Polish the QML/PdfViewer example

- Use QCommandLineParser
- Use QmlEngine::setInitialProperties() instead of context
  properties and make "source" a required property of type url
- Use startup documents from resource

Pick-to: 6.4
Change-Id: Idaad82be4d7cf862de96240af031ed317a401266
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

2 files changed, 21 insertions, 8 deletions

diff --git a/examples/pdf/pdfviewer/main.cpp b/examples/pdf/pdfviewer/main.cpp
index da940dd3f..bed0e5860 100644
--- a/examples/pdf/pdfviewer/main.cpp
+++ b/examples/pdf/pdfviewer/main.cpp
@@ -1,9 +1,13 @@
 // Copyright (C) 2020 The Qt Company Ltd.
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
 
-#include <QGuiApplication>
 #include <QQmlApplicationEngine>
 
+#include <QGuiApplication>
+
+#include <QCommandLineParser>
+#include <QCommandLineOption>
+
 int main(int argc, char* argv[])
 {
     QCoreApplication::setApplicationName("Qt Quick PDF Viewer Example");
@@ -11,14 +15,23 @@ int main(int argc, char* argv[])
     QCoreApplication::setApplicationVersion(QT_VERSION_STR);
     QGuiApplication app(argc, argv);
 
+    QCommandLineParser parser;
+    parser.addHelpOption();
+    parser.addVersionOption();
+    parser.addPositionalArgument("file", "The file to open.");
+    parser.process(app);
+
     QQmlApplicationEngine engine;
+
+    QUrl toLoad = QUrl("qrc:/pdfviewer/resources/test.pdf");
+    if (!parser.positionalArguments().isEmpty())
+        toLoad = QUrl::fromLocalFile(parser.positionalArguments().constFirst());
+
+    engine.setInitialProperties({{"source", toLoad}});
+
     engine.load(QUrl(QStringLiteral("qrc:///pdfviewer/viewer.qml")));
-    if (app.arguments().count() > 1) {
-        QUrl toLoad = QUrl::fromUserInput(app.arguments().at(1));
-        engine.rootObjects().first()->setProperty("source", toLoad);
-    } else {
-        engine.rootObjects().first()->setProperty("source", QStringLiteral("resources/test.pdf"));
-    }
+    if (engine.rootObjects().isEmpty())
+        return -1;
 
     return app.exec();
 }
diff --git a/examples/pdf/pdfviewer/viewer.qml b/examples/pdf/pdfviewer/viewer.qml
index 9f78c1404..a62035166 100644
--- a/examples/pdf/pdfviewer/viewer.qml
+++ b/examples/pdf/pdfviewer/viewer.qml
@@ -13,7 +13,7 @@ ApplicationWindow {
     color: "lightgrey"
     title: document.title
     visible: true
-    property string source // for main.cpp
+    required property url source // for main.cpp
     property real scaleStep: Math.sqrt(2)
 
     header: ToolBar {