[api-minor] Add basic support for the SetOCGState action (issue 15372)

Note that this patch implements the `SetOCGState`-handling in `PDFLinkService`, rather than as a new method in `OptionalContentConfig`[1], since this action is nothing but a series of `setVisibility`-calls and that it seems quite uncommon in real-world PDF documents.

The new functionality also required some tweaks in the `PDFLayerViewer`, to ensure that the `layersView` in the sidebar is updated correctly when the optional-content visibility changes from "outside" of `PDFLayerViewer`.

---
[1] We can obviously move this code into `OptionalContentConfig` instead, if deemed necessary, but for an initial implementation I figured that doing it this way might be acceptable.

web/interfaces.js

@@ -110,6 +110,11 @@ class IPDFLinkService {
    */
   executeNamedAction(action) {}
 
+  /**
+   * @param {Object} action
+   */
+  executeSetOCGState(action) {}
+
   /**
    * @param {number} pageNum - page number.
    * @param {Object} pageRef - reference to the page.

web/pdf_layer_viewer.js

@@ -34,13 +34,19 @@ class PDFLayerViewer extends BaseTreeViewer {
     super(options);
     this.l10n = options.l10n;
 
-    this.eventBus._on("resetlayers", this._resetLayers.bind(this));
+    this.eventBus._on("optionalcontentconfigchanged", evt => {
+      this.#updateLayers(evt.promise);
+    });
+    this.eventBus._on("resetlayers", () => {
+      this.#updateLayers();
+    });
     this.eventBus._on("togglelayerstree", this._toggleAllTreeItems.bind(this));
   }
 
   reset() {
     super.reset();
     this._optionalContentConfig = null;
+    this._optionalContentHash = null;
   }
 
   /**
@@ -59,6 +65,7 @@ class PDFLayerViewer extends BaseTreeViewer {
   _bindLink(element, { groupId, input }) {
     const setVisibility = () => {
       this._optionalContentConfig.setVisibility(groupId, input.checked);
+      this._optionalContentHash = this._optionalContentConfig.getHash();
 
       this.eventBus.dispatch("optionalcontentconfig", {
         source: this,
@@ -123,6 +130,7 @@ class PDFLayerViewer extends BaseTreeViewer {
       this._dispatchEvent(/* layersCount = */ 0);
       return;
     }
+    this._optionalContentHash = optionalContentConfig.getHash();
 
     const fragment = document.createDocumentFragment(),
       queue = [{ parent: fragment, groups }];
@@ -170,23 +178,29 @@ class PDFLayerViewer extends BaseTreeViewer {
     this._finishRendering(fragment, layersCount, hasAnyNesting);
   }
 
-  /**
-   * @private
-   */
-  async _resetLayers() {
+  async #updateLayers(promise = null) {
     if (!this._optionalContentConfig) {
       return;
     }
-    // Fetch the default optional content configuration...
-    const optionalContentConfig =
-      await this._pdfDocument.getOptionalContentConfig();
+    const pdfDocument = this._pdfDocument;
+    const optionalContentConfig = await (promise ||
+      pdfDocument.getOptionalContentConfig());
 
-    this.eventBus.dispatch("optionalcontentconfig", {
-      source: this,
-      promise: Promise.resolve(optionalContentConfig),
-    });
+    if (pdfDocument !== this._pdfDocument) {
+      return; // The document was closed while the optional content resolved.
+    }
+    if (promise) {
+      if (optionalContentConfig.getHash() === this._optionalContentHash) {
+        return; // The optional content didn't change, hence no need to reset the UI.
+      }
+    } else {
+      this.eventBus.dispatch("optionalcontentconfig", {
+        source: this,
+        promise: Promise.resolve(optionalContentConfig),
+      });
+    }
 
-    // ... and reset the sidebarView to the default state.
+    // Reset the sidebarView to the new state.
     this.render({
       optionalContentConfig,
       pdfDocument: this._pdfDocument,

web/pdf_link_service.js

@@ -493,6 +493,48 @@ class PDFLinkService {
     });
   }
 
+  /**
+   * @param {Object} action
+   */
+  async executeSetOCGState(action) {
+    const pdfDocument = this.pdfDocument;
+    const optionalContentConfig = await this.pdfViewer
+      .optionalContentConfigPromise;
+
+    if (pdfDocument !== this.pdfDocument) {
+      return; // The document was closed while the optional content resolved.
+    }
+    let operator;
+
+    for (const elem of action.state) {
+      switch (elem) {
+        case "ON":
+        case "OFF":
+        case "Toggle":
+          operator = elem;
+          continue;
+      }
+      switch (operator) {
+        case "ON":
+          optionalContentConfig.setVisibility(elem, true);
+          break;
+        case "OFF":
+          optionalContentConfig.setVisibility(elem, false);
+          break;
+        case "Toggle":
+          const group = optionalContentConfig.getGroup(elem);
+          if (group) {
+            optionalContentConfig.setVisibility(elem, !group.visible);
+          }
+          break;
+      }
+    }
+
+    this.pdfViewer.optionalContentConfigPromise = Promise.resolve(
+      optionalContentConfig
+    );
+  }
+
   /**
    * @param {number} pageNum - page number.
    * @param {Object} pageRef - reference to the page.
@@ -676,6 +718,11 @@ class SimpleLinkService {
    */
   executeNamedAction(action) {}
 
+  /**
+   * @param {Object} action
+   */
+  executeSetOCGState(action) {}
+
   /**
    * @param {number} pageNum - page number.
    * @param {Object} pageRef - reference to the page.

web/pdf_outline_viewer.js

@@ -109,7 +109,7 @@ class PDFOutlineViewer extends BaseTreeViewer {
   /**
    * @private
    */
-  _bindLink(element, { url, newWindow, action, dest }) {
+  _bindLink(element, { url, newWindow, action, dest, setOCGState }) {
     const { linkService } = this;
 
     if (url) {
@@ -124,6 +124,14 @@ class PDFOutlineViewer extends BaseTreeViewer {
       };
       return;
     }
+    if (setOCGState) {
+      element.href = linkService.getAnchorUrl("");
+      element.onclick = () => {
+        linkService.executeSetOCGState(setOCGState);
+        return false;
+      };
+      return;
+    }
 
     element.href = linkService.getDestinationHash(dest);
     element.onclick = evt => {