]> git.saurik.com Git - wxWidgets.git/blobdiff - samples/thread/thread.cpp
Use X64 machine type for MSVC linker instead of old AMD64.
[wxWidgets.git] / samples / thread / thread.cpp
index 3f90a35360d06b140f95976920a7c9c476199284..da8acbdc542570f84d0621975b6fac0e31912c26 100644 (file)
@@ -5,7 +5,7 @@
 // Modified by:
 // Created:     06/16/98
 // RCS-ID:      $Id$
-// Copyright:   (c) 1998-2002 wxWidgets team
+// Copyright:   (c) 1998-2009 wxWidgets team
 // Licence:     wxWindows license
 /////////////////////////////////////////////////////////////////////////////
 
 class MyThread;
 WX_DEFINE_ARRAY_PTR(wxThread *, wxArrayThread);
 
-// Define a new application type
+// ----------------------------------------------------------------------------
+// the application object
+// ----------------------------------------------------------------------------
+
 class MyApp : public wxApp
 {
 public:
@@ -82,29 +85,26 @@ public:
     bool m_shuttingDown;
 };
 
-// Define a new frame type
-class MyFrame: public wxFrame
+// ----------------------------------------------------------------------------
+// the main application frame
+// ----------------------------------------------------------------------------
+
+class MyFrame : public wxFrame,
+                private wxLog
 {
 public:
     // ctor
-    MyFrame(wxFrame *frame, const wxString& title, int x, int y, int w, int h);
+    MyFrame(const wxString& title);
     virtual ~MyFrame();
 
-    // this function is MT-safe, i.e. it can be called from worker threads
-    // safely without any additional locking
-    void LogThreadMessage(const wxString& text)
-    {
-        wxCriticalSectionLocker lock(m_csMessages);
-        m_messages.push_back(text);
-
-        // as we effectively log the messages from the idle event handler,
-        // ensure it's going to be called now that we have some messages to log
-        wxWakeUpIdle();
-    }
-
     // accessors for MyWorkerThread (called in its context!)
     bool Cancelled();
 
+protected:
+    virtual void DoLogRecord(wxLogLevel level,
+                             const wxString& msg,
+                             const wxLogRecordInfo& info);
+
 private:
     // event handlers
     // --------------
@@ -119,8 +119,8 @@ private:
     void OnResumeThread(wxCommandEvent& event);
 
     void OnStartWorker(wxCommandEvent& event);
-
     void OnExecMain(wxCommandEvent& event);
+    void OnStartGUIThread(wxCommandEvent& event);
 
     void OnShowCPUs(wxCommandEvent& event);
     void OnAbout(wxCommandEvent& event);
@@ -130,6 +130,13 @@ private:
     void OnUpdateWorker(wxUpdateUIEvent& event);
 
 
+    // logging helper
+    void DoLogLine(wxTextCtrl *text,
+                   const wxString& timestr,
+                   const wxString& threadstr,
+                   const wxString& msg);
+
+
     // thread helper functions
     // -----------------------
 
@@ -139,9 +146,6 @@ private:
     // update display in our status bar: called during idle handling
     void UpdateThreadStatus();
 
-    // log the messages queued by LogThreadMessage()
-    void DoLogThreadMessages();
-
 
     // internal variables
     // ------------------
@@ -149,6 +153,10 @@ private:
     // just some place to put our messages in
     wxTextCtrl *m_txtctrl;
 
+    // old log target, we replace it with one using m_txtctrl during this
+    // frame life time
+    wxLog *m_oldLogger;
+
     // the array of pending messages to be displayed and the critical section
     // protecting it
     wxArrayString m_messages;
@@ -163,9 +171,7 @@ private:
 
     // was the worker thread cancelled by user?
     bool m_cancelled;
-
-    // protects m_cancelled
-    wxCriticalSection m_critsectWork;
+    wxCriticalSection m_csCancelled;        // protects m_cancelled
 
