产品展示网站含后台网站模板下载,兰州建设工程信息网站,重庆可以建建网站的平台,本地高端网站建设信息大全我们有时候想发送自定义事件 1#xff1a;创建自定义事件#xff0c;首先我们需要知道它的条件 1#xff1a;自定义事件需要继承QEvent 2#xff1a;事件的类型需要在 QEvent::User 和 QEvent::MaxUser 范围之间#xff0c;在QEvent::User之前 是预留给系统的事件 3#… 我们有时候想发送自定义事件 1创建自定义事件首先我们需要知道它的条件 1自定义事件需要继承QEvent 2事件的类型需要在 QEvent::User 和 QEvent::MaxUser 范围之间在QEvent::User之前 是预留给系统的事件 3使用sendEvent() 和 postEvent()发送自定义消息 4接受自定义消息通过 重写 customEvent 或者 使用 eventFilter事件 来处理 2注册自定义事件ID 在注册自定义事件的时候我们有两种方法 一使用QEvent::registerEventType()这个是系统会帮助我们注册ID如果错误 返回-1 二我们自定义 取QEvent::User 和QEvent::MaxUser 之间的值 方法一
QEvent::Type CustomEvent::m_eventType (QEvent::Type)QEvent::registerEventType();方法二
const int CustomEventBaseID QEvent::User;
const int TextEventID CustomEventBaseID 1;3自定义事件
class CustomEvent :public QEvent
{
public:CustomEvent();virtual ~CustomEvent();static QEvent::Type eventType();
private:static QEvent::Type m_eventType;
};QEvent::Type CustomEvent::m_eventType (QEvent::Type)QEvent::registerEventType();//1、注册自定义事件类型CustomEvent::CustomEvent():QEvent(eventType()) //2、指定事件类型
{}CustomEvent::~CustomEvent()
{}QEvent::Type CustomEvent::eventType()
{return m_eventType;
}4:发送自定义事件 postEvent 方法异步发送向事件队列中 的发送一个指定接受者事件 不需要手动释放事件的内存QT框架自动释放 sendEvent方法此方法是阻塞发送的它发送对象事件等待对象处理结束返回 需要手动释放事件的内存 5自定义事件处理 写自定义事件 void customEvent(QEvent* event) override; 写事件过滤器 bool eventFilter(QObject* watched, QEvent* event) override; 还需要将对象添加到事件过滤器中 源码 .h
#pragma once#include QtWidgets/QWidget
#include ui_CustomEventTest.h
#include QEvent
#include QDebug//自定义事件
class CustomEvent :public QEvent
{
public:CustomEvent();virtual ~CustomEvent();void SetText(const QString str);QString GetText() const;void SetNumber(int number);int GetNumber() const;static QEvent::Type eventType();
private:QString m_str;int m_number;static QEvent::Type m_eventType;
};class CustomTwoEvent :public QEvent
{
public:CustomTwoEvent();virtual ~CustomTwoEvent();void SetStr(const QString str);QString GetStr() const;void SetNumber(int number);int GetNumber() const;
private:QString m_str;int m_number;};//测试自定义事件
class CustomEventTest : public QWidget
{Q_OBJECTpublic:CustomEventTest(QWidget *parent nullptr);~CustomEventTest();private slots://测试自定义事件一void on_btn1_1_clicked();void on_btn2_1_clicked();void on_btn3_1_clicked();void on_btn4_1_clicked();protected:void customEvent(QEvent* event) override;private slots://测试自定义事件二void on_btn5_1_clicked();void on_btn6_1_clicked();void on_btn7_1_clicked();void on_btn8_1_clicked();protected:bool eventFilter(QObject* watched, QEvent* event) override;private:Ui::CustomEventTestClass ui;
};
.cpp
#include CustomEventTest.h/************************自定义事件一********************************/
QEvent::Type CustomEvent::m_eventType (QEvent::Type)QEvent::registerEventType();//1、注册自定义事件类型CustomEvent::CustomEvent():QEvent(eventType()) //2、指定事件类型
{}CustomEvent::~CustomEvent()
{}void CustomEvent::SetText(const QString str)
{m_str str;
}QString CustomEvent::GetText() const
{return m_str;
}void CustomEvent::SetNumber(int number)
{m_number number;
}int CustomEvent::GetNumber() const
{return m_number;
}QEvent::Type CustomEvent::eventType()
{return m_eventType;
}/************************自定义事件一********************************//************************自定义事件二********************************/const int CustomEventBaseID QEvent::User;
