| /******************************************************************************* |
| * Copyright (c) 2006, 2007 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.ui.texteditor; |
| |
| import java.util.ResourceBundle; |
| |
| import org.eclipse.swt.custom.StyledText; |
| |
| import org.eclipse.jface.text.source.ISourceViewer; |
| |
| /** |
| * An action to handle emacs-like recenter. |
| * This function scrolls the selected window to put the cursor at the middle of the screen. |
| * |
| * @since 3.3 |
| */ |
| public class RecenterAction extends TextEditorAction { |
| |
| /** |
| * Creates a new action for the given text editor. The action configures its |
| * visual representation from the given resource bundle. |
| * |
| * @param bundle the resource bundle |
| * @param prefix a prefix to be prepended to the various resource keys |
| * (described in <code>ResourceAction</code> constructor), or |
| * <code>null</code> if none |
| * @param editor the text editor |
| */ |
| public RecenterAction(ResourceBundle bundle, String prefix, ITextEditor editor) { |
| super(bundle, prefix, editor); |
| } |
| |
| /* |
| * @see IAction#run() |
| */ |
| public void run() { |
| ITextEditor editor= getTextEditor(); |
| if (!(editor instanceof AbstractTextEditor)) |
| return; |
| |
| ISourceViewer viewer= ((AbstractTextEditor)editor).getSourceViewer(); |
| if (viewer == null) |
| return; |
| |
| StyledText st= viewer.getTextWidget(); |
| if (st == null) |
| return; |
| |
| // compute the number of lines displayed |
| int height= st.getClientArea().height; |
| int lineHeight= st.getLineHeight(); |
| |
| int caretOffset= st.getCaretOffset(); |
| int caretLine= st.getLineAtOffset(caretOffset); |
| |
| int topLine= Math.max(0, (caretLine - (height / (lineHeight * 2)))); |
| st.setTopIndex(topLine); |
| } |
| } |