I would like to catch QEvent in my custom cpp QObject (MyObject) if some of the properties is changed (QEvent::DynamicPropertyChange):
class MyObject : public QObject
{
Q_OBJECT
Q_PROPERTY(bool value MEMBER mValue)
public:
MyObject();
bool event(QEvent *e) override
{
qDebug() << "EVENT RECIEVED" << e->type();
return QObject::event(e);
}
private:
bool mValue = false;
};
It works great if i do this in cpp:
MyObject obj = MyObject();
obj.setProperty("val", true);
But it does not if I try to change property in QML:
MyObject {
id: obj
}
Button{
id: button
text: "set value"
onClicked: function () {
console.log('button clicked');
obj.value = true;
}
}
This is a simple github example of this.
Any ideas ?
Related
I've got a struct with two fields, for example:
struct testStruct
{
Q_GADGET
Q_PROPERTY(QString text MEMBER m_text);
Q_PROPERTY(QString value MEMBER m_value);
public:
QString m_text;
QString m_value;
};
There is a QList<testStruct> m_testStructs member of my "AppEngine" class exposed to QML via
Q_PROPERTY(QList<testStruct> testStructs READ testStructs NOTIFY testStructsChanged).
It is filled like that:
testStruct newStruct1, newStruct2;
newStruct1.m_text = "text1";
newStruct1.m_value = "value1";
newStruct2.m_text = "text2";
newStruct2.m_value = "value2";
m_testStructs << newStruct1 << newStruct2;
So I want to see "text" members in ComboBox list and use "value" members in further operations.
In fact QML ComboBox popup shows me the list of objects names when I set ComboBox's "textRole" property to "text" and "valueRole" to "value", but it does nothing for "currentText" or "currentValue" properties when I click the item, only "currentIndex" changes. Also "displayText" remains blank.
This is what I get in console when clicking those items:
qml: currentIndex: 0; currentText: ; currentValue: undefined
qml: currentIndex: 1; currentText: ; currentValue: undefined
So I see that ComboBox gets members of struct, but doesn't want to work with them. What should I do to make "currentText" and "currentValue" members of ComboBox work as they should?
Here are all the needed files:
main.cpp
#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QQmlContext>
#include "appengine.h"
int main(int argc, char *argv[])
{
QGuiApplication app(argc, argv);
QQmlApplicationEngine engine;
const QUrl url(u"qrc:/qml_testComboBoxStruct/main.qml"_qs);
QObject::connect(&engine, &QQmlApplicationEngine::objectCreated,
&app, [url](QObject *obj, const QUrl &objUrl) {
if (!obj && url == objUrl)
QCoreApplication::exit(-1);
}, Qt::QueuedConnection);
//exposing AppEngine class to QML
AppEngine appEngineObj;
QQmlContext *context = engine.rootContext();
context->setContextProperty("AppEngine", &appEngineObj);
engine.load(url);
return app.exec();
}
my custom class header AppEngine.h
#ifndef APPENGINE_H
#define APPENGINE_H
#include <QObject>
#include <QDebug>
struct testStruct
{
Q_GADGET
Q_PROPERTY(QString text MEMBER m_text);
Q_PROPERTY(QString value MEMBER m_value);
public:
QString m_text;
QString m_value;
};
Q_DECLARE_METATYPE(testStruct)
class AppEngine : public QObject
{
Q_OBJECT
Q_PROPERTY(QList<testStruct> testStructs READ testStructs NOTIFY testStructsChanged);
public:
explicit AppEngine(QObject *parent = nullptr);
QList<testStruct> testStructs();
private:
QList<testStruct> m_testStructs;
signals:
void testStructsChanged();
};
#endif // APPENGINE_H
my custom class cpp file AppEngine.cpp
#include "appengine.h"
AppEngine::AppEngine(QObject *parent)
: QObject{parent}
{
testStruct newStruct1, newStruct2;
newStruct1.m_text = "text1";
newStruct1.m_value = "value1";
newStruct2.m_text = "text2";
newStruct2.m_value = "value2";
m_testStructs << newStruct1 << newStruct2;
qDebug() << "m_testStructs.length():" << m_testStructs.length();
}
QList<testStruct> AppEngine::testStructs()
{
qDebug() << "testStructs()";
return m_testStructs;
}
main.qml
import QtQuick
import QtQuick.Controls
Window {
width: 640
height: 480
visible: true
title: qsTr("C++ struct to QML ComboBox")
ComboBox
{
anchors.centerIn: parent
width: 180
height: 30
id: comboBoxID
textRole: "text"
valueRole: "value"
model: AppEngine.testStructs
onActivated:
{
console.log('currentIndex:', currentIndex, '; currentText:', currentText, ';currentValue:', currentValue);
}
}
}
As I checked in the main.qml model property cant find and understand as you show it is undefined.
qml: currentIndex: 0; currentText: ; currentValue: undefined
qml: currentIndex: 1; currentText: ; currentValue: undefined
from ListView::model property
The model provides the set of data that is used to create the items in
the view. Models can be created directly in QML using ListModel,
ObjectModel, or provided by C++ model classes. If a C++ model class is
used, it must be a subclass of QAbstractItemModel or a simple list.
