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1 /////////////////////////////////////////////////////////////////////////////
2 // Name: dcclient.cpp
3 // Purpose: wxClientDC class
4 // Author: Julian Smart
5 // Modified by:
6 // Created: 01/02/97
7 // RCS-ID: $Id$
8 // Copyright: (c) Julian Smart and Markus Holzem
9 // Licence: wxWindows licence
10 /////////////////////////////////////////////////////////////////////////////
11
12 // ===========================================================================
13 // declarations
14 // ===========================================================================
15
16 // ----------------------------------------------------------------------------
17 // headers
18 // ----------------------------------------------------------------------------
19
20 #ifdef __GNUG__
21 #pragma implementation "dcclient.h"
22 #endif
23
24 // For compilers that support precompilation, includes "wx.h".
25 #include "wx/wxprec.h"
26
27 #ifdef __BORLANDC__
28 #pragma hdrstop
29 #endif
30
31 #include "wx/string.h"
32 #include "wx/log.h"
33 #include "wx/window.h"
34
35 #include "wx/msw/private.h"
36
37 #include "wx/dcclient.h"
38
39 // ----------------------------------------------------------------------------
40 // array/list types
41 // ----------------------------------------------------------------------------
42
43 struct WXDLLEXPORT wxPaintDCInfo
44 {
45 wxPaintDCInfo(wxWindow *win, wxDC *dc)
46 {
47 hwnd = win->GetHWND();
48 hdc = dc->GetHDC();
49 count = 1;
50 }
51
52 WXHWND hwnd; // window for this DC
53 WXHDC hdc; // the DC handle
54 size_t count; // usage count
55 };
56
57 #include "wx/arrimpl.cpp"
58
59 WX_DEFINE_OBJARRAY(wxArrayDCInfo);
60
61 // ----------------------------------------------------------------------------
62 // macros
63 // ----------------------------------------------------------------------------
64
65 #if !USE_SHARED_LIBRARY
66 IMPLEMENT_DYNAMIC_CLASS(wxWindowDC, wxDC)
67 IMPLEMENT_DYNAMIC_CLASS(wxClientDC, wxWindowDC)
68 IMPLEMENT_DYNAMIC_CLASS(wxPaintDC, wxWindowDC)
69 #endif
70
71 // ----------------------------------------------------------------------------
72 // global variables
73 // ----------------------------------------------------------------------------
74
75 static PAINTSTRUCT g_paintStruct;
76
77 #ifdef __WXDEBUG__
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 bool g_isPainting = FALSE;
83 #endif // __WXDEBUG__
84
85 // ===========================================================================
86 // implementation
87 // ===========================================================================
88
89 // ----------------------------------------------------------------------------
90 // wxWindowDC
91 // ----------------------------------------------------------------------------
92
93 wxWindowDC::wxWindowDC()
94 {
95 m_canvas = NULL;
96 }
97
98 wxWindowDC::wxWindowDC(wxWindow *the_canvas)
99 {
100 m_canvas = the_canvas;
101 m_hDC = (WXHDC) ::GetWindowDC(GetWinHwnd(the_canvas) );
102 m_hDCCount++;
103
104 SetBackground(wxBrush(m_canvas->GetBackgroundColour(), wxSOLID));
105 }
106
107 wxWindowDC::~wxWindowDC()
108 {
109 if (m_canvas && m_hDC)
110 {
111 SelectOldObjects(m_hDC);
112
113 ::ReleaseDC(GetWinHwnd(m_canvas), GetHdc());
114 m_hDC = 0;
115 }
116
117 m_hDCCount--;
118 }
119
120 // ----------------------------------------------------------------------------
121 // wxClientDC
122 // ----------------------------------------------------------------------------
123
124 wxClientDC::wxClientDC()
125 {
126 m_canvas = NULL;
127 }
128
129 wxClientDC::wxClientDC(wxWindow *the_canvas)
130 {
131 m_canvas = the_canvas;
132 m_hDC = (WXHDC) ::GetDC(GetWinHwnd(the_canvas));
133
134 SetBackground(wxBrush(m_canvas->GetBackgroundColour(), wxSOLID));
135 }
136
137 wxClientDC::~wxClientDC()
138 {
139 if ( m_canvas && GetHdc() )
140 {
141 SelectOldObjects(m_hDC);
142
143 ::ReleaseDC(GetWinHwnd(m_canvas), GetHdc());
144 m_hDC = 0;
145 }
146 }
147
148 // ----------------------------------------------------------------------------
149 // wxPaintDC
150 // ----------------------------------------------------------------------------
151
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.
156 //
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.
160 //
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.
167
168 wxArrayDCInfo wxPaintDC::ms_cache;
169
170 wxPaintDC::wxPaintDC()
171 {
172 m_canvas = NULL;
173 m_hDC = 0;
174 }
175
176 wxPaintDC::wxPaintDC(wxWindow *canvas)
177 {
178 wxCHECK_RET( canvas, "NULL canvas in wxPaintDC ctor" );
179
180 #ifdef __WXDEBUG__
181 if ( !g_isPainting )
182 {
183 wxFAIL_MSG( _T("wxPaintDC may be created only in EVT_PAINT handler!") );
184
185 return;
186 }
187 #endif // __WXDEBUG__
188
189 m_canvas = canvas;
190
191 // do we have a DC for this window in the cache?
192 wxPaintDCInfo *info = FindInCache();
193 if ( info )
194 {
195 m_hDC = info->hdc;
196 info->count++;
197 }
198 else // not in cache, create a new one
199 {
200 m_hDC = (WXHDC)::BeginPaint(GetWinHwnd(m_canvas), &g_paintStruct);
201 ms_cache.Add(new wxPaintDCInfo(m_canvas, this));
202 }
203
204 SetBackground(wxBrush(m_canvas->GetBackgroundColour(), wxSOLID));
205 }
206
207 wxPaintDC::~wxPaintDC()
208 {
209 if ( m_hDC )
210 {
211 size_t index;
212 wxPaintDCInfo *info = FindInCache(&index);
213
214 wxCHECK_RET( info, _T("existing DC should have a cache entry") );
215
216 if ( !--info->count )
217 {
218 ::EndPaint(GetWinHwnd(m_canvas), &g_paintStruct);
219
220 ms_cache.Remove(index);
221 }
222 //else: cached DC entry is still in use
223 }
224 }
225
226 wxPaintDCInfo *wxPaintDC::FindInCache(size_t *index) const
227 {
228 wxPaintDCInfo *info = NULL;
229 size_t nCache = ms_cache.GetCount();
230 for ( size_t n = 0; n < nCache; n++ )
231 {
232 info = &ms_cache[n];
233 if ( info->hwnd == m_canvas->GetHWND() )
234 {
235 if ( index )
236 *index = n;
237 break;
238 }
239 }
240
241 return info;
242 }