.
   Various drawing programs usually produce rectangles in this way.

*/


import javafx.application.Application;
import javafx.scene.input.MouseEvent;
import javafx.scene.* ;
import javafx.stage.Stage;
import javafx.geometry.* ; // Point2D
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle ;


public class DrawingRectanglesFX extends Application
{
   double starting_point_x, starting_point_y ;

   Group group_for_rectangles = new Group() ;

   Rectangle new_rectangle = null ;

   boolean new_rectangle_is_being_drawn = false ;

   Color[] rectangle_colors = { Color.TEAL,   Color.TOMATO,  Color.TURQUOISE,
                                Color.VIOLET, Color.YELLOWGREEN, Color.GOLD } ;

   int color_index = 0 ;

   //  The following method adjusts coordinates so that the rectangle
   //  is shown "in a correct way" in relation to the mouse movement.

   void adjust_rectangle_properties( double starting_point_x,
                                     double starting_point_y,
                                     double ending_point_x,
                                     double ending_point_y,
                                     Rectangle given_rectangle )
   {
      given_rectangle.setX( starting_point_x ) ;
      given_rectangle.setY( starting_point_y ) ;
      given_rectangle.setWidth( ending_point_x - starting_point_x ) ;
      given_rectangle.setHeight( ending_point_y - starting_point_y ) ;

      if ( given_rectangle.getWidth() < 0 )
      {
         given_rectangle.setWidth( - given_rectangle.getWidth() ) ;
         given_rectangle.setX( given_rectangle.getX() - given_rectangle.getWidth() ) ;
      }

      if ( given_rectangle.getHeight() < 0 )
      {
         given_rectangle.setHeight( - given_rectangle.getHeight() ) ;
         given_rectangle.setY( given_rectangle.getY() - given_rectangle.getHeight() ) ;
      }
   }



   public void start( Stage stage )
   {
      stage.setTitle( "DrawingRectanglesFX.java" ) ;

      Scene scene = new Scene( group_for_rectangles, 800, 600 ) ;

      scene.setFill( Color.BEIGE ) ;

      scene.setOnMousePressed( ( MouseEvent event ) ->
      {
         if ( new_rectangle_is_being_drawn == false )
         {
            starting_point_x = event.getSceneX() ;
            starting_point_y = event.getSceneY() ;

            new_rectangle = new Rectangle() ;

            // A non-finished rectangle has always the same color.
            new_rectangle.setFill( Color.SNOW ) ; // almost white color
            new_rectangle.setStroke( Color.BLACK ) ;

            group_for_rectangles.getChildren().add( new_rectangle ) ;
   
            new_rectangle_is_being_drawn = true ;
         }
      } ) ;

      scene.setOnMouseDragged( ( MouseEvent event ) ->
      {
         if ( new_rectangle_is_being_drawn == true )
         {
            double current_ending_point_x = event.getSceneX() ;
            double current_ending_point_y = event.getSceneY() ;

            adjust_rectangle_properties( starting_point_x,
                                         starting_point_y,
                                         current_ending_point_x,
                                         current_ending_point_y,
                                         new_rectangle ) ;
         }
      } ) ;

      scene.setOnMouseReleased( ( MouseEvent event ) ->
      {
         if ( new_rectangle_is_being_drawn == true )
         {
            // Now the drawing of the new rectangle is finished.
            // Let's set the final color for the rectangle.

            new_rectangle.setFill( rectangle_colors[ color_index ] ) ;

            color_index ++ ;  // Index for the next color to use.
   
            // If all colors have been used we'll start re-using colors from the
            // beginning of the array.
   
            if ( color_index >= rectangle_colors.length )
            {
               color_index = 0 ;
            }

            new_rectangle = null ;
            new_rectangle_is_being_drawn = false ;
         }
      } ) ;

      stage.setScene( scene ) ;
      stage.show();
   }


   public static void main( String[] command_line_parameters )
   {
      launch( command_line_parameters ) ;
   }
}

/* NOTES:

The following links were useful when this program was developed:

https://docs.oracle.com/javase/8/javafx/api/javafx/scene/shape/Rectangle.html
https://docs.oracle.com/javase/8/javafx/api/javafx/scene/Group.html

*/