]> git.saurik.com Git - wxWidgets.git/blobdiff - demos/life/life.cpp
use Windows standard icons instead of our own (patch 443856)
[wxWidgets.git] / demos / life / life.cpp
index d03ad5e579eccb999fa16d5722ea1ea17d0f0f3d..0043a399cc99cf43f5bcd02f5e506d764eff7686 100644 (file)
@@ -1,6 +1,6 @@
 /////////////////////////////////////////////////////////////////////////////
 // Name:        life.cpp
-// Purpose:     The game of life, created by J. H. Conway
+// Purpose:     The game of Life, created by J. H. Conway
 // Author:      Guillermo Rodriguez Garcia, <guille@iies.es>
 // Modified by:
 // Created:     Jan/2000
 /////////////////////////////////////////////////////////////////////////////
 
 // ==========================================================================
-// declarations
+// headers, declarations, constants
 // ==========================================================================
 
-// --------------------------------------------------------------------------
-// headers
-// --------------------------------------------------------------------------
-
 #ifdef __GNUG__
     #pragma implementation "life.h"
 #endif
 
-// for compilers that support precompilation, includes "wx/wx.h"
+// For compilers that support precompilation, includes "wx/wx.h".
 #include "wx/wxprec.h"
 
 #ifdef __BORLANDC__
     #pragma hdrstop
 #endif
 
-// for all others, include the necessary headers
 #ifndef WX_PRECOMP
     #include "wx/wx.h"
 #endif
 
 #include "wx/statline.h"
+#include "wx/wfstream.h"
+#include "wx/filedlg.h"
 
 #include "life.h"
 #include "game.h"
 #include "dialogs.h"
+#include "reader.h"
 
 // --------------------------------------------------------------------------
 // resources
 // --------------------------------------------------------------------------
 
-#if defined(__WXGTK__) || defined(__WXMOTIF__)
-    // the application icon
+#if defined(__WXGTK__) || defined(__WXMOTIF__) || defined(__WXMAC__)
+    // application icon
     #include "mondrian.xpm"
 
     // bitmap buttons for the toolbar
     #include "bitmaps/reset.xpm"
+    #include "bitmaps/open.xpm"
     #include "bitmaps/play.xpm"
     #include "bitmaps/stop.xpm"
+    #include "bitmaps/zoomin.xpm"
+    #include "bitmaps/zoomout.xpm"
+    #include "bitmaps/info.xpm"
+
+    // navigator
+    #include "bitmaps/north.xpm"
+    #include "bitmaps/south.xpm"
+    #include "bitmaps/east.xpm"
+    #include "bitmaps/west.xpm"
+    #include "bitmaps/center.xpm"
 #endif
 
 // --------------------------------------------------------------------------
 // IDs for the controls and the menu commands
 enum
 {
-    // menu items and toolbar buttons
-    ID_NEWGAME = 1001,
+    // timer
+    ID_TIMER = 1001,
+
+    // file menu
+    ID_NEW,
+    ID_OPEN,
     ID_SAMPLES,
     ID_ABOUT,
     ID_EXIT,
-    ID_CLEAR,
+
+    // view menu
+    ID_SHOWNAV,
+    ID_ORIGIN,
+    ID_CENTER,
+    ID_NORTH,
+    ID_SOUTH,
+    ID_EAST,
+    ID_WEST,
+    ID_ZOOMIN,
+    ID_ZOOMOUT,
+    ID_INFO,
+
+    // game menu
     ID_START,
     ID_STEP,
     ID_STOP,
-    ID_WRAP,
+    ID_TOPSPEED,
 
     // speed selection slider
-    ID_SLIDER
+    ID_SLIDER,
 };
 
 // --------------------------------------------------------------------------
@@ -81,44 +107,64 @@ enum
 
 // Event tables
 BEGIN_EVENT_TABLE(LifeFrame, wxFrame)
-    EVT_MENU           (ID_NEWGAME, LifeFrame::OnNewGame)
-    EVT_MENU           (ID_SAMPLES, LifeFrame::OnSamples)
-    EVT_MENU           (ID_ABOUT,   LifeFrame::OnMenu)
-    EVT_MENU           (ID_EXIT,    LifeFrame::OnMenu)
-    EVT_MENU           (ID_CLEAR,   LifeFrame::OnMenu)
-    EVT_MENU           (ID_START,   LifeFrame::OnMenu)
-    EVT_MENU           (ID_STEP,    LifeFrame::OnMenu)
-    EVT_MENU           (ID_STOP,    LifeFrame::OnMenu)
-    EVT_MENU           (ID_WRAP,    LifeFrame::OnMenu)
-    EVT_COMMAND_SCROLL (ID_SLIDER,  LifeFrame::OnSlider)
+    EVT_MENU            (ID_NEW,      LifeFrame::OnMenu)
+    EVT_MENU            (ID_OPEN,     LifeFrame::OnOpen)
+    EVT_MENU            (ID_SAMPLES,  LifeFrame::OnSamples)
+    EVT_MENU            (ID_ABOUT,    LifeFrame::OnMenu)
+    EVT_MENU            (ID_EXIT,     LifeFrame::OnMenu)
+    EVT_MENU            (ID_SHOWNAV,  LifeFrame::OnMenu)
+    EVT_MENU            (ID_ORIGIN,   LifeFrame::OnNavigate)
+    EVT_BUTTON          (ID_CENTER,   LifeFrame::OnNavigate)
+    EVT_BUTTON          (ID_NORTH,    LifeFrame::OnNavigate)
+    EVT_BUTTON          (ID_SOUTH,    LifeFrame::OnNavigate)
+    EVT_BUTTON          (ID_EAST,     LifeFrame::OnNavigate)
+    EVT_BUTTON          (ID_WEST,     LifeFrame::OnNavigate)
+    EVT_MENU            (ID_ZOOMIN,   LifeFrame::OnZoom)
+    EVT_MENU            (ID_ZOOMOUT,  LifeFrame::OnZoom)
+    EVT_MENU            (ID_INFO,     LifeFrame::OnMenu)
+    EVT_MENU            (ID_START,    LifeFrame::OnMenu)
+    EVT_MENU            (ID_STEP,     LifeFrame::OnMenu)
+    EVT_MENU            (ID_STOP,     LifeFrame::OnMenu)
+    EVT_MENU            (ID_TOPSPEED, LifeFrame::OnMenu)
+    EVT_COMMAND_SCROLL  (ID_SLIDER,   LifeFrame::OnSlider)
+    EVT_TIMER           (ID_TIMER,    LifeFrame::OnTimer)
+    EVT_CLOSE           (             LifeFrame::OnClose)
+END_EVENT_TABLE()
+
+BEGIN_EVENT_TABLE(LifeNavigator, wxMiniFrame)
+    EVT_CLOSE           (             LifeNavigator::OnClose)
 END_EVENT_TABLE()
 
