[RQt-devel] an easy way to rotate a layer?

[Michael Lawrence]

Again, moved this over to qtinterfaces-devel.

There are basically two transforms involved: one from item (layer) to scene
and one from scene to view (which might be translated by a third transform
to screen coordinates if there is a scrolled viewport). To rotate the entire
plot, axes layers included, it's probably best to modify the view transform.

Unfortunately, the view transform basically must be identity if you're using
the geometry rescale mode in the plot view (the plot view is then making
sure that the plot fits in the viewport by changing the geometry of the
layer in the scene). I might be able to improve that if necessary though. I
guess I had not anticipated this use-case. It doesn't make sense to zoom
with the geometry rescale mode but rotations might make sense.

Thanks for this suggestion,
Michael

On Tue, Oct 19, 2010 at 2:31 PM, Yihui Xie <xieyihui at gmail.com> wrote:

> Hi everyone,
>
> I still feel lost in the Qt sea, but I believe it should be very easy
> to rotate a layer by 90 degrees, and I feel it is something like
> qdeviceTransform(), but I just don't know how to use this function.
> Can anyone give me an example? e.g. switch x and y in a scatter plot
> (without really switching the values of x and y)
>
> This can reduce the efforts on considering the direction of a plot,
> being horizontal or vertical; in my par-coords plots, I did this on
> the R level long ago. Maybe that is a waste of time.
>
> Thanks!
>
> Regards,
> Yihui
> --
> Yihui Xie <xieyihui at gmail.com>
> Phone: 515-294-2465 Web: http://yihui.name
> Department of Statistics, Iowa State University
> 2215 Snedecor Hall, Ames, IA
>
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