Advanced MFC Programming

Chapter 9. Font
the same, it indicates that there is no text being selected. The two variables are initialized in the constructor
as follows:
……
CGDIDoc::CGDIDoc()
{
}
m_nCaretIndex=0;
m_nSelIndexBgn=-1;
m_nSelIndexEnd=-1;
In CGDIView::OnDraw(…), we need to retrieve the values of m_nSelIndexBgn and m_nSelIndexEnd,
swap forground and background colors for the selected text when outputting text string to the client
window. The following is the modified function CGDIView::OnDraw(…):
void CGDIView::OnDraw(CDC *pDC)
{
CString szText;
CString szStr;
CFont *ptrFontOld;
int nSelIndexBgn;
int nSelIndexEnd;
int nSel;
UINT uTextAlign;
COLORREF colorFg;
COLORREF colorBk;
}
CGDIDoc *pDoc=GetDocument();
ASSERT_VALID(pDoc);
szText=pDoc->GetText();
ptrFontOld=pDC->SelectObject(pDoc->GetFont());
nSelIndexBgn=pDoc->GetSelIndexBgn();
nSelIndexEnd=pDoc->GetSelIndexEnd();
if
(
nSelIndexBgn == -1 ||
nSelIndexEnd == -1 ||
(nSelIndexBgn == nSelIndexEnd)
)
{
pDC->TextOut(0, 0, szText);
}
else
{
if(nSelIndexEnd < nSelIndexBgn)
{
nSel=nSelIndexBgn;
nSelIndexBgn=nSelIndexEnd;
nSelIndexEnd=nSel;
}
uTextAlign=pDC->SetTextAlign(TA_UPDATECP);
szStr=szText.Left(nSelIndexBgn);
pDC->TextOut(0, 0, szStr);
colorFg=pDC->GetTextColor();
colorBk=pDC->GetBkColor();
pDC->SetTextColor(colorBk);
pDC->SetBkColor(colorFg);
szStr=szText.Mid(nSelIndexBgn, nSelIndexEnd-nSelIndexBgn);
pDC->TextOut(0, 0, szStr);
pDC->SetTextColor(colorFg);
pDC->SetBkColor(colorBk);
szStr=szText.Mid(nSelIndexEnd);
pDC->TextOut(0, 0, szStr);
pDC->SetTextAlign(uTextAlign);
}
pDC->SelectObject(ptrFontOld);
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