Trigger cleanup, once rendering has finished, in PDFThumbnailView.draw

web/base_viewer.js

@@ -115,6 +115,10 @@ function PDFPageViewBuffer(size) {
       data.shift().destroy();
     }
   };
+
+  this.has = function (view) {
+    return data.includes(view);
+  };
 }
 
 function isSameScale(oldScale, newScale) {
@@ -1096,9 +1100,15 @@ class BaseViewer {
     if (!this.pdfDocument) {
       return false;
     }
-    if (pageNumber < 1 || pageNumber > this.pagesCount) {
+    if (
+      !(
+        Number.isInteger(pageNumber) &&
+        pageNumber > 0 &&
+        pageNumber <= this.pagesCount
+      )
+    ) {
       console.error(
-        `${this._name}.isPageVisible: "${pageNumber}" is out of bounds.`
+        `${this._name}.isPageVisible: "${pageNumber}" is not a valid page.`
       );
       return false;
     }
@@ -1107,6 +1117,32 @@ class BaseViewer {
     });
   }
 
+  /**
+   * @param {number} pageNumber
+   */
+  isPageCached(pageNumber) {
+    if (!this.pdfDocument || !this._buffer) {
+      return false;
+    }
+    if (
+      !(
+        Number.isInteger(pageNumber) &&
+        pageNumber > 0 &&
+        pageNumber <= this.pagesCount
+      )
+    ) {
+      console.error(
+        `${this._name}.isPageCached: "${pageNumber}" is not a valid page.`
+      );
+      return false;
+    }
+    const pageView = this._pages[pageNumber - 1];
+    if (!pageView) {
+      return false;
+    }
+    return this._buffer.has(pageView);
+  }
+
   cleanup() {
     for (let i = 0, ii = this._pages.length; i < ii; i++) {
       if (

web/interfaces.js

@@ -95,6 +95,11 @@ class IPDFLinkService {
    * @param {number} pageNumber
    */
   isPageVisible(pageNumber) {}
+
+  /**
+   * @param {number} pageNumber
+   */
+  isPageCached(pageNumber) {}
 }
 
 /**

web/pdf_link_service.js

@@ -458,6 +458,13 @@ class PDFLinkService {
   isPageVisible(pageNumber) {
     return this.pdfViewer.isPageVisible(pageNumber);
   }
+
+  /**
+   * @param {number} pageNumber
+   */
+  isPageCached(pageNumber) {
+    return this.pdfViewer.isPageCached(pageNumber);
+  }
 }
 
 function isValidExplicitDestination(dest) {
@@ -609,6 +616,13 @@ class SimpleLinkService {
   isPageVisible(pageNumber) {
     return true;
   }
+
+  /**
+   * @param {number} pageNumber
+   */
+  isPageCached(pageNumber) {
+    return true;
+  }
 }
 
 export { PDFLinkService, SimpleLinkService };

web/pdf_thumbnail_view.js

@@ -363,6 +363,16 @@ class PDFThumbnailView {
         finishRenderTask(error);
       }
     );
+    // Only trigger cleanup, once rendering has finished, when the current
+    // pageView is *not* cached on the `BaseViewer`-instance.
+    resultPromise.finally(() => {
+      const pageCached = this.linkService.isPageCached(this.id);
+      if (pageCached) {
+        return;
+      }
+      this.pdfPage?.cleanup();
+    });
+
     return resultPromise;
   }