/*
SWT/JFace in Action
GUI Design with Eclipse 3.0
Matthew Scarpino, Stephen Holder, Stanford Ng, and Laurent Mihalkovic
ISBN: 1932394273
Publisher: Manning
*/
import java.util.LinkedList;
import java.util.List;
import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.ExtendedModifyEvent;
import org.eclipse.swt.custom.ExtendedModifyListener;
import org.eclipse.swt.custom.StyledText;
import org.eclipse.swt.events.KeyAdapter;
import org.eclipse.swt.events.KeyEvent;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Composite;
public class Ch5Undoable extends Composite {
private static final int MAX_STACK_SIZE = 25;
private List undoStack;
private List redoStack;
private StyledText styledText;
public Ch5Undoable(Composite parent) {
super(parent, SWT.NONE);
undoStack = new LinkedList();
redoStack = new LinkedList();
buildControls();
}
private void buildControls() {
this.setLayout(new FillLayout());
styledText = new StyledText(this, SWT.MULTI | SWT.V_SCROLL);
styledText.addExtendedModifyListener(new ExtendedModifyListener() {
public void modifyText(ExtendedModifyEvent event) {
String currText = styledText.getText();
String newText = currText.substring(event.start, event.start
+ event.length);
if (newText != null && newText.length() > 0) {
if (undoStack.size() == MAX_STACK_SIZE) {
undoStack.remove(undoStack.size() - 1);
}
undoStack.add(0, newText);
}
}
});
styledText.addKeyListener(new KeyAdapter() {
public void keyPressed(KeyEvent e) {
switch (e.keyCode) {
case SWT.F1:
undo();
break;
case SWT.F2:
redo();
break;
default:
//ignore everything else
}
}
});
}
private void undo() {
if (undoStack.size() > 0) {
String lastEdit = (String) undoStack.remove(0);
int editLength = lastEdit.length();
String currText = styledText.getText();
int startReplaceIndex = currText.length() - editLength;
styledText.replaceTextRange(startReplaceIndex, editLength, "");
redoStack.add(0, lastEdit);
}
}
private void redo() {
if (redoStack.size() > 0) {
String text = (String) redoStack.remove(0);
moveCursorToEnd();
styledText.append(text);
moveCursorToEnd();
}
}
private void moveCursorToEnd() {
styledText.setCaretOffset(styledText.getText().length());
}
}