Support using GetTextExtent() with empty string to get descent in wxOSX.

[wxWidgets.git] / include / wx / evtloop.h

diff --git a/include/wx/evtloop.h b/include/wx/evtloop.h
index 2a71defd7a741c8144070a3012d04452708aa5f5..a9034aeac8a03744c35bd82de5d53b72838c2c15 100644 (file)
--- a/include/wx/evtloop.h
+++ b/include/wx/evtloop.h
@@ -12,46 +12,425 @@
 #ifndef _WX_EVTLOOP_H_
 #define _WX_EVTLOOP_H_
 
 #ifndef _WX_EVTLOOP_H_
 #define _WX_EVTLOOP_H_
 

-#ifdef __GNUG__
-    #pragma interface "evtloop.h"
+#include "wx/event.h"
+#include "wx/utils.h"
+
+// TODO: implement wxEventLoopSource for MSW (it should wrap a HANDLE and be
+//       monitored using MsgWaitForMultipleObjects())
+#if defined(__WXOSX__) || (defined(__UNIX__) && !defined(__WXMSW__))
+    #define wxUSE_EVENTLOOP_SOURCE 1
+#else
+    #define wxUSE_EVENTLOOP_SOURCE 0
+#endif
+
+#if wxUSE_EVENTLOOP_SOURCE
+    class wxEventLoopSource;
+    class wxEventLoopSourceHandler;

 #endif
 
 #endif
 

+/*
+    NOTE ABOUT wxEventLoopBase::YieldFor LOGIC
+    ------------------------------------------
+
+    The YieldFor() function helps to avoid re-entrancy problems and problems
+    caused by out-of-order event processing
+    (see "wxYield-like problems" and "wxProgressDialog+threading BUG" wx-dev threads).
+
+    The logic behind YieldFor() is simple: it analyzes the queue of the native
+    events generated by the underlying GUI toolkit and picks out and processes
+    only those matching the given mask.
+
+    It's important to note that YieldFor() is used to selectively process the
+    events generated by the NATIVE toolkit.
+    Events syntethized by wxWidgets code or by user code are instead selectively
+    processed thanks to the logic built into wxEvtHandler::ProcessPendingEvents().
+    In fact, when wxEvtHandler::ProcessPendingEvents gets called from inside a
+    YieldFor() call, wxEventLoopBase::IsEventAllowedInsideYield is used to decide
+    if the pending events for that event handler can be processed.
+    If all the pending events associated with that event handler result as "not processable",
+    the event handler "delays" itself calling wxEventLoopBase::DelayPendingEventHandler
+    (so it's moved: m_handlersWithPendingEvents => m_handlersWithPendingDelayedEvents).
+    Last, wxEventLoopBase::ProcessPendingEvents() before exiting moves the delayed
+    event handlers back into the list of handlers with pending events
+    (m_handlersWithPendingDelayedEvents => m_handlersWithPendingEvents) so that
+    a later call to ProcessPendingEvents() (possibly outside the YieldFor() call)
+    will process all pending events as usual.
+*/
+

 // ----------------------------------------------------------------------------
 // ----------------------------------------------------------------------------

-// wxEventLoop: a GUI event loop
+// wxEventLoopBase: interface for wxEventLoop

 // ----------------------------------------------------------------------------
 
 // ----------------------------------------------------------------------------
 

-class WXDLLEXPORT wxEventLoop
+class WXDLLIMPEXP_BASE wxEventLoopBase

 {
 public:
 {
 public:

-    // ctor
-    wxEventLoop() { m_impl = NULL; }
+    // trivial, but needed (because of wxEventLoopBase) ctor
+    wxEventLoopBase();

 
     // dtor
 
     // dtor

-    virtual ~wxEventLoop();
+    virtual ~wxEventLoopBase() { }
+
+    // use this to check whether the event loop was successfully created before
+    // using it
+    virtual bool IsOk() const { return true; }
+
+    // returns true if this is the main loop
+    bool IsMain() const;
+
+#if wxUSE_EVENTLOOP_SOURCE
+    // create a new event loop source wrapping the given file descriptor and
+    // monitor it for events occurring on this descriptor in all event loops
+    static wxEventLoopSource *
+      AddSourceForFD(int fd, wxEventLoopSourceHandler *handler, int flags);
+#endif // wxUSE_EVENTLOOP_SOURCE
+
+    // dispatch&processing
+    // -------------------

