Basic undo/redo

5 files changed, 159 insertions, 92 deletions

diff --git a/noncore/graphics/drawpad/drawmode.h b/noncore/graphics/drawpad/drawmode.h
index d4ecadd..4e80fe2 100644
--- a/noncore/graphics/drawpad/drawmode.h
+++ b/noncore/graphics/drawpad/drawmode.h
@@ -1,37 +1,39 @@
 /***************************************************************************
  *                                                                         *
  *   DrawPad - a drawing program for Opie Environment                      *
  *                                                                         *
  *   (C) 2002 by S. Prud'homme <prudhomme@laposte.net>                     *
  *                                                                         *
  *   This program is free software; you can redistribute it and/or modify  *
  *   it under the terms of the GNU General Public License as published by  *
  *   the Free Software Foundation; either version 2 of the License, or     *
  *   (at your option) any later version.                                   *
  *                                                                         *
  ***************************************************************************/
 
 #ifndef DRAWMODE_H
 #define DRAWMODE_H
 
 #include <qobject.h>
 
 class DrawPad;
 class DrawPadCanvas;
 
 class DrawMode : QObject
 { 
-public:
+protected:
     DrawMode(DrawPad* drawPad, DrawPadCanvas* drawPadCanvas);
-    ~DrawMode();
+
+public:
+    virtual ~DrawMode();
 
     virtual void mousePressEvent(QMouseEvent* e) = 0;
     virtual void mouseReleaseEvent(QMouseEvent* e) = 0;
     virtual void mouseMoveEvent(QMouseEvent* e) = 0;
 
 protected:
     DrawPad* m_pDrawPad;
     DrawPadCanvas* m_pDrawPadCanvas;
 };
 
 #endif // DRAWMODE_H
diff --git a/noncore/graphics/drawpad/drawpad.cpp b/noncore/graphics/drawpad/drawpad.cpp
index 3c593b6..5cc2197 100644
--- a/noncore/graphics/drawpad/drawpad.cpp
+++ b/noncore/graphics/drawpad/drawpad.cpp
@@ -20,168 +20,183 @@
 #include "linedrawmode.h"
 #include "pointdrawmode.h"
 #include "rectangledrawmode.h"
 
 #include <qpe/global.h>
 #include <qpe/qpemenubar.h>
 #include <qpe/qpetoolbar.h>
 #include <qpe/resource.h>
 
 #include <qaction.h>
 #include <qfile.h>
 #include <qpainter.h>
 #include <qspinbox.h>
 #include <qtoolbutton.h>
 #include <qtooltip.h>
 
 DrawPad::DrawPad(QWidget* parent, const char* name, WFlags f)
     : QMainWindow(parent, name, f)
 {
     setCaption(tr("DrawPad"));
 
     // init members
 
     m_pDrawPadCanvas = new DrawPadCanvas(this, this);
+    connect(m_pDrawPadCanvas, SIGNAL(pagesChanged()), this, SLOT(updateNavigationToolButtons()));
+    connect(m_pDrawPadCanvas, SIGNAL(pageBackupsChanged()), this, SLOT(updateUndoRedoToolButtons()));
 
     QFile file(Global::applicationFileName("drawpad", "drawpad.xml"));
 
     if (file.open(IO_ReadOnly)) {
         m_pDrawPadCanvas->load(&file);
         file.close();
     }
 
     setCentralWidget(m_pDrawPadCanvas);
 
     m_colors.resize(8);
     m_colors.at(0) = Qt::black;
     m_colors.at(1) = Qt::white;
     m_colors.at(2) = Qt::red;
     m_colors.at(3) = Qt::green;
     m_colors.at(4) = Qt::blue;
     m_colors.at(5) = Qt::cyan;
     m_colors.at(6) = Qt::magenta;
     m_colors.at(7) = Qt::yellow;
 
     // init menu
 
     setToolBarsMovable(false);
 
     QPEToolBar* menuToolBar = new QPEToolBar(this);
     QPEMenuBar* menuBar = new QPEMenuBar(menuToolBar);
 
     QPopupMenu *toolsPopupMenu = new QPopupMenu(menuBar);
 