const int TextEventID CustomEventBaseID 1;CustomTwoEvent::CustomTwoEvent():QEvent(QEvent::Type(TextEventID))
{}CustomTwoEvent::~CustomTwoEvent()
{}void CustomTwoEvent::SetStr(const QString str)
{m_str str;
}QString CustomTwoEvent::GetStr() const
{return m_str;
}void CustomTwoEvent::SetNumber(int number)
{m_number number;
}int CustomTwoEvent::GetNumber() const
{return m_number;
}/************************自定义事件二********************************//************************测试自定义事件********************************/
CustomEventTest::CustomEventTest(QWidget *parent): QWidget(parent)
{ui.setupUi(this);qApp-installEventFilter(this);
}CustomEventTest::~CustomEventTest()
{}void CustomEventTest::on_btn1_1_clicked()
{QString str QStringLiteral(自定义事件一 我是post 发送指针);CustomEvent* event new CustomEvent;event-SetText(str);event-SetNumber(1);qApp-postEvent(this, event);
}void CustomEventTest::on_btn2_1_clicked()
{QString str QStringLiteral(自定义事件一 我是post 发送局部变量);CustomEvent event;event.SetText(str);event.SetNumber(2);//会出现崩溃qApp-postEvent(this, event);
}void CustomEventTest::on_btn3_1_clicked()
{QString str QStringLiteral(自定义事件一 我是send 发送指针);CustomEvent* event new CustomEvent;event-SetText(str);event-SetNumber(3);qApp-sendEvent(this, event);delete event;
}void CustomEventTest::on_btn4_1_clicked()
{QString str QStringLiteral(自定义事件一 我是send 发送局部变量);CustomEvent event;event.SetText(str);event.SetNumber(4);qApp-sendEvent(this, event);
}void CustomEventTest::on_btn5_1_clicked()
{QString str QStringLiteral(自定义事件二 我是post 发送指针);CustomTwoEvent* event new CustomTwoEvent;event-SetStr(str);event-SetNumber(5);qApp-postEvent(this, event);
}void CustomEventTest::on_btn6_1_clicked()
{QString str QStringLiteral(自定义事件二 我是post 发送局部变量);CustomTwoEvent event;event.SetStr(str);event.SetNumber(6);//会出现崩溃qApp-postEvent(this, event);
}void CustomEventTest::on_btn7_1_clicked()
{QString str QStringLiteral(自定义事件二 我是send 发送指针);CustomTwoEvent* event new CustomTwoEvent;event-SetStr(str);event-SetNumber(7);qApp-sendEvent(this, event);delete event;
}void CustomEventTest::on_btn8_1_clicked()
{QString str QStringLiteral(自定义事件二 我是send 发送局部变量);CustomTwoEvent event;event.SetStr(str);event.SetNumber(8);qApp-sendEvent(this, event);
}void CustomEventTest::customEvent(QEvent* event)
{if (event-type() CustomEvent::eventType()){CustomEvent* e dynamic_castCustomEvent*(event);if (e-GetNumber() 1)ui.btn1-setText(e-GetText());else if (e-GetNumber() 2)ui.btn2-setText(e-GetText());else if (e-GetNumber() 3)ui.btn3-setText(e-GetText());else if (e-GetNumber() 4)ui.btn4-setText(e-GetText());}
}bool CustomEventTest::eventFilter(QObject* watched, QEvent* event)
{if (event-type() TextEventID){CustomTwoEvent* e dynamic_castCustomTwoEvent*(event);if (e-GetNumber() 5)ui.btn5-setText(e-GetStr());else if (e-GetNumber() 6)ui.btn6-setText(e-GetStr());else if (e-GetNumber() 7)ui.btn7-setText(e-GetStr());else if (e-GetNumber() 8)ui.btn8-setText(e-GetStr());event-accept();}return QWidget::eventFilter(watched,event);
}
/************************测试自定义事件********************************/
错误在上面的代码中当我们post 局部变量的时候会出现错误
QCoreApplication::removePostedEvent: Event of type 65535 deleted while posted to CustomEventTest CustomEventTestClass原因postEvent 只能在堆上创建系统会自动释放
参考博客 Qt 自定义事件 Qt中的事件- 自定义事件 Qt事件自定义事件
