[vtkusers] Re: Some question of the using of vtkWin32VideoSource
zjzhang at ee.cuhk.edu.hk
Mon May 21 13:58:03 EDT 2001
But actually when I run the video.tcl the second time after I reset
my computer , there will be the "can't find video card" .
also I have use the multi-thread in a MFC based application
and every time in the work thread it will gives a update message to call
update redraw the video window, and in the update function for the video
window function these code is written: but I can only get a static image in
the video window, and it doesn't change with the frames of image changes.
and the program also turns to be very slow.
void CVideoView::OnUpdate(CView* pSender, LPARAM lHint, CObject* pHint)
// TODO: Add your specialized code here and/or call the base class
// first remove any old actors
propc = this->GetDocument()->GetProps1();
while (prop = propc->GetNextProp())
this->vtkMFCRenderView::OnUpdate(pSender, lHint, pHint);
----- Original Message -----
From: David Gobbi <dgobbi at irus.rri.on.ca>
To: zhangzhijun <zjzhang at ee.cuhk.edu.hk>
Cc: <vtkusers at public.kitware.com>
Sent: Tuesday, May 22, 2001 1:14 AM
Subject: Re: Some question of the using of vtkWin32VideoSource
> Hi Zhang,
> The problem is that while the 'for' loop is running, Windows is unable
> to process events. This is not a problem with e.g. the
> vtkMILVideoSource because the MIL interface is multi-threaded, but
> unfortunately Video for Windows relies on Windows event handling to
> process the callbacks.
> The only solution is for you write a program that does proper event
> handling. If you call Grab from somewhere within your main WNDPROC
> message handler, then Video for Windows won't be blocked.
> Does anyone out there who has used vtkWin32VideoSource have a simple
> example of this? I don't do much applications-level programming
> in C++ myself.
> Another solution is to write your program in tcl or python/Tkinter
> and to only do the grabs after you have started the 'mainloop'.
> See 'video.tcl' for an example.
> - David
> David Gobbi, MSc dgobbi at irus.rri.on.ca
> Advanced Imaging Research Group
> Robarts Research Institute, University of Western Ontario
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