Tree node icons, lines and white background

[mmakrzem]

After switching our Java application to using Radiance I noticed that our JTree nodes no longer render "folder" icons for parent nodes that have children, and the lines showing the connection between parent and child nodes are missing. See image below (left = new behaviour with Radiance) right = original behaviour without radiance.

How do I re-enable the original tree rendering behaviour with radiance? Additionally, I can't seem to figure out a way to force any JPanel to render a white background anymore. ie The JTree used to have a white background giving good contrast between the background and the content inside the panel. Now everything is a dull grey which is undesirable.

[kirill-grouchnikov]

• Tree lines have been removed a long time ago as a part of removing visual noise across all Swing components, and that is not coming back
• For that folder icon, you're probably getting it from this line in WindowsLookAndFeel - if this is what you're using, or from another look-and-feel that sets the Tree.closedIcon property in the UIDefaults during its initialization pass. In Radiance this entry is set to an empty icon by design.

For components with custom backgrounds, there are two answers.

• For versions before 9.5-SNAPSHOT, see RadianceThemingCortex.GlobalScope.setColorizationFactor API and its comments
• For versions 9.5-SNAPSHOT and above, see this issue and this commit for an example of using the more modern Radiance APIs for custom color configuration of specific components, if those cannot be done at the level of Radiance decoration areas.

[mmakrzem]

What would I need to do to force the tree lines to render again in a JTree? Do I need to implement my own TreeCellRenderer?

[kirill-grouchnikov]

The lines are drawn by paintHorizontalPartOfLeg and paintVerticalPartOfLeg methods in the tree UI delegate. Maybe they can be emulated at the level of a custom tree cell renderer if you keep track of the item level inside the tree model.

The tree UI delegates in Radiance are internal implementation details, and there is no official support for extending any of those internal classes - or any promise on the future availability of these classes. The current visual look of Radiance tree is the intended design, with no plans to provide customization hooks to enable the tree lines.