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/*******************************************************************************
* Copyright (c) 2000, 2016 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: compute the number of visible rows in a tree
*
* For a list of all SWT example snippets see
* http://www.eclipse.org/swt/snippets/
*/
import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;
public class Snippet254 {
static TreeItem nextItem(Tree tree, TreeItem item) {
if (item == null) return null;
if (item.getExpanded() && item.getItemCount() > 0) return item.getItem(0);
TreeItem childItem = item;
TreeItem parentItem = childItem.getParentItem();
int index = parentItem == null ? tree.indexOf(childItem) : parentItem.indexOf(childItem);
int count = parentItem == null ? tree.getItemCount() : parentItem.getItemCount();
while (true) {
if (index + 1 < count) return parentItem == null ? tree.getItem(index + 1) : parentItem.getItem(index + 1);
if (parentItem == null) return null;
childItem = parentItem;
parentItem = childItem.getParentItem();
index = parentItem == null ? tree.indexOf(childItem) : parentItem.indexOf(childItem);
count = parentItem == null ? tree.getItemCount() : parentItem.getItemCount();
}
}
public static void main(String[] args) {
final Display display = new Display();
final Shell shell = new Shell(display);
shell.setText("Snippet 254");
RowLayout layout = new RowLayout (SWT.VERTICAL);
layout.fill = true;
layout.wrap = false;
shell.setLayout (layout);
final Tree tree = new Tree (shell, SWT.NONE);
for (int i=0; i<32; i++) {
TreeItem item0 = new TreeItem (tree, SWT.NONE);
item0.setText ("Item " + i + " is quite long");
for (int j=0; j<3; j++) {
TreeItem item1 = new TreeItem (item0, SWT.NONE);
item1.setText ("Item " + i + " " + j + " is quite long");
for (int k=0; k<3; k++) {
TreeItem item2 = new TreeItem (item1, SWT.NONE);
item2.setText ("Item " + i + " " + j + " " + k + " is quite long");
for (int l=0; l<3; l++) {
TreeItem item3 = new TreeItem (item2, SWT.NONE);
item3.setText ("Item " + i + " " + j + " " + k + " " + l + " is quite long");
}
}
}
}
tree.setLayoutData(new RowData (200, 200));
final Button button = new Button (shell, SWT.PUSH);
button.setText ("Visible Items []");
button.addListener (SWT.Selection, e -> {
int visibleCount = 0;
Rectangle rect = tree.getClientArea ();
TreeItem item = tree.getTopItem ();
while (item != null) {
visibleCount++;
Rectangle itemRect = item.getBounds();
if (itemRect.y + itemRect.height > rect.y + rect.height) {
break;
}
item = nextItem (tree, item);
}
button.setText ("Visible Items [" + visibleCount + "]");
});
shell.pack();
shell.open();
while (!shell.isDisposed()) {
if (!display.readAndDispatch()) display.sleep();
}
display.dispose();
}
}
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