//  AnimationDemoActivity.java  Copyright (c) Kari Laitinen

//  http://www.naturalprogramming.com/

//  2012-01-30  File created.
//  2015-03-22  Last modification.


/*  This program demonstrates how a thread can be used to
    produce animation onto the screen. "Animation" in this program 
    means that there is a blinking ball on the screen.

    To run this program set up an Andoid Studio project and
    set AnimationDemoActivity as the name of its main activity.
    Use the package name given below. Overwrite the automatically
    created .java file with this file. This program does not 
    need any specific .xml files.

    See notes at the end of this file.
*/

// http://developer.android.com/reference/android/app/Activity.html
// http://developer.android.com/reference/android/graphics/Canvas.html
// http://developer.android.com/reference/android/view/View.html

package animation.demo ;

import android.app.Activity ;
import android.os.Bundle ;
import android.graphics.* ;  // Classes Canvas, Color, Paint, RectF, etc.
import android.view.* ;      // Classes View, Display, WindowManager, etc.
import android.content.Context ;

final class AnimationDemoView extends View implements Runnable
{
   int view_width, view_height ;

   Thread  animation_thread  =  null ;

   boolean  thread_must_be_executed  =  false ;

   boolean  ball_must_be_shown  =  true ;

   int ball_center_point_x, ball_center_point_y ;

   int  ball_color  =  0xFF008B8B ; // DarkCyan

   public AnimationDemoView( Context context,
                             int     given_display_width,
                             int     given_display_height ) 
   {
      super( context ) ;

      view_width = given_display_width ;
      view_height = given_display_height ;

      ball_center_point_x = view_width / 2 ;
      ball_center_point_y = view_height / 2 ;

      setBackgroundColor( 0xFFFFF5EE ) ; // Light color
   }

   public void start_animation_thread()
   {
      if ( animation_thread  ==  null )
      {
         animation_thread  =  new  Thread( this ) ;

         thread_must_be_executed  =  true ;

         animation_thread.start() ;
      }

      System.out.print( "\n Method start() executed. " ) ;
   }

   public void stop_animation_thread()
   {
      if ( animation_thread  !=  null )
      {
         animation_thread.interrupt() ;

         thread_must_be_executed  =  false ;

         animation_thread  =  null ;
      }

      System.out.print( "\n Method stop() executed. " ) ;
   }

   public void run()
   {
      System.out.print( "\n Method run() started." ) ;

      while ( thread_must_be_executed  ==  true )
      {
         System.out.print( " X " ) ;

         try
         {
            Thread.sleep( 1000 ) ;  //  Delay of 1000 milliseconds.
         }
         catch ( InterruptedException  caught_exception )
         {
            thread_must_be_executed  =  false ;
         }

         // Here we must use the method postInvalidate() instead of
         // invalidate(). postInvalidate() must be used to invalidate
         // a View from a non-UI thread.

         postInvalidate() ;
      }

      System.out.print( "\n Method run() stopped. " ) ;
   }

   protected void onDraw( Canvas canvas ) 
   {
      Paint filling_paint = new Paint() ;
      filling_paint.setStyle( Paint.Style.FILL ) ;
      filling_paint.setColor( ball_color ) ;
      
      if ( ball_must_be_shown  ==  true )
      {
         canvas.drawCircle( ball_center_point_x, ball_center_point_y,
                            64, filling_paint ) ;

         ball_must_be_shown  =  false ;
      }
      else
      {
         ball_must_be_shown  =  true ;
      }
   }
}


public class AnimationDemoActivity extends Activity
{
	AnimationDemoView animation_demo_view;

   public void onCreate( Bundle savedInstanceState )
   {
      super.onCreate( savedInstanceState ) ;

      Display display = ( (WindowManager)
             getSystemService( Context.WINDOW_SERVICE )).getDefaultDisplay() ;

      int display_width  = display.getWidth() ; 
      int display_height = display.getHeight() ;

      animation_demo_view = new AnimationDemoView( this, display_width,
                                                         display_height ) ;
        
      setContentView( animation_demo_view ) ;
   }

   public void onStart()
   {
      super.onStart() ;

      animation_demo_view.start_animation_thread() ;
   }

   public void onStop()
   {
      super.onStop() ;

      animation_demo_view.stop_animation_thread() ;
   }
}

/*  NOTES:

   A common mistake made by new Android developers is to use
   the width and height of a view inside its constructor. When
   a View constructor is called, Android does not know yet how
   big the view will be, so the sizes are set to zero. The real sizes
   are calculated during the layout stage, which occurs after
   construction but before anything is drawn. You can use the
   onSizeChanged( )method to be notified of the values when they
   are known, or you can use the getWidth( ) and getHeight( )methods
   later, such as in the onDraw() method. (This was written
   by Ed Burnette at http://www.coderanch.com)

*/