feat: promisify webContents.printToPDF() (#16795)

atom/browser/api/atom_api_web_contents.cc

@@ -1499,11 +1499,12 @@ std::vector<printing::PrinterBasicInfo> WebContents::GetPrinterList() {
   return printers;
 }
 
-void WebContents::PrintToPDF(
-    const base::DictionaryValue& settings,
-    const PrintPreviewMessageHandler::PrintToPDFCallback& callback) {
+v8::Local<v8::Promise> WebContents::PrintToPDF(
+    const base::DictionaryValue& settings) {
+  scoped_refptr<util::Promise> promise = new util::Promise(isolate());
   PrintPreviewMessageHandler::FromWebContents(web_contents())
-      ->PrintToPDF(settings, callback);
+      ->PrintToPDF(settings, promise);
+  return promise->GetHandle();
 }
 #endif
 

atom/browser/api/atom_api_web_contents.h

@@ -174,9 +174,7 @@ class WebContents : public mate::TrackableObject<WebContents>,
   void Print(mate::Arguments* args);
   std::vector<printing::PrinterBasicInfo> GetPrinterList();
   // Print current page as PDF.
-  void PrintToPDF(
-      const base::DictionaryValue& settings,
-      const PrintPreviewMessageHandler::PrintToPDFCallback& callback);
+  v8::Local<v8::Promise> PrintToPDF(const base::DictionaryValue& settings);
 #endif
 
   // DevTools workspace api.

atom/browser/printing/print_preview_message_handler.cc

@@ -89,7 +89,7 @@ void PrintPreviewMessageHandler::OnMetafileReadyForPrinting(
   const PrintHostMsg_DidPrintContent_Params& content = params.content;
   if (!content.metafile_data_region.IsValid() ||
       params.expected_pages_count <= 0) {
-    RunPrintToPDFCallback(ids.request_id, nullptr);
+    RejectPromise(ids.request_id);
     return;
   }
 
@@ -102,10 +102,9 @@ void PrintPreviewMessageHandler::OnMetafileReadyForPrinting(
         base::BindOnce(&PrintPreviewMessageHandler::OnCompositePdfDocumentDone,
                        weak_ptr_factory_.GetWeakPtr(), ids));
   } else {
-    RunPrintToPDFCallback(
-        ids.request_id,
-        base::RefCountedSharedMemoryMapping::CreateFromWholeRegion(
-            content.metafile_data_region));
+    ResolvePromise(ids.request_id,
+                   base::RefCountedSharedMemoryMapping::CreateFromWholeRegion(
+                       content.metafile_data_region));
   }
 }
 
@@ -117,11 +116,11 @@ void PrintPreviewMessageHandler::OnCompositePdfDocumentDone(
 
   if (status != printing::mojom::PdfCompositor::Status::SUCCESS) {
     DLOG(ERROR) << "Compositing pdf failed with error " << status;
-    RunPrintToPDFCallback(ids.request_id, nullptr);
+    RejectPromise(ids.request_id);
     return;
   }
 
-  RunPrintToPDFCallback(
+  ResolvePromise(
       ids.request_id,
       base::RefCountedSharedMemoryMapping::CreateFromWholeRegion(region));
 }
@@ -131,7 +130,7 @@ void PrintPreviewMessageHandler::OnPrintPreviewFailed(
     const PrintHostMsg_PreviewIds& ids) {
   StopWorker(document_cookie);
 
-  RunPrintToPDFCallback(ids.request_id, nullptr);
+  RejectPromise(ids.request_id);
 }
 
 void PrintPreviewMessageHandler::OnPrintPreviewCancelled(
@@ -139,15 +138,15 @@ void PrintPreviewMessageHandler::OnPrintPreviewCancelled(
     const PrintHostMsg_PreviewIds& ids) {
   StopWorker(document_cookie);
 
-  RunPrintToPDFCallback(ids.request_id, nullptr);
+  RejectPromise(ids.request_id);
 }
 
 void PrintPreviewMessageHandler::PrintToPDF(
     const base::DictionaryValue& options,
-    const PrintToPDFCallback& callback) {
+    scoped_refptr<atom::util::Promise> promise) {
   int request_id;
   options.GetInteger(printing::kPreviewRequestID, &request_id);
-  print_to_pdf_callback_map_[request_id] = callback;
+  promise_map_[request_id] = std::move(promise);
 
   auto* focused_frame = web_contents()->GetFocusedFrame();
   auto* rfh = focused_frame && focused_frame->HasSelection()
@@ -156,28 +155,44 @@ void PrintPreviewMessageHandler::PrintToPDF(
   rfh->Send(new PrintMsg_PrintPreview(rfh->GetRoutingID(), options));
 }
 
