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1 | /////////////////////////////////////////////////////////////////////////////// | |
2 | // Name: wx/eventfilter.h | |
3 | // Purpose: wxEventFilter class declaration. | |
4 | // Author: Vadim Zeitlin | |
5 | // Created: 2011-11-21 | |
6 | // Copyright: (c) 2011 Vadim Zeitlin <vadim@wxwidgets.org> | |
7 | // Licence: wxWindows licence | |
8 | /////////////////////////////////////////////////////////////////////////////// | |
9 | ||
10 | #ifndef _WX_EVENTFILTER_H_ | |
11 | #define _WX_EVENTFILTER_H_ | |
12 | ||
13 | #include "wx/defs.h" | |
14 | ||
15 | class WXDLLIMPEXP_FWD_BASE wxEvent; | |
16 | class WXDLLIMPEXP_FWD_BASE wxEvtHandler; | |
17 | ||
18 | // ---------------------------------------------------------------------------- | |
19 | // wxEventFilter is used with wxEvtHandler::AddFilter() and ProcessEvent(). | |
20 | // ---------------------------------------------------------------------------- | |
21 | ||
22 | class wxEventFilter | |
23 | { | |
24 | public: | |
25 | // Possible return values for FilterEvent(). | |
26 | // | |
27 | // Notice that the values of these enum elements are fixed due to backwards | |
28 | // compatibility constraints. | |
29 | enum | |
30 | { | |
31 | // Process event as usual. | |
32 | Event_Skip = -1, | |
33 | ||
34 | // Don't process the event normally at all. | |
35 | Event_Ignore = 0, | |
36 | ||
37 | // Event was already handled, don't process it normally. | |
38 | Event_Processed = 1 | |
39 | }; | |
40 | ||
41 | wxEventFilter() | |
42 | { | |
43 | m_next = NULL; | |
44 | } | |
45 | ||
46 | virtual ~wxEventFilter() | |
47 | { | |
48 | wxASSERT_MSG( !m_next, "Forgot to call wxEvtHandler::RemoveFilter()?" ); | |
49 | } | |
50 | ||
51 | // This method allows to filter all the events processed by the program, so | |
52 | // you should try to return quickly from it to avoid slowing down the | |
53 | // program to a crawl. | |
54 | // | |
55 | // Return value should be -1 to continue with the normal event processing, | |
56 | // or true or false to stop further processing and pretend that the event | |
57 | // had been already processed or won't be processed at all, respectively. | |
58 | virtual int FilterEvent(wxEvent& event) = 0; | |
59 | ||
60 | private: | |
61 | // Objects of this class are made to be stored in a linked list in | |
62 | // wxEvtHandler so put the next node ponter directly in the class itself. | |
63 | wxEventFilter* m_next; | |
64 | ||
65 | // And provide access to it for wxEvtHandler [only]. | |
66 | friend class wxEvtHandler; | |
67 | ||
68 | wxDECLARE_NO_COPY_CLASS(wxEventFilter); | |
69 | }; | |
70 | ||
71 | #endif // _WX_EVENTFILTER_H_ |