1 files changed, 62 insertions, 0 deletions
diff --git a/dom/base/AutoPrintEventDispatcher.h b/dom/base/AutoPrintEventDispatcher.h
new file mode 100644
index 0000000000..6b5999021b
--- /dev/null
+++ b/dom/base/AutoPrintEventDispatcher.h
@@ -0,0 +1,62 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_AutoPrintEventDispatcher_h
+#define mozilla_dom_AutoPrintEventDispatcher_h
+
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/DocumentInlines.h"
+#include "nsContentUtils.h"
+#include "nsIPrintSettings.h"
+
+namespace mozilla::dom {
+
+class AutoPrintEventDispatcher {
+  // NOTE(emilio): For fission iframes, we dispatch this event in
+  // RecvCloneDocumentTreeIntoSelf.
+  static void CollectInProcessSubdocuments(
+      Document& aDoc, nsTArray<nsCOMPtr<Document>>& aDocs) {
+    auto recurse = [&aDocs](Document& aSubDoc) {
+      aDocs.AppendElement(&aSubDoc);
+      CollectInProcessSubdocuments(aSubDoc, aDocs);
+      return CallState::Continue;
+    };
+    aDoc.EnumerateSubDocuments(recurse);
+  }
+
+  MOZ_CAN_RUN_SCRIPT void DispatchEvent(bool aBefore) {
+    for (auto& doc : mDocuments) {
+      nsContentUtils::DispatchTrustedEvent(
+          doc, doc->GetWindow(), aBefore ? u"beforeprint"_ns : u"afterprint"_ns,
+          CanBubble::eNo, Cancelable::eNo, nullptr);
+      if (RefPtr<nsPresContext> presContext = doc->GetPresContext()) {
+        presContext->EmulateMedium(aBefore ? nsGkAtoms::print : nullptr);
+        // Ensure media query listeners fire.
+        doc->FlushPendingNotifications(FlushType::Style);
+      }
+    }
+  }
+
+ public:
+  MOZ_CAN_RUN_SCRIPT explicit AutoPrintEventDispatcher(Document& aDoc) {
+    if (!aDoc.IsStaticDocument()) {
+      mDocuments.AppendElement(&aDoc);
+      CollectInProcessSubdocuments(aDoc, mDocuments);
+    }
+
+    DispatchEvent(true);
+  }
+
+  MOZ_CAN_RUN_SCRIPT ~AutoPrintEventDispatcher() { DispatchEvent(false); }
+
+  AutoTArray<nsCOMPtr<Document>, 8> mDocuments;
+  const nsSize mPageSize;
+  nsRect mVisibleAreaToRestore;
+};
+
+}  // namespace mozilla::dom
+
+#endif