[Qgis-user] Looking for a function or variable to retrieve canvas extent

[Alexandre Neto]

Great, thanks!

DelazJ <delazj at gmail.com> escreveu no dia quinta, 22/06/2017 às 13:37:

> Actually the expression using a constructed polygon for the canvas extent
> works;  I was messing with my polygon construction....
>
> Looks like canvas related variables are not available from the attribute
> table (using the select by expression or the field calculator) nor from the
> main select by expression tool in toolbar.
> I created a feature request at https://issues.qgis.org/issues/16744.
> Let's see...
>
> Thanks,
> Harrissou
>
> 2017-06-21 18:31 GMT+02:00 DelazJ <delazj at gmail.com>:
>
>> Unfortunately, this was also my conclusion.... And I'm not sure to
>> understand why: is it a choice of design to not expose them or a missing
>> feature (that i can open a report for)?
>>
>> I can do an ovelap check of the feature geometry and a static extent ie,
>> something like
>> within ($geometry, make_polygon(geom_from_wkt('LINESTRING(a closed
>> rectangle based on canvas extent coordinates in status bar)')))
>> and it seems to work once on two (not pretty sure of the result!) but
>> it's STATIC!
>>
>> 2017-06-21 18:05 GMT+02:00 Alexandre Neto <senhor.neto at gmail.com>:
>>
>>> I guess those variables are simply not accessible from the attribute
>>> table window. So there is no way you can use the map canvas for conditional
>>> formatting.
>>>
>>> DelazJ <delazj at gmail.com> escreveu no dia quarta, 21/06/2017 às 16:34:
>>>
>>>> Thanks Alexandre, but it's too hot to have me doing some maths right
>>>> now :-)
>>>>
>>>> Actually, what I want to do is to apply some conditional formatting in
>>>> the attribute table using the canvas extent values but for some reason,
>>>> those variables you mentioned are not exposed in that expression builder
>>>> dialog.
>>>> There's also a @map_extent variable in master which returns the
>>>> geometry (for composer map only? or canvas also?) but like others, it's not
>>>> exposed.
>>>>
>>>>
>>>> 2017-06-21 17:10 GMT+02:00 Alexandre Neto <senhor.neto at gmail.com>:
>>>>
>>>>> How about using the map_extent_center, map_extent_height and
>>>>> map_extent_width to create a geometry?
>>>>>
>>>>>
>>>>> DelazJ <delazj at gmail.com> escreveu no dia quarta, 21/06/2017 às 14:53:
>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> In the Expression dialog, is there a function or a variable that can
>>>>>> return the current map canvas?
>>>>>> I would like for example apply a value to all features that fall
>>>>>> within the current map canvas but fail to find the right combination (if
>>>>>> ever possible).
>>>>>>
>>>>>> Thanks for any hint,
>>>>>> Harrissou
>>>>>> _______________________________________________
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>>>>>
>>>>> --
>>>>> Alexandre Neto
>>>>> ---------------------
>>>>> @AlexNetoGeo
>>>>> http://sigsemgrilhetas.wordpress.com
>>>>> http://gisunchained.wordpress.com
>>>>>
>>>>
>>>> --
>>> Alexandre Neto
>>> ---------------------
>>> @AlexNetoGeo
>>> http://sigsemgrilhetas.wordpress.com
>>> http://gisunchained.wordpress.com
>>>
>>
>>
> --
Alexandre Neto
---------------------
@AlexNetoGeo
http://sigsemgrilhetas.wordpress.com
http://gisunchained.wordpress.com
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