 
     // start the event loop, return the exit code when it is finished
 
     // start the event loop, return the exit code when it is finished

+    //
+    // notice that wx ports should override DoRun(), this method is virtual
+    // only to allow overriding it in the user code for custom event loops

     virtual int Run();
 
     virtual int Run();
 

+    // is this event loop running now?
+    //
+    // notice that even if this event loop hasn't terminated yet but has just
+    // spawned a nested (e.g. modal) event loop, this would return false
+    bool IsRunning() const;
+

     // exit from the loop with the given exit code
     // exit from the loop with the given exit code

+    //
+    // this can be only used to exit the currently running loop, use
+    // ScheduleExit() if this might not be the case

     virtual void Exit(int rc = 0);
 
     virtual void Exit(int rc = 0);
 

-    // return TRUE if any events are available
-    virtual bool Pending() const;
+    // ask the event loop to exit with the given exit code, can be used even if
+    // this loop is not running right now but the loop must have been started,
+    // i.e. Run() should have been already called
+    virtual void ScheduleExit(int rc = 0) = 0;
+
+    // return true if any events are available
+    virtual bool Pending() const = 0;
+
+    // dispatch a single event, return false if we should exit from the loop
+    virtual bool Dispatch() = 0;
+
+    // same as Dispatch() but doesn't wait for longer than the specified (in
+    // ms) timeout, return true if an event was processed, false if we should
+    // exit the loop or -1 if timeout expired
+    virtual int DispatchTimeout(unsigned long timeout) = 0;
+
+    // implement this to wake up the loop: usually done by posting a dummy event
+    // to it (can be called from non main thread)
+    virtual void WakeUp() = 0;
+
+
+    // idle handling
+    // -------------
+
+        // make sure that idle events are sent again
+    virtual void WakeUpIdle();
+
+        // this virtual function is called  when the application
+        // becomes idle and by default it forwards to wxApp::ProcessIdle() and
+        // while it can be overridden in a custom event loop, you must call the
+        // base class version to ensure that idle events are still generated
+        //
+        // it should return true if more idle events are needed, false if not
+    virtual bool ProcessIdle();
+
+
+    // Yield-related hooks
+    // -------------------
+
+    // process all currently pending events right now
+    //
+    // it is an error to call Yield() recursively unless the value of
+    // onlyIfNeeded is true
+    //
+    // WARNING: this function is dangerous as it can lead to unexpected
+    //          reentrancies (i.e. when called from an event handler it
+    //          may result in calling the same event handler again), use
+    //          with _extreme_ care or, better, don't use at all!
+    bool Yield(bool onlyIfNeeded = false);
+    virtual bool YieldFor(long eventsToProcess) = 0;
+
+    // returns true if the main thread is inside a Yield() call
+    virtual bool IsYielding() const
+        { return m_isInsideYield; }
+
+    // returns true if events of the given event category should be immediately
+    // processed inside a wxApp::Yield() call or rather should be queued for
+    // later processing by the main event loop
+    virtual bool IsEventAllowedInsideYield(wxEventCategory cat) const
+        { return (m_eventsToProcessInsideYield & cat) != 0; }
+
+    // no SafeYield hooks since it uses wxWindow which is not available when wxUSE_GUI=0

 
 

-    // dispatch a single event, return FALSE if we should exit from the loop
-    virtual bool Dispatch();

 
 

-    // is the event loop running now?
-    virtual bool IsRunning() const;
-    
+    // active loop
+    // -----------
+

     // return currently active (running) event loop, may be NULL
     // return currently active (running) event loop, may be NULL

-    static wxEventLoop *GetActive() { return ms_activeLoop; }
+    static wxEventLoopBase *GetActive() { return ms_activeLoop; }
+
+    // set currently active (running) event loop
+    static void SetActive(wxEventLoopBase* loop);
+

 
 protected:
 
 protected:

