Re: [Qgis-developer] Processing: fixed, variable, and percentage buffer

2016-12-01 Thread Matthias Kuhn 
On 12/01/2016 12:23 PM, Paolo Cavallini wrote:
> Il 01/12/2016 12:20, Nyall Dawson ha scritto:
> 
>> I don't really understand what you mean by this - can you elaborate?
> 
> I think some expression (in this case the one calculating Percentage
> buffer) could be saved in a list, with a descriptive name, so the user
> could use it straight away, without typing or even understanding the
> details.
> All the best.
> 

I think the tricky part is the parameters for the expressions.

"scale_value_field" / @percentage * 100

    
   field parameter  integer literal parameter

I think it will be required to formalize these paratemers and create a
UI for them to make it really user friendly.

Or I didn't understand your idea yet.

Matthias
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Re: [Qgis-developer] Processing: fixed, variable, and percentage buffer

2016-12-01 Thread Paolo Cavallini 
Il 01/12/2016 12:20, Nyall Dawson ha scritto:

> I don't really understand what you mean by this - can you elaborate?

I think some expression (in this case the one calculating Percentage
buffer) could be saved in a list, with a descriptive name, so the user
could use it straight away, without typing or even understanding the
details.
All the best.
-- 
Paolo Cavallini - www.faunalia.eu
QGIS & PostGIS courses: http://www.faunalia.eu/training.html
https://www.google.com/trends/explore?date=all=IT=qgis,arcgis
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Re: [Qgis-developer] Processing: fixed, variable, and percentage buffer

2016-12-01 Thread Nyall Dawson 
On 1 Dec 2016 9:16 PM, "Paolo Cavallini"  wrote:

Il 01/12/2016 12:14, Nyall Dawson ha scritto:

> I've been thinking about something similar to the data defined buttons
> used by symbology. Ie default to a constant value input, but using a
> custom widget you can choose to use a fields value or a custom expression.

or also named preset expressions, possibly?
all the best.


I don't really understand what you mean by this - can you elaborate?

Nyall

--
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Re: [Qgis-developer] Processing: fixed, variable, and percentage buffer

2016-12-01 Thread Paolo Cavallini 
Il 01/12/2016 12:14, Nyall Dawson ha scritto:

> I've been thinking about something similar to the data defined buttons
> used by symbology. Ie default to a constant value input, but using a
> custom widget you can choose to use a fields value or a custom expression.

or also named preset expressions, possibly?
all the best.
-- 
Paolo Cavallini - www.faunalia.eu
QGIS & PostGIS courses: http://www.faunalia.eu/training.html
https://www.google.com/trends/explore?date=all=IT=qgis,arcgis
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Re: [Qgis-developer] Processing: fixed, variable, and percentage buffer

2016-12-01 Thread Nyall Dawson 
On 1 Dec 2016 8:47 PM, "Paolo Cavallini"  wrote:

Hi all,
with the recent addition of expressions as parameters, I think variable
buffer alg is a duplication of the fixed one, which should be renamed in
a generic "Buffer": am I wrong?
BTW: also Percentage buffer can be done with the same technique, so the
plugin[0] will possibly be useless.
Unsure about other plugins[1]: possibly these coud be unified as well?
Probably for the average user having to enter expression for this could
be intimidating at first: what about having a set of predefined expressions?



I've been thinking about something similar to the data defined buttons used
by symbology. Ie default to a constant value input, but using a custom
widget you can choose to use a fields value or a custom expression.

Nyall

All the best, and thanks.
===
[0]
http://plugins.qgis.org/plugins/BufferByPercentage/

[1]
http://plugins.qgis.org/plugins/Multi_Ring_Buffer/
http://plugins.qgis.org/plugins/MultiDistanceBuffer/
--
Paolo Cavallini - www.faunalia.eu
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Re: [Qgis-developer] Processing: fixed, variable, and percentage buffer

2016-12-01 Thread Paolo Cavallini 
Hi Matthias,

Il 01/12/2016 11:59, Matthias Kuhn ha scritto:

> That's where I expect the biggest impact as well. Do you have an idea
> how to make this as easy as possible? A list of useful predefined
> expressions?

Yes, that was my idea. Possible named ones, so users can use them even
when not fully understanding the details.
All the best.
-- 
Paolo Cavallini - www.faunalia.eu
QGIS & PostGIS courses: http://www.faunalia.eu/training.html
https://www.google.com/trends/explore?date=all=IT=qgis,arcgis
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Re: [Qgis-developer] Processing: fixed, variable, and percentage buffer

2016-12-01 Thread Matthias Kuhn 
Hi Paolo

Good thinking, deduplication is always a good move

On 12/01/2016 11:47 AM, Paolo Cavallini wrote:
> Probably for the average user having to enter expression for this could
> be intimidating at first: what about having a set of predefined expressions?

That's where I expect the biggest impact as well. Do you have an idea
how to make this as easy as possible? A list of useful predefined
expressions?

Matthias
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[Qgis-developer] Processing: fixed, variable, and percentage buffer

2016-12-01 Thread Paolo Cavallini 
Hi all,
with the recent addition of expressions as parameters, I think variable
buffer alg is a duplication of the fixed one, which should be renamed in
a generic "Buffer": am I wrong?
BTW: also Percentage buffer can be done with the same technique, so the
plugin[0] will possibly be useless.
Unsure about other plugins[1]: possibly these coud be unified as well?
Probably for the average user having to enter expression for this could
be intimidating at first: what about having a set of predefined expressions?
All the best, and thanks.
===
[0]
http://plugins.qgis.org/plugins/BufferByPercentage/

[1]
http://plugins.qgis.org/plugins/Multi_Ring_Buffer/
http://plugins.qgis.org/plugins/MultiDistanceBuffer/
-- 
Paolo Cavallini - www.faunalia.eu
QGIS & PostGIS courses: http://www.faunalia.eu/training.html
https://www.google.com/trends/explore?date=all=IT=qgis,arcgis
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