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, wxClientDC)
  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     InitDC();
 106 }
 107
 108 void wxWindowDC::InitDC()
 109 {
 110     // the background mode is only used for text background and is set in
 111     // DrawText() to OPAQUE as required, otherwise always TRANSPARENT,
 112     ::SetBkMode(GetHdc(), TRANSPARENT);
 113
 114     // default bg colour is pne of the window
 115     SetBackground(wxBrush(m_canvas->GetBackgroundColour(), wxSOLID));
 116 }
 117
 118 // ----------------------------------------------------------------------------
 119 // wxClientDC
 120 // ----------------------------------------------------------------------------
 121
 122 wxClientDC::wxClientDC()
 123 {
 124     m_canvas = NULL;
 125 }
 126
 127 wxClientDC::wxClientDC(wxWindow *canvas)
 128 {
 129     wxCHECK_RET( canvas, _T("invalid window in wxClientDC") );
 130
 131     m_canvas = canvas;
 132     m_hDC = (WXHDC)::GetDC(GetHwndOf(m_canvas));
 133
 134     // m_bOwnsDC was already set to false in the base class ctor, so the DC
 135     // will be released (and not deleted) in ~wxDC
 136
 137     InitDC();
 138 }
 139
 140 void wxClientDC::InitDC()
 141 {
 142     wxWindowDC::InitDC();
 143
 144     // in wxUniv build we must manually do some DC adjustments usually
 145     // performed by Windows for us
 146 #ifdef __WXUNIVERSAL__
 147     wxPoint ptOrigin = m_canvas->GetClientAreaOrigin();
 148     if ( ptOrigin.x || ptOrigin.y )
 149     {
 150         // no need to shift DC origin if shift is null
 151         SetDeviceOrigin(ptOrigin.x, ptOrigin.y);
 152     }
 153
 154     // clip the DC to avoid overwriting the non client area
 155     SetClippingRegion(wxPoint(0, 0), m_canvas->GetClientSize());
 156 #endif // __WXUNIVERSAL__
 157 }
 158
 159 wxClientDC::~wxClientDC()
 160 {
 161 }
 162
 163 // ----------------------------------------------------------------------------
 164 // wxPaintDC
 165 // ----------------------------------------------------------------------------
 166
 167 // VZ: initial implementation (by JACS) only remembered the last wxPaintDC
 168 //     created and tried to reuse it - this was supposed to take care of a
 169 //     situation when a derived class OnPaint() calls base class OnPaint()
 170 //     because in this case ::BeginPaint() shouldn't be called second time.
 171 //
 172 //     I'm not sure how useful this is, however we must remember the HWND
 173 //     associated with the last HDC as well - otherwise we may (and will!) try
 174 //     to reuse the HDC for another HWND which is a nice recipe for disaster.
 175 //
 176 //     So we store a list of windows for which we already have the DC and not
 177 //     just one single hDC. This seems to work, but I'm really not sure about
 178 //     the usefullness of the whole idea - IMHO it's much better to not call
 179 //     base class OnPaint() at all, or, if we really want to allow it, add a
 180 //     "wxPaintDC *" parameter to wxPaintEvent which should be used if it's
 181 //     !NULL instead of creating a new DC.
 182
 183 wxArrayDCInfo wxPaintDC::ms_cache;
 184
 185 wxPaintDC::wxPaintDC()
 186 {
 187     m_canvas = NULL;
 188 }
 189
 190 wxPaintDC::wxPaintDC(wxWindow *canvas)
 191 {
 192     wxCHECK_RET( canvas, wxT("NULL canvas in wxPaintDC ctor") );
 193
 194 #ifdef __WXDEBUG__
 195     if ( g_isPainting <= 0 )
 196     {
 197         wxFAIL_MSG( wxT("wxPaintDC may be created only in EVT_PAINT handler!") );
 198
 199         return;
 200     }
 201 #endif // __WXDEBUG__
 202
 203     m_canvas = canvas;
 204
 205     // do we have a DC for this window in the cache?
 206     wxPaintDCInfo *info = FindInCache();
 207     if ( info )
 208     {
 209         m_hDC = info->hdc;
 210         info->count++;
 211     }
 212     else // not in cache, create a new one
 213     {
 214         m_hDC = (WXHDC)::BeginPaint(GetHwndOf(m_canvas), &g_paintStruct);
 215         if (m_hDC)
 216             ms_cache.Add(new wxPaintDCInfo(m_canvas, this));
 217     }
 218
 219     // (re)set the DC parameters.
 220     // Note: at this point m_hDC can be NULL under MicroWindows, when dragging.
 221     if (GetHDC())
 222         InitDC();
 223 }
 224
 225 wxPaintDC::~wxPaintDC()
 226 {
 227     if ( m_hDC )
 228     {
 229         SelectOldObjects(m_hDC);
 230
 231         size_t index;
 232         wxPaintDCInfo *info = FindInCache(&index);
 233
 234         wxCHECK_RET( info, wxT("existing DC should have a cache entry") );
 235
 236         if ( !--info->count )
 237         {
 238             ::EndPaint(GetHwndOf(m_canvas), &g_paintStruct);
 239
 240             ms_cache.Remove(index);
 241
 242             // Reduce the number of bogus reports of non-freed memory
 243             // at app exit
 244             if (ms_cache.IsEmpty())
 245                 ms_cache.Clear();
 246         }
 247         //else: cached DC entry is still in use
 248
 249         // prevent the base class dtor from ReleaseDC()ing it again
 250         m_hDC = 0;
 251     }
 252 }
 253
 254 wxPaintDCInfo *wxPaintDC::FindInCache(size_t *index) const
 255 {
 256     wxPaintDCInfo *info = NULL;
 257     size_t nCache = ms_cache.GetCount();
 258     for ( size_t n = 0; n < nCache; n++ )
 259     {
 260         info = &ms_cache[n];
 261         if ( info->hwnd == m_canvas->GetHWND() )
 262         {
 263             if ( index )
 264                 *index = n;
 265             break;
 266         }
 267     }
 268
 269     return info;
 270 }
 271
 272 // find the entry for this DC in the cache (keyed by the window)
 273 WXHDC wxPaintDC::FindDCInCache(wxWindow* win)
 274 {
 275     wxPaintDCInfo *info = NULL;
 276     size_t nCache = ms_cache.GetCount();
 277     for ( size_t n = 0; n < nCache; n++ )
 278     {
 279         info = &ms_cache[n];
 280         if ( info->hwnd == win->GetHWND() )
 281         {
 282             return info->hdc;
 283         }
 284     }
 285     return 0;
 286 }
 287