1 /******************************************************************************* 2 * Copyright (c) 2000, 2016 IBM Corporation and others. 3 * 4 * This program and the accompanying materials 5 * are made available under the terms of the Eclipse Public License 2.0 6 * which accompanies this distribution, and is available at 7 * https://www.eclipse.org/legal/epl-2.0/ 8 * 9 * SPDX-License-Identifier: EPL-2.0 10 * 11 * Contributors: 12 * IBM Corporation - initial API and implementation 13 *******************************************************************************/ 14 package org.eclipse.swt.snippets; 15 16 /* 17 * Tree example snippet: compute the number of visible rows in a tree 18 * 19 * For a list of all SWT example snippets see 20 * http://www.eclipse.org/swt/snippets/ 21 */ 22 import org.eclipse.swt.*; 23 import org.eclipse.swt.graphics.*; 24 import org.eclipse.swt.layout.*; 25 import org.eclipse.swt.widgets.*; 26 27 public class Snippet254 { 28 nextItem(Tree tree, TreeItem item)29 static TreeItem nextItem(Tree tree, TreeItem item) { 30 if (item == null) return null; 31 if (item.getExpanded() && item.getItemCount() > 0) return item.getItem(0); 32 TreeItem childItem = item; 33 TreeItem parentItem = childItem.getParentItem(); 34 int index = parentItem == null ? tree.indexOf(childItem) : parentItem.indexOf(childItem); 35 int count = parentItem == null ? tree.getItemCount() : parentItem.getItemCount(); 36 while (true) { 37 if (index + 1 < count) return parentItem == null ? tree.getItem(index + 1) : parentItem.getItem(index + 1); 38 if (parentItem == null) return null; 39 childItem = parentItem; 40 parentItem = childItem.getParentItem(); 41 index = parentItem == null ? tree.indexOf(childItem) : parentItem.indexOf(childItem); 42 count = parentItem == null ? tree.getItemCount() : parentItem.getItemCount(); 43 } 44 } 45 main(String[] args)46 public static void main(String[] args) { 47 final Display display = new Display(); 48 final Shell shell = new Shell(display); 49 shell.setText("Snippet 254"); 50 RowLayout layout = new RowLayout (SWT.VERTICAL); 51 layout.fill = true; 52 layout.wrap = false; 53 shell.setLayout (layout); 54 final Tree tree = new Tree (shell, SWT.NONE); 55 for (int i=0; i<32; i++) { 56 TreeItem item0 = new TreeItem (tree, SWT.NONE); 57 item0.setText ("Item " + i + " is quite long"); 58 for (int j=0; j<3; j++) { 59 TreeItem item1 = new TreeItem (item0, SWT.NONE); 60 item1.setText ("Item " + i + " " + j + " is quite long"); 61 for (int k=0; k<3; k++) { 62 TreeItem item2 = new TreeItem (item1, SWT.NONE); 63 item2.setText ("Item " + i + " " + j + " " + k + " is quite long"); 64 for (int l=0; l<3; l++) { 65 TreeItem item3 = new TreeItem (item2, SWT.NONE); 66 item3.setText ("Item " + i + " " + j + " " + k + " " + l + " is quite long"); 67 } 68 } 69 } 70 } 71 tree.setLayoutData(new RowData (200, 200)); 72 final Button button = new Button (shell, SWT.PUSH); 73 button.setText ("Visible Items []"); 74 button.addListener (SWT.Selection, e -> { 75 int visibleCount = 0; 76 Rectangle rect = tree.getClientArea (); 77 TreeItem item = tree.getTopItem (); 78 while (item != null) { 79 visibleCount++; 80 Rectangle itemRect = item.getBounds(); 81 if (itemRect.y + itemRect.height > rect.y + rect.height) { 82 break; 83 } 84 item = nextItem (tree, item); 85 } 86 button.setText ("Visible Items [" + visibleCount + "]"); 87 }); 88 shell.pack(); 89 shell.open(); 90 while (!shell.isDisposed()) { 91 if (!display.readAndDispatch()) display.sleep(); 92 } 93 display.dispose(); 94 } 95 } 96