Qt Quick App的两种启动模式

QQmlApplicationEngine搭配Window

QQuickView搭配Item

两者不同之处在于：

使用QQuickView显示QML文档，对窗口的控制权（比如设置窗口标题、Icon、窗口的最小尺寸等）在C++代码；而使用QQmlApplicationEngine加载以Window为根对象的QML文档，QML文档则拥有窗口的完整控制权，可以直接设置标题、窗口尺寸等属性。

1、QQmlApplicationEngine搭配Window启动方式：

main.c文件

1. int main(int argc, char *argv[])
2. {
3.     QApplication app(argc, argv);
5.     QQmlApplicationEngine engine;
6.     engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
8.     return app.exec();
9. }

main.qml文件

1. ApplicationWindow {
2.   title: qsTr("Hello World")
3.   width: 640
4.   height: 480
5.   visible: true
7.   menuBar: MenuBar {
8.         Menu {
9.             title: qsTr("&File")
10.             MenuItem {
11.              text: qsTr("&Open")
12.              onTriggered: messageDialog.show(qsTr("Open action triggered"));
13.              }
14.             MenuItem {
15.                 text: qsTr("E&xit")
16.                 onTriggered: Qt.quit();
17.             }
18.         }
19.     }
21.     MainForm {
22.         anchors.fill: parent
23.         button1.onClicked: messageDialog.show(qsTr("Button 1 pressed"))
24.         button2.onClicked: messageDialog.show(qsTr("Button 2 pressed"))
25.         button3.onClicked: messageDialog.show(qsTr("Button 3 pressed"))
26.     }
28.     MessageDialog {
29.         id: messageDialog
30.         title: qsTr("May I have your attention, please?")
32.         function show(caption) {
33.             messageDialog.text = caption;
34.             messageDialog.open();
35.         }
36.     }
37. }

窗口

2、QQuickView搭配Item

main.c文件

1. #include <QApplication>
2. #include <QQuickView>
3. #include <QGuiApplication>
4. #include <QQmlApplicationEngine>
6. int main(int argc, char *argv[])
7. {
8.     QGuiApplication app(argc, argv);
9.     QQuickView viewer;
10.     viewer.setResizeMode(QQuickView::SizeRootObjectToView);
11.     viewer.setSource(QUrl("qrc:///main.qml"));
12.     viewer.show();
14.     return app.exec();
15. }

main.qml文件

1. import QtQuick 2.4
2. import QtQuick.Controls 1.3
3. import QtQuick.Window 2.2
4. import QtQuick.Dialogs 1.2
6.     Rectangle{
7.         width: 320;
8.         height: 240;
9.     }

来源：https://www.cnblogs.com/mcumagic/p/5320324.html