[Qgis-developer] Multicolumn legends in print composer

Tue Mar 19 04:33:46 PDT 2013

Some more thoughts about composer legend http://hub.qgis.org/issues/6960#note-12
please comment the issue if you care.

Radim

On Thu, Mar 14, 2013 at 10:26 AM, Radim Blazek <radim.blazek at gmail.com> wrote:
> On Thu, Mar 14, 2013 at 10:05 AM, Régis Haubourg
> <regis.haubourg at eau-adour-garonne.fr> wrote:
>> Hi,
>>
>> +1 with Radim. Such hacks do produce inconsistencies and bugs not compatible
>> with collaborative coding. IMHO, we need clean coding in QGIS.
>>
>> A feature already asked I remember could solve both issues. Some of us asked
>> that for layers having single symbol style, symbol in legend should be drawn
>> on the same line as layer’s title (like in Arcgis or mapinfo).
>
> That should be default, it is what most users are expecting, I
> believe. This should not be changed in major line, so if we want that,
> it must be implemented for 2.0.
>
>> http://hub.qgis.org/issues/6960
>
> He asked for single symbol item labels, I have commented and suggested
> single line representation of single symbol layers instead.
>
> Radim
>
>> Using groups will then help reaching Mathieu’s goal?
>>
>> Opinions?
>>
>>
>>
>> I’m ready to put that in a contract if needed
>>
>> Régis
>>
>>
>>
>> De : Radim Blazek-2 [via OSGeo.org] [mailto:ml-node+[hidden email]]
>> Envoyé : jeudi 14 mars 2013 09:47
>> À : HAUBOURG
>> Objet : Re: Multicolumn legends in print composer
>>
>>
>>
>> IMO, using empty layer title to achieve grouping of items from
>> multiple layers into a single layer (group) is just a workaround. If
>> it was working for some reason in previous versions (probably because
>> there was no difference between layer and item spacing) it does not
>> mean that we must add new and new hacks to the code to support it
>> forever.
>>
>> I am not convinced that removing layer space if the layer title is
>> empty
>> (http://hub.qgis.org/projects/quantum-gis/repository/revisions/08c8857/diff/src/core/composer/qgscomposerlegend.cpp)
>> is good. It is a hack to support your need but it introduces another
>> bug and inconsistency because other user may require hidden layer
>> titles (if empty) but still keeping layer spacing.
>>
>> A clean solution could be to add a new group "Road & Railways" with
>> roads and railways layers inside and implement something like flatten
>> sublayers check box for the group, which would put items of all
>> sublayers directly into the group, ignoring layer titles.
>>
>> Radim
>>
>>
>> On Wed, Mar 13, 2013 at 1:30 PM, Mathieu Pellerin <[hidden email]> wrote:
>>
>>
>>> 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 <[hidden email]>
>>> wrote:
>>>>
>>>> On Tue, Feb 19, 2013 at 4:48 AM, Mathieu Pellerin <[hidden email]>
>>>> 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 <[hidden email]>
>>>> > wrote:
>>>> >>
>>>> >> On Wed, Nov 14, 2012 at 11:11 AM, Andreas Neumann <[hidden email]>
>>>> >> 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
>>>> >> > [hidden email]
>>>> >> > http://lists.osgeo.org/mailman/listinfo/qgis-developer
>>>> >> _______________________________________________
>>>> >> Qgis-developer mailing list
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>>>> >> http://lists.osgeo.org/mailman/listinfo/qgis-developer
>>>> >
>>>> >
>>>
>>>
>>
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