[Qgis-developer] Listener for Atlas Change Page

[Shawn Tse]

Thanks, that looks like exactly the kind of function that I'm looking
for. I'm using QGIS 2.18.0, I'm wondering, is there any way to use
this function without having to select a menu item in the the plugin?

I'm not sure how to get started, because most of the existing plugins
seem to be activated by a menu item or a toolbar button in the main
editor instead of via the atlas interface.

Thank you and I really appreciate the help!

On Mon, Dec 12, 2016 at 11:02 PM, Nyall Dawson <nyall.dawson at gmail.com> wrote:
>
>
> On 13 Dec 2016 4:44 PM, "Shawn Tse" <shawntse at gmail.com> wrote:
>
> Hi all,
>
> I'm interested in being able to make graphs that update depending on
> what the active feature in the atlas is. I know some python and a
> little bit of the QGIS API, but I'm curious - is there some sort of
> listener function for the atlas that gets called whenever the Preview
> Atlas/Prev Feature/Next Feature/First Feature/Last Feature buttons are
> pressed?
>
>
> Try QgsAtlasComposition::featureChanged. See
> https://qgis.org/api/classQgsAtlasComposition.html#ab1a15fdb6d20ebb1254ebb6714254fac
>
> Nyall
>
>
> What I eventually want to do is to manipulate the node items that were
> created in a recent updated version of QGIS, and use them to make a
> line graph, gridlines, etc.
>
> I'm hoping to draw the data directly from the shapefiles themselves or
> from a .csv file.
>
> I originally tried to use an expression in a text box to do this, but
> it seems that expressions are unable to use custom functions to
> manipulate the composer. So I'm hoping that there's some sort of
> Listener method.
>
> Thanks.
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