For example, you can have this :
import QtQuick
import QtQuick.Controls
Window {
width: 640
height: 480
visible: true
title: qsTr("C++ struct to QML ComboBox")
ComboBox
{
id: comboBoxID
anchors.centerIn: parent
width: 180
height: 30
textRole: "text"
valueRole: "value"
model: ListModel {
id : model
ListElement { text: "text1" ; value : "value1" }
ListElement { text: "text2" ; value : "value2" }
ListElement { text: "text3" ; value : "value3" }
ListElement { text: "text4" ; value : "value4" }
}
onActivated:
{
console.log('currentIndex:', currentIndex, '; currentText:', currentText, '; currentValue:', currentValue);
}
}
}
Because you use QML ListModel if you want to define your model from C++ it must be a subclass of QAbstractItemModel or a simple list.
updated :
you need to use QStandardItemModel which inherits from QAbstractItemModel you cant inherit from the abstract interface because of that I use QStandardItemModel
in appengine.h:
#ifndef APPENGINE_H
#define APPENGINE_H
#include <QObject>
#include <QDebug>
#include <QStandardItemModel>
struct testStruct: public QStandardItemModel
{
Q_OBJECT
Q_PROPERTY(QString text MEMBER m_text);
Q_PROPERTY(QString value MEMBER m_value);
public:
QString m_text;
QString m_value;
};
Q_DECLARE_METATYPE(testStruct)
class AppEngine : public QObject
{
Q_OBJECT
Q_PROPERTY(QList<testStruct *> testStructs READ testStructs NOTIFY testStructsChanged);
public:
explicit AppEngine(QObject *parent = nullptr);
QList<testStruct *> testStructs();
private:
QList<testStruct *> m_testStructs;
signals:
void testStructsChanged();
};
#endif // APPENGINE_H
In appengine.cpp
#include "appengine.h"
AppEngine::AppEngine(QObject *parent)
: QObject{parent}
{
testStruct *newStruct1 = new testStruct;
testStruct *newStruct2 = new testStruct;
newStruct1->m_text = "text1";
newStruct1->m_value = "value1";
newStruct2->m_text = "text2";
newStruct2->m_value = "value2";
m_testStructs << newStruct1 << newStruct2;
qDebug() << "m_testStructs.length():" << m_testStructs.length();
}
QList<testStruct *> AppEngine::testStructs()
{
qDebug() << "testStructs()";
return m_testStructs;
}
My goal is to create a custom Component (lets call it ComponentLoader) which can instantiate another component (lets call it DelegateComponent) via delegate.
The problem is that the instance of DelegateComponent isn't displayed after is was created (white screen). Note: tst_component is loaded message IS present which means that DelegateComponent instance was actually created.
Here is a minimal example:
main.qml
ApplicationWindow {
id: mainWindow
width: 640
height: 480
visible: true
Component {
id: tst_component
Rectangle {
anchors.fill: parent
Component.onCompleted: {
console.debug("tst_component is loaded");
}
Label {
text: "hello world"
anchors.centerIn: parent
}
}
}
// doesn't work
ComponentLoader {
anchors.fill: parent
delegate: tst_component
}
// works
// Loader {
// anchors.fill: parent
// sourceComponent: tst_component
// }
}
componentloader.h + componentloader.cpp
#pragma once
#include <QQuickItem>
class ComponentLoader : public QQuickItem
{
Q_OBJECT
Q_PROPERTY(QQmlComponent* delegate READ delegate WRITE setDelegate NOTIFY delegateChanged)
public:
QQmlComponent* delegate() const;
void setDelegate(QQmlComponent*);
signals:
void delegateChanged();
private:
void generate();
protected:
void componentComplete() override;
private:
QQmlComponent* mDelegate = nullptr;
};
// componentloader.cpp
#include "componentloader.h"
#include <QtWidgets/QtWidgets>
#include <QtQmlModels/QtQmlModels>
#include <QQuickWindow>
QQmlComponent* ComponentLoader::delegate() const
{
return mDelegate;
}
void ComponentLoader::setDelegate(QQmlComponent* delegate)
{
if (delegate != mDelegate)
{
mDelegate = delegate;
emit delegateChanged();
}
}
void ComponentLoader::componentComplete()
{
QQuickItem::componentComplete();
generate();
}
void ComponentLoader::generate()
{
QQmlEngine* engine = qmlEngine(this);
QQmlContext* root_ctx = engine->rootContext();
QQmlContext* ctx = new QQmlContext(root_ctx);
QObject* item = mDelegate->create(ctx);
QQuickItem* quickItem = qobject_cast<QQuickItem*>(item);
QQuickItem* quickParent = qobject_cast<QQuickItem*>(parent());
quickItem->setParent(quickParent);
quickItem->setParentItem(quickParent);
}
Your quickParent pointer is taking the QObject parent() value instead of the QQuickItem parentItem() value.
