[Qgis-developer] Multicolumn legends in print composer

[Radim Blazek]

I'll look at it but currently I am quite occupied.

Radim

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.
>
> 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.
>
> 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
>> > _______________________________________________
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>