-void PrintPreviewMessageHandler::RunPrintToPDFCallback(
+scoped_refptr<atom::util::Promise> PrintPreviewMessageHandler::GetPromise(
+    int request_id) {
+  auto it = promise_map_.find(request_id);
+  DCHECK(it != promise_map_.end());
+
+  auto promise = it->second;
+  promise_map_.erase(it);
+
+  return promise;
+}
+
+void PrintPreviewMessageHandler::ResolvePromise(
     int request_id,
     scoped_refptr<base::RefCountedMemory> data_bytes) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
-  v8::Isolate* isolate = v8::Isolate::GetCurrent();
-  v8::Locker locker(isolate);
+  auto promise = GetPromise(request_id);
+
+  v8::Isolate* isolate = promise->isolate();
+  mate::Locker locker(isolate);
   v8::HandleScope handle_scope(isolate);
-  if (data_bytes && data_bytes->size()) {
-    v8::Local<v8::Value> buffer =
-        node::Buffer::Copy(isolate,
-                           reinterpret_cast<const char*>(data_bytes->front()),
-                           data_bytes->size())
-            .ToLocalChecked();
-    print_to_pdf_callback_map_[request_id].Run(v8::Null(isolate), buffer);
-  } else {
-    v8::Local<v8::String> error_message =
-        v8::String::NewFromUtf8(isolate, "Failed to generate PDF");
-    print_to_pdf_callback_map_[request_id].Run(
-        v8::Exception::Error(error_message), v8::Null(isolate));
-  }
-  print_to_pdf_callback_map_.erase(request_id);
+  v8::Context::Scope context_scope(
+      v8::Local<v8::Context>::New(isolate, promise->GetContext()));
+
+  v8::Local<v8::Value> buffer =
+      node::Buffer::Copy(isolate,
+                         reinterpret_cast<const char*>(data_bytes->front()),
+                         data_bytes->size())
+          .ToLocalChecked();
+
+  promise->Resolve(buffer);
+}
+
+void PrintPreviewMessageHandler::RejectPromise(int request_id) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+
+  auto promise = GetPromise(request_id);
+  promise->RejectWithErrorMessage("Failed to generate PDF");
 }
 
 }  // namespace atom

atom/browser/printing/print_preview_message_handler.h

@@ -7,6 +7,7 @@
 
 #include <map>
 
+#include "atom/common/promise_util.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/memory/weak_ptr.h"
 #include "components/services/pdf_compositor/public/interfaces/pdf_compositor.mojom.h"
@@ -28,13 +29,10 @@ class PrintPreviewMessageHandler
     : public content::WebContentsObserver,
       public content::WebContentsUserData<PrintPreviewMessageHandler> {
  public:
-  using PrintToPDFCallback =
-      base::Callback<void(v8::Local<v8::Value>, v8::Local<v8::Value>)>;
-
   ~PrintPreviewMessageHandler() override;
 
   void PrintToPDF(const base::DictionaryValue& options,
-                  const PrintToPDFCallback& callback);
+                  scoped_refptr<atom::util::Promise> promise);
 
  protected:
   // content::WebContentsObserver implementation.
@@ -57,11 +55,15 @@ class PrintPreviewMessageHandler
                             const PrintHostMsg_PreviewIds& ids);
   void OnPrintPreviewCancelled(int document_cookie,
                                const PrintHostMsg_PreviewIds& ids);
-  void RunPrintToPDFCallback(int request_id,
-                             scoped_refptr<base::RefCountedMemory> data_bytes);
 
-  using PrintToPDFCallbackMap = std::map<int, PrintToPDFCallback>;
-  PrintToPDFCallbackMap print_to_pdf_callback_map_;
+  scoped_refptr<atom::util::Promise> GetPromise(int request_id);
+
+  void ResolvePromise(int request_id,
+                      scoped_refptr<base::RefCountedMemory> data_bytes);
+  void RejectPromise(int request_id);
+
+  using PromiseMap = std::map<int, scoped_refptr<atom::util::Promise>>;
+  PromiseMap promise_map_;
 
   base::WeakPtrFactory<PrintPreviewMessageHandler> weak_ptr_factory_;