     QAction* clearAllAction = new QAction(tr("Clear All"), QString::null, 0, this);
-    connect(clearAllAction, SIGNAL(activated()), this, SLOT(clearAll()));
+    connect(clearAllAction, SIGNAL(activated()), m_pDrawPadCanvas, SLOT(clearAll()));
     clearAllAction->addTo(toolsPopupMenu);
 
     toolsPopupMenu->insertSeparator();
 
     QAction* setOptionsAction = new QAction(tr("Options"), tr("Options..."), 0, this);
     setOptionsAction->addTo(toolsPopupMenu);
 
     menuBar->insertItem(tr("Tools"), toolsPopupMenu);
 
     // init page toolbar
 
     QPEToolBar* pageToolBar = new QPEToolBar(this);
 
     QAction* newPageAction = new QAction(tr("New Page"), Resource::loadIconSet("new"), QString::null, 0, this);
-    connect(newPageAction, SIGNAL(activated()), this, SLOT(newPage()));
+    connect(newPageAction, SIGNAL(activated()), m_pDrawPadCanvas, SLOT(newPage()));
     newPageAction->addTo(pageToolBar);
 
     QAction* clearPageAction = new QAction(tr("Clear Page"), Resource::loadIconSet("drawpad/clear"), QString::null, 0, this);
     connect(clearPageAction, SIGNAL(activated()), m_pDrawPadCanvas, SLOT(clearPage()));
     clearPageAction->addTo(pageToolBar);
 
     QAction* deletePageAction = new QAction(tr("Delete Page"), Resource::loadIconSet("trash"), QString::null, 0, this);
-    connect(deletePageAction, SIGNAL(activated()), this, SLOT(deletePage()));
+    connect(deletePageAction, SIGNAL(activated()), m_pDrawPadCanvas, SLOT(deletePage()));
     deletePageAction->addTo(pageToolBar);
 
     QPEToolBar* emptyToolBar = new QPEToolBar(this);
     emptyToolBar->setHorizontalStretchable(true);
 
     // init navigation toolbar
 
     QPEToolBar* navigationToolBar = new QPEToolBar(this);
 
+    m_pUndoAction = new QAction(tr("Undo"), Resource::loadIconSet("drawpad/undo"), QString::null, 0, this);
+    connect(m_pUndoAction, SIGNAL(activated()), m_pDrawPadCanvas, SLOT(undo()));
+    m_pUndoAction->addTo(navigationToolBar);
+
+    m_pRedoAction = new QAction(tr("Redo"), Resource::loadIconSet("drawpad/redo"), QString::null, 0, this);
+    connect(m_pRedoAction, SIGNAL(activated()), m_pDrawPadCanvas, SLOT(redo()));
+    m_pRedoAction->addTo(navigationToolBar);
+
+    updateUndoRedoToolButtons();
+
     m_pFirstPageAction = new QAction(tr("First Page"), Resource::loadIconSet("fastback"), QString::null, 0, this);
-    connect(m_pFirstPageAction, SIGNAL(activated()), this, SLOT(goFirstPage()));
+    connect(m_pFirstPageAction, SIGNAL(activated()), m_pDrawPadCanvas, SLOT(goFirstPage()));
     m_pFirstPageAction->addTo(navigationToolBar);
 
     m_pPreviousPageAction = new QAction(tr("Previous Page"), Resource::loadIconSet("back"), QString::null, 0, this);
-    connect(m_pPreviousPageAction, SIGNAL(activated()), this, SLOT(goPreviousPage()));
+    connect(m_pPreviousPageAction, SIGNAL(activated()), m_pDrawPadCanvas, SLOT(goPreviousPage()));
     m_pPreviousPageAction->addTo(navigationToolBar);
 
     m_pNextPageAction = new QAction(tr("Next Page"), Resource::loadIconSet("forward"), QString::null, 0, this);
-    connect(m_pNextPageAction, SIGNAL(activated()), this, SLOT(goNextPage()));
+    connect(m_pNextPageAction, SIGNAL(activated()), m_pDrawPadCanvas, SLOT(goNextPage()));
     m_pNextPageAction->addTo(navigationToolBar);
 
     m_pLastPageAction = new QAction(tr("Last Page"), Resource::loadIconSet("fastforward"), QString::null, 0, this);
-    connect(m_pLastPageAction, SIGNAL(activated()), this, SLOT(goLastPage()));
+    connect(m_pLastPageAction, SIGNAL(activated()), m_pDrawPadCanvas, SLOT(goLastPage()));
     m_pLastPageAction->addTo(navigationToolBar);
 
