[Qgis-developer] Improving the legend for map-units, data-defined symbology, diagrams and labels

[Andreas Neumann]

I correct myself regarding issue 1:

It is not unpredictable and even corresponds nicely with the scale - so 
map display and legend display are nicely in sync. But I think we need 
to be able to restrict legends where map units are involved to a certain 
min/max scale range. So the symbols don't get too big or too small and 
get into each others way.

Andreas



On 13.11.2014 23:29, Andreas Neumann wrote:
> Hi,
>
> We need to solve a number of open issues with the legend - preferably 
> in the next QGIS release. This concerns mainly the print composer 
> legend, but perhaps the legend in the legend tree could be solved at 
> the same time. At the same time we should also think how these 
> improved legends could be exposed in QGIS server.
>
> I am trying to list the things I would like to see improved:
>
> 1. Support for legends for graphical properties defined with map 
> units. Currently these legends display in the print composer at very 
> strange, unpredictable and unusable sizes. E.g. a stroke-width or dash 
> defined in map units is either way too big or too small. Same for 
> symbol sizes defined in map units. We need a way to translate these 
> map units in usable paper units suitable for display in the legend. 
> Let the map author define a corresponding mm size (along with the map 
> units) - solely for the display of the legend.
>
> 2. Display of legends for graphical properties defined with 
> data-defined symbology. We need a way to specify common graphical 
> properties in the legend that are of interest in the legend. F.e. - if 
> I define the colors data-defined I would like to be able to specify 
> the expected colors that may appear in my data/project. This could be 
> either done dynamically (by scanning the data) or statically (decided 
> by the map author). Perhaps both methods. To me, the static method may 
> be more predictable and more performant.
>
> 3. Legends for diagrams (pie charts, bar charts) - something similar 
> to 
> http://esri.force.com/servlet/rtaImage?eid=087300000008Nki&feoid=Body&refid=0EM30000000Co0O 
> - showing both sizes and colors - nicely stacked into each other.
>
> 4. Legends for labels - here we also have the same issue: how can we 
> display a label legend where graphical properties are set based on 
> data-defined values?
>
> -------------------
>
> I know this is not yet well specified - but I would like to open the 
> discussion how we can solve the above issues. And I am looking for a 
> QGIS developer who is interested in solving the above issues. If you 
> are interested in developing above listed improvements, please join 
> the discussion or contact me offlist.
>
> Do you have ideas how to solve the issues with map units and 
> data-defined symbology?
>
> There is at least one other german organization (QGIS user) who is 
> interested in this and would help finance this effort. Perhaps we can 
> find more organizations who would help finance.
>
> Thank you for joining the discussion,
>
> Andreas
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