Add docs for new dashboard api

Signed-off-by: Julius Härtl <jus@bitgrid.net>

developer_manual/digging_deeper/dashboard.rst

@@ -0,0 +1,178 @@
+=========
+Dashboard
+=========
+
+The dashboard app aims to provide the user with a general overview of their
+Nextcloud and shows information that is currently important.
+
+App developers can integrate into the dashboard app and provide their own widgets.
+
+
+Register a dashboard widget
+---------------------------
+
+A dashboard widget is represented by a class implementing the `OCP\\Dashboard\\IWidget`
+interface. This class will be instantiated whenever the dashboard is loaded.
+Any bootstrap code that is needed for the widget can be implemented inside
+of the `load` method and will be called when the dashboard is loaded.
+
+.. code-block:: php
+
+    <?php
+
+    namespace OCA\MyApp\Dashboard;
+
+    use OCP\Dashboard\IWidget;
+    use OCP\IInitialStateService;
+    use OCP\IL10N;
+    use OCP\IURLGenerator;
+    use OCP\IUserSession;
+
+    class MyAppWidget implements IWidget {
+
+        public function __construct(
+            IInitialStateService $initialStateService,
+            IL10N $l10n,
+            IURLGenerator $urlGenerator
+        ) {
+            $this->initialStateService = $initialStateService;
+            $this->l10n = $l10n;
+            $this->urlGenerator = $urlGenerator;
+        }
+
+        /**
+         * @return string Unique id that identifies the widget, e.g. the app id
+         * @since 20.0.0
+         */
+        public function getId(): string {
+            return 'myappwidgetid';
+        }
+
+        /**
+         * @return string User facing title of the widget
+         * @since 20.0.0
+         */
+        public function getTitle(): string {
+            return $this->l10n->t('My app');
+        }
+
+        /**
+         * @return int Initial order for widget sorting
+         *   in the range of 10-100, 0-9 are reserved for shipped apps
+         * @since 20.0.0
+         */
+        public function getOrder(): int {
+            return 0;
+        }
+
+        /**
+         * @return string css class that displays an icon next to the widget title
+         * @since 20.0.0
+         */
+        public function getIconClass(): string {
+            return 'icon-class';
+        }
+
+        /**
+         * @return string|null The absolute url to the apps own view
+         * @since 20.0.0
+         */
+        public function getUrl(): ?string {
+            return $this->urlGenerator->linkToRouteAbsolute('myapp.view.index');
+        }
+
+        /**
+         * Execute widget bootstrap code like loading scripts and providing initial state
+         */
+        public function load(): void {
+            $initialStateService->provideInitialState('myapp', 'myData', []);
+            \OCP\Util::addScript('myapp', 'dashboard');
+        }
+    }
+
+
+The class needs to be registered during the :ref:`app bootstrap<Bootstrapping>`.
+
+.. code-block:: php
+
+    <?php
+
+    declare(strict_types=1);
+
+    namespace OCA\MyApp\AppInfo;
+
+    use OCP\AppFramework\App;
+    use OCP\AppFramework\Bootstrap\IBootContext;
+    use OCP\AppFramework\Bootstrap\IBootstrap;
+    use OCP\AppFramework\Bootstrap\IRegistrationContext;
+    use OCA\MyApp\Dashboard\MyAppWidget;
+
+    class Application extends App implements IBootstrap {
+
+        public const APP_ID = 'myapp';
+
+        public function __construct(array $urlParams = []) {
+            parent::__construct(self::APP_ID, $urlParams);
+        }
+
+        public function register(IRegistrationContext $context): void {
+            $context->registerDashboardWidget(MyAppWidget::class);
+        }
+
+        public function boot(IBootContext $context): void {
+        }
+    }
+
+For compatibility reasons the widget registration can also be performed by
+listening to the `OCP\\Dashboard\\RegisterWidgetEvent` for apps that still
+need to support older versions where the new app boostrap flow is not available,
+however this method is deprecated and will be removed once Nextcloud 19 is EOL.
+
+.. code-block:: php
+
+    use OCP\Dashboard\RegisterWidgetEvent;
+    use OCP\EventDispatcher\IEventDispatcher;
+
+    class Application extends App {
+        public function __construct(array $urlParams = []) {
+            parent::__construct(self::APP_ID, $urlParams);
+            $container = $this->getContainer();
+
+            /** @var IEventDispatcher $dispatcher */
+            $dispatcher = $container->getServer()->query(IEventDispatcher::class);
+            $dispatcher->addListener(RegisterWidgetEvent::class, function (RegisterWidgetEvent $event) use ($container) {
+                    \OCP\Util::addScript('myapp', 'dashboard');
+                    $event->registerWidget(MyAppWidget::class);
+            });
+        }
+    }
+
+
+Provide a user interface
+------------------------
+
+The user interface can be registered through the public `OCA.Dashboard.register`
+JavaScript method. The first parameter represents the widget id that has already
+been specified in the `IWidget` implementation. The callback parameter will be
+called to render the widget in the frontend. The user interface can be added to
+the provided DOM element `el`.
+
+The following example shows how a Vue.js component could be used to render the
+widget user interface, however this approach works for any other framework as well
+as plain JavaScript:
+
+
+.. code-block:: javascript
+
+    import Dashboard from './components/Dashboard.vue'
+
+    document.addEventListener('DOMContentLoaded', () => {
+        OCA.Dashboard.register('myappwidgetid', (el) => {
+            const View = Vue.extend(Dashboard)
+            const vm = new View({
+                propsData: {},
+                store,
+            }).$mount(el)
+        })
+    })
+

developer_manual/digging_deeper/index.rst

@@ -23,3 +23,4 @@ Digging deeper
    testing
    two-factor-provider
    users
+   dashboard