-    updateNavigationToolBar();
+    updateNavigationToolButtons();
 
     // init draw mode toolbar
 
     QPEToolBar* drawModeToolBar = new QPEToolBar(this);
 
     m_pPointDrawModeAction = new QAction(tr("Draw Point"), Resource::loadIconSet("drawpad/point.png"), QString::null, 0, this);
     m_pPointDrawModeAction->setToggleAction(true);
     connect(m_pPointDrawModeAction, SIGNAL(activated()), this, SLOT(setPointDrawMode()));
     m_pPointDrawModeAction->addTo(drawModeToolBar);
 
     m_pLineDrawModeAction = new QAction(tr("Draw Line"), Resource::loadIconSet("drawpad/line.png"), QString::null, 0, this);
     m_pLineDrawModeAction->setToggleAction(true);
     connect(m_pLineDrawModeAction, SIGNAL(activated()), this, SLOT(setLineDrawMode()));
     m_pLineDrawModeAction->addTo(drawModeToolBar);
 
     m_pRectangleDrawModeAction = new QAction(tr("Draw Rectangle"), Resource::loadIconSet("drawpad/rectangle.png"), QString::null, 0, this);
     m_pRectangleDrawModeAction->setToggleAction(true);
     connect(m_pRectangleDrawModeAction, SIGNAL(activated()), this, SLOT(setRectangleDrawMode()));
     m_pRectangleDrawModeAction->addTo(drawModeToolBar);
 
     m_pEllipseDrawModeAction = new QAction(tr("Draw Ellipse"), Resource::loadIconSet("drawpad/ellipse.png"), QString::null, 0, this);
     m_pEllipseDrawModeAction->setToggleAction(true);
     connect(m_pEllipseDrawModeAction, SIGNAL(activated()), this, SLOT(setEllipseDrawMode()));
     m_pEllipseDrawModeAction->addTo(drawModeToolBar);
 
     m_pFillDrawModeAction = new QAction(tr("Fill Region"), Resource::loadIconSet("drawpad/fill.png"), QString::null, 0, this);
     m_pFillDrawModeAction->setToggleAction(true);
     connect(m_pFillDrawModeAction, SIGNAL(activated()), this, SLOT(setFillDrawMode()));
     m_pFillDrawModeAction->addTo(drawModeToolBar);
 
     m_pEraseDrawModeAction = new QAction(tr("Erase Point"), Resource::loadIconSet("drawpad/erase.png"), QString::null, 0, this);
     m_pEraseDrawModeAction->setToggleAction(true);
     connect(m_pEraseDrawModeAction, SIGNAL(activated()), this, SLOT(setEraseDrawMode()));
     m_pEraseDrawModeAction->addTo(drawModeToolBar);
 
     m_pDrawMode = 0;
     setPointDrawMode();
 
     emptyToolBar = new QPEToolBar(this);
     emptyToolBar->setHorizontalStretchable(true);
+    emptyToolBar->addSeparator();
+
+    // init draw parameters toolbar
 
     QPEToolBar* drawParametersToolBar = new QPEToolBar(this);
 
     QSpinBox* penWidthSpinBox = new QSpinBox(1, 9, 1, drawParametersToolBar);
     connect(penWidthSpinBox, SIGNAL(valueChanged(int)), this, SLOT(changePenWidth(int)));
 
     penWidthSpinBox->setValue(1);
 
     m_pPenColorToolButton = new QToolButton(drawParametersToolBar);
     m_pPenColorToolButton->setPixmap(Resource::loadPixmap("drawpad/pencolor.png"));
 
     QPopupMenu* penColorPopupMenu = new QPopupMenu(m_pPenColorToolButton);
     connect(penColorPopupMenu, SIGNAL(activated(int)), this, SLOT(changePenColor(int)));
 
