C / C++ / MFC

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

COLORREF backgroundColour = 0;
{
    CDC dcCopy;
    dcCopy.CreateCompatibleDC(NULL);
    dcCopy.SaveDC();
    dcCopy.SelectObject(&toolbarBitmap);
    backgroundColour = dcCopy.GetPixel(0, 0);               // toolbars use pixel 0,0 of image 0 as the background colour
    dcCopy.RestoreDC(-1);
    dcCopy.DeleteDC();
}

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

// replace XXXXX with your current object version ID number
IMPLEMENT_SERIAL (CFoo, CObject,VERSIONABLE_SCHEMA|XXXXX)
 
void CFoo::Serialize( CArchive& ar )
{
   CObject::Serialize( ar );
 
   if ( ar.IsStoring() )
   {
      ...
   }
   else
   {
      int nVersion = ar.GetObjectSchema();
 
      switch(nVersion)
      {
         case 2: // newest version
           read new version data
           break;
         case 1: // next-to-newest version
           read data for that version    
           break;
         case 0: // etc...
      }
}

A CObject-derived class may use VERSIONABLE_SCHEMA combined (using bitwise OR) with the schema version itself (in the IMPLEMENT_SERIAL macro) to create a “versionable object,” that is, an object whose Serialize member function can read multiple versions. The default framework functionality (without VERSIONABLE_SCHEMA) is to throw an exception when the version is mismatched.