A standard widget for configuring text format properties for use
with QgsTextRenderer/QgsTextFormat.
It's modelled heavily off QgsColorButton, and supports lots of nice
things like dragging formats between buttons, copying and pasting
format settings, dropping colors from color buttons, dragging colors
from font buttons to color buttons, directly setting font size
and opacity/color without having to open a dialog.
Historically the configuration used to be stored in layer's custom properties, but that does not scale
beyond simple rendering and so rule-based labeling introduced storage of configuration natively in XML elements.
That left us with two different ways of reading/writing labeling configurations. This work makes all configuration
to use native XML elements.
To keep compatibility of 2.x projects, reading of configuration from custom properties is preserved.
This commit also adds Python APIs for direct manipulation of labeling configuration through vector layer's
setLabeling() and labeling() calls.
Allows applying a paint effect (such as blurs) to label buffers.
Blurring label buffers is a great way to get the text readability
of a label buffer without the distracting halo effect.
This change is being driven by:
- need for consistent terminology in the api. Currently there's
a confusing mix of border/outline used
- need for consistent terminology in the gui - we have a mix
of "border"/"outline"/"pen"
- bringing QGIS into line with the standard terminology used
in other graphic editing programs
These were not being used by QGIS code (always left at default 1.0
value), and removing them from the api allows us to simplify lots
of code. It also makes QgsRenderContext scaling much less confusing.
Moves all the drawing code out of labeling into a new class
which just handles rendering text. This allows other parts
of the code to utilise all the advanced formatting options
that labeling supports, eg rendering text with shadows,
buffers and backgrounds.