     QPixmap penColorPixmap(14, 14);
 
     for (uint i = 0; i < m_colors.size(); i++) {
         penColorPixmap.fill(m_colors.at(i));
         penColorPopupMenu->insertItem(penColorPixmap, i);
     }
 
     QToolTip::add(m_pPenColorToolButton, tr("Pen Color"));
     m_pPenColorToolButton->setPopup(penColorPopupMenu);
     m_pPenColorToolButton->setPopupDelay(0);
@@ -197,90 +212,48 @@ DrawPad::DrawPad(QWidget* parent, const char* name, WFlags f)
     QPixmap brushColorPixmap(14, 14);
 
     for (uint i = 0; i < m_colors.size(); i++) {
         brushColorPixmap.fill(m_colors.at(i));
         brushColorPopupMenu->insertItem(brushColorPixmap, i);
     }
 
     QToolTip::add(m_pBrushColorToolButton, tr("Fill Color"));
     m_pBrushColorToolButton->setPopup(brushColorPopupMenu);
     m_pBrushColorToolButton->setPopupDelay(0);
 
     brushColorPopupMenu->activateItemAt(1);
 }
 
 DrawPad::~DrawPad()
 {
     QFile file(Global::applicationFileName("drawpad", "drawpad.xml"));
 
     if (file.open(IO_WriteOnly)) {
         m_pDrawPadCanvas->save(&file);
         file.close();
     }
 }
 
-void DrawPad::clearAll()
-{
-    m_pDrawPadCanvas->clearAll();
-    updateNavigationToolBar();
-}
-
-void DrawPad::newPage()
-{
-    m_pDrawPadCanvas->newPage();
-    updateNavigationToolBar();
-}
-
-void DrawPad::deletePage()
-{
-    m_pDrawPadCanvas->deletePage();
-    updateNavigationToolBar();
-}
-
-void DrawPad::goFirstPage()
-{
-    m_pDrawPadCanvas->goFirstPage();
-    updateNavigationToolBar();
-}
-
-void DrawPad::goPreviousPage()
-{
-    m_pDrawPadCanvas->goPreviousPage();
-    updateNavigationToolBar();
-}
-
-void DrawPad::goNextPage()
-{
-    m_pDrawPadCanvas->goNextPage();
-    updateNavigationToolBar();
-}
-
-void DrawPad::goLastPage()
-{
-    m_pDrawPadCanvas->goLastPage();
-    updateNavigationToolBar();
-}
-
 void DrawPad::setPointDrawMode()
 {
     if (m_pDrawMode) {
         delete m_pDrawMode;
     }
 
     m_pDrawMode = new PointDrawMode(this, m_pDrawPadCanvas);
 
     m_pPointDrawModeAction->setOn(true);
     m_pLineDrawModeAction->setOn(false);
     m_pRectangleDrawModeAction->setOn(false);
     m_pEllipseDrawModeAction->setOn(false);
     m_pFillDrawModeAction->setOn(false);
     m_pEraseDrawModeAction->setOn(false);
 }
 
 void DrawPad::setLineDrawMode()
 {
     if (m_pDrawMode) {
         delete m_pDrawMode;
     }
 
     m_pDrawMode = new LineDrawMode(this, m_pDrawPadCanvas);
 
@@ -360,31 +333,37 @@ void DrawPad::changePenWidth(int value)
 {
     m_pen.setWidth(value);
 }
 
 void DrawPad::changePenColor(int index)
 {
     m_pen.setColor(m_colors.at(index));
 
     QPainter painter;
     painter.begin(m_pPenColorToolButton->pixmap());
     painter.fillRect(QRect(0, 12, 14, 2), m_pen.color());
     painter.end();
 }
 
 void DrawPad::changeBrushColor(int index)
 {
     m_brush = QBrush(m_colors.at(index));
 
     QPainter painter;
     painter.begin(m_pBrushColorToolButton->pixmap());
     painter.fillRect(QRect(0, 12, 14, 2), m_brush.color());
     painter.end();
 }
 