-BEGIN_EVENT_TABLE(LifeCanvas, wxScrolledWindow)
-    EVT_PAINT          (            LifeCanvas::OnPaint)
-    EVT_SIZE           (            LifeCanvas::OnSize)
-    EVT_MOUSE_EVENTS   (            LifeCanvas::OnMouse)
+BEGIN_EVENT_TABLE(LifeCanvas, wxWindow)
+    EVT_PAINT           (             LifeCanvas::OnPaint)
+    EVT_SCROLLWIN       (             LifeCanvas::OnScroll)
+    EVT_SIZE            (             LifeCanvas::OnSize)
+    EVT_MOTION          (             LifeCanvas::OnMouse)
+    EVT_LEFT_DOWN       (             LifeCanvas::OnMouse)
+    EVT_LEFT_UP         (             LifeCanvas::OnMouse)
+    EVT_LEFT_DCLICK     (             LifeCanvas::OnMouse)
+    EVT_ERASE_BACKGROUND(             LifeCanvas::OnEraseBackground)
 END_EVENT_TABLE()
 
 
 // Create a new application object
 IMPLEMENT_APP(LifeApp)
 
+
 // ==========================================================================
 // implementation
 // ==========================================================================
 
 // some shortcuts
-#define ADD_TOOL(a, b, c, d) \
-    toolBar->AddTool(a, b, wxNullBitmap, FALSE, -1, -1, (wxObject *)0, c, d)
+#define ADD_TOOL(id, bmp, tooltip, help) \
+    toolBar->AddTool(id, bmp, wxNullBitmap, FALSE, -1, -1, (wxObject *)0, tooltip, help)
 
-#define GET_FRAME() \
-    ((LifeFrame *) wxGetApp().GetTopWindow())
 
 // --------------------------------------------------------------------------
 // LifeApp
 // --------------------------------------------------------------------------
 
-// `Main program' equivalent: the program execution "starts" here
+// 'Main program' equivalent: the program execution "starts" here
 bool LifeApp::OnInit()
 {
     // create the main application window
@@ -128,6 +174,11 @@ bool LifeApp::OnInit()
     frame->Show(TRUE);
     SetTopWindow(frame);
 
+    // just for Motif
+#ifdef __WXMOTIF__
+    frame->UpdateInfoText();
+#endif
+
     // enter the main message loop and run the app
     return TRUE;
 }
@@ -137,178 +188,277 @@ bool LifeApp::OnInit()
 // --------------------------------------------------------------------------
 
 // frame constructor
-LifeFrame::LifeFrame() : wxFrame((wxFrame *)0, -1, _("Life!"), wxPoint(50, 50))
+LifeFrame::LifeFrame() : wxFrame((wxFrame *)0, -1, _("Life!"), wxPoint(200, 200))
 {
     // frame icon
     SetIcon(wxICON(mondrian));
 
     // menu bar
     wxMenu *menuFile = new wxMenu("", wxMENU_TEAROFF);
+    wxMenu *menuView = new wxMenu("", wxMENU_TEAROFF);
     wxMenu *menuGame = new wxMenu("", wxMENU_TEAROFF);
 
-    menuFile->Append(ID_NEWGAME, _("New game..."), _("Start a new game"));
-    menuFile->Append(ID_SAMPLES, _("Sample game..."), _("Select a sample configuration"));
+    menuFile->Append(ID_NEW, _("&New"), _("Start a new game"));
+    menuFile->Append(ID_OPEN, _("&Open..."), _("Open an existing Life pattern"));
+    menuFile->Append(ID_SAMPLES, _("&Sample game..."), _("Select a sample configuration"));
     menuFile->AppendSeparator();
     menuFile->Append(ID_ABOUT, _("&About...\tCtrl-A"), _("Show about dialog"));
     menuFile->AppendSeparator();
     menuFile->Append(ID_EXIT, _("E&xit\tAlt-X"), _("Quit this program"));
 
-    menuGame->Append(ID_CLEAR, _("&Clear\tCtrl-C"), _("Clear game field"));
+    menuView->Append(ID_SHOWNAV, _("Navigation &toolbox"), _("Show or hide toolbox"), TRUE);
+    menuView->Check (ID_SHOWNAV, TRUE);
+    menuView->AppendSeparator();
+    menuView->Append(ID_ORIGIN, _("&Absolute origin"), _("Go to (0, 0)"));
+    menuView->Append(ID_CENTER, _("&Center of mass"), _("Find center of mass"));
+    menuView->Append(ID_NORTH, _("&North"), _("Find northernmost cell"));
+    menuView->Append(ID_SOUTH, _("&South"), _("Find southernmost cell"));
+    menuView->Append(ID_EAST, _("&East"), _("Find easternmost cell"));
+    menuView->Append(ID_WEST, _("&West"), _("Find westernmost cell"));
+    menuView->AppendSeparator();
+    menuView->Append(ID_ZOOMIN, _("Zoom &in\tCtrl-I"), _("Zoom in"));
+    menuView->Append(ID_ZOOMOUT, _("Zoom &out\tCtrl-O"), _("Zoom out"));
+    menuView->Append(ID_INFO, _("&Description...\tCtrl-D"), _("View pattern description"));
+
     menuGame->Append(ID_START, _("&Start\tCtrl-S"), _("Start"));
     menuGame->Append(ID_STEP, _("&Next\tCtrl-N"), _("Single step"));
     menuGame->Append(ID_STOP, _("S&top\tCtrl-T"), _("Stop"));
     menuGame->Enable(ID_STOP, FALSE);
     menuGame->AppendSeparator();
-    menuGame->Append(ID_WRAP, _("&Wraparound\tCtrl-W"), _("Wrap around borders"), TRUE);
-    menuGame->Check (ID_WRAP, TRUE);
+    menuGame->Append(ID_TOPSPEED, _("T&op speed!"), _("Go as fast as possible"));
 
     wxMenuBar *menuBar = new wxMenuBar();
     menuBar->Append(menuFile, _("&File"));
+    menuBar->Append(menuView, _("&View"));
     menuBar->Append(menuGame, _("&Game"));
     SetMenuBar(menuBar);
 
