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 #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     int g_isPainting = 0;
  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     if ( !::ReleaseDC(GetWinHwnd(m_canvas), GetHdc()) )
 114     {
 115         wxLogLastError("ReleaseDC");
 116     }
 117
 118     m_hDC = 0;
 119   }
 120
 121   m_hDCCount--;
 122 }
 123
 124 // ----------------------------------------------------------------------------
 125 // wxClientDC
 126 // ----------------------------------------------------------------------------
 127
 128 wxClientDC::wxClientDC()
 129 {
 130   m_canvas = NULL;
 131 }
 132
 133 wxClientDC::wxClientDC(wxWindow *the_canvas)
 134 {
 135   m_canvas = the_canvas;
 136   m_hDC = (WXHDC) ::GetDC(GetWinHwnd(the_canvas));
 137
 138   // the background mode is only used for text background
 139   // and is set in DrawText() to OPAQUE as required, other-
 140   // wise always TRANSPARENT, RR
 141   ::SetBkMode( GetHdc(), TRANSPARENT );
 142
 143   SetBackground(wxBrush(m_canvas->GetBackgroundColour(), wxSOLID));
 144 }
 145
 146 wxClientDC::~wxClientDC()
 147 {
 148   if ( m_canvas && GetHdc() )
 149   {
 150     SelectOldObjects(m_hDC);
 151
 152     ::ReleaseDC(GetWinHwnd(m_canvas), GetHdc());
 153     m_hDC = 0;
 154   }
 155 }
 156
 157 // ----------------------------------------------------------------------------
 158 // wxPaintDC
 159 // ----------------------------------------------------------------------------
 160
 161 // VZ: initial implementation (by JACS) only remembered the last wxPaintDC
 162 //     created and tried to reuse - this was supposed to take care of a
 163 //     situation when a derived class OnPaint() calls base class OnPaint()
 164 //     because in this case ::BeginPaint() shouldn't be called second time.
 165 //
 166 //     I'm not sure how useful this is, however we must remember the HWND
 167 //     associated with the last HDC as well - otherwise we may (and will!) try
 168 //     to reuse the HDC for another HWND which is a nice recipe for disaster.
 169 //
 170 //     So we store a list of windows for which we already have the DC and not
 171 //     just one single hDC. This seems to work, but I'm really not sure about
 172 //     the usefullness of the whole idea - IMHO it's much better to not call
 173 //     base class OnPaint() at all, or, if we really want to allow it, add a
 174 //     "wxPaintDC *" parameter to wxPaintEvent which should be used if it's
 175 //     !NULL instead of creating a new DC.
 176
 177 wxArrayDCInfo wxPaintDC::ms_cache;
 178
 179 wxPaintDC::wxPaintDC()
 180 {
 181     m_canvas = NULL;
 182     m_hDC = 0;
 183 }
 184
 185 wxPaintDC::wxPaintDC(wxWindow *canvas)
 186 {
 187     wxCHECK_RET( canvas, wxT("NULL canvas in wxPaintDC ctor") );
 188
 189 #ifdef __WXDEBUG__
 190     if ( g_isPainting <= 0 )
 191     {
 192         wxFAIL_MSG( wxT("wxPaintDC may be created only in EVT_PAINT handler!") );
 193
 194         return;
 195     }
 196 #endif // __WXDEBUG__
 197
 198     m_canvas = canvas;
 199
 200     // do we have a DC for this window in the cache?
 201     wxPaintDCInfo *info = FindInCache();
 202     if ( info )
 203     {
 204         m_hDC = info->hdc;
 205         info->count++;
 206     }
 207     else // not in cache, create a new one
 208     {
 209         m_hDC = (WXHDC)::BeginPaint(GetWinHwnd(m_canvas), &g_paintStruct);
 210         ms_cache.Add(new wxPaintDCInfo(m_canvas, this));
 211     }
 212
 213     // the background mode is only used for text background
 214     // and is set in DrawText() to OPAQUE as required, other-
 215     // wise always TRANSPARENT, RR
 216     ::SetBkMode( GetHdc(), TRANSPARENT );
 217
 218     SetBackground(wxBrush(m_canvas->GetBackgroundColour(), wxSOLID));
 219 }
 220
 221 wxPaintDC::~wxPaintDC()
 222 {
 223     if ( m_hDC )
 224     {
 225         SelectOldObjects(m_hDC);
 226
 227         size_t index;
 228         wxPaintDCInfo *info = FindInCache(&index);
 229
 230         wxCHECK_RET( info, wxT("existing DC should have a cache entry") );
 231
 232         if ( !--info->count )
 233         {
 234             ::EndPaint(GetWinHwnd(m_canvas), &g_paintStruct);
 235
 236             ms_cache.Remove(index);
 237
 238             // Reduce the number of bogus reports of non-freed memory
 239             // at app exit
 240             if (ms_cache.IsEmpty())
 241                 ms_cache.Clear();
 242         }
 243         //else: cached DC entry is still in use
 244
 245         // prevent the base class dtor from ReleaseDC()ing it again
 246         m_hDC = 0;
 247     }
 248 }
 249
 250 wxPaintDCInfo *wxPaintDC::FindInCache(size_t *index) const
 251 {
 252     wxPaintDCInfo *info = NULL;
 253     size_t nCache = ms_cache.GetCount();
 254     for ( size_t n = 0; n < nCache; n++ )
 255     {
 256         info = &ms_cache[n];
 257         if ( info->hwnd == m_canvas->GetHWND() )
 258         {
 259             if ( index )
 260                 *index = n;
 261             break;
 262         }
 263     }
 264
 265     return info;
 266 }