-void DrawPad::updateNavigationToolBar()
+void DrawPad::updateUndoRedoToolButtons()
+{
+    m_pUndoAction->setEnabled(m_pDrawPadCanvas->undoEnabled());
+    m_pRedoAction->setEnabled(m_pDrawPadCanvas->redoEnabled());
+}
+
+void DrawPad::updateNavigationToolButtons()
 {
     m_pFirstPageAction->setEnabled(m_pDrawPadCanvas->goPreviousPageEnabled());
     m_pPreviousPageAction->setEnabled(m_pDrawPadCanvas->goPreviousPageEnabled());
     m_pNextPageAction->setEnabled(m_pDrawPadCanvas->goNextPageEnabled());
     m_pLastPageAction->setEnabled(m_pDrawPadCanvas->goNextPageEnabled());
 }
diff --git a/noncore/graphics/drawpad/drawpad.h b/noncore/graphics/drawpad/drawpad.h
index 0ece408..ee81ddf 100644
--- a/noncore/graphics/drawpad/drawpad.h
+++ b/noncore/graphics/drawpad/drawpad.h
@@ -18,71 +18,66 @@
 
 #include <qpen.h>
 
 class DrawMode;
 class DrawPadCanvas;
 
 class QAction;
 class QColor;
 class QToolButton;
 class QWidgetStack;
 
 class DrawPad : public QMainWindow
 { 
     Q_OBJECT
 
 public:
     DrawPad(QWidget* parent = 0, const char* name = 0, WFlags f = WType_TopLevel);
     ~DrawPad();
 
     DrawMode* drawMode() { return m_pDrawMode; }
     QPen pen() { return m_pen; }
     QBrush brush() { return m_brush; }
 
 private slots:
-    void clearAll();
-    void newPage();
-    void deletePage();
-
-    void goFirstPage();
-    void goPreviousPage();
-    void goNextPage();
-    void goLastPage();
-
     void setPointDrawMode();
     void setLineDrawMode();
     void setRectangleDrawMode();
     void setEllipseDrawMode();
     void setFillDrawMode();
     void setEraseDrawMode();
 
     void changePenWidth(int value);
     void changePenColor(int index);
     void changeBrushColor(int index);
 
-private:
-    void updateNavigationToolBar();
+    void updateUndoRedoToolButtons();
+    void updateNavigationToolButtons();
 
+private:
     DrawPadCanvas* m_pDrawPadCanvas;
     QArray<QColor> m_colors;
 
     DrawMode* m_pDrawMode;
     QPen m_pen;
     QBrush m_brush;
 
+    QAction* m_pUndoAction;
+    QAction* m_pRedoAction;
+
     QAction* m_pFirstPageAction;
     QAction* m_pPreviousPageAction;
     QAction* m_pNextPageAction;
     QAction* m_pLastPageAction;
 
     QAction* m_pPointDrawModeAction;
     QAction* m_pLineDrawModeAction;
     QAction* m_pRectangleDrawModeAction;
     QAction* m_pEllipseDrawModeAction;
     QAction* m_pFillDrawModeAction;
     QAction* m_pEraseDrawModeAction;
 
     QToolButton* m_pPenColorToolButton;
     QToolButton* m_pBrushColorToolButton;
 };
 
 #endif // DRAWPAD_H
diff --git a/noncore/graphics/drawpad/drawpadcanvas.cpp b/noncore/graphics/drawpad/drawpadcanvas.cpp
index f02f478..08f7b66 100644
--- a/noncore/graphics/drawpad/drawpadcanvas.cpp
+++ b/noncore/graphics/drawpad/drawpadcanvas.cpp
@@ -122,218 +122,299 @@ bool DrawPadCanvasXmlHandler::characters(const QString& ch)
         if (m_dataLenght < ch.length() * 5) {
             m_dataLenght = ch.length() * 5;
         }
 
         QByteArray byteArrayUnzipped(m_dataLenght);
         ::uncompress((uchar*)byteArrayUnzipped.data(), &m_dataLenght, (uchar*)byteArray.data(), byteArray.size());
 
         QImage image;
         image.loadFromData((const uchar*)byteArrayUnzipped.data(), m_dataLenght, "XPM");
 