     // tool bar
-    wxBitmap tbBitmaps[3];
+    wxBitmap tbBitmaps[7];
 
     tbBitmaps[0] = wxBITMAP(reset);
-    tbBitmaps[1] = wxBITMAP(play);
-    tbBitmaps[2] = wxBITMAP(stop);
+    tbBitmaps[1] = wxBITMAP(open);
+    tbBitmaps[2] = wxBITMAP(zoomin);
+    tbBitmaps[3] = wxBITMAP(zoomout);
+    tbBitmaps[4] = wxBITMAP(info);
+    tbBitmaps[5] = wxBITMAP(play);
+    tbBitmaps[6] = wxBITMAP(stop);
 
     wxToolBar *toolBar = CreateToolBar();
     toolBar->SetMargins(5, 5);
     toolBar->SetToolBitmapSize(wxSize(16, 16));
-    ADD_TOOL(ID_CLEAR, tbBitmaps[0], _("Clear"), _("Clear game board"));
-    ADD_TOOL(ID_START, tbBitmaps[1], _("Start"), _("Start"));
-    ADD_TOOL(ID_STOP , tbBitmaps[2], _("Stop"),  _("Stop"));
-    toolBar->EnableTool(ID_STOP, FALSE);
+
+    ADD_TOOL(ID_NEW, tbBitmaps[0], _("New"), _("Start a new game"));
+    ADD_TOOL(ID_OPEN, tbBitmaps[1], _("Open"), _("Open an existing Life pattern"));
+    toolBar->AddSeparator();
+    ADD_TOOL(ID_ZOOMIN, tbBitmaps[2], _("Zoom in"), _("Zoom in"));
+    ADD_TOOL(ID_ZOOMOUT, tbBitmaps[3], _("Zoom out"), _("Zoom out"));
+    ADD_TOOL(ID_INFO, tbBitmaps[4], _("Description"), _("Show description"));
+    toolBar->AddSeparator();
+    ADD_TOOL(ID_START, tbBitmaps[5], _("Start"), _("Start"));
+    ADD_TOOL(ID_STOP, tbBitmaps[6], _("Stop"), _("Stop"));
+
     toolBar->Realize();
+    toolBar->EnableTool(ID_STOP, FALSE);    // must be after Realize() !
 
     // status bar
     CreateStatusBar(2);
     SetStatusText(_("Welcome to Life!"));
 
-    // game
-    wxPanel *panel = new wxPanel(this, -1);
-    m_life         = new Life(20, 20);
-    m_canvas       = new LifeCanvas(panel, m_life);
-    m_timer        = new LifeTimer();
-    m_interval     = 500;
-    m_tics         = 0;
-    m_text         = new wxStaticText(panel, -1, "");
-    UpdateInfoText();
+    // game and timer
+    m_life     = new Life();
+    m_timer    = new wxTimer(this, ID_TIMER);
+    m_running  = FALSE;
+    m_topspeed = FALSE;
+    m_interval = 500;
+    m_tics     = 0;
+
+    // We use two different panels to reduce flicker in wxGTK, because
+    // some widgets (like wxStaticText) don't have their own X11 window,
+    // and thus updating the text would result in a refresh of the canvas
+    // if they belong to the same parent.
 
-    // slider
-    wxSlider *slider = new wxSlider(panel, ID_SLIDER,
+    wxPanel *panel1 = new wxPanel(this, -1);
+    wxPanel *panel2 = new wxPanel(this, -1);
+
+    // canvas
+    m_canvas = new LifeCanvas(panel1, m_life);
+
+    // info panel
+    m_text = new wxStaticText(panel2, -1,
+        wxEmptyString,
+        wxDefaultPosition,
+        wxDefaultSize,
+        wxALIGN_CENTER | wxST_NO_AUTORESIZE);
+
+    wxSlider *slider = new wxSlider(panel2, ID_SLIDER,
         5, 1, 10,
         wxDefaultPosition,
         wxSize(200, -1),
         wxSL_HORIZONTAL | wxSL_AUTOTICKS);
 
+    UpdateInfoText();
+
     // component layout
-    wxBoxSizer *sizer = new wxBoxSizer(wxVERTICAL);
-    sizer->Add(new wxStaticLine(panel, -1), 0, wxGROW | wxCENTRE);
-    sizer->Add(m_canvas, 1, wxGROW | wxCENTRE | wxALL, 5);
-    sizer->Add(new wxStaticLine(panel, -1), 0, wxGROW | wxCENTRE);
-    sizer->Add(m_text, 0, wxCENTRE | wxTOP, 5);
-    sizer->Add(slider, 0, wxCENTRE | wxALL, 5);
-    panel->SetSizer(sizer);
-    panel->SetAutoLayout(TRUE);
-    sizer->Fit(this);
-    sizer->SetSizeHints(this);
+    wxBoxSizer *sizer1 = new wxBoxSizer(wxVERTICAL);
+    wxBoxSizer *sizer2 = new wxBoxSizer(wxVERTICAL);
+    wxBoxSizer *sizer3 = new wxBoxSizer(wxVERTICAL);
+
+    sizer1->Add( new wxStaticLine(panel1, -1), 0, wxGROW );
+    sizer1->Add( m_canvas, 1, wxGROW | wxALL, 2 );
+    sizer1->Add( new wxStaticLine(panel1, -1), 0, wxGROW );
+    panel1->SetSizer( sizer1 );
+    panel1->SetAutoLayout( TRUE );
+    sizer1->Fit( panel1 );
+
+    sizer2->Add( m_text, 0, wxGROW | wxTOP, 4 );
+    sizer2->Add( slider, 0, wxCENTRE | wxALL, 4 );
+
+    panel2->SetSizer( sizer2 );
+    panel2->SetAutoLayout( TRUE );
+    sizer2->Fit( panel2 );
+
+    sizer3->Add( panel1, 1, wxGROW );
+    sizer3->Add( panel2, 0, wxGROW );
+    SetSizer( sizer3 );
+    SetAutoLayout( TRUE );
+    sizer3->Fit( this );
+
+    // set minimum frame size
+    sizer3->SetSizeHints( this );
+
+    // navigator frame
+    m_navigator = new LifeNavigator(this);
 }
 
 LifeFrame::~LifeFrame()
 {
     delete m_timer;
-    delete m_life;
 }
 
 void LifeFrame::UpdateInfoText()
 {
     wxString msg;
 
-    msg.Printf(_("Generation: %u,  Interval: %u ms"), m_tics, m_interval);
+    msg.Printf(_(" Generation: %u (T: %u ms),  Population: %u "),
+               m_tics,
+               m_topspeed? 0 : m_interval,
+               m_life->GetNumCells());
     m_text->SetLabel(msg);
 }
 
