import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;

/**
 * @author Thomas Singer
 */
public class VirtualOwnerDrawTree {

	// Static =================================================================

	public static void main(String[] args) {
		final Display display = new Display();
		final Shell shell = new Shell(display);
		shell.setLayout(new FillLayout());
		final Tree tree = new Tree(shell, SWT.MULTI | SWT.FULL_SELECTION | SWT.VIRTUAL);

		final int itemCount = 5;
		for (int i = 0; i < itemCount; i++) {
			final TreeItem item1 = new TreeItem(tree, SWT.NONE);

			for (int j = 0; j < i; j++) {
				final TreeItem item2 = new TreeItem(item1, SWT.NONE);

				for (int k = 0; k < j; k++) {
					new TreeItem(item2, SWT.NONE);
				}
			}
		}

		tree.addListener(SWT.SetData, event -> {
			final TreeItem item = (TreeItem)event.item;

			final TreeItem parentItem = item.getParentItem();
			final String text;

			if (parentItem != null) {
				final String parentText = (String)parentItem.getData();
				text = parentText + event.index + "/";
			}
			else {
				text = "/";
			}

			item.setData(text);
		});

		tree.addListener(SWT.MeasureItem, event -> {
			final TreeItem item = (TreeItem)event.item;
			final String text = (String)item.getData();
			final Point size = event.gc.stringExtent(text);
			event.width = size.x;
			event.height = size.y;
		});
		tree.addListener(SWT.EraseItem, event -> {
			event.gc.setClipping((Rectangle)null);
			final Rectangle clientArea = tree.getClientArea();

			int colorConstant = SWT.COLOR_WHITE;
			if ((event.detail & SWT.SELECTED) > 0) {
				colorConstant = SWT.COLOR_YELLOW;
			}
			else if ((event.detail & SWT.HOT) > 0) {
				colorConstant = SWT.COLOR_GRAY;
			}
			event.gc.setBackground(event.display.getSystemColor(colorConstant));

			event.gc.fillRectangle(clientArea.x, event.y, clientArea.width, event.height);
			event.detail &= ~(SWT.FOREGROUND | SWT.BACKGROUND | SWT.HOT | SWT.SELECTED);
		});
		tree.addListener(SWT.PaintItem, event -> {
			final TreeItem item = (TreeItem)event.item;
			final String text = (String)item.getData();
			final int colorConstant = (event.detail & SWT.HOT) > 0 ? SWT.COLOR_RED : SWT.COLOR_BLACK;
			event.gc.setForeground(event.display.getSystemColor(colorConstant));
			event.gc.drawString(text, event.x, event.y, true);
		});
		tree.setSelection(tree.getItem(0));
		shell.setSize(200, 200);
		shell.open();
		while (!shell.isDisposed()) {
			if (!display.readAndDispatch()) {
				display.sleep();
			}
		}
		display.dispose();
	}
}