microsoft.public.dotnet.framework.drawing

Eric Renken

10/12/2004 6:04:00 PM

You need to enable double buffering, check this article out. it is doing it
for a form, but it is the same concept.

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemwindowsformscontrolclasssetstyl...

This worked for me for a C# user control I created.

--
Eric Renken
Demiuirge Software LLC
http://www.d...


"Nuno Esculcas" <nesculcas@hotmail.com> wrote in message
news:38f0f14e.0410120349.76888160@posting.google.com...
> Hello,
>
> I''m working on VC7 and i''m trying to make a simple animation that
> have an image in the background and the animation is a text that is
> scrolling from right to left. I''m doing this in GDI+ and i''m using the
> technique DrawCachedBitmap to avoid the flicker, but i''m still getting
> the flicker.
> My question is what i''m doing wrong? or this technique is not valid?
> (only for better understanding i''m showing the code)
>
> //On the beginning i''m loading the background image into memory, and
> start the position of the text
> m_pcMemBitmap = Gdiplus::Bitmap::FromFile(strLastImageLoad);
> m_nPos=1024;
>
>
> //Then i have a function to draw the animation
> void CChildView::DrawImage(HDC hdc)
> {
> if(m_pcMemBitmap)
> {
> Graphics graphics(hdc);
> int nHeight = m_pcMemBitmap->GetHeight();
> int nWidth = m_pcMemBitmap->GetWidth();
>
> //here i make a copy of the image
> PixelFormat pixFrmt = m_pcMemBitmap->GetPixelFormat();
> Bitmap* bTemp = (Bitmap*)m_pcMemBitmap->Clone(
> 0,
> 0,
> nWidth,
> nHeight,
> pixFrmt);
> if( bTemp == NULL )
> {
> _ASSERTE(bTemp);
> return;
> }
>
> //now i draw the text in diferent positions
> Graphics grFrBk(bTemp);
> PointF p1((REAL)m_nPos,(REAL)0);
> grFrBk.DrawString(_T("Something to see the text scrolling..."),
> m_pcMemBitmap->GetWidth(),
> m_pcFont,
> p1,
> m_pcFontColor);
> CachedBitmap cCachedBitmap(bTemp,&graphics);
> graphics.DrawCachedBitmap(&cCachedBitmap,0,0);
>
> delete bTemp;
> }
> }
>
> //On my Paint and backgroud functions i do this
> void CChildView::OnPaint()
> {
> CPaintDC dc(this);
> DrawImage(dc.m_hDC);
> }
>
> BOOL CChildView::OnEraseBkgnd(CDC* pDC)
> {
> return TRUE;
> }
>
> //Then the animation is updated in one timer that i set
> (SetTimer(ID_TM_BETWEEN_REFRESHES, 30, 0);)
> void CChildView::OnTimer(UINT nIDEvent)
> {
> if( nIDEvent == ID_TM_BETWEEN_REFRESHES)
> {
> m_nPos-=5;
> CClientDC dc(this);
> DrawImage(dc.m_hDC);
> }
> CWnd::OnTimer(nIDEvent);
> }
>
>
> Then i get the text moving yes but with a slighty flickering... what
> i''m doing wrong? it''s another way of doing this? the GDI+ is not so
> good for this?
>
>
> Thanks for the attencion
>
> Nuno