-// event handlers
+// Enable or disable tools and menu entries according to the current
+// state. See also wxEVT_UPDATE_UI events for a slightly different
+// way to do this.
+void LifeFrame::UpdateUI()
+{
+    // start / stop
+    GetToolBar()->EnableTool(ID_START, !m_running);
+    GetToolBar()->EnableTool(ID_STOP,  m_running);
+    GetMenuBar()->GetMenu(2)->Enable(ID_START, !m_running);
+    GetMenuBar()->GetMenu(2)->Enable(ID_STEP,  !m_running);
+    GetMenuBar()->GetMenu(2)->Enable(ID_STOP,  m_running);
+
+    // zooming
+    int cellsize = m_canvas->GetCellSize();
+    GetToolBar()->EnableTool(ID_ZOOMIN,  cellsize < 32);
+    GetToolBar()->EnableTool(ID_ZOOMOUT, cellsize > 1);
+    GetMenuBar()->GetMenu(1)->Enable(ID_ZOOMIN,  cellsize < 32);
+    GetMenuBar()->GetMenu(1)->Enable(ID_ZOOMOUT, cellsize > 1);
+}
+
+// Event handlers -----------------------------------------------------------
+
+// OnMenu handles all events which don't have their own event handler
 void LifeFrame::OnMenu(wxCommandEvent& event)
 {
     switch (event.GetId())
     {
-        case ID_START   : OnStart(); break;
-        case ID_STEP    : OnTimer(); break;
-        case ID_STOP    : OnStop(); break;
-        case ID_WRAP    :
-        {
-            bool checked = GetMenuBar()->GetMenu(1)->IsChecked(ID_WRAP);
-            m_life->SetBorderWrap(checked);
-            break;
-        }
-        case ID_CLEAR   : 
+        case ID_NEW:
         {
+            // stop if it was running
             OnStop();
             m_life->Clear();
-            m_canvas->DrawEverything(TRUE);
-            m_canvas->Refresh(FALSE);
+            m_canvas->Recenter(0, 0);
             m_tics = 0;
             UpdateInfoText();
             break;
         }
-        case ID_ABOUT :
+        case ID_ABOUT:
         {
-            wxMessageBox(
-                _("This is the about dialog of the Life! sample.\n"
-                  "(c) 2000 Guillermo Rodriguez Garcia"),
-                _("About Life!"),
-                wxOK | wxICON_INFORMATION,
-                this);
+            LifeAboutDialog dialog(this);
+            dialog.ShowModal();
             break;
         }
-        case ID_EXIT :
+        case ID_EXIT:
         {
             // TRUE is to force the frame to close
             Close(TRUE);
             break;
         }
+        case ID_SHOWNAV :
+        {
+            bool checked = GetMenuBar()->GetMenu(1)->IsChecked(ID_SHOWNAV);
+            m_navigator->Show(checked);
+            break;
+        }
+        case ID_INFO:
+        {
+            wxString desc = m_life->GetDescription();
+            
+            if ( desc.IsEmpty() )
+                desc = _("Not available");
+
+            // should we make the description editable here?
+            wxMessageBox(desc, _("Description"), wxOK | wxICON_INFORMATION);
+
+            break;
+        }
+        case ID_START   : OnStart(); break;
+        case ID_STEP    : OnStep(); break;
+        case ID_STOP    : OnStop(); break;
+        case ID_TOPSPEED:
+        {
+            m_running = TRUE;
+            m_topspeed = TRUE;
+            UpdateUI();
+            while (m_running && m_topspeed)           
+            {
+                OnStep();
+                wxYield();
+            }
+            break;
+        }
     }
 }
 
-void LifeFrame::OnNewGame(wxCommandEvent& WXUNUSED(event))
+void LifeFrame::OnOpen(wxCommandEvent& WXUNUSED(event))
 {
-    int w = m_life->GetWidth();
-    int h = m_life->GetHeight();
-
-    // stop if it was running
-    OnStop();
-
-    // dialog box
-    LifeNewGameDialog dialog(this, &w, &h);
-
-    // new game?
-    if (dialog.ShowModal() == wxID_OK)
+    wxFileDialog filedlg(this,
+                         _("Choose a file to open"),
+                         _(""),
+                         _(""),
+                         _("Life patterns (*.lif)|*.lif|All files (*.*)|*.*"),
+                         wxOPEN | wxFILE_MUST_EXIST);
+
+    if (filedlg.ShowModal() == wxID_OK)
     {
-        // check dimensions
-        if (w >= LIFE_MIN && w <= LIFE_MAX &&
-            h >= LIFE_MIN && h <= LIFE_MAX)
+        wxFileInputStream stream(filedlg.GetPath());
+        LifeReader reader(stream);
+
+        // the reader handles errors itself, no need to do anything here
+        if (reader.IsOk())
         {
-            // resize game field
-            m_life->Destroy();
-            m_life->Create(w, h);
-            
-            // tell the canvas
-            m_canvas->Reset();
-            m_canvas->Refresh();
+            // stop if running and put the pattern
+            OnStop();
+            m_life->Clear();
+            m_life->SetPattern(reader.GetPattern());
+
+            // recenter canvas
+            m_canvas->Recenter(0, 0);
             m_tics = 0;
             UpdateInfoText();
         }
-        else
-        {
-            wxString msg;
-            msg.Printf(_("Both dimensions must be within %u and %u.\n"),
-                LIFE_MIN, LIFE_MAX);
-            wxMessageBox(msg, _("Error!"), wxOK | wxICON_EXCLAMATION, this);
-        }
     }
 }
 
@@ -320,60 +470,89 @@ void LifeFrame::OnSamples(wxCommandEvent& WXUNUSED(event))
     // dialog box
     LifeSamplesDialog dialog(this);
 
-    // new game?
     if (dialog.ShowModal() == wxID_OK)
     {
-        int result = dialog.GetValue();
+        const LifePattern pattern = dialog.GetPattern();
 
-        if (result == -1)
-            return;
+        // put the pattern
+        m_life->Clear();
+        m_life->SetPattern(pattern);
 
-        int gw   = g_shapes[result].m_fieldWidth;
-        int gh   = g_shapes[result].m_fieldHeight;
-        int wrap = g_shapes[result].m_wrap;
+        // recenter canvas
+        m_canvas->Recenter(0, 0);
+        m_tics = 0;
+        UpdateInfoText();
+    }
+}
 
-        // set wraparound (don't ask the user)
-        m_life->SetBorderWrap(wrap);
-        GetMenuBar()->GetMenu(1)->Check(ID_WRAP, wrap);
+void LifeFrame::OnZoom(wxCommandEvent& event)
+{
+    int cellsize = m_canvas->GetCellSize();
 
-        // need to resize the game field?
-        if (gw > m_life->GetWidth() || gh > m_life->GetHeight())
-        {
-            wxString s;
-            s.Printf(_("Your game field is too small for this configuration.\n"
-                       "It is recommended to resize it to %u x %u. Proceed?\n"),
-                       gw, gh);
+    if ((event.GetId() == ID_ZOOMIN) && cellsize < 32)
+    {
+        m_canvas->SetCellSize(cellsize * 2);
+        UpdateUI();
+    }
+    else if ((event.GetId() == ID_ZOOMOUT) && cellsize > 1)
+    {
+        m_canvas->SetCellSize(cellsize / 2);
+        UpdateUI();
+    }
+}
 
-            if (wxMessageBox(s, _("Question"), wxYES_NO | wxICON_QUESTION, this) == wxYES)
-            {
-                m_life->Destroy();
-                m_life->Create(gw, gh);
-            }
-        }
+void LifeFrame::OnNavigate(wxCommandEvent& event)
+{
+    LifeCell c;
 
