C / C++ / MFC

void GetTextSize(CSize& cResultSize,     // Receiving size of the text rectangle
                 CDC* pcDC,              // Surface context
                 CFont* pcFont,          // Font for the context
                 const CString& cszText) // Text to measure
{
  if (pcDC && pcFont) {
    CGdiObject* pcOldFont = pcDC->SelectObject(pcFont);
    cResultSize = pcDC->GetTextExtent(cszText); // dimensions of the text
                                                // at the given surface
                                                // with the given font
    pcDC->SelectObject(pcOldFont);
  }
}

/*virtual*/ void CYourView::OnDraw(CDC* pDC)
{
  if (pDC) {
    CString cszText(_T("Hello World !"));
    // Calculate the text rectangle from the start point(100, 100)
    // at this surface with the actual set font
    CRect cTextRect(CPoint(100, 100),
                    pDC->GetTextExtent(cszText));
    pDC->FillSolidRect(cTextRect, RGB(0, 200, 0)); // Text background
    pDC->DrawText(cszText, cTextRect, DT_LEFT | DT_TOP);
  }
}

#define GAP 20
CSize GetButtonDimensions(int iCharCount,
                          int iFontSize,
                          const CString& cszFontName)
{
  CSize cResultSize(0, 0);
 

  CFont cFont;
  if (cFont.CreatePointFont(iFontSize * 10, cszFontname)) {
    CDC cDC;
    if (cDC.CreateCompatibleDC(NULL)) {
      CGdiObject* pcOldFont = cDC.SelectObject(cFont);
       
      TEXTMETRIC tm = {0};
      cDC.GetTextMetrics(&tm);
 

      cResultSize.cy = tm.tmHeight                    + 2 * GAP;
      cResultSize.cx = tm.tmMaxCharWidth * iCharCount + 2 * GAP;
 

      cDC.SelectObject(pcOldFont);
    }
    cFont.DeleteObject();
  }
 
  return cResultSize;
}