FIX: CDC::CreatePointFont() May Create Wrong Size Font

• The Microsoft Foundation Classes (MFC), included with:
  • Microsoft Visual C++, 32-bit Editions, version 4.0

SYMPTOMS

Calling CDC::CreatePointFont() results in a font that is not of the point size requested. This will occur when the y component of the DC's viewport origin is not at 0. A common place for this to occur would be in a CScrollView class where the user has scrolled the view vertically.

CAUSE

MFC uses DPtoLP() to map the given device coordinates to logical coordinates. The case where the viewport origin is not at 0 is not taken into consideration by this code.

RESOLUTION

Set the y component of the viewport origin to 0 before calling CreatePointFont(). The following code demonstrates the workaround. Here pDC is a pointer to a CDC.

Sample Code

/* Compile options needed: default
*/ 
POINT pt;
SetViewportOrgEx(pDC->GetSafeHdc(), 0, 0, &pt); // set origin to 0,0
CreatePointFont(120, "Courier", pDC);
SetViewportOrgEx(pDC->GetSafeHdc(), pt.x, pt,y, NULL); // restore origin 

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug was corrected in Visual C++ 4.1.

Additional query words: kbVC400bug 4.10 4.00

Keywords : kbcode kbnokeyword kbMFC kbVC kbVC410fix
Version : 4.00
Platform : NT WINDOWS
Issue type :