         QPixmap* pixmap = new QPixmap(image.width(), image.height());
         pixmap->convertFromImage(image);
         m_pixmaps.append(pixmap);
     }
 
     return true;
 }
 
 DrawPadCanvas::DrawPadCanvas(DrawPad* drawPad, QWidget* parent, const char* name, WFlags f)
     : QWidget(parent, name, f)
 {
     setBackgroundMode(QWidget::PaletteBase);
 
     m_pDrawPad = drawPad;
-    m_buffers.setAutoDelete(true);
-    m_buffers.append(new QPixmap(width(), height()));
-    m_buffers.current()->fill(Qt::white);
+    m_pages.setAutoDelete(true);
+    m_pages.append(new QPixmap(width(), height()));
+    m_pages.current()->fill(Qt::white);
+    m_pageBackups.setAutoDelete(true);
+    m_pageBackups.append(new QPixmap(*(m_pages.current())));
 }
 
 DrawPadCanvas::~DrawPadCanvas()
 {
 }
 
 void DrawPadCanvas::load(QIODevice* ioDevice)
 {
     QTextStream textStream(ioDevice);
     textStream.setCodec(QTextCodec::codecForName("UTF-8"));
 
     QXmlInputSource xmlInputSource(textStream);
     QXmlSimpleReader xmlSimpleReader;
     DrawPadCanvasXmlHandler drawPadCanvasXmlHandler;
 
     xmlSimpleReader.setContentHandler(&drawPadCanvasXmlHandler);
     xmlSimpleReader.parse(xmlInputSource);
 
-    m_buffers = drawPadCanvasXmlHandler.pixmaps();
+    m_pages = drawPadCanvasXmlHandler.pixmaps();
 
-    if (m_buffers.isEmpty()) {
-        m_buffers.append(new QPixmap(width(), height()));
-        m_buffers.current()->fill(Qt::white);
+    if (m_pages.isEmpty()) {
+        m_pages.append(new QPixmap(width(), height()));
+        m_pages.current()->fill(Qt::white);
     }
 
+    m_pageBackups.clear();
+    m_pageBackups.append(new QPixmap(*(m_pages.current())));
+
     repaint();
 }
 
 void DrawPadCanvas::save(QIODevice* ioDevice)
 {
     QTextStream textStream(ioDevice);
     textStream.setCodec(QTextCodec::codecForName("UTF-8"));
 
     textStream << "<drawpad>" << endl;
     textStream << "    <images>" << endl;
 
-    QListIterator<QPixmap> bufferIterator(m_buffers);
+    QListIterator<QPixmap> bufferIterator(m_pages);
 
     for (bufferIterator.toFirst(); bufferIterator.current() != 0; ++bufferIterator) {
         textStream << "        <image>" << endl;
 
         QImage image = bufferIterator.current()->convertToImage();
         QByteArray byteArray;
         QBuffer buffer(byteArray);
         QImageIO imageIO(&buffer, "XPM");
 
         buffer.open(IO_WriteOnly);
         imageIO.setImage(image);
         imageIO.write();
         buffer.close();
 
         ulong size = byteArray.size() * 2;
         QByteArray byteArrayZipped(size);
         ::compress((uchar*)byteArrayZipped.data(), &size, (uchar*)byteArray.data(), byteArray.size());
 
         textStream << "            <data length=\"" << byteArray.size() << "\">";
 
         static const char hexchars[] = "0123456789abcdef";
 
         for (int i = 0; i < (int)size; i++ ) {
             uchar s = (uchar)byteArrayZipped[i];
             textStream << hexchars[s >> 4];
             textStream << hexchars[s & 0x0f];
         }
 
         textStream << "</data>" << endl;
         textStream << "        </image>" << endl;
     }
 
     textStream << "    </images>" << endl;
     textStream << "</drawpad>";
 }
 
 QPixmap* DrawPadCanvas::currentPage()
 {
-    return m_buffers.current();
+    return m_pages.current();
 }
 
 void DrawPadCanvas::clearAll()
 {
-    m_buffers.clear();
+    m_pages.clear();
+
+    m_pages.append(new QPixmap(width(), height()));
+    m_pages.current()->fill(Qt::white);
 