-        // put the shape
-        m_life->SetShape(g_shapes[result]);
+    switch (event.GetId())
+    {
+               case ID_NORTH:  c = m_life->FindNorth(); break;
+        case ID_SOUTH:  c = m_life->FindSouth(); break;
+        case ID_WEST:   c = m_life->FindWest(); break;
+        case ID_EAST:   c = m_life->FindEast(); break;
+        case ID_CENTER: c = m_life->FindCenter(); break;
+        case ID_ORIGIN: c.i = c.j = 0; break;
+    }
 
-        // tell the canvas about the change
-        m_canvas->Reset();
-        m_canvas->Refresh();
-        m_tics = 0;
-        UpdateInfoText();
+    m_canvas->Recenter(c.i, c.j);
+}
+
+void LifeFrame::OnSlider(wxScrollEvent& event)
+{
+    m_interval = event.GetPosition() * 100;
+
+    if (m_running)
+    {
+        OnStop();
+        OnStart();
     }
+    
+    UpdateInfoText();
+}
+
+void LifeFrame::OnTimer(wxTimerEvent& WXUNUSED(event))
+{
+    OnStep();
+}
+
+void LifeFrame::OnClose(wxCloseEvent& WXUNUSED(event))
+{
+    // Stop if it was running; this is absolutely needed because
+    // the frame won't be actually destroyed until there are no
+    // more pending events, and this in turn won't ever happen
+    // if the timer is running faster than the window can redraw.
+    OnStop();
+    Destroy();   
 }
 
 void LifeFrame::OnStart()
 {
     if (!m_running)
     {
-        GetToolBar()->EnableTool(ID_START, FALSE);
-        GetToolBar()->EnableTool(ID_STOP,  TRUE);
-        GetMenuBar()->GetMenu(1)->Enable(ID_START, FALSE);
-        GetMenuBar()->GetMenu(1)->Enable(ID_STEP,  FALSE);
-        GetMenuBar()->GetMenu(1)->Enable(ID_STOP,  TRUE);
-
         m_timer->Start(m_interval);
         m_running = TRUE;
+        UpdateUI();
     }
 }
 
@@ -381,51 +560,108 @@ void LifeFrame::OnStop()
 {
     if (m_running)
     {
-        GetToolBar()->EnableTool(ID_START, TRUE);
-        GetToolBar()->EnableTool(ID_STOP,  FALSE);
-        GetMenuBar()->GetMenu(1)->Enable(ID_START, TRUE);
-        GetMenuBar()->GetMenu(1)->Enable(ID_STEP,  TRUE);
-        GetMenuBar()->GetMenu(1)->Enable(ID_STOP,  FALSE);
-        
         m_timer->Stop();
         m_running = FALSE;
+        m_topspeed = FALSE;
+        UpdateUI();
     }
 }
 
-void LifeFrame::OnTimer()
+void LifeFrame::OnStep()
 {
     if (m_life->NextTic())
         m_tics++;
     else
         OnStop();
 
+    m_canvas->DrawChanged();
     UpdateInfoText();
-    m_canvas->DrawEverything();
-    m_canvas->Refresh(FALSE);
 }
 
-void LifeFrame::OnSlider(wxScrollEvent& event)
+
+// --------------------------------------------------------------------------
+// LifeNavigator miniframe
+// --------------------------------------------------------------------------
+
+LifeNavigator::LifeNavigator(wxWindow *parent)
+             : wxMiniFrame(parent, -1,
+                           _("Navigation"),
+                           wxDefaultPosition,
+                           wxDefaultSize,
+                           wxCAPTION | wxSIMPLE_BORDER)
 {
-    m_interval = event.GetPosition() * 100;
+    wxPanel    *panel  = new wxPanel(this, -1);
+    wxBoxSizer *sizer1 = new wxBoxSizer(wxVERTICAL);
+    wxBoxSizer *sizer2 = new wxBoxSizer(wxHORIZONTAL);
+
+    // create bitmaps and masks for the buttons
+    wxBitmap
+        bmpn = wxBITMAP(north),
+        bmpw = wxBITMAP(west),  
+        bmpc = wxBITMAP(center),
+        bmpe = wxBITMAP(east),  
+        bmps = wxBITMAP(south);
+
+#if !defined(__WXGTK__) && !defined(__WXMOTIF__)
+    bmpn.SetMask(new wxMask(bmpn, *wxLIGHT_GREY));
+    bmpw.SetMask(new wxMask(bmpw, *wxLIGHT_GREY));
+    bmpc.SetMask(new wxMask(bmpc, *wxLIGHT_GREY));
+    bmpe.SetMask(new wxMask(bmpe, *wxLIGHT_GREY)); 
+    bmps.SetMask(new wxMask(bmps, *wxLIGHT_GREY));
+#endif
 
-    // restart timer if running, to set the new interval
-    if (m_running)
-    {
-        m_timer->Stop();
-        m_timer->Start(m_interval);
-    }
+    // create the buttons and attach tooltips to them
+    wxBitmapButton
+        *bn = new wxBitmapButton(panel, ID_NORTH,  bmpn),
+        *bw = new wxBitmapButton(panel, ID_WEST ,  bmpw),
+        *bc = new wxBitmapButton(panel, ID_CENTER, bmpc),
+        *be = new wxBitmapButton(panel, ID_EAST ,  bmpe),
+        *bs = new wxBitmapButton(panel, ID_SOUTH,  bmps);
+
+#if wxUSE_TOOLTIPS
+    bn->SetToolTip(_("Find northernmost cell"));
+    bw->SetToolTip(_("Find westernmost cell"));
+    bc->SetToolTip(_("Find center of mass"));
+    be->SetToolTip(_("Find easternmost cell"));
+    bs->SetToolTip(_("Find southernmost cell"));
+#endif
 
-    UpdateInfoText();
-}
+    // add buttons to sizers
+    sizer2->Add( bw, 0, wxCENTRE | wxWEST,  4 );
+    sizer2->Add( bc, 0, wxCENTRE);
+    sizer2->Add( be, 0, wxCENTRE | wxEAST,  4 );
+    sizer1->Add( bn, 0, wxCENTRE | wxNORTH, 4 );
+    sizer1->Add( sizer2 );
+    sizer1->Add( bs, 0, wxCENTRE | wxSOUTH, 4 );
 
-// --------------------------------------------------------------------------
-// LifeTimer
-// --------------------------------------------------------------------------
+    // set the miniframe size
+    panel->SetSizer(sizer1);
+    panel->SetAutoLayout(TRUE);
+    sizer1->Fit(this);
+    sizer1->SetSizeHints(this);
+
+    // move it to a sensible position
+    wxRect parentRect = parent->GetRect();
+    wxSize childSize  = GetSize();
+    int x = parentRect.GetX() +
+            parentRect.GetWidth();
+    int y = parentRect.GetY() +
+            (parentRect.GetHeight() - childSize.GetHeight()) / 4;
+    Move(x, y);
+
+    // done
+    Show(TRUE);
+}
 
