Ensure PDF scale-on-load optimisation uses background #4398

docs/src/content/docs/changelog.md

@@ -13,6 +13,7 @@ Requires libvips v8.16.1
 
 * Ensure `pdfBackground` constructor property is used.
   [#4207](https://github.com/lovell/sharp/pull/4207)
+  [#4398](https://github.com/lovell/sharp/issues/4398)
 
 * Add support for prebuilt Windows ARM64 binaries.
   [#4375](https://github.com/lovell/sharp/pull/4375)

src/pipeline.cc

@@ -294,6 +294,7 @@ class PipelineWorker : public Napi::AsyncWorker {
           option->set("n", baton->input->pages);
           option->set("page", baton->input->page);
           option->set("dpi", baton->input->density);
+          option->set("background", baton->input->pdfBackground);
 
           if (baton->input->buffer != nullptr) {
             // Reload PDF buffer