     DECLARE_EVENT_TABLE()
 };
@@ -186,42 +192,36 @@ enum
     THREAD_STOP_THREAD,
     THREAD_PAUSE_THREAD,
     THREAD_RESUME_THREAD,
-    THREAD_START_WORKER,
 
+    THREAD_START_WORKER,
     THREAD_EXEC_MAIN,
-    THREAD_EXEC_THREAD,
+    THREAD_START_GUI_THREAD,
 
     THREAD_SHOWCPUS,
 
-    WORKER_EVENT = wxID_HIGHEST+1   // this one gets sent from the worker thread
+    WORKER_EVENT = wxID_HIGHEST+1,   // this one gets sent from MyWorkerThread
+    GUITHREAD_EVENT                  // this one gets sent from MyGUIThread
 };
 
 // ----------------------------------------------------------------------------
-// GUI thread
+// a simple thread
 // ----------------------------------------------------------------------------
 
 class MyThread : public wxThread
 {
 public:
-    MyThread(MyFrame *frame);
+    MyThread();
     virtual ~MyThread();
 
     // thread execution starts here
     virtual void *Entry();
 
-    // write something to the text control in the main frame
-    void WriteText(const wxString& text)
-    {
-        m_frame->LogThreadMessage(text);
-    }
-
 public:
     unsigned m_count;
-    MyFrame *m_frame;
 };
 
 // ----------------------------------------------------------------------------
-// worker thread
+// worker thread
 // ----------------------------------------------------------------------------
 
 class MyWorkerThread : public wxThread
@@ -241,6 +241,53 @@ public:
     unsigned m_count;
 };
 
+// ----------------------------------------------------------------------------
+// a thread which executes GUI calls using wxMutexGuiEnter/Leave
+// ----------------------------------------------------------------------------
+
+#define GUITHREAD_BMP_SIZE          300
+#define GUITHREAD_NUM_UPDATES       50
+class MyImageDialog;
+
+class MyGUIThread : public wxThread
+{
+public:
+    MyGUIThread(MyImageDialog *dlg) : wxThread(wxTHREAD_JOINABLE)
+    {
+        m_dlg = dlg;
+    }
+
+    virtual ExitCode Entry();
+
+private:
+    MyImageDialog *m_dlg;
+};
+
+// ----------------------------------------------------------------------------
+// an helper dialog used by MyFrame::OnStartGUIThread
+// ----------------------------------------------------------------------------
+
+class MyImageDialog: public wxDialog
+{
+public:
+    // ctor
+    MyImageDialog(wxFrame *frame);
+    ~MyImageDialog();
+
+    // stuff used by MyGUIThread:
+    wxBitmap m_bmp;    // the bitmap drawn by MyGUIThread
+    wxCriticalSection m_csBmp;        // protects m_bmp
+
+private:
+    void OnGUIThreadEvent(wxThreadEvent& event);
+    void OnPaint(wxPaintEvent&);
+
+    MyGUIThread m_thread;
+    int m_nCurrentProgress;
+
+    DECLARE_EVENT_TABLE()
+};
+
 // ============================================================================
 // implementation
 // ============================================================================
@@ -268,12 +315,7 @@ bool MyApp::OnInit()
     wxLog::AddTraceMask("thread");
 
     // Create the main frame window
-    MyFrame *frame = new MyFrame((wxFrame *)NULL, _T("wxWidgets threads sample"),
-                                 50, 50, 450, 340);
-    SetTopWindow(frame);
-
-    // Show the frame
-    frame->Show(true);
+    new MyFrame("wxWidgets threads sample");
 
     return true;
 }
@@ -290,8 +332,10 @@ BEGIN_EVENT_TABLE(MyFrame, wxFrame)
     EVT_MENU(THREAD_STOP_THREAD, MyFrame::OnStopThread)
     EVT_MENU(THREAD_PAUSE_THREAD, MyFrame::OnPauseThread)
     EVT_MENU(THREAD_RESUME_THREAD, MyFrame::OnResumeThread)
+
     EVT_MENU(THREAD_START_WORKER, MyFrame::OnStartWorker)
     EVT_MENU(THREAD_EXEC_MAIN, MyFrame::OnExecMain)
+    EVT_MENU(THREAD_START_GUI_THREAD, MyFrame::OnStartGUIThread)
 
