feat: splash screen support for Electron

Enhances the ElectronMainApplication to optionally render a splash
screen until the frontend is ready.

The splash screen can be configured via the application config object
"theia.frontend.config.electron.splashScreenOptions". Mandatory is the
option "content" which specifies a relative path from the application
root to the content of the splash screen. Optionally "width", "height",
"minDuration" and "maxDuration" can be handed over too.

Configures the Electron example application to show a Theia logo splash
screen.

Implements eclipse-theia#13410

Contributed on behalf of Pragmatiqu IT GmbH

CHANGELOG.md

@@ -7,7 +7,8 @@
 ## not yet released
 
 - [application-package] bumped the default supported API from `1.86.2` to `1.87.2` [#13514](https://github.com/eclipse-theia/theia/pull/13514) - contributed on behalf of STMicroelectronics
-- [core]  Fix quickpick problems found in IDE testing [#13451](https://github.com/eclipse-theia/theia/pull/13451) - contributed on behalf of STMicroelectronics
+- [core] Fix quickpick problems found in IDE testing [#13451](https://github.com/eclipse-theia/theia/pull/13451) - contributed on behalf of STMicroelectronics
+- [core] Splash Screen Support for Electron [#13505](https://github.com/eclipse-theia/theia/pull/13505) - contributed on behalf of Pragmatiqu IT GmbH
 - [plugin] Extend TextEditorLineNumbersStyle with Interval [#13458](https://github.com/eclipse-theia/theia/pull/13458) - contributed on behalf of STMicroelectronics
 
 <a name="breaking_changes_not_yet_released">[Breaking Changes:](#breaking_changes_not_yet_released)</a>

dev-packages/application-package/src/application-props.ts

@@ -33,8 +33,36 @@ export type ElectronFrontendApplicationConfig = RequiredRecursive<ElectronFronte
 export namespace ElectronFrontendApplicationConfig {
     export const DEFAULT: ElectronFrontendApplicationConfig = {
         windowOptions: {},
-        showWindowEarly: true
+        showWindowEarly: true,
+        splashScreenOptions: {}
     };
+    export interface SplashScreenOptions {
+        /**
+         * Initial width of the splash screen. Defaults to 640.
+         */
+        width?: number;
+        /**
+         * Initial height of the splash screen. Defaults to 480.
+         */
+        height?: number;
+        /**
+         * Minimum amount of time in milliseconds to show the splash screen before main window is shown.
+         * Defaults to 0, i.e. the splash screen will be shown until the frontend application is ready.
+         */
+        minDuration?: number;
+        /**
+         * Maximum amount of time in milliseconds before splash screen is removed and main window is shown.
+         * Defaults to 30000.
+         */
+        maxDuration?: number;
+        /**
+         * The content to load in the splash screen.
+         * Will be resolved from application root.
+         *
+         * Mandatory attribute.
+         */
+        content?: string;
+    }
     export interface Partial {
 
         /**
@@ -50,6 +78,13 @@ export namespace ElectronFrontendApplicationConfig {
          * Defaults to `true`.
          */
         readonly showWindowEarly?: boolean;
+
+        /**
+         * Configuration options for splash screen.
+         *
+         * Defaults to `{}` which results in no splash screen being displayed.
+         */
+        readonly splashScreenOptions?: SplashScreenOptions;
     }
 }
 

examples/electron/package.json

@@ -10,7 +10,13 @@
     "frontend": {
       "config": {
         "applicationName": "Theia Electron Example",
-        "reloadOnReconnect": true
+        "reloadOnReconnect": true,
+        "electron": {
+          "splashScreenOptions": {
+            "content": "resources/theia-logo.svg",
+            "height": 90
+          }
+        }
       }
     },
     "backend": {