Qml定义自定义属性组

Question

如何在qml中定义自定义属性组，等于anchors属性？

用法示例：

Item { 
    anchors { 
    leftMargin: 5 
    rightMargin: 5 
    } 
} 

Answer 1

恐怕这是你在想它可能不是那么简单。

据我所知，你有两个选择：

1.-请您将通过@BaCaRoZzo提供的link看到并实施your own object type的建议。

2.-在C++中编写更复杂的QML类型并将其用于您的QML文件。或多或少的@folibis指出的想法。例如：

的main.cpp

#include <QGuiApplication> 
#include <QQmlApplicationEngine> 
#include <QtQml> 
#include "customitem.h" 

int main(int argc, char *argv[]) 
{ 
    QGuiApplication app(argc, argv); 
    qmlRegisterType<CustomItem>("CustomItem", 1,0, "CustomItem"); 

    QQmlApplicationEngine engine; 
    engine.load(QUrl(QStringLiteral("qrc:/main.qml"))); 

    return app.exec(); 
} 

customitem.h

#ifndef CUSTOMITEM_H 
#define CUSTOMITEM_H 

#include <QObject> 

class CustomItem: public QObject 
{ 
    Q_OBJECT 

    /* 
    * Any property that is writable should have an associated NOTIFY signal. 
    * Ref: http://doc.qt.io/qt-5/qtqml-cppintegration-exposecppattributes.html#exposing-properties 
    */ 

    Q_PROPERTY(int x READ x WRITE setX NOTIFY xChanged) 
    Q_PROPERTY(int y READ y WRITE setY NOTIFY yChanged) 


public: 
    CustomItem(QObject *parent = 0); 

    int x() const; 
     void setX(int); 

     int y() const; 
     void setY(int); 

private: 
    int m_x; 
    int m_y; 

signals: 
    void xChanged(); 
    void yChanged(); 

public slots: 
}; 

#endif // CUSTOMITEM_H 

customitem.cpp

#include "customitem.h" 

CustomItem::CustomItem(QObject *parent) 
: QObject(parent), m_x(0), m_y(0) 
{ 
} 

int CustomItem::x() const 
{ 
    return m_x; 
} 

void CustomItem::setX(int x) 
{ 
    m_x = x; 
} 

int CustomItem::y() const 
{ 
    return m_y; 
} 

void CustomItem::setY(int y) 
{ 
    m_y = y; 
} 

main.qml

import QtQuick 2.5 
import QtQuick.Window 2.2 
import CustomItem 1.0 

Window { 
    visible: true 

    CustomItem { 
     id: customItem 
     x: 50 
     y: 50 
    } 

    Rectangle { 
     id: rect 
     x: customItem.x 
     y: customItem.y 
     width: 100; height: 100 
     color: "red" 
    }  
}