src/msw/dcclient.cpp

   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     IMPLEMENT_DYNAMIC_CLASS(wxWindowDC, wxDC)
  66     IMPLEMENT_DYNAMIC_CLASS(wxClientDC, wxWindowDC)
  67     IMPLEMENT_DYNAMIC_CLASS(wxPaintDC, wxWindowDC)
  68
  69 // ----------------------------------------------------------------------------
  70 // global variables
  71 // ----------------------------------------------------------------------------
  72
  73 static PAINTSTRUCT g_paintStruct;
  74
  75 #ifdef __WXDEBUG__
  76     // a global variable which we check to verify that wxPaintDC are only
  77     // created in resopnse to WM_PAINT message - doing this from elsewhere is a
  78     // common programming error among wxWindows programmers and might lead to
  79     // very subtle and difficult to debug refresh/repaint bugs.
  80     int g_isPainting = 0;
  81 #endif // __WXDEBUG__
  82
  83 // ===========================================================================
  84 // implementation
  85 // ===========================================================================
  86
  87 // ----------------------------------------------------------------------------
  88 // wxWindowDC
  89 // ----------------------------------------------------------------------------
  90
  91 wxWindowDC::wxWindowDC()
  92 {
  93   m_canvas = NULL;
  94 }
  95
  96 wxWindowDC::wxWindowDC(wxWindow *the_canvas)
  97 {
  98   m_canvas = the_canvas;
  99   m_hDC = (WXHDC) ::GetWindowDC(GetWinHwnd(the_canvas) );
 100   m_hDCCount++;
 101
 102   SetBackground(wxBrush(m_canvas->GetBackgroundColour(), wxSOLID));
 103 }
 104
 105 wxWindowDC::~wxWindowDC()
 106 {
 107   if (m_canvas && m_hDC)
 108   {
 109     SelectOldObjects(m_hDC);
 110
 111     if ( !::ReleaseDC(GetWinHwnd(m_canvas), GetHdc()) )
 112     {
 113         wxLogLastError(wxT("ReleaseDC"));
 114     }
 115
 116     m_hDC = 0;
 117   }
 118
 119   m_hDCCount--;
 120 }
 121
 122 // ----------------------------------------------------------------------------
 123 // wxClientDC
 124 // ----------------------------------------------------------------------------
 125
 126 wxClientDC::wxClientDC()
 127 {
 128   m_canvas = NULL;
 129 }
 130
 131 wxClientDC::wxClientDC(wxWindow *the_canvas)
 132 {
 133   m_canvas = the_canvas;
 134   m_hDC = (WXHDC) ::GetDC(GetWinHwnd(the_canvas));
 135
 136   // the background mode is only used for text background
 137   // and is set in DrawText() to OPAQUE as required, other-
 138   // wise always TRANSPARENT, RR
 139   ::SetBkMode( GetHdc(), TRANSPARENT );
 140
 141   SetBackground(wxBrush(m_canvas->GetBackgroundColour(), wxSOLID));
 142 }
 143
 144 wxClientDC::~wxClientDC()
 145 {
 146   if ( m_canvas && GetHdc() )
 147   {
 148     SelectOldObjects(m_hDC);
 149
 150     ::ReleaseDC(GetWinHwnd(m_canvas), GetHdc());
 151     m_hDC = 0;
 152   }
 153 }
 154
 155 // ----------------------------------------------------------------------------
 156 // wxPaintDC
 157 // ----------------------------------------------------------------------------
 158
 159 // VZ: initial implementation (by JACS) only remembered the last wxPaintDC
 160 //     created and tried to reuse - this was supposed to take care of a
 161 //     situation when a derived class OnPaint() calls base class OnPaint()
 162 //     because in this case ::BeginPaint() shouldn't be called second time.
 163 //
 164 //     I'm not sure how useful this is, however we must remember the HWND
 165 //     associated with the last HDC as well - otherwise we may (and will!) try
 166 //     to reuse the HDC for another HWND which is a nice recipe for disaster.
