Question

我有一个gauge.qml，如下所示

Gauge.qml

Item {
    property real gaugevalue //this determine the gaugevalue.
    width: 100
    height: 100

    Rectangle {

        Image {
            x: 0
            y: 0
            source: "qrc:/gaugebg.png"
        }

        Image {
            x: 50
            y: 49
            source: "qrc:/needle.png";
            rotation: 0
            // I am doing some rotation logic with gaugevalue. please ignore logic for now
            transform: Rotation {
                origin.x: 10; origin.y:10;
                angle: gaugevalue
            }
        }
    }
 }

另外，我有一个main.qml，如下所示，我放置了我的仪表

main.qml

Window {
    id: main
    width: 640
    height: 480

    //gauge position
    property int gaugeX: 50
    property int gaugeY: 60

    Gauge {
        id : id_gauge
        gaugevalue : 50  //Now I am setting the gaugevalue from here. I need this to be controlled from my GaugeController class. 

        x:gaugeX
        y:gaugeY
    }
}

我想要实现的是让我的代码适合MVC架构。我打算用C ++编写一个'GaugeController'类，它将设置'gaugevalue'（后面会有更多的属性）。通过阅读许多导致以不同方式思考的文章我真的很困惑（我看到许多解决方案，比如使用Q_PROPERTY或setProperty等等。（请参阅此链接：https://www.zhieng.com/exposing-qml-object-pointer-to-cc/）。所以如果你能纠正我的代码会很棒在MVC架构中实现这一点。

Answer 1

使用qmlRegisterType<>()，然后在QML文件中创建一个GuageController实例，可以通过信号/插槽传递值来控制Guage

的main.cpp

    qmlRegisterType<GaugeController>("myApp", 1, 0, "GaugeController");

main.qml

import myApp 1.0
...
GaugeController {
         id: id_controller

         // heres how you implment a method as a SLOT via QML
         onGaugeValueChanged(gaugeValue): {
            id_gauge.gaugeValue = id_controller.gaugeValue
          }
}

gaugeController.cpp

class GaugeController : public QQuickItem
{
    Q_OBJECT


    // Q_PROPERTY MACRO allows the property to be read by QML
    Q_PROPERTY(int gaugeValue READ gaugeValue WRITE setGaugeValue NOTIFY gaugeValueChanged)

public: 


    int gaugeValue() { return _gaugeValue; };

signals:

    void gaugeValueChanged();
public slots:
    void setGaugeValue(newVal) { _gaugeValue = newVal; }

private: 

    int _gaugeValue;

**编辑**

从main.qml

将参数传递给GuageController

 GaugeController {
       id: controller
       gaugeValue:  10
  }
  //  or

  function myfunction {   controller.gaugeValue = 5 }

如何通过保持MVC结构来处理qt c ++与qml

1 个答案: