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<TITLE>RE: [vtkusers] QVTKWidget signal/slot question</TITLE>
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<P><FONT SIZE=2>Thanks all. I am actually using Ubuntu 8.04 with compiz turned on. I will run some tests without it - thanks a lot.<BR>
<BR>
And Clint I will also follow your suggestions. I currently have 100 ticks, didnt think it would be a problem though but without the ticks valueChanged will only be signaled after mouse up from the slider which isnt really the effect I am looking for<BR>
<BR>
<BR>
-----Original Message-----<BR>
From: Clinton Stimpson [<A HREF="mailto:clinton@elemtech.com">mailto:clinton@elemtech.com</A>]<BR>
Sent: Wed 3/18/2009 6:30 PM<BR>
To: John Eke<BR>
Cc: David Post; vtkusers@vtk.org<BR>
Subject: Re: [vtkusers] QVTKWidget signal/slot question<BR>
<BR>
<BR>
Perhaps moving the mouse in the graphics window to change window level<BR>
skips levels that your QSlider approach doesn't skip. Are you doing<BR>
tracking with the QSlider with a high number of ticks forcing the render<BR>
window to go through each level?<BR>
<BR>
Consider doing some of the following if you aren't already.<BR>
Call QVTKWidget::update() instead of vtkRenderWindow::Render() in your slot.<BR>
Reduce the number of ticks on your QSlider to a practical number (for<BR>
example, more ticks than your screen resolution probably isn't a good idea).<BR>
Turn tracking off and connect to the valueChanged() signal.<BR>
<BR>
Or maybe its only a compiz related problem like others are warning about.<BR>
<BR>
Clint<BR>
<BR>
John Eke wrote:<BR>
> Hi,<BR>
><BR>
> I currently have a Qt dialog with a slider. The valueChanged signal<BR>
> from this slider is connected to a slot in my QVTKWidget subclass<BR>
> which performs some Window-Level modifications on a vtkImageActor<BR>
> inside the renderer.<BR>
><BR>
> In the vtk example (Examples/GUI/Qt/ImageViewer) dragging the mouse<BR>
> across the image is fast enough. So why does it get ridiculously slow<BR>
> when I send the commands through a slot? Is there a way I can speed it up?<BR>
><BR>
> - John E<BR>
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