= Gerrit Code Review - PolyGerrit Plugin Styling

CAUTION: Work in progress. Hard hat area. +
This document will be populated with details along with implementation. +
link:https://groups.google.com/d/topic/repo-discuss/vb8WJ4m0hK0/discussion[Join the discussion.]

== Plugin styles

Plugins may provide link:https://www.polymer-project.org/2.0/docs/devguide/style-shadow-dom#style-modules[Polymer style modules] for UI CSS-based customization.

PolyGerrit UI implements number of styling endpoints, which apply CSS mixins link:https://tabatkins.github.io/specs/css-apply-rule/[using @apply] to its direct contents.

NOTE: Only items (ie CSS properties and mixin targets) documented here are guaranteed to work in the long term, since they are covered by integration tests. +
When there is a need to add new property or endpoint, please link:https://bugs.chromium.org/p/gerrit/issues/entry?template=PolyGerrit%20Issue[file a bug] stating your usecase to track and maintain for future releases.

Plugin should be html-based and imported following PolyGerrit's link:dev-plugins-pg.html#loading[dev guide].

Plugin should provide Style Module, for example:

``` html
  <dom-module id="some-style">
    <style>
      :root {
        --css-mixin-name: {
          property: value;
        }
      }
    </style>
  </dom-module>
```

Plugin should register style module with a styling endpoint using `Plugin.prototype.registerStyleModule(endpointName, styleModuleName)`, for example:

``` js
  Gerrit.install(function(plugin) {
    plugin.registerStyleModule('some-endpoint', 'some-style');
  });
```

== Available styling endpoints
=== change-metadata
Following custom css mixins are recognized:

* `--change-metadata-assignee`
+
is applied to `gr-change-metadata section.assignee`
* `--change-metadata-label-status`
+
is applied to `gr-change-metadata section.labelStatus`
* `--change-metadata-strategy`
+
is applied to `gr-change-metadata section.strategy`
* `--change-metadata-topic`
+
is applied to `gr-change-metadata section.topic`

Following CSS properties have link:https://gerrit.googlesource.com/gerrit/+/master/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata-it_test.html[long-term support via integration test]:

* `display`
+
can be set to `none` to hide a section.