Add label functions in field calculator

[qgib]

Author Name: Reinhard Reiterer (Reinhard Reiterer) Original Redmine Issue: 16382

Redmine category:field_calculator

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There should be a function in the field calculator that returns the hight/width of labels.

[qgib]

Author Name: Reinhard Reiterer (Reinhard Reiterer)

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This would be quite helpful to create 'Geometry generator' based leader lines that are not covered by the labels:

@-- Geometry generator: make_line( make_point(label_x, label_y), $geometry)@

See also:

http://gis.stackexchange.com/questions/232709/creating-leader-lines-for-moved-labels

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• easy_fix was configured as 0

[pjshelton]

I think #37862 is asking the same thing.

[m-kuhn]

Copy pasting information from #37862

Add font metrics methods as expression functions

If you're thinking of adding this, you'll likely need to first create a new "render context" expression scope, since these metrics are all highly render context dependent.