[Qgis-developer] Diagram improvements

[Marco Hugentobler]

Hi Matthias

>In my opinion this is a bug in the current version and should be changed without option

It will be good to have an additional option to scale proportional to 
the area. But I think you should leave the option to scale the diameter. 
This was done on purpose, because the diagram size you specify is the 
radius, not the area (and this again is similar to the symbology system, 
where point symbol size is also diameter, not area). Btw, I have read 
that there might also be cases where you want to scale diagram sizes 
proportional to the volume (e.g. to display content of lakes, etc.).


Regards,
Marco



Am 09.08.2012 14:48, schrieb Kuhn Matthias, Vermessung:
> Do you think circular diagrams (i.e. text and pie) need to have an option to scale their radius instead of their area?
> In my opinion this is a bug in the current version and should be changed without option as it overexagerates bigger values. But maybe there is a reason to leave this choice to the user?
>
> --
> Matthias Kuhn
>   
>
>> -----Original Message-----
>> From: qgis-developer-bounces at lists.osgeo.org
>> [mailto:qgis-developer-bounces at lists.osgeo.org] On Behalf Of
>> Matthias Kuhn
>> Sent: Tuesday, August 07, 2012 5:37 PM
>> To: Qgis Developer List
>> Subject: [Qgis-developer] Diagram improvements
>>
>> Hi,
>>
>> I recently started an internship at Uster (a city in
>> Switzerland). My job will mostly be to improve QGIS. I'm
>> really looking forward to this great opportunity.
>>
>> My first job is, to improve the diagrams. Any comments are
>> highly appreciated. (If you think something can be done
>> better differently, if you think something is useless, if you
>> are already working on something or you know about somebody
>> already working on something, if you wanna say thank you...)
>>
>> Here a short list of what I've got on my ToDo list.
>>
>> - Minimum size for diagrams (As an option, scale any diagram smaller
>> than...): Done
>> - Text diagram: Center text better vertically (As an option): Done
>> - Charts are not placed on some polygons (e.g. banana shaped polygons.
>> Should this be done with PAL library? Any help appreciated)
>> - Ordering: Draw smaller charts on top of bigger one instead of hiding
>> (randomly?) colliding diagrams.
>> - Make diagrams area accurate! By now the radius instead of
>> area is scaled.
>> - New diagram type: Bar chart
>> - New diagram option: Split diagrams. (Pie charts / Bar
>> charts e.g. age
>> pyramid)
>>
>> If you're interested in the current state of work, have a
>> look at my git repo [0] on master. Where it says done in the
>> list above you should be able to check it out.
>>
>> [0] https://github.com/matthias-kuhn/Quantum-GIS.git
>>
>> Regards,
>> I'm looking forward for comments
>>
>> Disclaimer: Sorry if you get this topic the second time. I
>> thought I'd written something about it yesterday, but
>> couldn't find it in my history nor in the archives, so I'll
>> repeat myself and just believe, that I missed the send button
>> when I tried to click it.
>>
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-- 
Dr. Marco Hugentobler
Sourcepole -  Linux & Open Source Solutions
Weberstrasse 5, CH-8004 Zürich, Switzerland
marco.hugentobler at sourcepole.ch http://www.sourcepole.ch
Technical Advisor QGIS Project Steering Committee