CS 100: Lecture L11

March 2

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Template for programs with User-Defined Graphics methods:

import java.awt.*;
public class ShowClock extends Frame
{   
   
    // Put methods here that operate on the ShowClock object:
    
    
    
    
    // This method is called by the system whenever the window needs to be
    // redrawn. g "does the drawing"
	public void paint(Graphics g)
	{
	  
	   
	  
	}
	
}

public class L11
{
	public static void main(String args[])
	{
	    // Create a ShowClock object. This is just a window, border, and title bar.
	    
		ShowClock d = new ShowClock();
		d.resize(800,600);                    
		d.move(0,75);
		d.setTitle("Time");                 
		d.show();
		d.toFront();
	}
}

The ShowClock Example

import java.awt.*;
public class ShowClock extends Frame
{   
    // Graphics g draws a clock face showing the time specified by hour and minute. 
    // The center is at (hc,vc) and the radius of the clock face is r.
    public static void drawClock(Graphics g, int hc, int vc, int r, int hour, int min)
    {
        drawFace(g,hc,vc,r);
        int rHour = (int) (.6*r);                // Length of hour hand.
        int angleHour = 90 - 30*hour - min/2;    // Angle of hour hand.
        drawRay(g,hc,vc,rHour,angleHour);
        int rMin  = (int) (.85*r);               // Length of minute hand.
        int angleMin  = 90 - 6*min;              // Angle of minute hand.
        drawRay(g,hc,vc,rMin,angleMin);
    }
    
    // Graphics g draws a length r line segment from (hc,vc). The line segment
    // makes a counter clockwise angle of theta degrees with the positive h-axis.
    public static void drawRay(Graphics g, int hc, int vc, int r, int theta)
    {
        g.setColor(Color.black);
        int h1 = (int)(hc + r*Math.cos(theta*Math.PI/180));
        int v1 = (int)(vc - r*Math.sin(theta*Math.PI/180));
        g.drawLine(hc,vc,h1,v1);
    }
    
    // Graphics g draws a filled disk of radius r and center (hc,vc).
    public static void fillCircle(Graphics g,int hc,int vc, int r)
    {
       g.fillOval(hc-r,vc-r,2*r,2*r);
    }
    
    // Graphics g draws a designer clock face of radius r and center (hc,vc).
    public static void drawFace(Graphics g, int hc, int vc, int r)
    {
        // Color the light gray face and black rim.
        g.setColor(Color.black);
        fillCircle(g,hc,vc,r);
        g.setColor(Color.lightGray);
        fillCircle(g,hc,vc,(int)(.9*r));
        
        // Draw 60 equally spaced markers around the rim.
        int hTick,vTick;               // (hTick,vTick) = center of kth marker
        double tau;                    // angle of kth marker.
        int rTick = (int)(.03*r);      // radius of the 5-minute markers
        for(int k=0;k<=59;k++)
        {
           tau = 6*k*Math.PI/180;
           hTick = (int)(hc + .95*r*Math.cos(tau));
           vTick = (int)(vc - .95*r*Math.sin(tau));
           if(k%5==0)
           {
              // Draw a 5-minute marker.
              g.setColor(Color.red);
              fillCircle(g,hTick,vTick,rTick);
           }
           else
           {
              // Draw a non 5-minute marker.
              g.setColor(Color.blue);
              fillCircle(g,hTick,vTick,rTick/2);
           }
        }
    }
    
	public void paint(Graphics g)
	{
	   // Draw a clock
	   int hour = 12;
	   int min  = 43;
	   
	   drawClock(g,400,300,200,hour,min); 
	     
	   
	   // "Pretty print" the exact time in digital form.
	   String s;
	   if (min&lt10)
	      s =  hour + ":0" + min;
	   else
	      s =  hour + ":" + min;
	     
	   g.setFont(new Font("TimesRoman",Font.PLAIN,36)); 
	   g.drawString(s,360,550);
	   
	  
	}
	
}

public class L11
{
	public static void main(String args[])
	{
		ShowClock d = new ShowClock();
		d.resize(800,600);                    
		d.move(0,75);
		d.setTitle("Time");                 
		d.show();
		d.toFront();
	}
}