drawingshapes.java

来自「32个java程序源代码」· Java 代码 · 共 141 行

// Tutorial 27: DrawingShapes.java
// Application allows user to draw lines, rectangles and ovals and 
// choose the color of the drawn shape.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class DrawingShapes extends JFrame 
{
   // JPanel for the shape and color controls
   private JPanel controlsJPanel;

   // JComboBox to allow selection of a shape
   private JComboBox shapeJComboBox;

   // JButton to select the color
   private JButton colorJButton;

   // PaintJPanel for drawing shapes
   private PaintJPanel painterPaintJPanel;

   // array of shape types
   private String[] shapeTypes = { "Line", "Rectangle", "Oval" };

   // no-argument constructor
   public DrawingShapes()
   {
      createUserInterface();
   }

   // create and position GUI components; register event handlers
   private void createUserInterface()
   {
      // get content pane for attaching GUI components
      Container contentPane = getContentPane();

      // enable explicit positioning of GUI components
      contentPane.setLayout( null );

      // set up controlsJPanel
      controlsJPanel = new JPanel();
      controlsJPanel.setBounds( 0, 0, 400, 40 );
      controlsJPanel.setLayout( null );
      contentPane.add( controlsJPanel );
      
      // set up painterPaintJPanel
      painterPaintJPanel = new PaintJPanel();
      painterPaintJPanel.setBounds( 0, 40, 400, 340 );
      painterPaintJPanel.setBackground( Color.WHITE );
      contentPane.add( painterPaintJPanel );

      // set up shapeJComboBox
      shapeJComboBox = new JComboBox( shapeTypes );
      shapeJComboBox.setBounds( 90, 2, 100, 24 );
      controlsJPanel.add( shapeJComboBox );
      shapeJComboBox.addActionListener(

         new ActionListener() // anonymous inner class
         {
            // event handler called when shapeJComboBox is selected
            public void actionPerformed( ActionEvent event )
            {
               shapeJComboBoxActionPerformed( event );
            }

         } // end anonymous inner class

      ); // end call to addActionListener

      // set up colorJButton
      colorJButton = new JButton();
      colorJButton.setBounds( 210, 2, 80, 24 );
      colorJButton.setText( "Color" );
      controlsJPanel.add( colorJButton );
      colorJButton.addActionListener(

         new ActionListener() // anonymous inner class
         {
            // event handler called when colorJButton is pressed
            public void actionPerformed( ActionEvent event )
            {
               colorJButtonActionPerformed( event );
            }

         } // end anonymous inner class

      ); // end call to addActionListener

      // set properties of application's window
      setTitle( "Drawing Shapes" ); // set title bar string
      setSize( 408, 407 );          // set window size
      setVisible( true );           // display window

   } // end method createUserInterface

   // select a new color for the shape
   private void colorJButtonActionPerformed( ActionEvent event )
   {
      Color selection = JColorChooser.showDialog( this, 
         "Select a Color", Color.BLACK );

      if ( selection != null )
      {
         colorJButton.setBackground( selection );
         painterPaintJPanel.setCurrentColor( selection );
      }

   } // end method colorJButtonActionPerformed

   // set the selected shape in the painting panel
   private void shapeJComboBoxActionPerformed( ActionEvent event ) 
   {
      painterPaintJPanel.setCurrentShapeType( 
         ( String )shapeJComboBox.getSelectedItem() );

   } // end method shapeJComboBoxActionPerformed

   // main method
   public static void main( String args[] )
   {
      DrawingShapes application = new DrawingShapes();
      application.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );

   } // end method main

} // end class DrawingShapes

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