[Qgis-user] data defined labelling field details?

[a.neumann at carto.net]

> - As I noted, data-driven offsets as an alternative to absolute 
> position.

 This is already partially possible - for labeling of linear features 
 you can define a label distance data-defined setting. This could be 
 handeld similar for point features, but would require two fields for 
 relative offsets of course.

> - I see that the data-driven buffer settings are inconsistent between
> the old and new.  The old can set transparency from data but not
> color, and the new can set color from data but not transparency.  How
> about both?

 yes, this should be improved.

> Additional options to consider:
>
> - data-driven scale dependent rendering values.  And same for the
> general feature rendering.  I've been designing my data with this in
> mind and was disappointed that it isn't possible yet - scale 
> dependent
> rendering is only per layer.

 you mean that you want to have multiple settings for multiple scale 
 ranges in one single layer? I know, this would be really nice to have. 
 The same for the normal symbology. Others systems, like Autocad Map, 
 already offer this functionality. It would often reduce the number of 
 layers people have to put into a project.

 A first step, however, is already made. With the rule-based renderer 
 you can at least have multiple rules for multiple scale ranges within a 
 single layer.

> - some way to specify in any data-driven setting to use the non-data
> driven setting, like an invalid or null value.  That is, say for
> placement, if the data value is NULL or empty use the around/over
> setting in the Advanced tab.  That way you can let the engine
> calculate fixed/dynamic settings and override them to fine-tune
> labelling of specific features.

 yes - that's partially already possible, though probably not for all 
 values. Would be nice if it worked for all settings where it makes 
 sense.

 In summary I think there isn't much missing in the new labeling that 
 isn't present in the old engine. There are bits and pieces here and 
 there.

 The ability to have multiple scale ranges for label and symbology 
 settings within a single layer would be a big plus! But probably more 
 work than the other missing bits.

 Andreas