Bug report #19910
Marker opacity is not working on a Marker Lines
|Affected QGIS version:||3.3(master)||Regression?:||No|
|Operating System:||Windows and Linux||Easy fix?:||No|
|Pull Request or Patch supplied:||No||Resolution:|
|Crashes QGIS or corrupts data:||No||Copied to github as #:||27734|
When using a marker line, changing the marker's opacity has no consequences on the final symbol. In fact, if you set it to 50% and move to another setting, if you go back, it will be set to 100% again.
Color opacity works as expected.
Make QgsSymbolLayerUtils::symbolPreview* methods const, and utilise
internal symbol clones
Rendering symbols is a NON-CONST operation, which can permanently
alter the symbol instance (e.g. via changes made by the symbol
or symbol layer's startRender methods.).
This makes debugging super complex - because methods which look
like they are just generating previews of symbols can actually
change the original symbol instances, resulting in permanent changes
to a layer's style.
Refs #19910 (specifically, me pulling my hair out trying to deduce
seemingly random changes to layer's symbols)