Separate page label extraction

src/core/module/module.js

@@ -172,6 +172,16 @@ export class Module {
   }
 
   async getPageLabels() {
-    return getPageLabels(this._pdfDocument, this._structuredCharsProvider);
+    if (this._pageLabelsPromise) {
+      await this._pageLabelsPromise;
+      return this._pageLabels;
+    }
+    let resolvePageLabelsPromise;
+    this._pageLabelsPromise = new Promise((resolve) => {
+      resolvePageLabelsPromise = resolve;
+    });
+    this._pageLabels = await getPageLabels(this._pdfDocument, this._structuredCharsProvider);
+    resolvePageLabelsPromise();
+    return this._pageLabels;
   }
 }

src/core/worker.js

@@ -850,6 +850,19 @@ class WorkerMessageHandler {
       return pageData;
     });
 
+    handler.on("GetPageLabels2", async function (data) {
+      let task = new WorkerTask('GetPageLabels2: ');
+      startWorkerTask(task);
+      let pageLabels;
+      try {
+        pageLabels = await pdfManager.pdfDocument.module.getPageLabels(data);
+      } catch (e) {
+        console.log(e);
+      }
+      finishWorkerTask(task);
+      return pageLabels;
+    });
+
     handler.on("GetOutline2", async function (data) {
       let task = new WorkerTask('GetOutline2');
       startWorkerTask(task);

src/display/api.js

@@ -953,6 +953,10 @@ class PDFDocumentProxy {
     return this._transport.messageHandler.sendWithPromise("GetProcessedData", data);
   }
 
+  getPageLabels2(data) {
+    return this._transport.messageHandler.sendWithPromise("GetPageLabels2", data);
+  }
+
   getOutline2(data) {
     return this._transport.messageHandler.sendWithPromise("GetOutline2", data);
   }