From 1648d51bcb7633efde873b986b4a9e2af005f119 Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Fri, 18 Jul 2003 00:39:05 +0000
Subject: [PATCH] allow to change the event propagation level (modified patch
 743086)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@22068 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
---
 docs/latex/wx/event.tex  |  58 ++++++++++++++++++++-
 docs/latex/wx/tevent.tex |  25 +++++----
 include/wx/event.h       | 109 +++++++++++++++++++++++++++++++++++----
 src/common/event.cpp     |   5 ++
 4 files changed, 174 insertions(+), 23 deletions(-)

diff --git a/docs/latex/wx/event.tex b/docs/latex/wx/event.tex
index 9e542c58c9..c48dd65ac5 100644
--- a/docs/latex/wx/event.tex
+++ b/docs/latex/wx/event.tex
@@ -44,6 +44,25 @@ The type of the event, such as wxEVENT\_TYPE\_BUTTON\_COMMAND.
 
 Identifier for the window.
 
+\membersection{wxEvent::m\_propagationLevel}
+
+\member{int}{m\_propagationLevel}
+
+Indicates how many levels the event can propagate. This member is protected and
+should typically only be set in the constructors of the derived classes. It
+may be temporarily changed by \helpref{StopPropagation}{wxeventstoppropagation} 
+and \helpref{ResumePropagation}{wxeventresumepropagation} and tested with 
+\helpref{ShouldPropagate}{wxeventshouldpropagate}.
+
+The initial value is set to either {\tt wxEVENT\_PROPAGATION\_NONE} (by
+default) meaning that the event shouldn't be propagated at all or to 
+{\tt wxEVENT\_PROPAGATION\_MAX} (for command events) meaning that it should be
+propagated as much as necessary.
+
+Any positive number means that the event should be propagated but no more than
+the given number of times. E.g. the propagation level may be set to $1$ to
+propagate the event to its parent only, but not to its grandparent.
+
 \membersection{wxEvent::m\_skipped}
 
 \member{bool}{m\_skipped}
@@ -92,13 +111,13 @@ such as wxEVENT\_TYPE\_BUTTON\_COMMAND.
 
 \membersection{wxEvent::GetId}
 
-\func{int}{GetId}{\void}
+\constfunc{int}{GetId}{\void}
 
 Returns the identifier associated with this event, such as a button command id.
 
 \membersection{wxEvent::GetSkipped}
 
-\func{bool}{GetSkipped}{\void}
+\constfunc{bool}{GetSkipped}{\void}
 
 Returns true if the event handler should be skipped, false otherwise.
 
@@ -108,6 +127,23 @@ Returns true if the event handler should be skipped, false otherwise.
 
 Gets the timestamp for the event.
 
+\membersection{wxEvent::IsCommandEvent}\label{wxeventiscommandevent}
+
+\constfunc{bool}{IsCommandEvent}{\void}
+
+Returns true if the event is or is derived from
+\helpref{wxCommandEvent}{wxcommandevent} else it returns false.
+Note: Exists only for optimization purposes.
+
+
+\membersection{wxEvent::ResumePropagation}\label{wxeventresumepropagation}
+
+\func{void}{ResumePropagation}{\param{int }{propagationLevel}}
+
+Sets the propagation level to the given value (for example returned from an
+earlier call to \helpref{StopPropagation}{wxeventstoppropagation}).
+
+
 \membersection{wxEvent::SetEventObject}
 
 \func{void}{SetEventObject}{\param{wxObject* }{object}}
@@ -134,6 +170,13 @@ Sets the timestamp for the event.
 
 Sets the originating object.
 
+\membersection{wxEvent::ShouldPropagate}\label{wxeventshouldpropagate}
+
+\constfunc{bool}{ShouldPropagate}{\void}
+
+Test if this event should be propagated or not, i.e. if the propagation level
+is currently greater than $0$.
+
 \membersection{wxEvent::Skip}\label{wxeventskip}
 
 \func{void}{Skip}{\param{bool}{ skip = true}}
@@ -142,3 +185,14 @@ Called by an event handler to tell the event system that the
 event handler should be skipped, and the next valid handler used
 instead.
 
