canvas1.java

Eclipse从入门到精通源代码/第二篇 SWT_JFace篇(6-16章)

/**
 * @作者：陈刚
 * @Email：[e-mail]
 * @Blog：http://blog.csdn.net/glchengang
 */
package swt;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.PaintEvent;
import org.eclipse.swt.events.PaintListener;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.layout.RowLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Canvas;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

public class Canvas1 {
    static Image image;

    public static void main(String[] args) {
        final Display display = Display.getDefault();
        final Shell shell = new Shell();
        shell.setSize(327, 253);
        shell.setText("SWT Application");
        //------------------新插入的界面核心代码------------------------

        shell.setLayout(new RowLayout());
        final Canvas canvas = new Canvas(shell, SWT.BORDER);
        //监听canvas的重绘事件。当调用canvas.redraw会发
        canvas.addPaintListener(new PaintListener() {
            public void paintControl(final PaintEvent event) {
                //将其图像显示在canvas上，（10,10）是显示图像的左上角坐标
                if (image != null)
                    event.gc.drawImage(image, 10, 10);
            }
        });

        Button button1 = new Button(shell, SWT.NONE);
        button1.setText("图片1");
        button1.addSelectionListener(new SelectionAdapter() {
            public void widgetSelected(SelectionEvent e) {
                image = new Image(display, "icons/next.gif");
                canvas.redraw();
            }
        });

        Button button2 = new Button(shell, SWT.NONE);
        button2.setText("图片2");
        button2.addSelectionListener(new SelectionAdapter() {
            public void widgetSelected(SelectionEvent e) {
                image = new Image(display, "icons/refresh.gif");
                canvas.redraw();
            }
        });

        Button clearButton = new Button(shell, SWT.NONE);
        clearButton.setText("清除图像");
        clearButton.addSelectionListener(new SelectionAdapter() {
            public void widgetSelected(SelectionEvent e) {
                if (image != null) {
                    image.dispose();
                    image = null;
                    canvas.redraw();
                }
            }
        });

        //------------------END---------------------------------------------
        shell.layout();
        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch())
                display.sleep();
        }
    }
}