1 /////////////////////////////////////////////////////////////////////////////
3 // Purpose: wxClientDC class
4 // Author: Julian Smart
8 // Copyright: (c) Julian Smart and Markus Holzem
9 // Licence: wxWindows licence
10 /////////////////////////////////////////////////////////////////////////////
12 // ===========================================================================
14 // ===========================================================================
16 // ----------------------------------------------------------------------------
18 // ----------------------------------------------------------------------------
21 #pragma implementation "dcclient.h"
24 // For compilers that support precompilation, includes "wx.h".
25 #include "wx/wxprec.h"
31 #include "wx/string.h"
33 #include "wx/window.h"
35 #include "wx/msw/private.h"
37 #include "wx/dcclient.h"
39 // ----------------------------------------------------------------------------
41 // ----------------------------------------------------------------------------
43 struct WXDLLEXPORT wxPaintDCInfo
45 wxPaintDCInfo(wxWindow
*win
, wxDC
*dc
)
47 hwnd
= win
->GetHWND();
52 WXHWND hwnd
; // window for this DC
53 WXHDC hdc
; // the DC handle
54 size_t count
; // usage count
57 #include "wx/arrimpl.cpp"
59 WX_DEFINE_OBJARRAY(wxArrayDCInfo
);
61 // ----------------------------------------------------------------------------
63 // ----------------------------------------------------------------------------
65 #if !USE_SHARED_LIBRARY
66 IMPLEMENT_DYNAMIC_CLASS(wxWindowDC
, wxDC
)
67 IMPLEMENT_DYNAMIC_CLASS(wxClientDC
, wxWindowDC
)
68 IMPLEMENT_DYNAMIC_CLASS(wxPaintDC
, wxWindowDC
)
71 // ----------------------------------------------------------------------------
73 // ----------------------------------------------------------------------------
75 static PAINTSTRUCT g_paintStruct
;
78 // a global variable which we check to verify that wxPaintDC are only
79 // created in resopnse to WM_PAINT message - doing this from elsewhere is a
80 // common programming error among wxWindows programmers and might lead to
81 // very subtle and difficult to debug refresh/repaint bugs.
85 // ===========================================================================
87 // ===========================================================================
89 // ----------------------------------------------------------------------------
91 // ----------------------------------------------------------------------------
93 wxWindowDC::wxWindowDC()
98 wxWindowDC::wxWindowDC(wxWindow
*the_canvas
)
100 m_canvas
= the_canvas
;
101 m_hDC
= (WXHDC
) ::WinOpenWindowDC(GetWinHwnd(the_canvas
) );
104 SetBackground(wxBrush(m_canvas
->GetBackgroundColour(), wxSOLID
));
107 wxWindowDC::~wxWindowDC()
109 if (m_canvas
&& m_hDC
)
111 SelectOldObjects(m_hDC
);
114 // In PM one does not explicitly close or release an open WindowDC
115 // They automatically close with the window, unless explicitly detached
123 // ----------------------------------------------------------------------------
125 // ----------------------------------------------------------------------------
127 wxClientDC::wxClientDC()
132 wxClientDC::wxClientDC(wxWindow
*the_canvas
)
134 m_canvas
= the_canvas
;
135 m_hDC
= (WXHDC
) ::GetDC(GetWinHwnd(the_canvas
));
137 // the background mode is only used for text background
138 // and is set in DrawText() to OPAQUE as required, other-
139 // wise always TRANSPARENT, RR
140 ::SetBkMode( GetHdc(), TRANSPARENT
);
142 SetBackground(wxBrush(m_canvas
->GetBackgroundColour(), wxSOLID
));
145 wxClientDC::~wxClientDC()
147 if ( m_canvas
&& GetHdc() )
149 SelectOldObjects(m_hDC
);
151 ::ReleaseDC(GetWinHwnd(m_canvas
), GetHdc());
156 // ----------------------------------------------------------------------------
158 // ----------------------------------------------------------------------------
160 // VZ: initial implementation (by JACS) only remembered the last wxPaintDC
161 // created and tried to reuse - this was supposed to take care of a
162 // situation when a derived class OnPaint() calls base class OnPaint()
163 // because in this case ::BeginPaint() shouldn't be called second time.
165 // I'm not sure how useful this is, however we must remember the HWND
166 // associated with the last HDC as well - otherwise we may (and will!) try
167 // to reuse the HDC for another HWND which is a nice recipe for disaster.
169 // So we store a list of windows for which we already have the DC and not
170 // just one single hDC. This seems to work, but I'm really not sure about
171 // the usefullness of the whole idea - IMHO it's much better to not call
172 // base class OnPaint() at all, or, if we really want to allow it, add a
173 // "wxPaintDC *" parameter to wxPaintEvent which should be used if it's
174 // !NULL instead of creating a new DC.
176 wxArrayDCInfo
wxPaintDC::ms_cache
;
178 wxPaintDC::wxPaintDC()
184 wxPaintDC::wxPaintDC(wxWindow
*canvas
)
186 wxCHECK_RET( canvas
, _T("NULL canvas in wxPaintDC ctor") );
189 if ( g_isPainting
<= 0 )
191 wxFAIL_MSG( _T("wxPaintDC may be created only in EVT_PAINT handler!") );
195 #endif // __WXDEBUG__
199 // do we have a DC for this window in the cache?
200 wxPaintDCInfo
*info
= FindInCache();
206 else // not in cache, create a new one
208 m_hDC
= (WXHDC
)::BeginPaint(GetWinHwnd(m_canvas
), &g_paintStruct
);
209 ms_cache
.Add(new wxPaintDCInfo(m_canvas
, this));
212 // the background mode is only used for text background
213 // and is set in DrawText() to OPAQUE as required, other-
214 // wise always TRANSPARENT, RR
215 ::SetBkMode( GetHdc(), TRANSPARENT
);
217 SetBackground(wxBrush(m_canvas
->GetBackgroundColour(), wxSOLID
));
220 wxPaintDC::~wxPaintDC()
224 SelectOldObjects(m_hDC
);
227 wxPaintDCInfo
*info
= FindInCache(&index
);
229 wxCHECK_RET( info
, _T("existing DC should have a cache entry") );
231 if ( !--info
->count
)
233 ::EndPaint(GetWinHwnd(m_canvas
), &g_paintStruct
);
235 ms_cache
.Remove(index
);
237 //else: cached DC entry is still in use
239 // prevent the base class dtor from ReleaseDC()ing it again
244 wxPaintDCInfo
*wxPaintDC::FindInCache(size_t *index
) const
246 wxPaintDCInfo
*info
= NULL
;
247 size_t nCache
= ms_cache
.GetCount();
248 for ( size_t n
= 0; n
< nCache
; n
++ )
251 if ( info
->hwnd
== m_canvas
->GetHWND() )