-    // the pointer to the port specific implementation class
-    class WXDLLEXPORT wxEventLoopImpl *m_impl;
+    // real implementation of Run()
+    virtual int DoRun() = 0;
+
+    // this function should be called before the event loop terminates, whether
+    // this happens normally (because of Exit() call) or abnormally (because of
+    // an exception thrown from inside the loop)
+    virtual void OnExit();
+
+    // Return true if we're currently inside our Run(), even if another nested
+    // event loop is currently running, unlike IsRunning() (which should have
+    // been really called IsActive() but it's too late to change this now).
+    bool IsInsideRun() const { return m_isInsideRun; }
+
+

     // the pointer to currently active loop
     // the pointer to currently active loop

-    static wxEventLoop *ms_activeLoop;
+    static wxEventLoopBase *ms_activeLoop;
+
+    // should we exit the loop?
+    bool m_shouldExit;
+
+    // YieldFor() helpers:
+    bool m_isInsideYield;
+    long m_eventsToProcessInsideYield;
+
+private:
+    // this flag is set on entry into Run() and reset before leaving it
+    bool m_isInsideRun;
+
+    wxDECLARE_NO_COPY_CLASS(wxEventLoopBase);
+};
+
+#if defined(__WINDOWS__) || defined(__WXMAC__) || defined(__WXDFB__) || (defined(__UNIX__) && !defined(__WXOSX__))
+
+// this class can be used to implement a standard event loop logic using
+// Pending() and Dispatch()
+//
+// it also handles idle processing automatically
+class WXDLLIMPEXP_BASE wxEventLoopManual : public wxEventLoopBase
+{
+public:
+    wxEventLoopManual();
+
+    // sets the "should exit" flag and wakes up the loop so that it terminates
+    // soon
+    virtual void ScheduleExit(int rc = 0);
+
+protected:
+    // enters a loop calling OnNextIteration(), Pending() and Dispatch() and
+    // terminating when Exit() is called
+    virtual int DoRun();
+
+    // may be overridden to perform some action at the start of each new event
+    // loop iteration
+    virtual void OnNextIteration() { }
+
+
+    // the loop exit code
+    int m_exitcode;
+
+private:
+    // process all already pending events and dispatch a new one (blocking
+    // until it appears in the event queue if necessary)
+    //
+    // returns the return value of Dispatch()
+    bool ProcessEvents();
+
+    wxDECLARE_NO_COPY_CLASS(wxEventLoopManual);

 };
 
 };
 