     EVT_MENU(THREAD_SHOWCPUS, MyFrame::OnShowCPUs)
     EVT_MENU(THREAD_ABOUT, MyFrame::OnAbout)
@@ -302,55 +346,84 @@ BEGIN_EVENT_TABLE(MyFrame, wxFrame)
 END_EVENT_TABLE()
 
 // My frame constructor
-MyFrame::MyFrame(wxFrame *frame, const wxString& title,
-                 int x, int y, int w, int h)
-       : wxFrame(frame, wxID_ANY, title, wxPoint(x, y), wxSize(w, h))
+MyFrame::MyFrame(const wxString& title)
+       : wxFrame(NULL, wxID_ANY, title)
 {
+    m_oldLogger = wxLog::GetActiveTarget();
+
     SetIcon(wxIcon(sample_xpm));
 
     // Make a menubar
     wxMenuBar *menuBar = new wxMenuBar;
 
     wxMenu *menuFile = new wxMenu;
-    menuFile->Append(THREAD_CLEAR, _T("&Clear log\tCtrl-L"));
+    menuFile->Append(THREAD_CLEAR, wxT("&Clear log\tCtrl-L"));
     menuFile->AppendSeparator();
-    menuFile->Append(THREAD_QUIT, _T("E&xit\tAlt-X"));
-    menuBar->Append(menuFile, _T("&File"));
+    menuFile->Append(THREAD_QUIT, wxT("E&xit\tAlt-X"));
+    menuBar->Append(menuFile, wxT("&File"));
 
     wxMenu *menuThread = new wxMenu;
-    menuThread->Append(THREAD_START_THREAD, _T("&Start a new thread\tCtrl-N"));
-    menuThread->Append(THREAD_START_THREADS, _T("Start &many threads at once"));
-    menuThread->Append(THREAD_STOP_THREAD, _T("S&top the last spawned thread\tCtrl-S"));
+    menuThread->Append(THREAD_START_THREAD, wxT("&Start a new thread\tCtrl-N"));
+    menuThread->Append(THREAD_START_THREADS, wxT("Start &many threads at once"));
+    menuThread->Append(THREAD_STOP_THREAD, wxT("S&top the last spawned thread\tCtrl-S"));
     menuThread->AppendSeparator();
-    menuThread->Append(THREAD_PAUSE_THREAD, _T("&Pause the last spawned running thread\tCtrl-P"));
-    menuThread->Append(THREAD_RESUME_THREAD, _T("&Resume the first suspended thread\tCtrl-R"));
+    menuThread->Append(THREAD_PAUSE_THREAD, wxT("&Pause the last spawned running thread\tCtrl-P"));
+    menuThread->Append(THREAD_RESUME_THREAD, wxT("&Resume the first suspended thread\tCtrl-R"));
     menuThread->AppendSeparator();
-    menuThread->Append(THREAD_START_WORKER, _T("Start a &worker thread\tCtrl-W"));
-    menuThread->Append(THREAD_EXEC_MAIN, _T("&Launch a program from main thread\tF5"));
-    menuBar->Append(menuThread, _T("&Thread"));
+    menuThread->Append(THREAD_START_WORKER, wxT("Start a &worker thread\tCtrl-W"));
+    menuThread->Append(THREAD_EXEC_MAIN, wxT("&Launch a program from main thread\tF5"));
+    menuThread->Append(THREAD_START_GUI_THREAD, wxT("Launch a &GUI thread\tF6"));
+    menuBar->Append(menuThread, wxT("&Thread"));
 
     wxMenu *menuHelp = new wxMenu;
-    menuHelp->Append(THREAD_SHOWCPUS, _T("&Show CPU count"));
+    menuHelp->Append(THREAD_SHOWCPUS, wxT("&Show CPU count"));
     menuHelp->AppendSeparator();
-    menuHelp->Append(THREAD_ABOUT, _T("&About..."));
-    menuBar->Append(menuHelp, _T("&Help"));
+    menuHelp->Append(THREAD_ABOUT, wxT("&About..."));
+    menuBar->Append(menuHelp, wxT("&Help"));
 
