[Qgis-developer] Multicolumn legends in print composer

[Mathieu Pellerin]

Radim,

Thanks for fixing the width issue.

Regarding layers with no titles and the need for treating the space like a
layer item, see http://hub.qgis.org/issues/3605. We've discussed this with
Marco Hugentobler back then and came up with a nice compromise.

Beyond being a regression as it stands (i.e. legends from 1.8 projects will
have visible vertical spacing issues), here's a simple scenario in picture:
http://hub.qgis.org/attachments/3161/legend-simple-scenario.jpg (the
spacing should be equal for all companies, as well as btween roads and
railways.

Having no layer title is a way to regroup many layers under one layer name
(i.e. having 5 shapefile polygons representing different ago-industrial
crops might nicely be represented under one layer title even though the
items are in five different physical shapefiles).

Math


On Wed, Mar 13, 2013 at 5:31 PM, Radim Blazek <radim.blazek at gmail.com>wrote:

> On Tue, Feb 19, 2013 at 4:48 AM, Mathieu Pellerin <nirvn.asia at gmail.com>
> wrote:
> > Radim,
> >
> > Following up on your implementation of the nice legend's multicolumn
> > feature. I've noticed two regression (one of which I've filed a bug
> > already).
> >
> > 1) The right-side box spacing is now miscalculated as it fails to add the
> > icon label space value. Issue 7099 (http://hub.qgis.org/issues/7099) has
> > been filed with more details and a accompanying screenshot.
>
> Fixed.
>
> > 2) There also was a regression in the way vertical spacing is calculate
> > between layer items and layers. An old issue, 3605, highlighted a similar
> > visual problem which was fixed in revision 08c88575
> > (
> http://hub.qgis.org/projects/quantum-gis/repository/revisions/08c885759bd280339605ea07a221ab20f7dfdb75/diff/
> ).
> > Long story short, layers with no titles are often used as part of a
> group of
> > layer items. As such, the solution found in the cited revision was to
> take
> > into account the layer item vertical spacing to the layer vertical
> spacing.
> > The multicolumn appear to have regressed this. I can open an issue with
> > screenshots if necessary.
>
> Layers with no titles? Is it a hack to avoid the layer title to be
> drawn in the legend for single symbol layers? Wouldn't it be better to
> modify composer legend so that single symbol layers will be drawn
> without separated layer title above symbol and the layer title text
> will be used as the symbol label?
>
> Radim
>
> > Mathieu
> >
> >
> > On Sun, Nov 18, 2012 at 12:10 AM, Radim Blazek <radim.blazek at gmail.com>
> > wrote:
> >>
> >> On Wed, Nov 14, 2012 at 11:11 AM, Andreas Neumann <a.neumann at carto.net>
> >> wrote:
> >> > Hi,
> >> >
> >> > Thanks to Radim we now have multi-column legends in print composer.
> >>
> >> Thanks to Régis and Agence de l'eau Adour as it was already mentioned by
> >> others.
> >>
> >> > This
> >> > was one of my long-time feature requests - but it never got to the top
> >> > of my requests so that we could pay for the work.
> >> >
> >> > Generally it works great, but I noticed two strange behaviors:
> >> >
> >> > * when having only one column (default) - the background rectangle is
> >> > way too small, not covering the full bouding box of the legend
> >>
> >> Width? Fixed.
> >>
> >> > * when going beyong 4 columns, QGIS gets really slow, hangs or
> crashes.
> >>
> >> Splitting of layers into columns is not that easy as it seems to be.
> >> It is a special sort of bin packing problem (NP-hard). Maybe it has
> >> its own name? I have used brute force because:
> >>  - I thought that the number of layer will never be too big
> >>  - implementaion of heuristic algorithm for such a marginal feature
> >> seemed to be overkill
> >>  - suboptimal solution could look quite bad
> >>
> >> You proved immediately that I was wrong. How many layers do you have?
> >> 70 I have read somewhere? My original idea was to calculate number of
> >> possibilities first and decide if heuristic should be used. Now it
> >> seems a necessity.
> >>
> >> Maybe I am wrong and there is a simple solution? Well, I did not know
> >> at the beginning that I am going to solve combinatorial exercises.
> >>
> >> Regarding the crash, I was quite careful, using value() where there
> >> was minimum suspicion that it could run out of range. Many
> >> combinations should not mean allocation of a lot of memory, just more
> >> computational time. Only one combination is always evaluated at time.
> >> Does it seem to be a memory allocation problem or out of list bounds?
> >> Could you send me backtrace off list?
> >>
> >> Please follow/comment http://hub.qgis.org/issues/1841
> >>
> >> Radim
> >>
> >> > Did other test the new multicolumn legends?
> >> >
> >> > Thanks Radim for your work!
> >> >
> >> > Andreas
> >> > _______________________________________________
> >> > Qgis-developer mailing list
> >> > Qgis-developer at lists.osgeo.org
> >> > http://lists.osgeo.org/mailman/listinfo/qgis-developer
> >> _______________________________________________
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> >> http://lists.osgeo.org/mailman/listinfo/qgis-developer
> >
> >
>
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