Fix print button of PDF viewer plugin

Do not try to start print preview automatically, just notify the
embedder via printRequested signal instead of crashing.
Also fix the signal name in WebEngineView docs.

Task-number: QTBUG-104610
Change-Id: I251e0b8f6f03a73236320a66a0d3c7690939d88b
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
(cherry picked from commit 3801a9244cb57bfb6b6b08be652f42a135b71142)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

3 files changed, 17 insertions, 4 deletions

diff --git a/src/core/printing/print_view_manager_qt.cpp b/src/core/printing/print_view_manager_qt.cpp
index 7d8a796f7..892c9e406 100644
--- a/src/core/printing/print_view_manager_qt.cpp
+++ b/src/core/printing/print_view_manager_qt.cpp
@@ -336,12 +336,23 @@ void PrintViewManagerQt::ShowScriptedPrintPreview(bool /*source_is_modifiable*/)
     // ignore for now
 }
 
-void PrintViewManagerQt::RequestPrintPreview(printing::mojom::RequestPrintPreviewParamsPtr /*params*/)
+void PrintViewManagerQt::RequestPrintPreview(printing::mojom::RequestPrintPreviewParamsPtr params)
 {
+    if (!m_printPreviewRfh && params->webnode_only) {
+        // The preview was requested by the print button of PDF viewer plugin. The code path ends up here, because
+        // Chromium automatically initiated a preview generation. We don't want that, just notify our embedder
+        // like we do in SetupScriptedPrintPreview() after window.print() and let them decide what to do.
+        content::WebContentsView *view = static_cast<content::WebContentsImpl*>(web_contents()->GetOutermostWebContents())->GetView();
+        if (WebContentsAdapterClient *client = WebContentsViewQt::from(view)->client())
+            client->printRequested();
+        return;
+    }
+
     if (m_printSettings.empty()) {
         PrintPreviewDone();
         return;
     }
+
     mojo::AssociatedRemote<printing::mojom::PrintRenderFrame> printRenderFrame;
     m_printPreviewRfh->GetRemoteAssociatedInterfaces()->GetInterface(&printRenderFrame);
     printRenderFrame->PrintPreview(m_printSettings.Clone());
diff --git a/src/webenginequick/doc/src/webengineview_lgpl.qdoc b/src/webenginequick/doc/src/webengineview_lgpl.qdoc
index c4d87dc4d..8ba247d35 100644
--- a/src/webenginequick/doc/src/webengineview_lgpl.qdoc
+++ b/src/webenginequick/doc/src/webengineview_lgpl.qdoc
@@ -1334,10 +1334,11 @@
 */
 
 /*!
-    \qmlsignal WebEngineView::printRequest
+    \qmlsignal WebEngineView::printRequested
     \since QtWebEngine 1.8
 
-    This signal is emitted when the JavaScript \c{window.print()} method is called.
+    This signal is emitted when the JavaScript \c{window.print()} method is called or the user pressed the print
+    button of PDF viewer plugin.
     Typically, the signal handler can simply call printToPdf().
 
     \sa printToPdf
diff --git a/src/webenginewidgets/api/qwebengineview.cpp b/src/webenginewidgets/api/qwebengineview.cpp
index 35fb98138..8d88726fa 100644
--- a/src/webenginewidgets/api/qwebengineview.cpp
+++ b/src/webenginewidgets/api/qwebengineview.cpp
@@ -1379,7 +1379,8 @@ void QWebEngineView::printToPdf(const std::function<void(const QByteArray&)> &re
     \fn void QWebEngineView::printRequested()
     \since 6.2
 
-    This signal is emitted when the JavaScript \c{window.print()} method is called.
+    This signal is emitted when the JavaScript \c{window.print()} method is called or the user pressed the print
+    button of PDF viewer plugin.
     Typically, the signal handler can simply call print().
 
     \sa print()