Eliminate a warning

[wxWidgets.git] / src / common / dcbufcmn.cpp

diff --git a/src/common/dcbufcmn.cpp b/src/common/dcbufcmn.cpp
index d57648f99a5454d627ddfae94d1c3e5302fc30ad..6ae9f3ef8240df581a5d6707601d971c8c487201 100644 (file)
--- a/src/common/dcbufcmn.cpp
+++ b/src/common/dcbufcmn.cpp
@@ -24,16 +24,19 @@
     #pragma hdrstop
 #endif
 
+#include "wx/dcbuffer.h"
+
 #ifndef WX_PRECOMP
     #include "wx/module.h"
 #endif
 
-#include "wx/dcbuffer.h"
-
 // ============================================================================
 // implementation
 // ============================================================================
 
+IMPLEMENT_DYNAMIC_CLASS(wxBufferedDC,wxMemoryDC)
+IMPLEMENT_ABSTRACT_CLASS(wxBufferedPaintDC,wxBufferedDC)
+
 // ----------------------------------------------------------------------------
 // wxSharedDCBufferManager: helper class maintaining backing store bitmap
 // ----------------------------------------------------------------------------
@@ -46,25 +49,54 @@ public:
     virtual bool OnInit() { return true; }
     virtual void OnExit() { wxDELETE(ms_buffer); }
 
-    static wxBitmap GetBuffer(int w, int h)
+    static wxBitmap* GetBuffer(int w, int h)
     {
+        if ( ms_usingSharedBuffer )
+            return new wxBitmap(w, h);
+
         if ( !ms_buffer ||
                 w > ms_buffer->GetWidth() ||
                     h > ms_buffer->GetHeight() )
         {
             delete ms_buffer;
+
+            // we must always return a valid bitmap but creating a bitmap of
+            // size 0 would fail, so create a 1*1 bitmap in this case
+            if ( !w )
+                w = 1;
+            if ( !h )
+                h = 1;
+
             ms_buffer = new wxBitmap(w, h);
         }
 
-        return *ms_buffer;
+        ms_usingSharedBuffer = true;
+        return ms_buffer;
+    }
+
+    static void ReleaseBuffer(wxBitmap* buffer)
+    {
+        if ( buffer == ms_buffer )
+        {
+            wxASSERT_MSG( ms_usingSharedBuffer, wxT("shared buffer already released") );
+            ms_usingSharedBuffer = false;
+        }
+        else
+        {
+            delete buffer;
+        }
     }
 
 private:
     static wxBitmap *ms_buffer;
+    static bool ms_usingSharedBuffer;
 
     DECLARE_DYNAMIC_CLASS(wxSharedDCBufferManager)
 };
 
+wxBitmap* wxSharedDCBufferManager::ms_buffer = NULL;
+bool wxSharedDCBufferManager::ms_usingSharedBuffer = false;
+
 IMPLEMENT_DYNAMIC_CLASS(wxSharedDCBufferManager, wxModule)
 
 // ============================================================================
@@ -73,14 +105,46 @@ IMPLEMENT_DYNAMIC_CLASS(wxSharedDCBufferManager, wxModule)
 
 void wxBufferedDC::UseBuffer(wxCoord w, wxCoord h)
 {
-    if ( !m_buffer.IsOk() )
+    if ( !m_buffer || !m_buffer->IsOk() )
     {
         if ( w == -1 || h == -1 )
             m_dc->GetSize(&w, &h);
 
         m_buffer = wxSharedDCBufferManager::GetBuffer(w, h);
+        m_style |= wxBUFFER_USES_SHARED_BUFFER;
     }
 
-    SelectObject(m_buffer);
+    SelectObject(*m_buffer);
 }
 
+void wxBufferedDC::UnMask()
+{
+    wxCHECK_RET( m_dc, _T("no underlying wxDC?") );
+    wxASSERT_MSG( m_buffer && m_buffer->IsOk(), _T("invalid backing store") );
+
+    wxCoord x = 0,
+            y = 0;
+
+    if ( m_style & wxBUFFER_CLIENT_AREA )
+        GetDeviceOrigin(&x, &y);
+
+    // avoid blitting too much: if we were created for a bigger bitmap (and
+    // reused for a smaller one later) we should only blit the real bitmap area
+    // and not the full allocated back buffer
+    int widthDC,
+        heightDC;
+
+    m_dc->GetSize(&widthDC, &heightDC);
+
+    int widthBuf = m_buffer->GetWidth(),
+        heightBuf = m_buffer->GetHeight();
+
+    m_dc->Blit(0, 0,
+               wxMin(widthDC, widthBuf), wxMin(heightDC, heightBuf),
+               this,
+               -x, -y);
+    m_dc = NULL;
+
+    if ( m_style & wxBUFFER_USES_SHARED_BUFFER )
+        wxSharedDCBufferManager::ReleaseBuffer(m_buffer);
+}