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