D29386: [systemtray] Fix SNI icon not rendering

[Konrad Materka]

kmaterka created this revision.
kmaterka added reviewers: Plasma: Workspaces, Plasma, davidedmundson, broulik, ngraham.
Herald added a project: Plasma.
Herald added a subscriber: plasma-devel.
kmaterka requested review of this revision.

REVISION SUMMARY
  In some rare situations SNI icons are not rendered. It happens randomly, only some users are affected. It does not happen on every login.
  Only SNI icons are not rendered, Plasmoids are fine. Restarting plasmashell or re-adding systemtray applet helps.
  
  In QML all roles need to be defined before model is used. When data engines is used a a source for a data model, all roles has to be defined and proper value assigned (not a null QVariant). StatusNotifierItemSource does this properly, but in some situations it sets null QVariant for Icon. Setting empty/null QVariant removes key/role from the date set (DataConteiner implementation). If data model was loaded earlier or later when Icon has proper value it will work properly. In some rare situation it is possible that data model is loaded when Icon has null value assigned (in other words - removed), role is removed from the data model and not avaiable to system tray applet.
  
  This fix makes sure that there is always a value for Icon role. To check if icon is null native method has to be used - QML does not understand that QIcon can be null.
  
  BUG: 419305
  FIXED-IN: 5.18.5

TEST PLAN
  I don't have any reliable method to reproduce this issue.

REPOSITORY
  R120 Plasma Workspace

BRANCH
  Plasma/5.18

REVISION DETAIL
  https://phabricator.kde.org/D29386

AFFECTED FILES
  applets/systemtray/package/contents/ui/items/StatusNotifierItem.qml
  applets/systemtray/systemtray.cpp
  applets/systemtray/systemtray.h
  dataengines/statusnotifieritem/statusnotifieritemsource.cpp

To: kmaterka, #plasma_workspaces, #plasma, davidedmundson, broulik, ngraham
Cc: plasma-devel, Orage, LeGast00n, The-Feren-OS-Dev, cblack, jraleigh, zachus, fbampaloukas, ragreen, ZrenBot, ngraham, himcesjf, lesliezhai, ali-mohamed, jensreuterberg, abetts, sebas, apol, ahiemstra, mart
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