[R] get mouse position without waiting for a click

[Bert Gunter]

On Windows or X11, (others ???)

?getGraphicsEvent

Cheers,
Bert

On Mon, Sep 30, 2013 at 7:46 AM, Stanislav Aggerwal
<stan.aggerwal at gmail.com> wrote:
> Consider the following:
>
> par(mar=c(0,0,0,0),xaxs = 'i',yaxs='i')
> plot.new()
> for(i in 1:20)
>   {
>   z <- matrix(runif(256*256), ncol=256)
>   dev.hold()
>   image(z, col=grey(0:255/255),zlim=c(0,1),useRaster=TRUE)
>   dev.flush()
>   Sys.sleep(.1)
>   }
>
> I would like to continuously display the animation until a mouse click
> happens. Obviously, locator() can't be used for this, because it will halt
> the animation while waiting for the mouse click. So something like this
> won't work:
>
> while((r<-locator(n=1)) == NULL)
>   {
>   z <- matrix(runif(256*256), ncol=256)
>   dev.hold()
>   image(z, col=grey(0:255/255),zlim=c(0,1),useRaster=TRUE)
>   dev.flush()
>   Sys.sleep(.1)
>   }
>
> Can somebody suggest a way to get user input while displaying the
> animation? I am willing to use a keypress if not the mouse. Essentially, I
> need an input routine that does not wait for a response but just checks at
> one instant (like kbhit in C).
>
> Thanks very much for any help.
>
> Stan
>
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>
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-- 

Bert Gunter
Genentech Nonclinical Biostatistics

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