#pragma hdrstop
#endif
-#include "wx/dcclient.h"
+#include "wx/string.h"
#include "wx/log.h"
+#include "wx/window.h"
#include "wx/msw/private.h"
+#include "wx/dcclient.h"
+
+// ----------------------------------------------------------------------------
+// array/list types
+// ----------------------------------------------------------------------------
+
+struct WXDLLEXPORT wxPaintDCInfo
+{
+ wxPaintDCInfo(wxWindow *win, wxDC *dc)
+ {
+ hwnd = win->GetHWND();
+ hdc = dc->GetHDC();
+ count = 1;
+ }
+
+ WXHWND hwnd; // window for this DC
+ WXHDC hdc; // the DC handle
+ size_t count; // usage count
+};
+
+#include "wx/arrimpl.cpp"
+
+WX_DEFINE_OBJARRAY(wxArrayDCInfo);
+
// ----------------------------------------------------------------------------
// macros
// ----------------------------------------------------------------------------
// created in resopnse to WM_PAINT message - doing this from elsewhere is a
// common programming error among wxWindows programmers and might lead to
// very subtle and difficult to debug refresh/repaint bugs.
- extern bool g_isPainting = FALSE;
+ int g_isPainting = 0;
#endif // __WXDEBUG__
// ===========================================================================
{
SelectOldObjects(m_hDC);
- ::ReleaseDC(GetWinHwnd(m_canvas), GetHdc());
+ if ( !::ReleaseDC(GetWinHwnd(m_canvas), GetHdc()) )
+ {
+ wxLogLastError("ReleaseDC");
+ }
+
m_hDC = 0;
}
// wxPaintDC
// ----------------------------------------------------------------------------
-// TODO (VZ) I have still some doubts about this hack and I still think that we
-// should store pairs of (hwnd, hdc) and not just the DC - what if
-// BeginPaint() was called on other window? It seems to work like
-// this, but to be sure about it we'd need to store hwnd too...
-
-WXHDC wxPaintDC::ms_PaintHDC = 0;
-size_t wxPaintDC::ms_PaintCount = 0; // count of ms_PaintHDC usage
+// VZ: initial implementation (by JACS) only remembered the last wxPaintDC
+// created and tried to reuse - this was supposed to take care of a
+// situation when a derived class OnPaint() calls base class OnPaint()
+// because in this case ::BeginPaint() shouldn't be called second time.
+//
+// I'm not sure how useful this is, however we must remember the HWND
+// associated with the last HDC as well - otherwise we may (and will!) try
+// to reuse the HDC for another HWND which is a nice recipe for disaster.
+//
+// So we store a list of windows for which we already have the DC and not
+// just one single hDC. This seems to work, but I'm really not sure about
+// the usefullness of the whole idea - IMHO it's much better to not call
+// base class OnPaint() at all, or, if we really want to allow it, add a
+// "wxPaintDC *" parameter to wxPaintEvent which should be used if it's
+// !NULL instead of creating a new DC.
+
+wxArrayDCInfo wxPaintDC::ms_cache;
wxPaintDC::wxPaintDC()
{
- m_canvas = NULL;
+ m_canvas = NULL;
+ m_hDC = 0;
}
wxPaintDC::wxPaintDC(wxWindow *canvas)
{
- wxCHECK_RET( canvas, "NULL canvas in wxPaintDC ctor" );
- wxCHECK_RET( g_isPainting,
- _T("wxPaintDC may be created only in EVT_PAINT handler!") );
+ wxCHECK_RET( canvas, _T("NULL canvas in wxPaintDC ctor") );
- m_canvas = canvas;
+#ifdef __WXDEBUG__
+ if ( g_isPainting <= 0 )
+ {
+ wxFAIL_MSG( _T("wxPaintDC may be created only in EVT_PAINT handler!") );
- // Don't call Begin/EndPaint if it's already been called: for example, if
- // calling a base class OnPaint.
- if ( ms_PaintCount > 0 ) {
- // it means that we've already called BeginPaint and so we must just
- // reuse the same HDC (BeginPaint shouldn't be called more than once)
- wxASSERT( ms_PaintHDC );
+ return;
+ }
+#endif // __WXDEBUG__
- m_hDC = ms_PaintHDC;
- ms_PaintCount++;
- }
- else {
- ms_PaintHDC =
- m_hDC = (WXHDC)::BeginPaint((HWND)m_canvas->GetHWND(), &g_paintStruct);
- ms_PaintCount = 1;
- m_hDCCount++;
- }
+ m_canvas = canvas;
- SetBackground(wxBrush(m_canvas->GetBackgroundColour(), wxSOLID));
+ // do we have a DC for this window in the cache?
+ wxPaintDCInfo *info = FindInCache();
+ if ( info )
+ {
+ m_hDC = info->hdc;
+ info->count++;
+ }
+ else // not in cache, create a new one
+ {
+ m_hDC = (WXHDC)::BeginPaint(GetWinHwnd(m_canvas), &g_paintStruct);
+ ms_cache.Add(new wxPaintDCInfo(m_canvas, this));
+ }
+
+ SetBackground(wxBrush(m_canvas->GetBackgroundColour(), wxSOLID));
}
wxPaintDC::~wxPaintDC()
{
- if ( m_hDC ) {
- if ( !--ms_PaintCount ) {
- ::EndPaint((HWND)m_canvas->GetHWND(), &g_paintStruct);
- m_hDCCount--;
- m_hDC = (WXHDC) NULL;
- ms_PaintHDC = (WXHDC) NULL;
+ if ( m_hDC )
+ {
+ SelectOldObjects(m_hDC);
+
+ size_t index;
+ wxPaintDCInfo *info = FindInCache(&index);
+
+ wxCHECK_RET( info, _T("existing DC should have a cache entry") );
+
+ if ( !--info->count )
+ {
+ ::EndPaint(GetWinHwnd(m_canvas), &g_paintStruct);
+
+ ms_cache.Remove(index);
+ }
+ //else: cached DC entry is still in use
+
+ // prevent the base class dtor from ReleaseDC()ing it again
+ m_hDC = 0;
}
- //else: ms_PaintHDC still in use
- }
}
+wxPaintDCInfo *wxPaintDC::FindInCache(size_t *index) const
+{
+ wxPaintDCInfo *info = NULL;
+ size_t nCache = ms_cache.GetCount();
+ for ( size_t n = 0; n < nCache; n++ )
+ {
+ info = &ms_cache[n];
+ if ( info->hwnd == m_canvas->GetHWND() )
+ {
+ if ( index )
+ *index = n;
+ break;
+ }
+ }
+
+ return info;
+}
projects / wxWidgets.git / blobdiff