RoundRectangleExample.java Source code

Introduction

Here is the source code for RoundRectangleExample.java

Source

//Send questions, comments, bug reports, etc. to the authors:

//Rob Warner (rwarner@interspatial.com)
//Robert Harris (rbrt_harris@yahoo.com)

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;

public class RoundRectangleExample {
    private Text txtArcWidth = null;
    private Text txtArcHeight = null;

    /**
     * Runs the application
     */
    public void run() {
        Display display = new Display();
        Shell shell = new Shell(display);
        shell.setText("RoundRectangle Example");
        createContents(shell);
        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }
        }
        display.dispose();
    }

    /**
     * Creates the main window's contents
     * 
     * @param shell the main window
     */
    private void createContents(Shell shell) {
        shell.setLayout(new FillLayout(SWT.VERTICAL));

        // Create the composite that holds the input fields
        Composite widgetComposite = new Composite(shell, SWT.NONE);
        widgetComposite.setLayout(new GridLayout(2, false));

        // Create the input fields
        new Label(widgetComposite, SWT.NONE).setText("Arc Width:");
        txtArcWidth = new Text(widgetComposite, SWT.BORDER);

        new Label(widgetComposite, SWT.NONE).setText("Arc Height");
        txtArcHeight = new Text(widgetComposite, SWT.BORDER);

        // Create the button that launches the redraw
        Button button = new Button(widgetComposite, SWT.PUSH);
        button.setText("Redraw");
        shell.setDefaultButton(button);

        // Create the canvas to draw the round rectangle on
        final Canvas drawingCanvas = new Canvas(shell, SWT.NONE);
        drawingCanvas.addPaintListener(new RoundRectangleExamplePaintListener());

        // Add a handler to redraw the round rectangle when pressed
        button.addSelectionListener(new SelectionAdapter() {
            public void widgetSelected(SelectionEvent e) {
                drawingCanvas.redraw();
            }
        });
    }

    /**
     * This class gets the user input and draws the requested round rectangle
     */
    private class RoundRectangleExamplePaintListener implements PaintListener {
        public void paintControl(PaintEvent e) {
            // Get the canvas for drawing and its width and height
            Canvas canvas = (Canvas) e.widget;
            int x = canvas.getBounds().width;
            int y = canvas.getBounds().height;

            // Determine user input, defaulting everything to zero.
            // Any blank fields are converted to zero
            int arcWidth = 0;
            int arcHeight = 0;
            try {
                arcWidth = txtArcWidth.getText().length() == 0 ? 0 : Integer.parseInt(txtArcWidth.getText());
                arcHeight = txtArcWidth.getText().length() == 0 ? 0 : Integer.parseInt(txtArcHeight.getText());
            } catch (NumberFormatException ex) {
                // Any problems, set them both to zero
                arcWidth = 0;
                arcHeight = 0;
            }

            // Set the line width
            e.gc.setLineWidth(4);

            // Draw the round rectangle
            e.gc.drawRoundRectangle(10, 10, x - 20, y - 20, arcWidth, arcHeight);
        }
    }

    /**
     * The application entry point
     * 
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        new RoundRectangleExample().run();
    }
}