[QGIS-Developer] Legend symbol and geometry generator

[Julien Cabieces]

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Hi devs,

I would like to fix the legend symbol rendering when a geometry generator is involved in the browser and in the layout. I would like to ask you what it is the expected behavior, because it doesn't look very consistent to me.

Every layer in my project as a geometry generator with a big buffer.

In browser, As you can see on attachmed file, only marker with categorized or rule renderer can be bigger than a 16x16 pixel icon. Is it wanted ?

Its size is limited by the parameter "Options > Canvas & legend > Maximum legend symbol size"
Note that the marker symbol is drawn "big" according to geometry generator definition, and QGIS keep a square subset in the center regarding the max size. This is different when you chose a very big symbol for your marker where it is scaled to fit the icon size. 

Is it wanted ? 

Same questions apply for layout.
Do we want the exact same behavior than browser ?
Do we want to scale the content to the legend symbol given size or do we
want to keep only what's in the center ?
Do we want a different way of dealing with marker on one side, and
line/polygon on other side ?
Do we want a different rendering whether there is a categorized/rule renderer or not ? 

Regards,
Julien