     SetMenuBar(menuBar);
 
     m_nRunning = m_nCount = 0;
 
-    m_dlgProgress = (wxProgressDialog *)NULL;
+    m_dlgProgress = NULL;
 
 #if wxUSE_STATUSBAR
     CreateStatusBar(2);
 #endif // wxUSE_STATUSBAR
 
-    m_txtctrl = new wxTextCtrl(this, wxID_ANY, _T(""), wxPoint(0, 0), wxSize(0, 0),
+    // create the logging text control and a header showing the meaning of the
+    // different columns
+    wxTextCtrl *header = new wxTextCtrl(this, wxID_ANY, "",
+                                        wxDefaultPosition, wxDefaultSize,
+                                        wxTE_READONLY);
+    DoLogLine(header, "  Time", " Thread", "Message");
+    m_txtctrl = new wxTextCtrl(this, wxID_ANY, "",
+                               wxDefaultPosition, wxDefaultSize,
                                wxTE_MULTILINE | wxTE_READONLY);
+    wxLog::SetActiveTarget(this);
+
+    // use fixed width font to align output in nice columns
+    wxFont font(wxNORMAL_FONT->GetPointSize(), wxFONTFAMILY_TELETYPE,
+                wxFONTSTYLE_NORMAL, wxFONTWEIGHT_NORMAL);
+    header->SetFont(font);
+    m_txtctrl->SetFont(font);
+
+    m_txtctrl->SetFocus();
+
+    // layout and show the frame
+    wxBoxSizer *sizer = new wxBoxSizer(wxVERTICAL);
+    sizer->Add(header, wxSizerFlags().Expand());
+    sizer->Add(m_txtctrl, wxSizerFlags(1).Expand());
+    SetSizer(sizer);
+
+    SetSize(600, 350);
+    Show();
 }
 
 MyFrame::~MyFrame()
 {
+    wxLog::SetActiveTarget(m_oldLogger);
+
     // NB: although the OS will terminate all the threads anyhow when the main
     //     one exits, it's good practice to do it ourselves -- even if it's not
     //     completely trivial in this example
@@ -377,9 +450,43 @@ MyFrame::~MyFrame()
     wxGetApp().m_semAllDone.Wait();
 }
 
+void
+MyFrame::DoLogLine(wxTextCtrl *text,
+                   const wxString& timestr,
+                   const wxString& threadstr,
+                   const wxString& msg)
+{
+    text->AppendText(wxString::Format("%9s %10s %s", timestr, threadstr, msg));
+}
+
+void
+MyFrame::DoLogRecord(wxLogLevel level,
+                     const wxString& msg,
+                     const wxLogRecordInfo& info)
+{
+    // let the default GUI logger treat warnings and errors as they should be
+    // more noticeable than just another line in the log window and also trace
+    // messages as there may be too many of them
+    if ( level <= wxLOG_Warning || level == wxLOG_Trace )
+    {
+        m_oldLogger->LogRecord(level, msg, info);
+        return;
+    }
+
+    DoLogLine
+    (
+        m_txtctrl,
+        wxDateTime(info.timestamp).FormatISOTime(),
+        info.threadId == wxThread::GetMainId()
+            ? wxString("main")
+            : wxString::Format("%x", info.threadId),
+        msg + "\n"
+    );
+}
+
 MyThread *MyFrame::CreateThread()
 {
-    MyThread *thread = new MyThread(this);
+    MyThread *thread = new MyThread;
 
     if ( thread->Create() != wxTHREAD_NO_ERROR )
     {
@@ -392,12 +499,46 @@ MyThread *MyFrame::CreateThread()
     return thread;
 }
 
