[Qgis-developer] Composer Legend items: what are the differences between "auto-update" and "update all" options?

DelazJ delazj at gmail.com
Tue Oct 13 09:39:46 PDT 2015

Sorry, I think I do not well express my thoughts [0] . Maybe it's an UX
matter instead of developer's (so CCing UX-list). Let me reword it. Do we
need at the same place two "buttons" that do same thing?
I'll take QGIS2.4 as basis since these changes were introduced in 2.6 (if
i'm not wrong) and I haven't really tested legends in newer releases till

In 2.4, after you add a legend in the composer, it adds all layers that are
visible. And legend item is by default independent of what happens to the
TOC. For example, renaming layers in the TOC won't be applied unless the
user decided to do so. 3 options were proposed:
- "auto-update" checkbox (checked by default) which automatically triggers
the changes done in the style of an *already added* layer to the legend
item. Issue : changes done to a layer when the option is unchecked are not
applied unless you redo changes in the same layer.
- This issue can be fixed by the use of "update item" option which applies
the classification of the selected legend item, one by one.
- and "update all" a contrario, resets all the legend according to layers
shown in the main map canvas : delete ALL the modifications added by the
user in the legend, add all the visible layers, removes the invisible ones
The main issue with this system is that legend may not be synchrone with
the map item since updating procedure in legend was mainly on either
already added layers or visible layers in canvas and these layers may not
be the ones in the map item. But on the other hand, there are three options
that do three different things.

In the current design (master 43c046b and it should be same thing in LTR),
if you add a legend, it  adds ALL the layers available in the project,
visible or not [1]. And any change applied to the properties of a layer
listed in the legend item is immediately triggered, meaning that the
"update item" option is no more needed. I agree with you. And having a real
and direct relation between layer panel and legend item is a great
But I notice that changes in a layer properties are echoed in the legend
with or without "auto-update" option checked. Actually "auto-update" option
just resets the legend list, ensuring that the legend looks like the layer
panel (added/removed/moved layers). And so does "update all". Same thing!
One is automatic, the other one isn't.
Isn't there another way to provide same capabilities without two buttons?

Notice that there is a "Reset default" option in the contextual menu of
legend item. Better move it up?

[0] http://comments.gmane.org/gmane.comp.gis.qgis.devel/38833
 [1] http://hub.qgis.org/issues/13575


2015-10-12 18:14 GMT+02:00 m roy <royroge at outlook.com>:

> "After changing the symbology in the QGIS main window you can click on
> *[Update]* to adapt the changes in the legend element of the print
> composer"
> I think that now changes in the legend element of print composer is
> automatic when you change, say, layer name color,
> and that was the purpose of "update item"
> Il 12/10/2015 18.02, DelazJ ha scritto:
> For the recall :
> http://docs.qgis.org/2.0/en/docs/user_manual/print_composer/print_composer.html#legend-items
> 2015-10-12 17:51 GMT+02:00 m roy <royroge at outlook.com>:
>> > In previous releases (till 2.4 I think), there was another option
>> > "Update item" that keeps user customization and can explain why there
>> > was an "Update all" option that resets all modifications. Now, both
>> > options do reset.
>> >
>> Well this is another issue, but i don't remember what was Update item
>> purpose ...sorry
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