-    m_buffers.append(new QPixmap(width(), height()));
-    m_buffers.current()->fill(Qt::white);
+    m_pageBackups.clear();
+    m_pageBackups.append(new QPixmap(*(m_pages.current())));
 
     repaint();
+
+    emit pagesChanged();
+    emit pageBackupsChanged();
 }
 
 void DrawPadCanvas::newPage()
 {
-    m_buffers.insert(m_buffers.at() + 1, new QPixmap(width(), height()));
-    m_buffers.current()->fill(Qt::white);
+    m_pages.insert(m_pages.at() + 1, new QPixmap(width(), height()));
+    m_pages.current()->fill(Qt::white);
+    m_pageBackups.clear();
+    m_pageBackups.append(new QPixmap(*(m_pages.current())));
     repaint();
+
+    emit pagesChanged();
+    emit pageBackupsChanged();
 }
 
 void DrawPadCanvas::clearPage()
 {
-    m_buffers.current()->fill(Qt::white);
+    m_pages.current()->fill(Qt::white);
     repaint();
 }
 
 void DrawPadCanvas::deletePage()
 {
-    m_buffers.remove(m_buffers.current());
+    m_pages.remove(m_pages.current());
 
-    if (m_buffers.isEmpty()) {
-        m_buffers.append(new QPixmap(width(), height()));
-        m_buffers.current()->fill(Qt::white);
+    if (m_pages.isEmpty()) {
+        m_pages.append(new QPixmap(width(), height()));
+        m_pages.current()->fill(Qt::white);
     }
 
+    m_pageBackups.clear();
+    m_pageBackups.append(new QPixmap(*(m_pages.current())));
+
     repaint();
+
+    emit pagesChanged();
+    emit pageBackupsChanged();
+}
+
+bool DrawPadCanvas::undoEnabled()
+{
+    return (m_pageBackups.current() != m_pageBackups.getFirst());
+}
+
+bool DrawPadCanvas::redoEnabled()
+{
+    return (m_pageBackups.current() != m_pageBackups.getLast());
 }
 
 bool DrawPadCanvas::goPreviousPageEnabled()
 {
-    return (m_buffers.current() != m_buffers.getFirst());
+    return (m_pages.current() != m_pages.getFirst());
 }
 
 bool DrawPadCanvas::goNextPageEnabled()
 {
-    return (m_buffers.current() != m_buffers.getLast());
+    return (m_pages.current() != m_pages.getLast());
+}
+
+void DrawPadCanvas::undo()
+{
+    *(m_pages.current()) = *(m_pageBackups.prev());
+    repaint();
+
+    emit pageBackupsChanged();
+}
+
+void DrawPadCanvas::redo()
+{
+    *(m_pages.current()) = *(m_pageBackups.next());
+    repaint();
+
+    emit pageBackupsChanged();
 }
 
 void DrawPadCanvas::goFirstPage()
 {
-    m_buffers.first();
+    m_pages.first();
+    m_pageBackups.clear();
+    m_pageBackups.append(new QPixmap(*(m_pages.current())));
     repaint();
+
+    emit pagesChanged();
+    emit pageBackupsChanged();
 }
 
 void DrawPadCanvas::goPreviousPage()
 {
-    m_buffers.prev();
+    m_pages.prev();
+    m_pageBackups.clear();
+    m_pageBackups.append(new QPixmap(*(m_pages.current())));
     repaint();
+
+    emit pagesChanged();
+    emit pageBackupsChanged();
 }
 
 void DrawPadCanvas::goNextPage()
 {
-    m_buffers.next();
+    m_pages.next();
+    m_pageBackups.clear();
+    m_pageBackups.append(new QPixmap(*(m_pages.current())));
     repaint();
+
+    emit pagesChanged();
+    emit pageBackupsChanged();
 }
 
 void DrawPadCanvas::goLastPage()
 {
-    m_buffers.last();
+    m_pages.last();
+    m_pageBackups.clear();
+    m_pageBackups.append(new QPixmap(*(m_pages.current())));
     repaint();
+
+    emit pagesChanged();
+    emit pageBackupsChanged();
 }
 
 void DrawPadCanvas::mousePressEvent(QMouseEvent* e)
 {
     m_pDrawPad->drawMode()->mousePressEvent(e);
 }
 