+void MyFrame::UpdateThreadStatus()
+{
+    wxCriticalSectionLocker enter(wxGetApp().m_critsect);
+
+    // update the counts of running/total threads
+    size_t nRunning = 0,
+           nCount = wxGetApp().m_threads.Count();
+    for ( size_t n = 0; n < nCount; n++ )
+    {
+        if ( wxGetApp().m_threads[n]->IsRunning() )
+            nRunning++;
+    }
+
+    if ( nCount != m_nCount || nRunning != m_nRunning )
+    {
+        m_nRunning = nRunning;
+        m_nCount = nCount;
+
+        wxLogStatus(this, wxT("%u threads total, %u running."), unsigned(nCount), unsigned(nRunning));
+    }
+    //else: avoid flicker - don't print anything
+}
+
+bool MyFrame::Cancelled()
+{
+    wxCriticalSectionLocker lock(m_csCancelled);
+
+    return m_cancelled;
+}
+
+// ----------------------------------------------------------------------------
+// MyFrame - event handlers
+// ----------------------------------------------------------------------------
+
 void MyFrame::OnStartThreads(wxCommandEvent& WXUNUSED(event) )
 {
     static long s_num;
 
-    s_num = wxGetNumberFromUser(_T("How many threads to start: "), _T(""),
-                                _T("wxThread sample"), s_num, 1, 10000, this);
+    s_num = wxGetNumberFromUser(wxT("How many threads to start: "), wxT(""),
+                                wxT("wxThread sample"), s_num, 1, 10000, this);
     if ( s_num == -1 )
     {
         s_num = 10;
@@ -450,7 +591,7 @@ void MyFrame::OnStartThread(wxCommandEvent& WXUNUSED(event) )
     }
 
 #if wxUSE_STATUSBAR
-    SetStatusText(_T("New thread started."), 1);
+    SetStatusText(wxT("New thread started."), 1);
 #endif // wxUSE_STATUSBAR
 }
 
@@ -468,7 +609,7 @@ void MyFrame::OnStopThread(wxCommandEvent& WXUNUSED(event) )
         wxGetApp().m_threads.Last()->Delete();
 
 #if wxUSE_STATUSBAR
-        SetStatusText(_T("Last thread stopped."), 1);
+        SetStatusText(wxT("Last thread stopped."), 1);
 #endif // wxUSE_STATUSBAR
     }
 }
@@ -491,7 +632,7 @@ void MyFrame::OnResumeThread(wxCommandEvent& WXUNUSED(event) )
         wxGetApp().m_threads[n]->Resume();
 
 #if wxUSE_STATUSBAR
-        SetStatusText(_T("Thread resumed."), 1);
+        SetStatusText(wxT("Thread resumed."), 1);
 #endif // wxUSE_STATUSBAR
     }
 }
@@ -514,56 +655,18 @@ void MyFrame::OnPauseThread(wxCommandEvent& WXUNUSED(event) )
         wxGetApp().m_threads[n]->Pause();
 
 #if wxUSE_STATUSBAR
-        SetStatusText(_T("Thread paused."), 1);
+        SetStatusText(wxT("Thread paused."), 1);
 #endif // wxUSE_STATUSBAR
     }
 }
 
 void MyFrame::OnIdle(wxIdleEvent& event)
 {
-    DoLogThreadMessages();
-
     UpdateThreadStatus();
 
     event.Skip();
 }
 
-void MyFrame::DoLogThreadMessages()
-{
-    wxCriticalSectionLocker lock(m_csMessages);
-
-    const size_t count = m_messages.size();
-    for ( size_t n = 0; n < count; n++ )
-    {
-        m_txtctrl->AppendText(m_messages[n]);
-    }
-
-    m_messages.clear();
-}
-
-void MyFrame::UpdateThreadStatus()
-{
-    wxCriticalSectionLocker enter(wxGetApp().m_critsect);
-
-    // update the counts of running/total threads
-    size_t nRunning = 0,
-           nCount = wxGetApp().m_threads.Count();
-    for ( size_t n = 0; n < nCount; n++ )
-    {
-        if ( wxGetApp().m_threads[n]->IsRunning() )
-            nRunning++;
-    }
-
-    if ( nCount != m_nCount || nRunning != m_nRunning )
-    {
-        m_nRunning = nRunning;
-        m_nCount = nCount;
-
-        wxLogStatus(this, wxT("%u threads total, %u running."), unsigned(nCount), unsigned(nRunning));
-    }
-    //else: avoid flicker - don't print anything
-}
-
 void MyFrame::OnQuit(wxCommandEvent& WXUNUSED(event) )
 {
     Close(true);
@@ -594,15 +697,15 @@ void MyFrame::OnShowCPUs(wxCommandEvent& WXUNUSED(event))
     switch ( nCPUs )
     {
         case -1:
-            msg = _T("Unknown number of CPUs");
+            msg = wxT("Unknown number of CPUs");
             break;
 
