本文主要是介绍在QML中使用QSystemTrayIcon(系统托盘)，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
【写在前面】
写这篇文章的时候应该不算晚，因为 qml 中并没有正式的系统托盘组件。
但是，在 Qt Labs Platform 模块中( 实验模块，Qt 5.8引入 )，已经有了 SystemTrayIcon，相信以后会作为正式的模块进入 qml。
即便如此，本文仍提供了一种在qml中使用 QSystemTrayIcon 的方法，或者也可以作为 qml 与 c++ 交互的例子来看。
【正文开始】
先上完成后的 qml 代码：
main.qml
import QtQuick 2.7
import QtQuick.Window 2.2
import an.utility 1.0Window
{id: rootvisible: truewidth: 400height: 200title: qsTr("Hello World")Rectangle{anchors.fill: parentcolor: "red"}SystemTray{id: systemTraymenu: menuvisible: trueicon: "qrc:/winIcon.png"toolTip: "托盘运行中..."onTrigger:{root.requestActivate();root.show();}MyMenu{id: menuMyAction{text: "我在线上"icon: "qrc:/winIcon.png"}MyAction{text: "Q我吧"icon: "qrc:/winIcon.png"}MySeparator {}MyAction{text: "离开"icon: "qrc:/winIcon.png"}MyAction{text: "忙碌"icon: "qrc:/winIcon.png"}}}
}效果图：
可以看到，效果和 widget 下使用是一样的，但用 qml 更简单更方便。
自定义的 SystemTrayIcon 我注册到 an.utility 1.0 中。下面讲解其实现。
systemtrayicon.h
#ifndef SYSTEMTRAYICON_H
#define SYSTEMTRAYICON_H#include <QAction>
#include <QQuickItem>
#include <QSystemTrayIcon>class MyAction : public QAction
{Q_OBJECTQ_PROPERTY(QUrl icon READ icon WRITE setIcon NOTIFY iconChanged) //Q_PROPERTY宏提供在qml中访问的信号槽等等public:MyAction(QObject *parent = nullptr);~MyAction();QUrl icon() const;signals:void iconChanged();public slots:void setIcon(const QUrl &arg);private:QUrl m_icon;
};class MySeparator : public QObject
{
public:MySeparator(QObject *parent = nullptr);~MySeparator();
};class SystemTray;
class MyMenu : public QQuickItem
{Q_OBJECTQ_PROPERTY(int width READ width WRITE setWidth NOTIFY widthChanged)Q_PROPERTY(int height READ height WRITE setHeight NOTIFY heightChanged)public:MyMenu(QQuickItem *parent = nullptr);~MyMenu();int width() const;int height() const;void clear();signals:void widthChanged();void heightChanged();public slots:void setWidth(int arg);void setHeight(int arg);void addSeparator();void addAction(MyAction *action);void addMenu(MyMenu *menu);protected:void componentComplete();private:friend class SystemTrayIcon; //让SystemTray能够直接访问m_menuQMenu *m_menu;
};class SystemTrayIcon : public QQuickItem
{Q_OBJECTQ_PROPERTY(int x READ x CONSTANT)Q_PROPERTY(int y READ y CONSTANT)Q_PROPERTY(QUrl icon READ icon WRITE setIcon NOTIFY iconChanged)Q_PROPERTY(QString toolTip READ toolTip WRITE setToolTip NOTIFY toolTipChanged)Q_PROPERTY(MyMenu* menu READ menu WRITE setMenu NOTIFY menuChanged)public:SystemTrayIcon(QQuickItem *parent = nullptr);~SystemTrayIcon();int x() const;int y() const;QUrl icon() const;QString toolTip() const;MyMenu* menu() const;signals:void trigger();void iconChanged();void toolTipChanged();void menuChanged();public slots:void setIcon(const QUrl &arg);void setToolTip(const QString &arg);void setMenu(MyMenu *arg);void onVisibleChanged();void onActivated(QSystemTrayIcon::ActivationReason reason);void onExit();private:QSystemTrayIcon *m_systemTray;MyMenu *m_menu;QString m_toolTip;QUrl m_icon;
};#endif // SYSTEMTRAYICON_H要将 c++ 类导入到 qml 必须继承自 QObject 或其派生类，并使用 Q_OBJECT 宏。
而继承 QQuickItem 是为了得到 item 中的其他一些属性和信号，以及重实现 void componentComplete()。
该函数在组件完成时调用，重新实现来添加必要的操作。
systemTrayIcon.cpp
#include <QApplication>
#include <QMenu>
#include <QAction>
#include "systemtrayicon.h"MyAction::MyAction(QObject *parent): QAction(parent)
{setObjectName("MyAction");
}MyAction::~MyAction()
{}QUrl MyAction::icon() const
{return m_icon;
}void MyAction::setIcon(const QUrl &arg)
{if(m_icon != arg){QString str = arg.toLocalFile();if(str == "") str = arg.toString(); //如果转换失败if( str.mid (0, 3) == "qrc")str = str.mid (3, str.count() - 3);QAction::setIcon(QIcon(str));m_icon = arg;emit iconChanged();}
}MySeparator::MySeparator(QObject *parent): QObject(parent)
{setObjectName("MySeparator");
}MySeparator::~MySeparator()
