Re: something about clipping in OnCustomdraw

From:

Malachy Moses <malachy.moses@gmail.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Fri, 10 Oct 2008 15:48:51 -0700 (PDT)

Message-ID:

<6f4eadbf-016a-462f-af30-45fb4b862edc@31g2000prz.googlegroups.com>

On Oct 10, 10:40 am, ".rhavin grobert" <cl...@yahoo.de> wrote:

On 10 Okt., 18:16, ".rhavin grobert" <cl...@yahoo.de> wrote:

On 10 Okt., 18:02, ".rhavin grobert" <cl...@yahoo.de> wrote:

hi folks;-)

the following snipped comes from a customdraw-fn in a slider. As you
can see, i draw my own thumb and want to set some text in the control=

____________________________________________________________

class SHTC_API CQSlider : public CSliderCtrl
{
public:
        CQSlider();
        virtual ~CQSlider();

        // ... other stuff ... //

        // set sliders text, may contain '%d' (or %x...) for =

value

        void QTitleSet(LPCTSTR szTitle);

protected:
        //{{AFX_MSG(CQSlider)
        afx_msg void OnCustomdraw(NMHDR* pNMHDR, LRESULT* pRe=

sult);

        //}}AFX_MSG

        DECLARE_MESSAGE_MAP()

private:
        void _DrawThumb(NMCUSTOMDRAW& nmcd);
        void _DrawText(NMCUSTOMDRAW& nmcd);

        CString m_scTitle;

};

//-------------------------------------------------------------------=

------=AD----

void CQSlider::OnCustomdraw(NMHDR* pNMHDR, LRESULT* pResult)
{
    NMCUSTOMDRAW nmcd = *(LPNMCUSTOMDRAW)pNMHDR;

        switch (nmcd.dwDrawStage)
        {
        case CDDS_PREPAINT:
                *pResult = CDRF_NOTIFYITEMDRAW | CD=

RF_NOTIFYPOSTPAINT;

                break;

        case CDDS_ITEMPREPAINT:
                switch (nmcd.dwItemSpec)
                {
                case TBCD_TICS:
                        *pResult = CDRF_DOD=

EFAULT;

                        break;
                case TBCD_THUMB:
                        _DrawThumb(nmcd);
                        *pResult = CDRF_SKI=

PDEFAULT;

                        break;
                case TBCD_CHANNEL:
                        *pResult = CDRF_DOD=

EFAULT;

                        break;
                }
                break;

        case CDDS_POSTPAINT:
                _DrawText(nmcd);
                break;

        default:
                *pResult = CDRF_DODEFAULT;
        }

}

//-------------------------------------------------------------------=

------=AD----

void CQSlider::_DrawText(NMCUSTOMDRAW& nmcd)
{
        CDC* pDC = CDC::FromHandle(nmcd.hdc);

        CRect rcClient;
        GetClientRect(&rcClient);

        CString scText;
        scText.Format(m_scTitle, GetPos());
        pDC->SetBkMode(TRANSPARENT);
        pDC->SelectClipRgn(NULL);
        pDC->DrawText(scText, rcClient, DT_CENTER | DT_BOTTOM=

DT_SINGLELINE);

}

____________________________________________________________

the problem is: first time (initial, get focus), the text is drawn
correctly, but then, when moving the slider, everything except the
thumb gets clipped, so pDC->SelectClipRgn(NULL) seems to dont do
anything at all.

any suggestions welcome,

~.rhavin;)

oh and i should add that pDC->SelectClipRgn(NULL) returns SIMPLEREGION
but shouldnt it return NULLREGION !?

played with SetBoundsRect(), but that doesnt help either;-/- Hide quoted =

text -

- Show quoted text -

I'm not certain that this will help, but I recommend two changes:
Surround your work with the DC with calls to SaveDC and RestoreDC, and
call CDC::Detach before exiting. So:

//-------------------------------------------------------------------------=
=AD----
void CQSlider::_DrawText(NMCUSTOMDRAW& nmcd)
{
        CDC* pDC = CDC::FromHandle(nmcd.hdc);

        int iSaveDC = pDC->SaveDC();

        CRect rcClient;
        GetClientRect(&rcClient);

        CString scText;
        scText.Format(m_scTitle, GetPos());
        pDC->SetBkMode(TRANSPARENT);
        pDC->SelectClipRgn(NULL);
        pDC->DrawText(scText, rcClient, DT_CENTER | DT_BOTTOM |
DT_SINGLELINE);

         pDC->RestoreDC( iSaveDC );
         pDC->Detach();

}