         case 0:
-            msg = _T("WARNING: you're running without any CPUs!");
+            msg = wxT("WARNING: you're running without any CPUs!");
             break;
 
         case 1:
-            msg = _T("This system only has one CPU.");
+            msg = wxT("This system only has one CPU.");
             break;
 
         default:
@@ -615,11 +718,11 @@ void MyFrame::OnShowCPUs(wxCommandEvent& WXUNUSED(event))
 void MyFrame::OnAbout(wxCommandEvent& WXUNUSED(event) )
 {
     wxMessageDialog dialog(this,
-                           _T("wxWidgets multithreaded application sample\n")
-                           _T("(c) 1998 Julian Smart, Guilhem Lavaux\n")
-                           _T("(c) 1999 Vadim Zeitlin\n")
-                           _T("(c) 2000 Robert Roebling"),
-                           _T("About wxThread sample"),
+                           wxT("wxWidgets multithreaded application sample\n")
+                           wxT("(c) 1998 Julian Smart, Guilhem Lavaux\n")
+                           wxT("(c) 2000 Robert Roebling\n")
+                           wxT("(c) 1999,2009 Vadim Zeitlin"),
+                           wxT("About wxThread sample"),
                            wxOK | wxICON_INFORMATION);
 
     dialog.ShowModal();
@@ -647,8 +750,8 @@ void MyFrame::OnStartWorker(wxCommandEvent& WXUNUSED(event))
 
     m_dlgProgress = new wxProgressDialog
                         (
-                         _T("Progress dialog"),
-                         _T("Wait until the thread terminates or press [Cancel]"),
+                         wxT("Progress dialog"),
+                         wxT("Wait until the thread terminates or press [Cancel]"),
                          100,
                          this,
                          wxPD_CAN_ABORT |
@@ -681,30 +784,112 @@ void MyFrame::OnWorkerEvent(wxThreadEvent& event)
     {
         if ( !m_dlgProgress->Update(n) )
         {
-            wxCriticalSectionLocker lock(m_critsectWork);
+            wxCriticalSectionLocker lock(m_csCancelled);
 
             m_cancelled = true;
         }
     }
 }
 
-bool MyFrame::Cancelled()
+void MyFrame::OnStartGUIThread(wxCommandEvent& WXUNUSED(event))
 {
-    wxCriticalSectionLocker lock(m_critsectWork);
+    // we use this to check that disabling logging only affects the main thread
+    // but the messages from the worker thread will still be logged
+    wxLogNull noLog;
+    wxLogMessage("You shouldn't see this message because of wxLogNull");
 
