SWT之ScrolledComposite

import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.ScrolledComposite;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Shell;
public class ss {
    public static void main(String[] args) {
        Display display = new Display();
        Color red = display.getSystemColor(SWT.COLOR_RED);
        Color blue = display.getSystemColor(SWT.COLOR_BLUE);
        Shell shell = new Shell(display);
        shell.setLayout(new FillLayout());
        // set the size of the scrolled content - method 1
        final ScrolledComposite sc1 = new ScrolledComposite(shell, SWT.H_SCROLL
                | SWT.V_SCROLL | SWT.BORDER);
        final Composite c1 = new Composite(sc1, SWT.NONE);
        sc1.setContent(c1);
        c1.setBackground(red);
        GridLayout layout = new GridLayout();
        layout.numColumns = 4;
        c1.setLayout(layout);
        Button b1 = new Button(c1, SWT.PUSH);
        b1.setText("first button");
        /*
         * 这是两种用法中的一种，效果是：根据已经存在的组件，计算需要的composite的区域的大小
         * 即运行结果中红色显示的部分。
         */
        c1.setSize(c1.computeSize(SWT.DEFAULT, SWT.DEFAULT));

        // set the minimum width and height of the scrolled content - method 2
        final ScrolledComposite sc2 = new ScrolledComposite(shell, SWT.H_SCROLL
                | SWT.V_SCROLL | SWT.BORDER);
        sc2.setExpandHorizontal(true);
        sc2.setExpandVertical(true);
        final Composite c2 = new Composite(sc2, SWT.NONE);
        sc2.setContent(c2);
        c2.setBackground(blue);
        layout = new GridLayout();
        layout.numColumns = 4;
        c2.setLayout(layout);
        Button b2 = new Button(c2, SWT.PUSH);
        b2.setText("first button");
        /*
         * 这是第二种用法，整个composite区域是用到的Composite区域
         */
        sc2.setMinSize(c2.computeSize(SWT.DEFAULT, SWT.DEFAULT));
        Button add = new Button(shell, SWT.PUSH);
        add.setText("add children");
        final int[] index = new int[] { 0 };
        add.addListener(SWT.Selection, new Listener() {
            public void handleEvent(Event e) {
                index[0]++;
                Button button = new Button(c1, SWT.PUSH);
                button.setText("button " + index[0]);
                // reset size of content so children can be seen - method 1
                c1.setSize(c1.computeSize(SWT.DEFAULT, SWT.DEFAULT));
                c1.layout();
                button = new Button(c2, SWT.PUSH);
                button.setText("button " + index[0]);
                // reset the minimum width and height so children can be seen -
                // method 2
                sc2.setMinSize(c2.computeSize(SWT.DEFAULT, SWT.DEFAULT));
                c2.layout();
            }
        });
        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch())
                display.sleep();
        }
        display.dispose();
    }
}