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.
82 extern bool g_isPainting
= FALSE
;
85 // ===========================================================================
87 // ===========================================================================
89 // ----------------------------------------------------------------------------
91 // ----------------------------------------------------------------------------
93 wxWindowDC::wxWindowDC()
98 wxWindowDC::wxWindowDC(wxWindow
*the_canvas
)
100 m_canvas
= the_canvas
;
101 m_hDC
= (WXHDC
) ::GetWindowDC(GetWinHwnd(the_canvas
) );
104 SetBackground(wxBrush(m_canvas
->GetBackgroundColour(), wxSOLID
));
107 wxWindowDC::~wxWindowDC()
109 if (m_canvas
&& m_hDC
)
111 SelectOldObjects(m_hDC
);
113 ::ReleaseDC(GetWinHwnd(m_canvas
), GetHdc());
120 // ----------------------------------------------------------------------------
122 // ----------------------------------------------------------------------------
124 wxClientDC::wxClientDC()
129 wxClientDC::wxClientDC(wxWindow
*the_canvas
)
131 m_canvas
= the_canvas
;
132 m_hDC
= (WXHDC
) ::GetDC(GetWinHwnd(the_canvas
));
134 SetBackground(wxBrush(m_canvas
->GetBackgroundColour(), wxSOLID
));
137 wxClientDC::~wxClientDC()
139 if ( m_canvas
&& GetHdc() )
141 SelectOldObjects(m_hDC
);
143 ::ReleaseDC(GetWinHwnd(m_canvas
), GetHdc());
148 // ----------------------------------------------------------------------------
150 // ----------------------------------------------------------------------------
152 // VZ: initial implementation (by JACS) only remembered the last wxPaintDC
153 // created and tried to reuse - this was supposed to take care of a
154 // situation when a derived class OnPaint() calls base class OnPaint()
155 // because in this case ::BeginPaint() shouldn't be called second time.
157 // I'm not sure how useful this is, however we must remember the HWND
158 // associated with the last HDC as well - otherwise we may (and will!) try
159 // to reuse the HDC for another HWND which is a nice recipe for disaster.
161 // So we store a list of windows for which we already have the DC and not
162 // just one single hDC. This seems to work, but I'm really not sure about
163 // the usefullness of the whole idea - IMHO it's much better to not call
164 // base class OnPaint() at all, or, if we realyl want to allow it, add a
165 // "wxPaintDC *" parameter to wxPaintEvent which should be used if it's
166 // !NULL instead of creating a new DC.
168 wxArrayDCInfo
wxPaintDC::ms_cache
;
170 wxPaintDC::wxPaintDC()
176 wxPaintDC::wxPaintDC(wxWindow
*canvas
)
178 wxCHECK_RET( canvas
, "NULL canvas in wxPaintDC ctor" );
183 wxFAIL_MSG( _T("wxPaintDC may be created only in EVT_PAINT handler!") );
187 #endif // __WXDEBUG__
191 // do we have a DC for this window in the cache?
192 wxPaintDCInfo
*info
= FindInCache();
198 else // not in cache, create a new one
200 m_hDC
= (WXHDC
)::BeginPaint(GetWinHwnd(m_canvas
), &g_paintStruct
);
201 ms_cache
.Add(new wxPaintDCInfo(m_canvas
, this));
204 SetBackground(wxBrush(m_canvas
->GetBackgroundColour(), wxSOLID
));
207 wxPaintDC::~wxPaintDC()
212 wxPaintDCInfo
*info
= FindInCache(&index
);
214 wxCHECK_RET( info
, _T("existing DC should have a cache entry") );
216 if ( !--info
->count
)
218 ::EndPaint(GetWinHwnd(m_canvas
), &g_paintStruct
);
220 ms_cache
.Remove(index
);
222 //else: cached DC entry is still in use
226 wxPaintDCInfo
*wxPaintDC::FindInCache(size_t *index
) const
228 wxPaintDCInfo
*info
= NULL
;
229 size_t nCache
= ms_cache
.GetCount();
230 for ( size_t n
= 0; n
< nCache
; n
++ )
233 if ( info
->hwnd
== m_canvas
->GetHWND() )