-    return m_cancelled;
+    MyImageDialog dlg(this);
+
+    dlg.ShowModal();
+}
+
+
+// ----------------------------------------------------------------------------
+// MyImageDialog
+// ----------------------------------------------------------------------------
+
+BEGIN_EVENT_TABLE(MyImageDialog, wxDialog)
+    EVT_THREAD(GUITHREAD_EVENT, MyImageDialog::OnGUIThreadEvent)
+    EVT_PAINT(MyImageDialog::OnPaint)
+END_EVENT_TABLE()
+
+MyImageDialog::MyImageDialog(wxFrame *parent)
+    : wxDialog(parent, wxID_ANY, "Image created by a secondary thread",
+               wxDefaultPosition, wxSize(GUITHREAD_BMP_SIZE,GUITHREAD_BMP_SIZE)*1.5, wxDEFAULT_DIALOG_STYLE),
+      m_thread(this)
+{
+    m_nCurrentProgress = 0;
+
+    CentreOnScreen();
+
+    // NOTE: no need to lock m_csBmp until the thread isn't started:
+
+    // create the bitmap
+    if (!m_bmp.Create(GUITHREAD_BMP_SIZE,GUITHREAD_BMP_SIZE) || !m_bmp.IsOk())
+    {
+        wxLogError("Couldn't create the bitmap!");
+        return;
+    }
+
+    // clean it
+    wxMemoryDC dc(m_bmp);
+    dc.SetBackground(*wxBLACK_BRUSH);
+    dc.Clear();
+
+    // draw the bitmap from a secondary thread
+    if ( m_thread.Create() != wxTHREAD_NO_ERROR ||
+         m_thread.Run() != wxTHREAD_NO_ERROR )
+    {
+        wxLogError(wxT("Can't create/run thread!"));
+        return;
+    }
+}
+
+MyImageDialog::~MyImageDialog()
+{
+    // in case our thread is still running and for some reason we are destroyed,
+    // do wait for the thread to complete as it assumes that its MyImageDialog
+    // pointer is always valid
+    m_thread.Delete();
 }
 
+void MyImageDialog::OnGUIThreadEvent(wxThreadEvent& event)
+{
+    m_nCurrentProgress = int(((float)event.GetInt()*100)/GUITHREAD_NUM_UPDATES);
+
+    Refresh();
+}
+
+void MyImageDialog::OnPaint(wxPaintEvent& WXUNUSED(evt))
+{
+    wxPaintDC dc(this);
+
+    const wxSize& sz = dc.GetSize();
+
+    {
+        // paint the bitmap
+        wxCriticalSectionLocker locker(m_csBmp);
+        dc.DrawBitmap(m_bmp, (sz.GetWidth()-GUITHREAD_BMP_SIZE)/2,
+                             (sz.GetHeight()-GUITHREAD_BMP_SIZE)/2);
+    }
+
+    // paint a sort of progress bar with a 10px border:
+    dc.SetBrush(*wxRED_BRUSH);
+    dc.DrawRectangle(10,10, m_nCurrentProgress*(sz.GetWidth()-20)/100,30);
+    dc.SetTextForeground(*wxBLUE);
+    dc.DrawText(wxString::Format("%d%%", m_nCurrentProgress),
+                (sz.GetWidth()-dc.GetCharWidth()*2)/2,
+                25-dc.GetCharHeight()/2);
+}
 
 // ----------------------------------------------------------------------------
 // MyThread
 // ----------------------------------------------------------------------------
 
-MyThread::MyThread(MyFrame *frame)
+MyThread::MyThread()
         : wxThread()
 {
     m_count = 0;
-    m_frame = frame;
 }
 
 MyThread::~MyThread()
@@ -727,14 +912,9 @@ MyThread::~MyThread()
     }
 }
 
-void *MyThread::Entry()
+wxThread::ExitCode MyThread::Entry()
 {
-    wxString text;
-
-    text.Printf(wxT("Thread %p started (priority = %u).\n"),
-                GetId(), GetPriority());
-    WriteText(text);
-    // wxLogMessage(text); -- test wxLog thread safeness
+    wxLogMessage("Thread started (priority = %u).", GetPriority());
 
     for ( m_count = 0; m_count < 10; m_count++ )
     {
@@ -750,16 +930,13 @@ void *MyThread::Entry()
         if ( TestDestroy() )
             break;
 
-        text.Printf(wxT("[%u] Thread %p here.\n"), m_count, GetId());
-        WriteText(text);
+        wxLogMessage("Thread progress: %u", m_count);
 
         // wxSleep() can't be called from non-GUI thread!
         wxThread::Sleep(1000);
     }
 