-void LifeTimer::Notify()
+void LifeNavigator::OnClose(wxCloseEvent& event)
 {
-    GET_FRAME()->OnTimer();
-};
+    // avoid if we can
+    if (event.CanVeto())
+        event.Veto();
+    else
+        Destroy();
+}
+
 
 // --------------------------------------------------------------------------
 // LifeCanvas
@@ -433,129 +669,207 @@ void LifeTimer::Notify()
 
 // canvas constructor
 LifeCanvas::LifeCanvas(wxWindow *parent, Life *life, bool interactive)
-          : wxScrolledWindow(parent, -1, wxPoint(0, 0), wxSize(100, 100))
+          : wxWindow(parent, -1, wxPoint(0, 0), wxSize(100, 100),
+            wxSUNKEN_BORDER)
 {
     m_life        = life;
     m_interactive = interactive;
     m_cellsize    = 8;
-    m_bmp         = NULL;
-    Reset();
+    m_status      = MOUSE_NOACTION;
+    m_viewportX   = 0;
+    m_viewportY   = 0;
+    m_viewportH   = 0;
+    m_viewportW   = 0;
+
+    if (m_interactive)
+        SetCursor(*wxCROSS_CURSOR);
+
+    // reduce flicker if wxEVT_ERASE_BACKGROUND is not available
+    SetBackgroundColour(*wxWHITE);       
 }
 
 LifeCanvas::~LifeCanvas()
 {
-    delete m_bmp;
+    delete m_life;   
 }
 
-void LifeCanvas::Reset()
+// recenter at the given position
+void LifeCanvas::Recenter(wxInt32 i, wxInt32 j)
 {
-    if (m_bmp)
-        delete m_bmp;
-
-    m_status   = MOUSE_NOACTION;
-    m_width    = CellToCoord(m_life->GetWidth()) + 1;
-    m_height   = CellToCoord(m_life->GetHeight()) + 1;
-    m_bmp      = new wxBitmap(m_width, m_height);
-    wxCoord w  = GetClientSize().GetX();
-    wxCoord h  = GetClientSize().GetY();
-    m_xoffset  = (w > m_width)?  ((w - m_width) / 2)  : 0;
-    m_yoffset  = (h > m_height)? ((h - m_height) / 2) : 0;
+    m_viewportX = i - m_viewportW / 2;
+    m_viewportY = j - m_viewportH / 2;
 
     // redraw everything
-    DrawEverything(TRUE);
-    SetScrollbars(10, 10, (m_width + 9) / 10, (m_height + 9) / 10);
+    Refresh(FALSE);
 }
 
-void LifeCanvas::DrawEverything(bool force)
+// set the cell size and refresh display
+void LifeCanvas::SetCellSize(int cellsize)
 {
-    wxMemoryDC dc;
-
-    dc.SelectObject(*m_bmp);
-    dc.BeginDrawing();
-
-    // draw cells
-    const CellArray *cells =
-        force? m_life->GetCells() : m_life->GetChangedCells();
+    m_cellsize = cellsize;
+
+    // find current center
+    wxInt32 cx = m_viewportX + m_viewportW / 2;
+    wxInt32 cy = m_viewportY + m_viewportH / 2;
+
+    // get current canvas size and adjust viewport accordingly
+    int w, h;
+    GetClientSize(&w, &h);
+    m_viewportW = (w + m_cellsize - 1) / m_cellsize;
+    m_viewportH = (h + m_cellsize - 1) / m_cellsize;
+    
+    // recenter
+    m_viewportX = cx - m_viewportW / 2;
+    m_viewportY = cy - m_viewportH / 2;
+
+    // adjust scrollbars
+    if (m_interactive)
+    {
+        SetScrollbar(wxHORIZONTAL, m_viewportW, m_viewportW, 3 * m_viewportW);
+        SetScrollbar(wxVERTICAL,   m_viewportH, m_viewportH, 3 * m_viewportH);
+        m_thumbX = m_viewportW;
+        m_thumbY = m_viewportH;
+    }
+    
+    Refresh(FALSE);
+}
 
-    for (unsigned i = 0; i < cells->GetCount(); i++)
-        DrawCell(cells->Item(i), dc);
+// draw a cell
+void LifeCanvas::DrawCell(wxInt32 i, wxInt32 j, bool alive)
+{
+    wxClientDC dc(this);
 
-    // bounding rectangle (always drawn - better than clipping region)
-    dc.SetPen(*wxBLACK_PEN);
-    dc.SetBrush(*wxTRANSPARENT_BRUSH);
-    dc.DrawRectangle(0, 0, m_width, m_height);
+    dc.SetPen(alive? *wxBLACK_PEN : *wxWHITE_PEN);
+    dc.SetBrush(alive? *wxBLACK_BRUSH : *wxWHITE_BRUSH);
 
+    dc.BeginDrawing();
+    DrawCell(i, j, dc);
     dc.EndDrawing();
-    dc.SelectObject(wxNullBitmap);
 }
 
-void LifeCanvas::DrawCell(Cell c)
+void LifeCanvas::DrawCell(wxInt32 i, wxInt32 j, wxDC &dc)
 {
-    wxMemoryDC dc;
+    wxCoord x = CellToX(i);
+    wxCoord y = CellToY(j);
 
-    dc.SelectObject(*m_bmp);
-    dc.BeginDrawing();
-
-    dc.SetClippingRegion(1, 1, m_width - 2, m_height - 2);
-    DrawCell(c, dc);
-
-    dc.EndDrawing();
-    dc.SelectObject(wxNullBitmap);
+    // if cellsize is 1 or 2, there will be no grid
+    switch (m_cellsize)
+    {
+        case 1:
+            dc.DrawPoint(x, y);
+            break;
+        case 2:
+            dc.DrawRectangle(x, y, 2, 2);
+            break;
+        default:
+            dc.DrawRectangle(x + 1, y + 1, m_cellsize - 1, m_cellsize - 1);
+    }
 }
 