 void DrawPadCanvas::mouseReleaseEvent(QMouseEvent* e)
 {
     m_pDrawPad->drawMode()->mouseReleaseEvent(e);
+
+    QPixmap* currentBackup = m_pageBackups.current();
+    while (m_pageBackups.last() != currentBackup) {
+        m_pageBackups.removeLast();
+    }
+
+    while (m_pageBackups.count() >= (5 + 1)) {
+        m_pageBackups.removeFirst();
+    }
+
+    m_pageBackups.append(new QPixmap(*(m_pages.current())));
+
+    emit pageBackupsChanged();
 }
 
 void DrawPadCanvas::mouseMoveEvent(QMouseEvent* e)
 {
     m_pDrawPad->drawMode()->mouseMoveEvent(e);
 }
 
 void DrawPadCanvas::resizeEvent(QResizeEvent* e)
 {
     QWidget::resizeEvent(e);
 
-    QListIterator<QPixmap> bufferIterator(m_buffers);
+    QListIterator<QPixmap> bufferIterator(m_pages);
 
     for (bufferIterator.toFirst(); bufferIterator.current() != 0; ++bufferIterator) {
         int w = width() > bufferIterator.current()->width() ? width() : bufferIterator.current()->width();
         int h = height() > bufferIterator.current()->height() ? height() : bufferIterator.current()->height();
 
         QPixmap tmpPixmap(*(bufferIterator.current()));
         bufferIterator.current()->resize(w, h);
         bufferIterator.current()->fill(Qt::white);
 
         bitBlt(bufferIterator.current(), 0, 0, &tmpPixmap, 0, 0, tmpPixmap.width(), tmpPixmap.height());
     }
 }
 
 void DrawPadCanvas::paintEvent(QPaintEvent* e)
 {
     QWidget::paintEvent(e);
 
     QArray<QRect> rects = e->region().rects();
 
     for (uint i = 0; i < rects.count(); i++) {
         QRect r = rects[i];
-        bitBlt(this, r.x(), r.y(), m_buffers.current(), r.x(), r.y(), r.width(), r.height());
+        bitBlt(this, r.x(), r.y(), m_pages.current(), r.x(), r.y(), r.width(), r.height());
     }
 }
diff --git a/noncore/graphics/drawpad/drawpadcanvas.h b/noncore/graphics/drawpad/drawpadcanvas.h
index 2ec9298..eddcb43 100644
--- a/noncore/graphics/drawpad/drawpadcanvas.h
+++ b/noncore/graphics/drawpad/drawpadcanvas.h
@@ -13,53 +13,63 @@
 
 #ifndef DRAWPADCANVAS_H
 #define DRAWPADCANVAS_H
 
 #include <qwidget.h>
 
 #include <qlist.h>
 #include <qpointarray.h>
 
 class DrawPad;
 
 class QPixmap;
 
 class DrawPadCanvas : public QWidget
 { 
     Q_OBJECT
 
 public:
     DrawPadCanvas(DrawPad* drawPad, QWidget* parent = 0, const char* name = 0, WFlags f = 0);
     ~DrawPadCanvas();
 
     void load(QIODevice* ioDevice);
     void save(QIODevice* ioDevice);
 
+    bool undoEnabled();
+    bool redoEnabled();
     bool goPreviousPageEnabled();
     bool goNextPageEnabled();
 
     QPixmap* currentPage();
 
 public slots:
     void clearAll();
     void newPage();
     void clearPage();
     void deletePage();
 
+    void undo();
+    void redo();
+
     void goFirstPage();
     void goPreviousPage();
     void goNextPage();
     void goLastPage();
 
+signals:
+    void pagesChanged();
+    void pageBackupsChanged();
+
 protected:
     void mousePressEvent(QMouseEvent* e);
     void mouseReleaseEvent(QMouseEvent* e);
     void mouseMoveEvent(QMouseEvent* e);
     void resizeEvent(QResizeEvent* e);
     void paintEvent(QPaintEvent* e);
 
 private:
     DrawPad* m_pDrawPad;
-    QList<QPixmap> m_buffers;
+    QList<QPixmap> m_pages;
+    QList<QPixmap> m_pageBackups;
 };
 
 #endif // DRAWPADCANVAS_H