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 *canvas)
  97 {
  98     wxCHECK_RET( canvas, _T("invalid window in wxWindowDC") );
  99
 100     m_canvas = canvas;
 101     m_hDC = (WXHDC) ::GetWindowDC(GetHwndOf(m_canvas));
 102
 103     // m_bOwnsDC was already set to false in the base class ctor, so the DC
 104     // will be released (and not deleted) in ~wxDC
 105
 106     InitDC();
 107 }
 108
 109 void wxWindowDC::InitDC()
 110 {
 111     // the background mode is only used for text background and is set in
 112     // DrawText() to OPAQUE as required, otherwise always TRANSPARENT,
 113     ::SetBkMode(GetHdc(), TRANSPARENT);
 114
 115     // default bg colour is pne of the window
 116     SetBackground(wxBrush(m_canvas->GetBackgroundColour(), wxSOLID));
 117 }
 118
 119 // ----------------------------------------------------------------------------
 120 // wxClientDC
 121 // ----------------------------------------------------------------------------
 122
 123 wxClientDC::wxClientDC()
 124 {
 125     m_canvas = NULL;
 126 }
 127
 128 wxClientDC::wxClientDC(wxWindow *canvas)
 129 {
 130     wxCHECK_RET( canvas, _T("invalid window in wxClientDC") );
 131
 132     m_canvas = canvas;
 133     m_hDC = (WXHDC)::GetDC(GetHwndOf(m_canvas));
 134
 135     // m_bOwnsDC was already set to false in the base class ctor, so the DC
 136     // will be released (and not deleted) in ~wxDC
 137
 138     InitDC();
 139 }
 140
 141 // ----------------------------------------------------------------------------
 142 // wxPaintDC
 143 // ----------------------------------------------------------------------------
 144
 145 // VZ: initial implementation (by JACS) only remembered the last wxPaintDC
 146 //     created and tried to reuse it - this was supposed to take care of a
 147 //     situation when a derived class OnPaint() calls base class OnPaint()
 148 //     because in this case ::BeginPaint() shouldn't be called second time.
 149 //
 150 //     I'm not sure how useful this is, however we must remember the HWND
 151 //     associated with the last HDC as well - otherwise we may (and will!) try
 152 //     to reuse the HDC for another HWND which is a nice recipe for disaster.
 153 //
 154 //     So we store a list of windows for which we already have the DC and not
 155 //     just one single hDC. This seems to work, but I'm really not sure about
 156 //     the usefullness of the whole idea - IMHO it's much better to not call
 157 //     base class OnPaint() at all, or, if we really want to allow it, add a
 158 //     "wxPaintDC *" parameter to wxPaintEvent which should be used if it's
 159 //     !NULL instead of creating a new DC.
 160
 161 wxArrayDCInfo wxPaintDC::ms_cache;
 162
 163 wxPaintDC::wxPaintDC()
 164 {
 165     m_canvas = NULL;
 166 }
 167
 168 wxPaintDC::wxPaintDC(wxWindow *canvas)
 169 {
 170     wxCHECK_RET( canvas, wxT("NULL canvas in wxPaintDC ctor") );
 171
 172 #ifdef __WXDEBUG__
 173     if ( g_isPainting <= 0 )
 174     {
 175         wxFAIL_MSG( wxT("wxPaintDC may be created only in EVT_PAINT handler!") );
 176
 177         return;
 178     }
 179 #endif // __WXDEBUG__
 180
 181     m_canvas = canvas;
 182
 183     // do we have a DC for this window in the cache?
 184     wxPaintDCInfo *info = FindInCache();
 185     if ( info )
 186     {
 187         m_hDC = info->hdc;
 188         info->count++;
 189     }
 190     else // not in cache, create a new one
 191     {
 192         m_hDC = (WXHDC)::BeginPaint(GetHwndOf(m_canvas), &g_paintStruct);
 193         ms_cache.Add(new wxPaintDCInfo(m_canvas, this));
 194     }
 195
 196     InitDC();
 197 }
 198
 199 wxPaintDC::~wxPaintDC()
 200 {
 201     if ( m_hDC )
 202     {
 203         SelectOldObjects(m_hDC);
 204
 205         size_t index;
 206         wxPaintDCInfo *info = FindInCache(&index);
 207
 208         wxCHECK_RET( info, wxT("existing DC should have a cache entry") );
 209
 210         if ( !--info->count )
 211         {
 212             ::EndPaint(GetHwndOf(m_canvas), &g_paintStruct);
 213
 214             ms_cache.Remove(index);
 215
 216             // Reduce the number of bogus reports of non-freed memory
 217             // at app exit
 218             if (ms_cache.IsEmpty())
 219                 ms_cache.Clear();
 220         }
 221         //else: cached DC entry is still in use
 222
 223         // prevent the base class dtor from ReleaseDC()ing it again
 224         m_hDC = 0;
 225     }
 226 }
 227
 228 wxPaintDCInfo *wxPaintDC::FindInCache(size_t *index) const
 229 {
 230     wxPaintDCInfo *info = NULL;
 231     size_t nCache = ms_cache.GetCount();
 232     for ( size_t n = 0; n < nCache; n++ )
 233     {
 234         info = &ms_cache[n];
 235         if ( info->hwnd == m_canvas->GetHWND() )
 236         {
 237             if ( index )
 238                 *index = n;
 239             break;
 240         }
 241     }
 242
 243     return info;
 244 }
 245
 246 // find the entry for this DC in the cache (keyed by the window)
 247 WXHDC wxPaintDC::FindDCInCache(wxWindow* win)
 248 {
 249     wxPaintDCInfo *info = NULL;
 250     size_t nCache = ms_cache.GetCount();
 251     for ( size_t n = 0; n < nCache; n++ )
 252     {
 253         info = &ms_cache[n];
 254         if ( info->hwnd == win->GetHWND() )
 255         {
 256             return info->hdc;
 257         }
 258     }
 259     return 0;
 260 }
 261