[英]Qt Signals and Slots - nothing happens
我目前正在嘗試將QML信號連接到C ++插槽失敗。
我剛看了幾個其他的例子,但我想我沒有得到如何獲取qml文檔的根對象...
我的問題是,似乎信號將從qml文件發送,但在cpp文件中沒有收到。 執行此代碼時沒有錯誤。
//Counter.h
#ifndef COUNTER_H
#define COUNTER_H
#include <QObject>
class Counter : public QObject
{
Q_OBJECT
private:
int counter;
public:
explicit Counter(QObject *parent = 0);
signals:
void counterHasChanged(int);
public slots:
void click();
};
#endif // COUNTER_H
//counter.cpp
#include "counter.h"
#include <QDebug>
Counter::Counter(QObject *parent) :
QObject(parent)
{
this->counter = 0;
qDebug() << "Class Counter created";
}
void Counter::click() {
this->counter++;
qDebug() << "clickRegistered() - emit counterHasChanged()";
emit counterHasChanged(counter);
}
//main.cpp
#include <QtGui/QGuiApplication>
#include "qtquick2applicationviewer.h"
#include "counter.h"
#include <QObject>
#include <QtQuick>
#include <QDebug>
#include <QQuickItem>
#include <QQmlContext>
#include <QtCore>
int main(int argc, char *argv[])
{
QGuiApplication app(argc, argv);
QtQuick2ApplicationViewer viewer;
viewer.setMainQmlFile(QStringLiteral("qml/StatesTest2/main.qml"));
viewer.showExpanded();
QQuickView view;
view.setSource(QUrl::fromLocalFile("qml/StatesTest2/main.qml"));
QObject *item = view.rootObject();
Counter counter;
QObject::connect(item, SIGNAL(click()), &counter, SLOT(click()));
return app.exec();
}
//main.qml
import QtQuick 2.0
Rectangle {
id: root
width: 360
height: 360
signal click
Text {
text: qsTr("Hello World")
anchors.centerIn: parent
}
MouseArea {
anchors.fill: parent
onClicked: {
root.click
console.log("click() qml")
}
}
Text {
text: "clicks: "
x: 30
y: 250
}
Text {
id: counter
text: "0"
x: 75
y: 250
}
}
我知道有很多這樣的話題..出於某種原因,沒有其他解決方案對我有用..也許我應該改變我的IDE:D
我建議你添加計數器作為上下文屬性..這需要進行以下更改。
//Counter.h
#ifndef COUNTER_H
#define COUNTER_H
#include <QObject>
class Counter : public QObject
{
Q_OBJECT
private:
int counter;
public:
explicit Counter(QObject *parent = 0);
signals:
void counterHasChanged(int Value);
public slots:
void click();
};
#endif // COUNTER_H
Counter.cpp文件
//counter.cpp
#include "counter.h"
#include <QDebug>
Counter::Counter(QObject *parent) :
QObject(parent)
{
this->counter = 0;
qDebug() << "Class Counter created";
}
void Counter::click() {
this->counter++;
qDebug() << "clickRegistered() - emit counterHasChanged()";
emit counterHasChanged(counter);
}
main.cpp文件
//main.cpp
#include <QtGui/QGuiApplication>
#include "qtquick2applicationviewer.h"
#include "counter.h"
#include <QObject>
#include <QtQuick>
#include <QDebug>
#include <QQuickItem>
#include <QQmlContext>
#include <QtCore>
int main(int argc, char *argv[])
{
QGuiApplication app(argc, argv);
Counter counter;
QtQuick2ApplicationViewer viewer;
viewer.rootContext()->setContextProperty("counterObj",&counter);
viewer.setMainQmlFile(QStringLiteral("qml/SO_QMLCPPCommunication/main.qml"));
viewer.showExpanded();
return app.exec();
}
在qml文件中,您可以通過引用counterObj來訪問Counter對象的插槽。
//main.qml
import QtQuick 2.0
Rectangle {
id: root
width: 360
height: 360
signal click
Text {
text: qsTr("Hello World")
anchors.centerIn: parent
}
MouseArea {
anchors.fill: parent
onClicked: {
counterObj.click()
console.log("click() qml")
}
}
Text {
text: "clicks: "
x: 30
y: 250
}
Text {
id: counter
text: "0"
x: 75
y: 250
}
Connections
{
id:cppConnection
target:counterObj
ignoreUnknownSignals : true
onCounterHasChanged:{
//To access signal parameter,please name the parameter.
console.debug("Counter value changed")
counter.text = Value
}
}
}
QQuickView::rootObject()
返回一個QQuickItem
,顯然在Qt5.0上沒有任何點擊信號( http://qt-project.org/doc/qt-5.0/qtquick/qquickitem.html )
確保將正確(現有)信號鏈接到正確的插槽,並確保信號實際被調用。
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