Move printing operation to a new thread

Printing operations were blocking the UI thread, so applications
were irresponsive when printing in large size or high resolution.
Introduce a new worker for the painting logic and use shared pointers
to carry the data around and avoid copying PDF data between threads.

Task-number: QTBUG-68561
Change-Id: I30633380b75acd14f1a1df87985c99540168a9f1
Reviewed-by: Michael Brüning <michael.bruning@qt.io>

2 files changed, 3 insertions, 3 deletions

diff --git a/src/webengine/api/qquickwebengineview.cpp b/src/webengine/api/qquickwebengineview.cpp
index d9667a643..e2a8b562d 100644
--- a/src/webengine/api/qquickwebengineview.cpp
+++ b/src/webengine/api/qquickwebengineview.cpp
@@ -1130,12 +1130,12 @@ void QQuickWebEngineViewPrivate::didFindText(quint64 requestId, int matchCount)
     callback.call(args);
 }
 
-void QQuickWebEngineViewPrivate::didPrintPage(quint64 requestId, const QByteArray &result)
+void QQuickWebEngineViewPrivate::didPrintPage(quint64 requestId, QSharedPointer<QByteArray> result)
 {
     Q_Q(QQuickWebEngineView);
     QJSValue callback = m_callbacks.take(requestId);
     QJSValueList args;
-    args.append(qmlEngine(q)->toScriptValue(result));
+    args.append(qmlEngine(q)->toScriptValue(*(result.data())));
     callback.call(args);
 }
 
diff --git a/src/webengine/api/qquickwebengineview_p_p.h b/src/webengine/api/qquickwebengineview_p_p.h
index cbba9b568..88a670867 100644
--- a/src/webengine/api/qquickwebengineview_p_p.h
+++ b/src/webengine/api/qquickwebengineview_p_p.h
@@ -128,7 +128,7 @@ public:
     void didFetchDocumentMarkup(quint64, const QString&) override { }
     void didFetchDocumentInnerText(quint64, const QString&) override { }
     void didFindText(quint64, int) override;
-    void didPrintPage(quint64 requestId, const QByteArray &result) override;
+    void didPrintPage(quint64 requestId, QSharedPointer<QByteArray>) override;
     void didPrintPageToPdf(const QString &filePath, bool success) override;
     void passOnFocus(bool reverse) override;
     void javaScriptConsoleMessage(JavaScriptConsoleMessageLevel level, const QString& message, int lineNumber, const QString& sourceID) override;