Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2013 IBM Corporation and others. * * This program and the accompanying materials * are made available under the terms of the Eclipse Public License 2.0 * which accompanies this distribution, and is available at * https://www.eclipse.org/legal/epl-2.0/ * * SPDX-License-Identifier: EPL-2.0 * * Contributors: * IBM Corporation - initial API and implementation *******************************************************************************/ package org.eclipse.swt.snippets; /* * Tree example snippet: draw multiple lines of text in a tree item * * For more info on custom-drawing TableItem and TreeItem content see * http://www.eclipse.org/articles/article.php?file=Article-CustomDrawingTableAndTreeItems/index.html * * For a list of all SWT example snippets see * http://www.eclipse.org/swt/snippets/ * * @since 3.2 */ import org.eclipse.swt.*; import org.eclipse.swt.graphics.*; import org.eclipse.swt.layout.*; import org.eclipse.swt.widgets.*; public class Snippet227 { public static void main(String[] args) { Display display = new Display(); Shell shell = new Shell(display); shell.setText("Multiple lines in a TreeItem"); shell.setLayout(new FillLayout()); final 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); column.setWidth(100); } 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() { @Override public void handleEvent(Event event) { switch (event.type) { case SWT.MeasureItem: { TreeItem item = (TreeItem) event.item; String text = getText(item, event.index); Point size = event.gc.textExtent(text); event.width = size.x; event.height = Math.max(event.height, size.y); break; } case SWT.PaintItem: { TreeItem item = (TreeItem) event.item; String text = getText(item, event.index); Point size = event.gc.textExtent(text); int offset2 = event.index == 0 ? Math.max(0, (event.height - size.y) / 2) : 0; event.gc.drawText(text, event.x, event.y + offset2, true); break; } case SWT.EraseItem: { event.detail &= ~SWT.FOREGROUND; break; } } } String getText(TreeItem item, int column) { String text = item.getText(column); if (column != 0) { TreeItem parent = item.getParentItem(); int index = parent == null ? tree.indexOf(item) : parent.indexOf(item); if ((index + column) % 3 == 1) { text += "\nnew line"; } if ((index + column) % 3 == 2) { text += "\nnew line\nnew line"; } } return text; } }; tree.addListener(SWT.MeasureItem, paintListener); tree.addListener(SWT.PaintItem, paintListener); tree.addListener(SWT.EraseItem, paintListener); shell.setSize(600, 400); shell.open(); while (!shell.isDisposed()) { if (!display.readAndDispatch()) display.sleep(); } display.dispose(); } }