{}MyMenu::MyMenu(QQuickItem *parent): QQuickItem(parent)
{setObjectName("MyMenu");m_menu = new QMenu();
}MyMenu::~MyMenu()
{}int MyMenu::width() const
{return m_menu->width();
}int MyMenu::height() const
{return m_menu->height();
}void MyMenu::clear() //清空caidan
{m_menu->clear();
}void MyMenu::setWidth(int arg)
{if (m_menu->width() != arg){m_menu->setFixedWidth(arg);emit widthChanged();}
}void MyMenu::setHeight(int arg)
{if (m_menu->height() != arg){m_menu->setFixedHeight(arg);emit heightChanged();}
}void MyMenu::addAction(MyAction *action)
{m_menu->addAction(action);
}void MyMenu::addSeparator()
{m_menu->addSeparator();
}void MyMenu::addMenu(MyMenu *menu)
{m_menu->addMenu(menu->m_menu);
}void MyMenu::componentComplete() //在菜单完成构建后调用，将自定义Action,Menu,Separator通过objectName判断加入
{QQuickItem::componentComplete();QObjectList list = children();for (auto it : list){if (it->objectName() == "MyAction"){MyAction *action = qobject_cast<MyAction *>(it);m_menu->addAction(action);}else if (it->objectName() == "MySeparator"){m_menu->addSeparator();}else if (it->objectName() == "MyMenu"){MyMenu *menu = qobject_cast<MyMenu *>(it);m_menu->addMenu(menu->m_menu);}}
}SystemTrayIcon::SystemTrayIcon(QQuickItem *parent): QQuickItem(parent)
{m_systemTray = new QSystemTrayIcon(this);connect(m_systemTray, &QSystemTrayIcon::activated, this, &SystemTrayIcon::onActivated);connect(this, &SystemTrayIcon::visibleChanged, this, &SystemTrayIcon::onVisibleChanged);setVisible(false); //给visible一个初始值，否则会不显示
}SystemTrayIcon::~SystemTrayIcon()
{}int SystemTrayIcon::x() const
{return m_systemTray->geometry().x();
}int SystemTrayIcon::y() const
{return m_systemTray->geometry().y();
}QUrl SystemTrayIcon::icon() const
{return m_icon;
}QString SystemTrayIcon::toolTip() const
{return m_systemTray->toolTip();
}MyMenu *SystemTrayIcon::menu() const
{return m_menu;
}void SystemTrayIcon::setIcon(const QUrl &arg)
{if(m_icon != arg){QString str = arg.toLocalFile();if(str == "") str = arg.toString(); //如果转换失败if( str.mid (0, 3) == "qrc")str = str.mid (3, str.count() - 3);m_systemTray->setIcon(QIcon(str));m_icon = arg;emit iconChanged();}
}void SystemTrayIcon::setToolTip(const QString &arg)
{if (m_toolTip != arg){m_systemTray->setToolTip(arg);m_toolTip = arg;emit toolTipChanged();}
}void SystemTrayIcon::setMenu(MyMenu *arg) //设置托盘上下文菜单
{if (m_menu != arg){m_menu = arg;m_systemTray->setContextMenu(m_menu->m_menu);m_systemTray->installEventFilter(this);emit menuChanged();}
}void SystemTrayIcon::onVisibleChanged() //visible可见性改变时显示/隐藏托盘
{m_systemTray->setVisible(isVisible());
}void SystemTrayIcon::onActivated(QSystemTrayIcon::ActivationReason reason)
{switch (reason){case QSystemTrayIcon::DoubleClick:case QSystemTrayIcon::Trigger:emit trigger(); //单击双击托盘图标时发送trigger()信号, reason类似还有Context,MiddleClick,Unknowdefault:break;}
}void SystemTrayIcon::onExit() //应在程序退出时调用，防止图标不消失
{m_systemTray->hide();QApplication::exit(0);
}
main.cpp
#include <QApplication>
#include <QQmlApplicationEngine>
#include "systemtrayicon.h"int main(int argc, char *argv[])
{QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);QApplication app(argc, argv);QQmlApplicationEngine engine;qmlRegisterType<MyMenu>("an.utility", 1, 0, "MyMenu"); //注册到qml中qmlRegisterType<MyAction>("an.utility", 1, 0, "MyAction");qmlRegisterType<MySeparator>("an.utility", 1, 0, "MySeparator");qmlRegisterType<SystemTrayIcon>("an.utility", 1, 0, "SystemTrayIcon");engine.load(QUrl(QLatin1String("qrc:/main.qml")));if (engine.rootObjects().isEmpty())return -1;return app.exec();
}【结语】
好吧，还有很多地方没有完善，比如快捷键。
其实写自定义组件和写 widget 差不多。。不过写好之后，在qml中使用起来就非常方便了。
当然，最后我自己试了试 Qt.labs.platform 1.0 中的 SystemTrayIcon，嗯基本上差不多吧。。所以期待以后的版本正式加入咯。
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