Ship file viewer, editor improvements, and private package releases

packages/viewer/src/actions.ts

@@ -0,0 +1,60 @@
+import type { Renderer, ViewerSource } from "./types.ts";
+
+/**
+ * What an action can see when it is offered and when it runs. `content` is the
+ * element the renderer drew into, so an action can read or print what is on
+ * screen rather than re-fetching the file.
+ */
+export interface ViewerActionContext {
+  host: HTMLElement;
+  content: HTMLElement;
+  source: ViewerSource;
+  /** Absent while the preview is still resolving, or when nothing could render. */
+  renderer?: Renderer;
+  kind?: string;
+}
+
+export interface ViewerAction {
+  /** Stable identifier; registering the same id again replaces the earlier one. */
+  id: string;
+  label: string;
+  /** Name from the built-in icon set. Falls back to one derived from the label. */
+  icon?: string;
+  /** Toolbar side: alongside the renderer's own controls, or with download. */
+  placement?: "controls" | "actions";
+  /** Offered only when this returns true. Defaults to always. */
+  when?: (context: ViewerActionContext) => boolean;
+  run: (context: ViewerActionContext) => void | Promise<void>;
+}
+
+const registered = new Map<string, ViewerAction>();
+
+/**
+ * Adds a toolbar action to every viewer in the page. Returns an unregister
+ * function, so a component can add one for as long as it is mounted.
+ *
+ * ```ts
+ * registerViewerAction({
+ *   id: "open-in-tab",
+ *   label: "Open in new tab",
+ *   when: ({ source }) => Boolean(source.src),
+ *   run: ({ source }) => window.open(source.src, "_blank", "noopener"),
+ * });
+ * ```
+ */
+export function registerViewerAction(action: ViewerAction): () => void {
+  registered.set(action.id, action);
+  return () => {
+    if (registered.get(action.id) === action) registered.delete(action.id);
+  };
+}
+
+/** Globally registered actions, in registration order. */
+export function viewerActions(): ViewerAction[] {
+  return [...registered.values()];
+}
+
+/** Testing helper: drops every globally registered action. */
+export function clearViewerActions(): void {
+  registered.clear();
+}