Source code
Revision control
Copy as Markdown
// Copyright (C) 2020 Sze Howe Koh <szehowe.koh@gmail.com>
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
#include "signalslotsyntaxes.h"
#include <QQuickWidget>
#include <QQuickItem>
#include <QAudioInput>
void DemoWidget::demoImplicitConversion() {
//! [implicitconversion]
auto slider = new QSlider(this);
auto doubleSpinBox = new QDoubleSpinBox(this);
// OK: The compiler can convert an int into a double
connect(slider, &QSlider::valueChanged,
doubleSpinBox, &QDoubleSpinBox::setValue);
// ERROR: The string table doesn't contain conversion information
connect(slider, SIGNAL(valueChanged(int)),
doubleSpinBox, SLOT(setValue(double)));
//! [implicitconversion]
}
void DemoWidget::demoTypeResolution() {
//! [typeresolution]
auto audioInput = new QAudioInput(QAudioFormat(), this);
auto widget = new QWidget(this);
// OK
connect(audioInput, SIGNAL(stateChanged(QAudio::State)),
widget, SLOT(show()));
// ERROR: The strings "State" and "QAudio::State" don't match
using namespace QAudio;
connect(audioInput, SIGNAL(stateChanged(State)),
widget, SLOT(show()));
// ...
//! [typeresolution]
}
//! [lambda]
TextSender::TextSender(QWidget *parent) : QWidget(parent) {
lineEdit = new QLineEdit(this);
button = new QPushButton("Send", this);
connect(button, &QPushButton::clicked, [=] {
emit textCompleted(lineEdit->text());
});
// ...
}
//! [lambda]
void DemoWidget::demoCrossLanguageConnect()
{
//! [crosslanguage]
auto cppObj = new CppGui(this);
auto quickWidget = new QQuickWidget(QUrl("QmlGui.qml"), this);
auto qmlObj = quickWidget->rootObject();
// Connect QML signal to C++ slot
connect(qmlObj, SIGNAL(qmlSignal(QString)),
cppObj, SLOT(cppSlot(QString)));
// Connect C++ signal to QML slot
connect(cppObj, SIGNAL(cppSignal(QVariant)),
qmlObj, SLOT(qmlSlot(QVariant)));
//! [crosslanguage]
}
//! [defaultparams]
DemoWidget::DemoWidget(QWidget *parent) : QWidget(parent) {
// OK: printNumber() will be called with a default value of 42
connect(qApp, SIGNAL(aboutToQuit()),
this, SLOT(printNumber()));
// ERROR: Compiler requires compatible arguments
connect(qApp, &QCoreApplication::aboutToQuit,
this, &DemoWidget::printNumber);
}
//! [defaultparams]
void DemoWidget::demoOverloadConnect()
{
//! [overload]
auto slider = new QSlider(this);
auto lcd = new QLCDNumber(this);
// String-based syntax
connect(slider, SIGNAL(valueChanged(int)),
lcd, SLOT(display(int)));
// Functor-based syntax
connect(slider, &QSlider::valueChanged,
lcd, qOverload<int>(&QLCDNumber::display));
//! [overload]
}