Tree event: Measure TreeItem, Paint TreeItem and Erase TreeItem : Tree Event « SWT « Java Tutorial






Tree event: Measure TreeItem, Paint TreeItem and Erase TreeItem
/*******************************************************************************
 * Copyright (c) 2000, 2006 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
//package org.eclipse.swt.snippets;
/* 
 * Tree example snippet: Images on the right side of the TreeItem
 *
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 * 
 * @since 3.2
 */

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Tree;
import org.eclipse.swt.widgets.TreeColumn;
import org.eclipse.swt.widgets.TreeItem;

public class TreeEventMeasurePaintErase {

  public static void main(String[] args) {
    Display display = new Display();
    final Image image = display.getSystemImage(SWT.ICON_INFORMATION);
    Shell shell = new Shell(display);
    shell.setText("Images on the right side of the TreeItem");
    shell.setLayout(new FillLayout());
    Tree tree = new Tree(shell, SWT.MULTI | SWT.FULL_SELECTION);
    tree.setHeaderVisible(true);
    tree.setLinesVisible(true);
    int columnCount = 4;
    for (int i = 0; i < columnCount; i++) {
      TreeColumn column = new TreeColumn(tree, SWT.NONE);
      column.setText("Column " + i);
    }
    int itemCount = 3;
    for (int i = 0; i < itemCount; i++) {
      TreeItem item1 = new TreeItem(tree, SWT.NONE);
      item1.setText("item " + i);
      for (int c = 1; c < columnCount; c++) {
        item1.setText(c, "item [" + i + "-" + c + "]");
      }
      for (int j = 0; j < itemCount; j++) {
        TreeItem item2 = new TreeItem(item1, SWT.NONE);
        item2.setText("item [" + i + " " + j + "]");
        for (int c = 1; c < columnCount; c++) {
          item2.setText(c, "item [" + i + " " + j + "-" + c + "]");
        }
        for (int k = 0; k < itemCount; k++) {
          TreeItem item3 = new TreeItem(item2, SWT.NONE);
          item3.setText("item [" + i + " " + j + " " + k + "]");
          for (int c = 1; c < columnCount; c++) {
            item3.setText(c, "item [" + i + " " + j + " " + k + "-" + c + "]");
          }
        }
      }
    }
    /*
     * NOTE: MeasureItem, PaintItem and EraseItem are called repeatedly.
     * Therefore, it is critical for performance that these methods be as
     * efficient as possible.
     */
    Listener paintListener = new Listener() {
      public void handleEvent(Event event) {
        switch (event.type) {
        case SWT.MeasureItem: {
          Rectangle rect = image.getBounds();
          event.width += rect.width;
          event.height = Math.max(event.height, rect.height + 2);
          break;
        }
        case SWT.PaintItem: {
          int x = event.x + event.width;
          Rectangle rect = image.getBounds();
          int offset = Math.max(0, (event.height - rect.height) / 2);
          event.gc.drawImage(image, x, event.y + offset);
          break;
        }
        }
      }
    };
    tree.addListener(SWT.MeasureItem, paintListener);
    tree.addListener(SWT.PaintItem, paintListener);

    for (int i = 0; i < columnCount; i++) {
      tree.getColumn(i).pack();
    }
    shell.setSize(500, 200);
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch())
        display.sleep();
    }
    if (image != null)
      image.dispose();
    display.dispose();
  }
}








17.60.Tree Event
17.60.1.Tree event: Measure TreeItem, Paint TreeItem and Erase TreeItemTree event: Measure TreeItem, Paint TreeItem and Erase TreeItem
17.60.2.Get TreeItem from Mouse position in mouse down eventGet TreeItem from Mouse position in mouse down event
17.60.3.Limit selection to items that match a pattern
17.60.4.Tree node Collapse listenerTree node Collapse listener
17.60.5.Tree Exapand listenerTree Exapand listener
17.60.6.Tree node selection listenerTree node selection listener
17.60.7.Tree default selection listenerTree default selection listener
17.60.8.Tree node selection eventTree node selection event