packages/core: added initial AppThemeApi

packages/core/src/api/apis/definitions/AppThemeApi.ts

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2020 Spotify AB
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { ApiRef } from '../ApiRef';
+import { BackstageTheme } from '@backstage/theme';
+
+/**
+ * Describes a theme provided by the app.
+ */
+export type AppTheme = {
+  /**
+   * Title of the theme
+   */
+  title: string;
+
+  /**
+   * Theme variant
+   */
+  variant: 'light' | 'dark';
+
+  /**
+   * The specialized MaterialUI theme instance.
+   */
+  theme: BackstageTheme;
+};
+
+/**
+ * The AppThemeApi gives access to the current app theme, and allows switching
+ * to other options that have been registered as a part of the App.
+ */
+export type AppThemeApi = {
+  /**
+   * Get a list of available themes.
+   */
+  getThemeOptions(): AppTheme[];
+
+  /**
+   * Get the current theme. Returns undefined if the default theme is used.
+   */
+  getTheme(): AppTheme | undefined;
+
+  /**
+   * Set a specific theme to use in the app, overriding the default theme selection.
+   */
+  setTheme(theme?: AppTheme): void;
+};
+
+export const appThemeApiRef = new ApiRef<AppThemeApi>({
+  id: 'core.apptheme',
+  description: 'API Used to configure the app theme, and enumerate options',
+});

packages/core/src/api/apis/definitions/index.ts

@@ -21,6 +21,7 @@
 // If you think some API definition is missing, please open an Issue or send a PR!
 
 export * from './AlertApi';
+export * from './AppThemeApi';
 export * from './ErrorApi';
 export * from './FeatureFlagsApi';
 export * from './OAuthRequestApi';