+\membersection{wxEvent::StopPropagation}
+
+\func{int}{StopPropagation}{\void}\label{wxeventstoppropagation}
+
+Stop the event from propagating to its parent window.
+
+Returns the old propagation level value which may be later passed to 
+\helpref{ResumePropagation}{wxeventresumepropagation} to allow propagating the
+event again.
+
+
diff --git a/docs/latex/wx/tevent.tex b/docs/latex/wx/tevent.tex
index b3cf6814fd..12d45d3e2c 100644
--- a/docs/latex/wx/tevent.tex
+++ b/docs/latex/wx/tevent.tex
@@ -142,18 +142,20 @@ class table is tried, and so on until no more tables exist or an appropriate fun
 in which case the function exits.
 \item The search is applied down the entire chain of event handlers (usually the chain has a length
 of one). If this succeeds, the function exits.
-\item If the object is a wxWindow and the event is a wxCommandEvent, {\bf ProcessEvent} is
-recursively applied to the parent window's event handler. If this returns true, the function exits.
+\item If the object is a wxWindow and the event is set to set to propagate (in the library only
+wxCommandEvent based events are set to propagate), {\bf ProcessEvent} is recursively applied
+to the parent window's event handler. If this returns true, the function exits.
 \item Finally, {\bf ProcessEvent} is called on the wxApp object.
 \end{enumerate}
 
 {\bf Pay close attention to Step 5.}  People often overlook or get
 confused by this powerful feature of the wxWindows event processing
-system.  To put it a different way, events derived either directly or
-indirectly from wxCommandEvent will travel up the containment
-hierarchy from child to parent until an event handler is found that
-doesn't call event.Skip().  Events not derived from wxCommandEvent are
-sent only to the window they occurred in and then stop.
+system.  To put it a different way, events set to propagate 
+(\helpref{See: wxEvent::ShouldPropagate}{wxeventshouldpropagate})
+(most likely derived either directly or indirectly from wxCommandEvent)
+will travel up the containment hierarchy from child to parent until the 
+maximal propagation level is reached or an event handler is found that
+doesn't call \helpref{event.Skip()}{wxeventskip}.
 
 Finally, there is another additional complication (which, in fact, simplifies
 life of wxWindows programmers significantly): when propagating the command
@@ -182,12 +184,13 @@ event.
 Note that your application may wish to override ProcessEvent to redirect processing of
 events. This is done in the document/view framework, for example, to allow event handlers
 to be defined in the document or view. To test for command events (which will probably
-be the only events you wish to redirect), you may use wxEvent::IsCommandEvent for
-efficiency, instead of using the slower run-time type system.
+be the only events you wish to redirect), you may use 
+\helpref{wxEvent::IsCommandEvent}{wxeventiscommandevent} for efficiency, 
+instead of using the slower run-time type system.
 
 As mentioned above, only command events are recursively applied to the parents event
-handler. As this quite often causes confusion for users, here is a list of system
-events which will NOT get sent to the parent's event handler:
+handler in the libary itself. As this quite often causes confusion for users,
+here is a list of system events which will NOT get sent to the parent's event handler:
 
 \begin{twocollist}\itemsep=0pt
 \twocolitem{\helpref{wxEvent}{wxevent}}{The event base class}
diff --git a/include/wx/event.h b/include/wx/event.h
index a6850785f4..d1c0090e57 100644
--- a/include/wx/event.h
+++ b/include/wx/event.h
@@ -9,8 +9,8 @@
 // Licence:     wxWindows licence
 /////////////////////////////////////////////////////////////////////////////
 
-#ifndef _WX_EVENTH__
-#define _WX_EVENTH__
+#ifndef _WX_EVENT_H__
+#define _WX_EVENT_H__
 
 #if defined(__GNUG__) && !defined(__APPLE__)
     #pragma interface "event.h"
@@ -335,6 +335,17 @@ END_DECLARE_EVENT_TYPES()
 
 #endif // WXWIN_COMPATIBILITY
 
+// the predefined constants for the number of times we propagate event
+// upwards window child-parent chain
+enum Propagation_state
+{
+    // don't propagate it at all
+    wxEVENT_PROPAGATE_NONE = 0,
+
+    // propagate it until it is processed
+    wxEVENT_PROPAGATE_MAX = INT_MAX
+};
+
 /*
  * wxWindows events, covering all interesting things that might happen
  * (button clicking, resizing, setting text in widgets, etc.).
@@ -374,30 +385,108 @@ public:
     void Skip(bool skip = TRUE) { m_skipped = skip; }
     bool GetSkipped() const { return m_skipped; };
 
-    // Implementation only: this test is explicitlty anti OO and this functions
-    // exists only for optimization purposes.
-    bool IsCommandEvent() const { return m_isCommandEvent; }
-
     // this function is used to create a copy of the event polymorphically and
     // all derived classes must implement it because otherwise wxPostEvent()
     // for them wouldn't work (it needs to do a copy of the event)
     virtual wxEvent *Clone() const = 0;
 
