Bug report #19910

Marker opacity is not working on a Marker Lines

Added by Alexandre Neto over 5 years ago. Updated about 5 years ago.

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.

marker_opacity_error.gif (401 KB) Alexandre Neto, 2018-09-21 11:08 AM

Associated revisions

Revision 4022c5fc
Added by Nyall Dawson about 5 years ago

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)


#1 Updated by João Gaspar over 5 years ago

Tested in Windows 7 64-bits with same version have the same behavior.

In QGIS 3.2.0 have the same behavior.

#2 Updated by Alexandre Neto over 5 years ago

  • Regression? changed from No to Yes
  • Operating System changed from Ubuntu 18.04 to Windows and Linux
  • Affected QGIS version changed from 3.2.3 to 3.3(master)

Still valid on QGIS 3.3 (a0d46d12c1).

#3 Updated by Nyall Dawson about 5 years ago

  • Regression? changed from Yes to No

This is not a regression - as far as I can tell it's never behaved that way (tested back a few versions).

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