Undo/Redo 기능 추가 StyledText

delta 값 기록 방식이 아닌 전체 이미지 저장하는 방식이라 커서 위치 복원 문제나 메모리 과다 사용 문제가 있을 수 있다.
event listener를 이용해 caret pos, replaced text, replacing text 등을 얻어와 처리할 수는 있을 것 같다. 

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.graphics.Font;

import org.eclipse.swt.widgets.Composite;

public class HistoryStyledText extends StyledText {

private class UndoInfo {

String text;

int cursorIndex = 0;

private UndoInfo(String text, int cursorIndex) {

this.text = text;

this.cursorIndex = cursorIndex;

}

}

private List undoStack;

private int undoIndex;

private boolean isModifyEventOn; 

public HistoryStyledText(Composite parent, int style) {

super(parent, style);

undoStack = new LinkedList();

   

addKeyListener(new KeyAdapter() {

public void keyPressed(KeyEvent e) {

if((e.stateMask & SWT.CTRL) != 0) {

if(e.keyCode == 122) {

isModifyEventOn = false;

undo();

isModifyEventOn = true;

return;

}

else if(e.keyCode == 121) {

isModifyEventOn = false;

redo();

isModifyEventOn = true;

return;

}

}

}

});

addExtendedModifyListener(new ExtendedModifyListener() {

public void modifyText(ExtendedModifyEvent event) {

if(isModifyEventOn) {

UndoInfo undo = new UndoInfo(getText(), getCaretOffset());

++undoIndex;

undoStack.add(undoIndex, undo);

}

}

});

Font traceFont = new Font(null, "Fixedsys", 10, SWT.NORMAL);

setFont(traceFont);

undoIndex = 0;

undoStack.add(0, new UndoInfo("", 0));

isModifyEventOn = true;

}

private void undo() {

if(undoIndex > 0 && undoStack.size() > 0) {

--undoIndex;

UndoInfo undo = (UndoInfo)undoStack.get(undoIndex);

setText(undo.text);

setCaretOffset(undo.cursorIndex);

}

}

private void redo() {

if(undoIndex < undoStack.size() - 1) {

++undoIndex;

UndoInfo undo = (UndoInfo)undoStack.get(undoIndex);

setText(undo.text);

setCaretOffset(undo.cursorIndex);

}

}

}