+#endif // platforms using "manual" loop
+
+// we're moving away from old m_impl wxEventLoop model as otherwise the user
+// code doesn't have access to platform-specific wxEventLoop methods and this
+// can sometimes be very useful (e.g. under MSW this is necessary for
+// integration with MFC) but currently this is not done for all ports yet (e.g.
+// wxX11) so fall back to the old wxGUIEventLoop definition below for them
+
+#if defined(__DARWIN__)
+    // CoreFoundation-based event loop is currently in wxBase so include it in
+    // any case too (although maybe it actually shouldn't be there at all)
+    #include "wx/osx/core/evtloop.h"
+#endif
+
+// include the header defining wxConsoleEventLoop
+#if defined(__UNIX__) && !defined(__WXMSW__)
+    #include "wx/unix/evtloop.h"
+#elif defined(__WINDOWS__)
+    #include "wx/msw/evtloopconsole.h"
+#endif
+
+#if wxUSE_GUI
+
+// include the appropriate header defining wxGUIEventLoop
+
+#if defined(__WXMSW__)
+    #include "wx/msw/evtloop.h"
+#elif defined(__WXCOCOA__)
+    #include "wx/cocoa/evtloop.h"
+#elif defined(__WXOSX__)
+    #include "wx/osx/evtloop.h"
+#elif defined(__WXDFB__)
+    #include "wx/dfb/evtloop.h"
+#elif defined(__WXGTK20__)
+    #include "wx/gtk/evtloop.h"
+#else // other platform
+
+#include "wx/stopwatch.h"   // for wxMilliClock_t
+
+class WXDLLIMPEXP_FWD_CORE wxEventLoopImpl;
+
+class WXDLLIMPEXP_CORE wxGUIEventLoop : public wxEventLoopBase
+{
+public:
+    wxGUIEventLoop() { m_impl = NULL; }
+    virtual ~wxGUIEventLoop();
+
+    virtual void ScheduleExit(int rc = 0);
+    virtual bool Pending() const;
+    virtual bool Dispatch();
+    virtual int DispatchTimeout(unsigned long timeout)
+    {
+        // TODO: this is, of course, horribly inefficient and a proper wait with
+        //       timeout should be implemented for all ports natively...
+        const wxMilliClock_t timeEnd = wxGetLocalTimeMillis() + timeout;
+        for ( ;; )
+        {
+            if ( Pending() )
+                return Dispatch();
+
+            if ( wxGetLocalTimeMillis() >= timeEnd )
+                return -1;
+        }
+    }
+    virtual void WakeUp() { }
+    virtual bool YieldFor(long eventsToProcess);
+
+protected:
+    virtual int DoRun();
+
+    // the pointer to the port specific implementation class
+    wxEventLoopImpl *m_impl;
+
+    wxDECLARE_NO_COPY_CLASS(wxGUIEventLoop);
+};
+
+#endif // platforms
+
+#endif // wxUSE_GUI
+
+#if wxUSE_GUI
+    // we use a class rather than a typedef because wxEventLoop is
+    // forward-declared in many places
+    class wxEventLoop : public wxGUIEventLoop { };
+#else // !wxUSE_GUI
+    // we can't define wxEventLoop differently in GUI and base libraries so use
+    // a #define to still allow writing wxEventLoop in the user code
+    #if wxUSE_CONSOLE_EVENTLOOP && (defined(__WINDOWS__) || defined(__UNIX__))
+        #define wxEventLoop wxConsoleEventLoop
+    #else // we still must define it somehow for the code below...
+        #define wxEventLoop wxEventLoopBase
+    #endif
+#endif
+
+inline bool wxEventLoopBase::IsRunning() const { return GetActive() == this; }
+
+#if wxUSE_GUI && !defined(__WXOSX__)
+// ----------------------------------------------------------------------------
+// wxModalEventLoop
+// ----------------------------------------------------------------------------
+
+// this is a naive generic implementation which uses wxWindowDisabler to
+// implement modality, we will surely need platform-specific implementations
+// too, this generic implementation is here only temporarily to see how it
+// works
+class WXDLLIMPEXP_CORE wxModalEventLoop : public wxGUIEventLoop
+{
+public:
+    wxModalEventLoop(wxWindow *winModal)
+    {
+        m_windowDisabler = new wxWindowDisabler(winModal);
+    }
+
+protected:
+    virtual void OnExit()
+    {
+        delete m_windowDisabler;
+        m_windowDisabler = NULL;
+
+        wxGUIEventLoop::OnExit();
+    }
+
+private:
+    wxWindowDisabler *m_windowDisabler;
+};
+
+#endif //wxUSE_GUI
+
+// ----------------------------------------------------------------------------
+// wxEventLoopActivator: helper class for wxEventLoop implementations
+// ----------------------------------------------------------------------------
+
+// this object sets the wxEventLoop given to the ctor as the currently active
+// one and unsets it in its dtor, this is especially useful in presence of
+// exceptions but is more tidy even when we don't use them
+class wxEventLoopActivator
+{
+public:
+    wxEventLoopActivator(wxEventLoopBase *evtLoop)
+    {
+        m_evtLoopOld = wxEventLoopBase::GetActive();
+        wxEventLoopBase::SetActive(evtLoop);
+    }
+
+    ~wxEventLoopActivator()
+    {
+        // restore the previously active event loop
+        wxEventLoopBase::SetActive(m_evtLoopOld);
+    }
+
+private:
+    wxEventLoopBase *m_evtLoopOld;
+};
+
+#if wxUSE_CONSOLE_EVENTLOOP
+
+class wxEventLoopGuarantor
+{
+public:
+    wxEventLoopGuarantor()
+    {
+        m_evtLoopNew = NULL;
+        if (!wxEventLoop::GetActive())
+        {
+            m_evtLoopNew = new wxEventLoop;
+            wxEventLoop::SetActive(m_evtLoopNew);
+        }
+    }
+
+    ~wxEventLoopGuarantor()
+    {
+        if (m_evtLoopNew)
+        {
+            wxEventLoop::SetActive(NULL);
+            delete m_evtLoopNew;
+        }
+    }
+
+private:
+    wxEventLoop *m_evtLoopNew;
+};
+
+#endif // wxUSE_CONSOLE_EVENTLOOP
+

 #endif // _WX_EVTLOOP_H_
 #endif // _WX_EVTLOOP_H_