 167 //
 168 //     So we store a list of windows for which we already have the DC and not
 169 //     just one single hDC. This seems to work, but I'm really not sure about
 170 //     the usefullness of the whole idea - IMHO it's much better to not call
 171 //     base class OnPaint() at all, or, if we really want to allow it, add a
 172 //     "wxPaintDC *" parameter to wxPaintEvent which should be used if it's
 173 //     !NULL instead of creating a new DC.
 174
 175 wxArrayDCInfo wxPaintDC::ms_cache;
 176
 177 wxPaintDC::wxPaintDC()
 178 {
 179     m_canvas = NULL;
 180     m_hDC = 0;
 181 }
 182
 183 wxPaintDC::wxPaintDC(wxWindow *canvas)
 184 {
 185     wxCHECK_RET( canvas, wxT("NULL canvas in wxPaintDC ctor") );
 186
 187 #ifdef __WXDEBUG__
 188     if ( g_isPainting <= 0 )
 189     {
 190         wxFAIL_MSG( wxT("wxPaintDC may be created only in EVT_PAINT handler!") );
 191
 192         return;
 193     }
 194 #endif // __WXDEBUG__
 195
 196     m_canvas = canvas;
 197
 198     // do we have a DC for this window in the cache?
 199     wxPaintDCInfo *info = FindInCache();
 200     if ( info )
 201     {
 202         m_hDC = info->hdc;
 203         info->count++;
 204     }
 205     else // not in cache, create a new one
 206     {
 207         m_hDC = (WXHDC)::BeginPaint(GetWinHwnd(m_canvas), &g_paintStruct);
 208         ms_cache.Add(new wxPaintDCInfo(m_canvas, this));
 209     }
 210
 211     // the background mode is only used for text background
 212     // and is set in DrawText() to OPAQUE as required, other-
 213     // wise always TRANSPARENT, RR
 214     ::SetBkMode( GetHdc(), TRANSPARENT );
 215
 216     SetBackground(wxBrush(m_canvas->GetBackgroundColour(), wxSOLID));
 217 }
 218
 219 wxPaintDC::~wxPaintDC()
 220 {
 221     if ( m_hDC )
 222     {
 223         SelectOldObjects(m_hDC);
 224
 225         size_t index;
 226         wxPaintDCInfo *info = FindInCache(&index);
 227
 228         wxCHECK_RET( info, wxT("existing DC should have a cache entry") );
 229
 230         if ( !--info->count )
 231         {
 232             ::EndPaint(GetWinHwnd(m_canvas), &g_paintStruct);
 233
 234             ms_cache.Remove(index);
 235
 236             // Reduce the number of bogus reports of non-freed memory
 237             // at app exit
 238             if (ms_cache.IsEmpty())
 239                 ms_cache.Clear();
 240         }
 241         //else: cached DC entry is still in use
 242
 243         // prevent the base class dtor from ReleaseDC()ing it again
 244         m_hDC = 0;
 245     }
 246 }
 247
 248 wxPaintDCInfo *wxPaintDC::FindInCache(size_t *index) const
 249 {
 250     wxPaintDCInfo *info = NULL;
 251     size_t nCache = ms_cache.GetCount();
 252     for ( size_t n = 0; n < nCache; n++ )
 253     {
 254         info = &ms_cache[n];
 255         if ( info->hwnd == m_canvas->GetHWND() )
 256         {
 257             if ( index )
 258                 *index = n;
 259             break;
 260         }
 261     }
 262
 263     return info;
 264 }
 265
 266 // find the entry for this DC in the cache (keyed by the window)
 267 WXHDC wxPaintDC::FindDCInCache(wxWindow* win)
 268 {
 269     wxPaintDCInfo *info = NULL;
 270     size_t nCache = ms_cache.GetCount();
 271     for ( size_t n = 0; n < nCache; n++ )
 272     {
 273         info = &ms_cache[n];
 274         if ( info->hwnd == win->GetHWND() )
 275         {
 276             return info->hdc;
 277         }
 278     }
 279     return 0;
 280 }
 281