-void LifeCanvas::DrawCell(Cell c, wxDC &dc)
+// draw all changed cells
+void LifeCanvas::DrawChanged()
 {
-    if (m_life->IsAlive(c))
+    wxClientDC dc(this);
+
+    size_t ncells;
+    LifeCell *cells;
+    bool done = FALSE;
+
+    m_life->BeginFind(m_viewportX,
+                      m_viewportY,
+                      m_viewportX + m_viewportW,
+                      m_viewportY + m_viewportH,
+                      TRUE);
+   
+    dc.BeginDrawing();
+
+    if (m_cellsize == 1)
     {
         dc.SetPen(*wxBLACK_PEN);
-        dc.SetBrush(*wxBLACK_BRUSH);
-        dc.DrawRectangle(CellToCoord( m_life->GetX(c) ),
-                         CellToCoord( m_life->GetY(c) ),
-                         m_cellsize,
-                         m_cellsize);
     }
     else
     {
-        dc.SetPen(*wxLIGHT_GREY_PEN);
-        dc.SetBrush(*wxTRANSPARENT_BRUSH);
-        dc.DrawRectangle(CellToCoord( m_life->GetX(c) ),
-                         CellToCoord( m_life->GetY(c) ),
-                         m_cellsize,
-                         m_cellsize);
-        dc.SetPen(*wxWHITE_PEN);
-        dc.SetBrush(*wxWHITE_BRUSH);
-        dc.DrawRectangle(CellToCoord( m_life->GetX(c) ) + 1,
-                         CellToCoord( m_life->GetY(c) ) + 1,
-                         m_cellsize - 1,
-                         m_cellsize - 1);
+        dc.SetPen(*wxTRANSPARENT_PEN);
+        dc.SetBrush(*wxBLACK_BRUSH);
+    }
+    dc.SetLogicalFunction(wxINVERT);
+
+    while (!done)
+    {
+        done = m_life->FindMore(&cells, &ncells);
+
+        for (size_t m = 0; m < ncells; m++)
+            DrawCell(cells[m].i, cells[m].j, dc);
     }
+    dc.EndDrawing();
 }
 
 // event handlers
 void LifeCanvas::OnPaint(wxPaintEvent& event)
 {
     wxPaintDC dc(this);
-    wxMemoryDC memdc;
+    wxRect  rect = GetUpdateRegion().GetBox();
+    wxCoord x, y, w, h;
+    wxInt32 i0, j0, i1, j1;
+
+    // find damaged area
+    x = rect.GetX();
+    y = rect.GetY();
+    w = rect.GetWidth();
+    h = rect.GetHeight();
+
+    i0 = XToCell(x);
+    j0 = YToCell(y);
+    i1 = XToCell(x + w - 1);
+    j1 = YToCell(y + h - 1);
 
-    wxRegionIterator upd(GetUpdateRegion());
-    wxCoord x, y, w, h, xx, yy;
+    size_t ncells;
+    LifeCell *cells;
+    bool done = FALSE;
 
+    m_life->BeginFind(i0, j0, i1, j1, FALSE);
+    done = m_life->FindMore(&cells, &ncells);
+
+    // erase all damaged cells and draw the grid
     dc.BeginDrawing();
-    memdc.SelectObject(*m_bmp);
+    dc.SetBrush(*wxWHITE_BRUSH);
+
+    if (m_cellsize <= 2)
+    {
+       // no grid
+       dc.SetPen(*wxWHITE_PEN);
+       dc.DrawRectangle(x, y, w, h);
+    }
+    else
+    {
+        x = CellToX(i0);
+        y = CellToY(j0);
+        w = CellToX(i1 + 1) - x + 1;
+        h = CellToY(j1 + 1) - y + 1;
+
+        dc.SetPen(*wxLIGHT_GREY_PEN);
+        for (wxInt32 yy = y; yy <= (y + h - m_cellsize); yy += m_cellsize)
+            dc.DrawRectangle(x, yy, w, m_cellsize + 1);
+        for (wxInt32 xx = x; xx <= (x + w - m_cellsize); xx += m_cellsize)
+            dc.DrawLine(xx, y, xx, y + h);
+    }
+
+    // draw all alive cells
+    dc.SetPen(*wxBLACK_PEN);
+    dc.SetBrush(*wxBLACK_BRUSH);
 
-    while(upd)
+    while (!done)
     {
-        x = upd.GetX();
-        y = upd.GetY();
-        w = upd.GetW();
-        h = upd.GetH();
-        CalcUnscrolledPosition(x, y, &xx, &yy);
+        for (size_t m = 0; m < ncells; m++)
+            DrawCell(cells[m].i, cells[m].j, dc);
 
-        dc.Blit(x, y, w, h, &memdc, xx - m_xoffset, yy - m_yoffset);
-        upd++;
+        done = m_life->FindMore(&cells, &ncells);
     }
 
-    memdc.SelectObject(wxNullBitmap);
+    // last set
+    for (size_t m = 0; m < ncells; m++)
+        DrawCell(cells[m].i, cells[m].j, dc);
+
     dc.EndDrawing();
 }
 
@@ -564,67 +878,233 @@ void LifeCanvas::OnMouse(wxMouseEvent& event)
     if (!m_interactive)
         return;
 
-    int x, y, xx, yy, i, j;
-
     // which cell are we pointing at?
-    x = event.GetX();
-    y = event.GetY();
-    CalcUnscrolledPosition(x, y, &xx, &yy);
-    i = CoordToCell( xx - m_xoffset );
-    j = CoordToCell( yy - m_yoffset );
+    wxInt32 i = XToCell( event.GetX() );
+    wxInt32 j = YToCell( event.GetY() );
 
-    // adjust x, y to point to the upper left corner of the cell
-    CalcScrolledPosition( CellToCoord(i) + m_xoffset,
-                          CellToCoord(j) + m_yoffset,
-                          &x, &y );
+    // set statusbar text
+    wxString msg;
+    msg.Printf(_("Cell: (%d, %d)"), i, j);
+    ((LifeFrame *) wxGetApp().GetTopWindow())->SetStatusText(msg, 1);
 
-    // set cursor shape and statusbar text
-    if (i < 0 || i >= m_life->GetWidth() ||
-        j < 0 || j >= m_life->GetHeight())
-    {
-        GET_FRAME()->SetStatusText(wxEmptyString, 1);
-        SetCursor(*wxSTANDARD_CURSOR);
-    }
-    else
-    {
-        wxString msg;
-        msg.Printf(_("Cell: (%u, %u)"), i, j);
-        GET_FRAME()->SetStatusText(msg, 1);
-        SetCursor(*wxCROSS_CURSOR);
-    }
+    // NOTE that wxMouseEvent::LeftDown() and wxMouseEvent::LeftIsDown()
+    // have different semantics. The first one is used to signal that the
+    // button was just pressed (i.e., in "button down" events); the second
+    // one just describes the current status of the button, independently
+    // of the mouse event type. LeftIsDown is typically used in "mouse
+    // move" events, to test if the button is _still_ pressed.
 
