Re: something about clipping in OnCustomdraw

From:
".rhavin grobert" <clqrq@yahoo.de>
Newsgroups:
microsoft.public.vc.mfc
Date:
Mon, 13 Oct 2008 05:53:24 -0700 (PDT)
Message-ID:
<57af92df-b9ad-4ef1-a854-987e57a1d116@m74g2000hsh.googlegroups.com>
On 12 Okt., 08:58, Joseph M. Newcomer <newco...@flounder.com> wrote:

On Fri, 10 Oct 2008 15:48:51 -0700 (PDT), Malachy Moses <malachy.mo...@gm=

ail.com> wrote:

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 y=

ou

can see, i draw my own thumb and want to set some text in the cont=

rol:

____________________________________________________________

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

        // ... other stuff ... //

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

or value

        void QTitleSet(LPCTSTR szTitle);

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

pResult);

        //}}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 |=

 CDRF_NOTIFYPOSTPAINT;

                break;

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

DODEFAULT;

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

SKIPDEFAULT;

                        break;
                case TBCD_CHANNEL:
                        *pResult = CDRF_=

DODEFAULT;

                        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_BOT=

TOM |

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 SIMPLEREGI=

ON

but shouldnt it return NULLREGION !?


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

ed 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();

}


The Detach is not required. There is no call on a destructor when a CDC*=

 leaves scope.

                                joe
Joseph M. Newcomer [MVP]
email: newco...@flounder.com
Web:http://www.flounder.com
MVP Tips:http://www.flounder.com/mvp_tips.htm


....and the SaveDC()/RestoreDC() doesnt help either. So there is is
still the problem of clipping. *MAY* it be that the hdc i get in
NMCUSTOMDRAW is some kind of memory-dc and that my work is clipped
because just a certain part is bitblt'ed into screen? but that leaves
the question why a simple ::SelectClipRgn(nmcd.hdc, NULL) returns
SIMPLEREGION instead of the expected NULLREGION.

Any enlightenment highly appreciated,
~.rhavin;)

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