-    text.Printf(wxT("Thread %p finished.\n"), GetId());
-    WriteText(text);
-    // wxLogMessage(text); -- test wxLog thread safeness
+    wxLogMessage("Thread finished.");
 
     return NULL;
 }
@@ -769,6 +946,12 @@ void *MyThread::Entry()
 // MyWorkerThread
 // ----------------------------------------------------------------------------
 
+// define this symbol to 1 to test if the YieldFor() call in the wxProgressDialog::Update
+// function provokes a race condition in which the second wxThreadEvent posted by
+// MyWorkerThread::Entry is processed by the YieldFor() call of wxProgressDialog::Update
+// and results in the destruction of the progress dialog itself, resulting in a crash later.
+#define TEST_YIELD_RACE_CONDITION       0
+
 MyWorkerThread::MyWorkerThread(MyFrame *frame)
         : wxThread()
 {
@@ -780,13 +963,7 @@ void MyWorkerThread::OnExit()
 {
 }
 
-// define this symbol to 1 to test if the YieldFor() call in the wxProgressDialog::Update
-// function provokes a race condition in which the second wxThreadEvent posted by
-// MyWorkerThread::Entry is processed by the YieldFor() call of wxProgressDialog::Update
-// and results in the destruction of the progress dialog itself, resulting in a crash later.
-#define TEST_YIELD_RACE_CONDITION       0
-
-void *MyWorkerThread::Entry()
+wxThread::ExitCode MyWorkerThread::Entry()
 {
 #if TEST_YIELD_RACE_CONDITION
     if ( TestDestroy() )
@@ -824,3 +1001,68 @@ void *MyWorkerThread::Entry()
     return NULL;
 }
 
+
+// ----------------------------------------------------------------------------
+// MyGUIThread
+// ----------------------------------------------------------------------------
+
+wxThread::ExitCode MyGUIThread::Entry()
+{
+    // uncomment this to check that disabling logging here does disable it for
+    // this thread -- but not the main one if you also comment out wxLogNull
+    // line in MyFrame::OnStartGUIThread()
+    //wxLogNull noLog;
+
+    // this goes to the main window
+    wxLogMessage("GUI thread starting");
+
+    // use a thread-specific log target for this thread to show that its
+    // messages don't appear in the main window while it runs
+    wxLogBuffer logBuf;
+    wxLog::SetThreadActiveTarget(&logBuf);
+
+    for (int i=0; i<GUITHREAD_NUM_UPDATES && !TestDestroy(); i++)
+    {
+        // inform the GUI toolkit that we're going to use GUI functions
+        // from a secondary thread:
+        wxMutexGuiEnter();
+
+        {
+            wxCriticalSectionLocker lock(m_dlg->m_csBmp);
+
+            // draw some more stuff on the bitmap
+            wxMemoryDC dc(m_dlg->m_bmp);
+            dc.SetBrush((i%2)==0 ? *wxBLUE_BRUSH : *wxGREEN_BRUSH);
+            dc.DrawRectangle(rand()%GUITHREAD_BMP_SIZE, rand()%GUITHREAD_BMP_SIZE, 30, 30);
+
+            // simulate long drawing time:
+            wxMilliSleep(200);
+        }
+
+        // if we don't release the GUI mutex the MyImageDialog won't be able to refresh
+        wxMutexGuiLeave();
+
+        // notify the dialog that another piece of our masterpiece is complete:
+        wxThreadEvent event( wxEVT_COMMAND_THREAD, GUITHREAD_EVENT );
+        event.SetInt(i+1);
+        wxQueueEvent( m_dlg, event.Clone() );
+
+        if ( !((i + 1) % 10) )
+        {
+            // this message will go to the buffer
+            wxLogMessage("Step #%d.", i + 1);
+        }
+
+        // give the main thread the time to refresh before we lock the GUI mutex again
+        // FIXME: find a better way to do this!
+        wxMilliSleep(100);
+    }
+
+    // now remove the thread-specific thread target
+    wxLog::SetThreadActiveTarget(NULL);
+
+    // so that this goes to the main window again
+    wxLogMessage("GUI thread finished.");
+
+    return (ExitCode)0;
+}