+    // Implementation only: this test is explicitlty anti OO and this functions
+    // exists only for optimization purposes.
+    bool IsCommandEvent() const { return m_isCommandEvent; }
+
+    // Determine if this event should be propagating to the parent window.
+    bool ShouldPropagate() const
+        { return m_propagationLevel != wxEVENT_PROPAGATE_NONE; }
+
+    // Stop an event from propagating to its parent window, returns the old
+    // propagation level value
+    int StopPropagation()
+    {
+        int propagationLevel = m_propagationLevel;
+        m_propagationLevel = wxEVENT_PROPAGATE_NONE;
+        return propagationLevel;
+    }
+
+    // Resume the event propagation by restoring the propagation level
+    // (returned by StopPropagation())
+    void ResumePropagation(int propagationLevel)
+    {
+        m_propagationLevel = propagationLevel;
+    }
+
 public:
     wxObject*         m_eventObject;
     wxEventType       m_eventType;
     long              m_timeStamp;
     int               m_id;
     wxObject*         m_callbackUserData;
+
+protected:
+    // the propagation level: while it is positive, we propagate the event to
+    // the parent window (if any)
+    //
+    // this one doesn't have to be public, we don't have to worry about
+    // backwards compatibility as it is new
+    int               m_propagationLevel;
+
+public:
     bool              m_skipped;
     bool              m_isCommandEvent;
-
+    
 private:
+    // it needs to access our m_propagationLevel
+    friend class WXDLLIMPEXP_BASE wxPropagateOnce;
+
     DECLARE_ABSTRACT_CLASS(wxEvent)
 };
 
+/*
+ * Helper class to temporarily change an event not to propagate.
+ */
+class WXDLLIMPEXP_BASE wxPropagationDisabler
+{
+public:
+    wxPropagationDisabler(wxEvent& event) : m_event(event)
+    {
+        m_propagationLevelOld = m_event.StopPropagation();
+    }
+
+    ~wxPropagationDisabler()
+    {
+        m_event.ResumePropagation(m_propagationLevelOld);
+    }
+
+private:
+    wxEvent& m_event;
+    int m_propagationLevelOld;
+};
+
+/*
+ * Another one to temporarily lower propagation level.
+ */
+class WXDLLIMPEXP_BASE wxPropagateOnce
+{
+public:
+    wxPropagateOnce(wxEvent& event) : m_event(event)
+    {
+        wxASSERT_MSG( m_event.m_propagationLevel > 0,
+                        _T("shouldn't be used unless ShouldPropagate()!") );
+
+        m_event.m_propagationLevel--;
+    }
+
+    ~wxPropagateOnce()
+    {
+        m_event.m_propagationLevel++;
+    }
+
+private:
+    wxEvent& m_event;
+};
+
 #if wxUSE_GUI
 
+
 // Item or menu event class
 /*
  wxEVT_COMMAND_BUTTON_CLICKED
@@ -1119,7 +1208,7 @@ private:
 };
 
 // wxChildFocusEvent notifies the parent that a child has got the focus: unlike
-// wxFocusEvent it is propgated upwards the window chain
+// wxFocusEvent it is propagated upwards the window chain
 class WXDLLIMPEXP_CORE wxChildFocusEvent : public wxCommandEvent
 {
 public:
@@ -2635,5 +2724,5 @@ wxWindow* wxFindFocusDescendant(wxWindow* ancestor);
 
 #endif // wxUSE_GUI
 
-#endif
-        // _WX_EVENTH__
+#endif // _WX_EVENT_H__
+
diff --git a/src/common/event.cpp b/src/common/event.cpp
index 083e52a709..574363c74d 100644
--- a/src/common/event.cpp
+++ b/src/common/event.cpp
@@ -339,6 +339,7 @@ wxEvent::wxEvent(int theId, wxEventType commandType )
     m_skipped = FALSE;
     m_callbackUserData = (wxObject *) NULL;
     m_isCommandEvent = FALSE;
+    m_propagationLevel = wxEVENT_PROPAGATE_NONE;
 }
 
 wxEvent::wxEvent(const wxEvent &src)
@@ -350,6 +351,7 @@ wxEvent::wxEvent(const wxEvent &src)
     , m_callbackUserData(src.m_callbackUserData)
     , m_skipped(src.m_skipped)
     , m_isCommandEvent(src.m_isCommandEvent)
+    , m_propagationLevel(src.m_propagationLevel)
 {
 }
 
@@ -370,6 +372,9 @@ wxCommandEvent::wxCommandEvent(wxEventType commandType, int theId)
     m_extraLong = 0;
     m_commandInt = 0;
     m_isCommandEvent = TRUE;
+
+    // the command events are propagated upwards by default
+    m_propagationLevel = wxEVENT_PROPAGATE_MAX;
 }
 
 /*
-- 
2.50.0

