Graphics Demo 3

Here are some more examples of the various functions at your disposal in Java's graphics library. Type in the following code and get it to compile.

Files Needed

import java.awt.*;
import javax.swing.JFrame;

public class GraphicsDemo3 extends Canvas
{
    public void paint( Graphics g )
    {
        // lines
        g.setColor(Color.green);
        g.drawLine(10,100,400,100);
        g.setColor(Color.blue);
        g.drawLine(50,150,100,180);
        g.setColor(Color.magenta);
        g.drawLine(100,350,300,230);

        g.setColor(Color.black);

        // fonts
        g.drawString("Graphics are pretty neat.", 500, 100);
        g.setFont(new Font("Consolas", Font.PLAIN, 36)); // 36-pt plain
        g.drawString("Yes, they are.", 400, 200);

        g.setColor(Color.white);
        g.setFont(new Font("Calibri", Font.BOLD+Font.ITALIC, 60)); // 60-pt italic bold
        g.drawString("Leander Lions", 300, 350);

        g.setColor(Color.blue);
        g.setFont(Font.decode("Calibri-BOLDITALIC-60")); // a different way to specify the same font
        g.drawString("Leander Lions", 290, 360);
        
        g.setColor(Color.black);
        g.setFont(new Font(null)); // restore default font

        int x=400, y=490;
        g.drawRect(x,y,150,20);
        g.drawString("Where is the starting point?", x,y);
        g.setColor(Color.red);
        g.drawLine(x,y,x,y);	// drawing a line from a point to itself makes a 1px-by-1px dot

    }

    public static void main( String[] args )
    {
        JFrame win = new JFrame("GraphicsDemo3: Fonts and Lines");
        win.setSize(800,600);
        win.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        GraphicsDemo3 canvas = new GraphicsDemo3();
        win.add( canvas );
        win.setVisible(true);
    }
}

What You Should Do on Your Own

Assignments turned in without these things will receive half credit or less. Answer any questions in comments at the top of GraphicsDemo3.java.

  1. When drawing a line, what do the four numbers represent?
  2. Make a short red line that intersects the long green line.
  3. Make a short red line that is roughly perpendicular to the diagonal "magenta" line.
  4. When drawing a rectangle, where on the rectangle is the starting point you provide? Use the key below.
      the upper-left corner? - o......     ......o - the upper-right corner?
                               .......     .......
                               .......     .......
    
                               .......     .......
                               .......     .......
      the lower-left corner? - o......     ....... - the lower-right corner?
    
    ---------------------------------------------------------------------------------
    
                                     ...o... - the top of the center line?
                                     .......
                                     .......
    
                               .......     .......
    middle of the left side? - o......     ......o - middle of the right side?
                               .......     .......
    
                                     .......
                                     .......
                                     ...o... - the bottom of the center line?
    
    ---------------------------------------------------------------------------------
    
                                     .......
                    or, the absolute ...o... center of the rectangle?
                                     .......
    
  5. When drawing strings, where on the string is the starting point you provide?
  6. When setting a custom font, what happens if you provide a font that doesn't exist?
  7. When setting a custom font, what happens if you provide a font that isn't installed on this machine?
  8. Change the first "Leander Lions" (the white one) to a different font. Change the blue "Leander Lions" to match it.



©2013 Graham Mitchell

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