Extents.java Source code

Introduction

Here is the source code for Extents.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.custom.*;
import org.eclipse.swt.events.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.widgets.*;

/**
 * This class demonstrates FontMetrics and extents
 */
public class Extents {
    // The string to display
    private static final String STRING = "Go Celtics!";

    // The size options for the combo
    private static final String[] SIZES = { "8", "10", "12", "14", "16", "18" };

    // The font used to draw the string
    private Font font;

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

    /**
     * Creates the main window's contents
     * 
     * @param shell the main window
     */
    private void createContents(final Shell shell) {
        // Create a canvas to draw on
        final Canvas canvas = new Canvas(shell, SWT.NONE);

        // Add a listener to the shell to resize the canvas to fill the window
        // any time the window is resized
        shell.addControlListener(new ControlAdapter() {
            public void controlResized(ControlEvent event) {
                canvas.setBounds(shell.getClientArea());
            }
        });

        // Add a listener to the canvas. This is where we draw the text.
        canvas.addPaintListener(new PaintListener() {
            public void paintControl(PaintEvent event) {
                // Set the font into the gc
                event.gc.setFont(font);

                // Calcalute the width (nad height) of the string
                Point pt = event.gc.stringExtent(STRING);

                // Figure out how big our drawing area is
                Rectangle rect = canvas.getBounds();

                // Calculate the height of the font. We could have used pt.y,
                // but this demonstrates FontMetrics
                int height = event.gc.getFontMetrics().getHeight();

                // Outside loop goes from the top of the window to the bottom.
                // Since the (x, y) passed to drawString represents the upper left
                // corner, subtract the height of the font from the height of the
                // drawing area, so we don't have any partial drawing.
                for (int i = 0, n = rect.height - height; i < n; i += height) {
                    // Inside loop goes from the left to the right, stopping far enough
                    // from the right to ensure no partial string drawing.
                    for (int j = 0, m = rect.width - pt.x; j < m; j += pt.x) {
                        // Draw the string
                        event.gc.drawString(STRING, j, i);
                    }
                }
            }
        });

        // Create an editor to house the dropdown
        ControlEditor editor = new ControlEditor(canvas);

        // Create the combo and fill it
        final Combo combo = new Combo(canvas, SWT.READ_ONLY);
        for (int i = 0, n = SIZES.length; i < n; i++) {
            combo.add(SIZES[i]);
        }

        // Set up the editor
        editor.horizontalAlignment = SWT.CENTER;
        editor.verticalAlignment = SWT.TOP;
        Point size = combo.computeSize(SWT.DEFAULT, SWT.DEFAULT);
        editor.minimumWidth = size.x;
        editor.minimumHeight = size.y;
        editor.setEditor(combo);

        // Add a listener to the combo, so that when the selection changes,
        // we change the font and redraw the canvas
        combo.addSelectionListener(new SelectionAdapter() {
            public void widgetSelected(SelectionEvent event) {
                if (font != null)
                    font.dispose();
                font = new Font(shell.getDisplay(), "Helvetica", new Integer(combo.getText()).intValue(), SWT.BOLD);
                canvas.redraw();
            }
        });

        // Select the first item in the combo
        combo.select(0);
    }

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