-    // button pressed?
+    // is the button down?
     if (!event.LeftIsDown())
     {
         m_status = MOUSE_NOACTION;
+        return;
     }
-    else if (i >= 0 && i < m_life->GetWidth() &&
-             j >= 0 && j < m_life->GetHeight())
-    {
-        bool alive = m_life->IsAlive(i, j);
 
-        // if just pressed, update status
-        if (m_status == MOUSE_NOACTION)
-            m_status = (alive? MOUSE_ERASING : MOUSE_DRAWING);
-
-        // toggle cell and refresh if needed
-        if (((m_status == MOUSE_ERASING) && alive) ||
-            ((m_status == MOUSE_DRAWING) && !alive))
+    // was it pressed just now?
+    if (event.LeftDown())
+    {
+        // yes: start a new action and toggle this cell
+        m_status = (m_life->IsAlive(i, j)? MOUSE_ERASING : MOUSE_DRAWING);
+            
+        m_mi = i;
+        m_mj = j;
+        m_life->SetCell(i, j, m_status == MOUSE_DRAWING);
+        DrawCell(i, j, m_status == MOUSE_DRAWING);
+    }
+    else if ((m_mi != i) || (m_mj != j))
+    {
+        // no: continue ongoing action
+        bool alive = (m_status == MOUSE_DRAWING);
+
+        // prepare DC and pen + brush to optimize drawing
+        wxClientDC dc(this);
+        dc.SetPen(alive? *wxBLACK_PEN : *wxWHITE_PEN);
+        dc.SetBrush(alive? *wxBLACK_BRUSH : *wxWHITE_BRUSH);
+        dc.BeginDrawing();
+
+        // draw a line of cells using Bresenham's algorithm
+        wxInt32 d, ii, jj, di, ai, si, dj, aj, sj;
+        di = i - m_mi;
+        ai = abs(di) << 1;
+        si = (di < 0)? -1 : 1;
+        dj = j - m_mj;
+        aj = abs(dj) << 1;
+        sj = (dj < 0)? -1 : 1;
+
+        ii = m_mi;
+        jj = m_mj;
+  
+        if (ai > aj)
         {
-            wxRect rect(x, y, m_cellsize + 1, m_cellsize + 1);
-            DrawCell( m_life->SetCell(i, j, !alive) );
-            Refresh(FALSE, &rect);
+            // iterate over i
+            d = aj - (ai >> 1);        
+               
+            while (ii != i)
+            {
+                m_life->SetCell(ii, jj, alive);
+                DrawCell(ii, jj, dc);
+                if (d >= 0)
+                {
+                    jj += sj;
+                    d  -= ai;   
+                }
+                ii += si;
+                d  += aj;
+            }
         }
+        else
+        {
+            // iterate over j
+            d = ai - (aj >> 1);
+
+            while (jj != j)
+            {
+                m_life->SetCell(ii, jj, alive);
+                DrawCell(ii, jj, dc);
+                if (d >= 0)
+                {
+                    ii += si;
+                    d  -= aj;   
+                }
+                jj += sj;
+                d  += ai;
+            }
+        }
+
+        // last cell
+        m_life->SetCell(ii, jj, alive);
+        DrawCell(ii, jj, dc);
+        m_mi = ii;
+        m_mj = jj;
+
+        dc.EndDrawing();
     }
+
+    ((LifeFrame *) wxGetApp().GetTopWindow())->UpdateInfoText();
 }
 
 void LifeCanvas::OnSize(wxSizeEvent& event)
 {
+    // find center
+    wxInt32 cx = m_viewportX + m_viewportW / 2;
+    wxInt32 cy = m_viewportY + m_viewportH / 2;
+
+    // get new size
     wxCoord w = event.GetSize().GetX();
     wxCoord h = event.GetSize().GetY();
-    m_xoffset = (w > m_width)?  ((w - m_width) / 2)  : 0;
-    m_yoffset = (h > m_height)? ((h - m_height) / 2) : 0;
+    m_viewportW = (w + m_cellsize - 1) / m_cellsize;
+    m_viewportH = (h + m_cellsize - 1) / m_cellsize;
+
+    // recenter
+    m_viewportX = cx - m_viewportW / 2;
+    m_viewportY = cy - m_viewportH / 2;
+
+    // scrollbars
+    if (m_interactive)
+    {
+        SetScrollbar(wxHORIZONTAL, m_viewportW, m_viewportW, 3 * m_viewportW);
+        SetScrollbar(wxVERTICAL,   m_viewportH, m_viewportH, 3 * m_viewportH);
+        m_thumbX = m_viewportW;
+        m_thumbY = m_viewportH;
+    }
 
     // allow default processing
     event.Skip();
 }
+
+void LifeCanvas::OnScroll(wxScrollWinEvent& event)
+{
+    WXTYPE type = event.GetEventType();
+    int pos     = event.GetPosition();
+    int orient  = event.GetOrientation();
+
+    // calculate scroll increment
+    int scrollinc = 0;
+    if (type == wxEVT_SCROLLWIN_TOP)
+    {
+        if (orient == wxHORIZONTAL)
+            scrollinc = -m_viewportW;
+        else
+            scrollinc = -m_viewportH;
+    }
+    else
+    if (type == wxEVT_SCROLLWIN_BOTTOM)
+    {
+        if (orient == wxHORIZONTAL)
+            scrollinc = m_viewportW;
+        else
+            scrollinc = m_viewportH;
+    }
+    else
+    if (type == wxEVT_SCROLLWIN_LINEUP)
+    {
+        scrollinc = -1;
+    }
+    else
+    if (type == wxEVT_SCROLLWIN_LINEDOWN)
+    {
+        scrollinc = +1;
+    }
+    else
+    if (type == wxEVT_SCROLLWIN_PAGEUP)
+    {
+        scrollinc = -10;
+    }
+    else
+    if (type == wxEVT_SCROLLWIN_PAGEDOWN)
+    {
+        scrollinc = -10;
+    }
+    else
+    if (type == wxEVT_SCROLLWIN_THUMBTRACK)
+    {
+        if (orient == wxHORIZONTAL)
+        {
+            scrollinc = pos - m_thumbX;
+            m_thumbX = pos;
+        }
+        else
+        {
+            scrollinc = pos - m_thumbY;
+            m_thumbY = pos;
+        }
+    }
+    else
+    if (type == wxEVT_SCROLLWIN_THUMBRELEASE)
+    {
+        m_thumbX = m_viewportW;
+        m_thumbY = m_viewportH;
+    }
+
+#if defined(__WXGTK__) || defined(__WXMOTIF__)
+    // wxGTK and wxMotif update the thumb automatically (wxMSW doesn't);
+    // so reset it back as we always want it to be in the same position.
+    if (type != wxEVT_SCROLLWIN_THUMBTRACK)
+    {
+        SetScrollbar(wxHORIZONTAL, m_viewportW, m_viewportW, 3 * m_viewportW);
+        SetScrollbar(wxVERTICAL,   m_viewportH, m_viewportH, 3 * m_viewportH);
+    }
+#endif
+
+    if (scrollinc == 0) return;
+    
+    // scroll the window and adjust the viewport
+    if (orient == wxHORIZONTAL)
+    {
+        m_viewportX += scrollinc;
+        ScrollWindow( -m_cellsize * scrollinc, 0, (const wxRect *) NULL);
+    }
+    else
+    {
+        m_viewportY += scrollinc;    
+        ScrollWindow( 0, -m_cellsize * scrollinc, (const wxRect *) NULL);
+    }
+}
+
+void LifeCanvas::OnEraseBackground(wxEraseEvent& WXUNUSED(event))
+{
+    // do nothing. I just don't want the background to be erased, you know.
+}
+
+