Simply changing it to this worked for me when I tried your code:
QQuickItem* quickParent = qobject_cast<QQuickItem*>(parentItem());
I also don't think you need to call setParent() at all. Just setParentItem().
I need to push a qml page to stackview from other qml page.
So i am using c++-qml interacting for this problem.
my c++ code finds page item, but does not find stackView.
main.cpp:
int main(int argc, char *argv[])
{
...
QQmlEngine engine;
QQmlComponent component(&engine, QUrl("qrc:/qml/main.qml"));
QObject* object = component.create();
Settings::defineObject(object);
return app.exec();
}
settings.h:
class Settings : public QObject
{
Q_OBJECT
private:
static QObject* object;
public:
...
Q_INVOKABLE void push(QString fileName);
static void defineObject(QObject* obj);
};
settings.cpp:
QObject* Settings::object = nullptr;
...
void Settings::push(QString fileName)
{
if (Settings::object == nullptr) QCoreApplication::exit(-3);
QObject* page = Settings::object->findChild<QObject*>("page");
if (!page) QCoreApplication::exit(-4);
QObject* stackView = page->findChild<QObject*>("stackView");
if (!stackView) QCoreApplication::exit(-5);
QMetaObject::invokeMethod(stackView, "push", Q_ARG(QString, fileName));
}
void Settings::defineObject(QObject* obj)
{
object = obj;
}
main.qml:
ApplicationWindow {
...
Page {
id: page
...
StackView {
id: stackView
initialItem: "Home.qml"
anchors.fill: parent
}
}
}
My program always exits -5 code.
How I can do this:
When signal finishedreply(from c++) send variable replydata(from c++) to TextArea(qml)
How i can connect this? Maybe Q_PROPERTY is a good way?
I use Qt 5.3
QQmlApplicationEngine engine;
engine.load(QUrl(QStringLiteral("qrc:///main.qml")));
SendGetSMS *Connection = new SendGetSMS();
engine.rootContext()->setContextProperty("abc1", Connection);
QObject::connect(Connection,&SendGetSMS::finishedReply,engine,...);
from the documentation
in the c++:
class Message : public QObject
{
Q_OBJECT
Q_PROPERTY(QString author READ author WRITE setAuthor NOTIFY authorChanged)
public:
void setAuthor(const QString &a) {
if (a != m_author) {
m_author = a;
emit authorChanged();
}
}
QString author() const {
return m_author;
}
private:
QString m_author;
};
Message msg;
engine.rootContext()->setContextProperty("msg", &msg);
in the qml:
Text {
width: 100; height: 100
text: msg.author // invokes Message::author() to get this value
Component.onCompleted: {
msg.author = "Jonah" // invokes Message::setAuthor()
}
}
I have a sub-class of QWidget that is a popup widget. I would like to add some animation when it shows and disappears. So I re-implemented showEvent(QShowEvent * event) and hideEvent and added some QPropertyAnimation in the functions. The showEvent works just fine for me but the hideEvent doesn't. Because
Hide events are sent to widgets immediately after they have been hidden.
Any idea about how to do it?
Update:
I don't think it's the right reason. When I use Nejat's solution. The show part works. But when I click outside the widget. It disappears immediately.
You should override QWidget::closeEvent() so when trying to close immediatly it will be ignored AND we start our animation and after finishing (QPropertyAnimation::finished()) we close the widget as normal.
Here is a demo to demonstrate:
class AnimatedWidget : public QWidget {
Q_OBJECT
Q_PROPERTY(qreal alpha READ alpha WRITE setAlpha)
public:
AnimatedWidget(QWidget* parent = nullptr) :QWidget{ parent }, opacityAnimation{ new QPropertyAnimation{this, "alpha",this} } {
setWindowFlags(windowFlags() | Qt::WindowFlags(Qt::FramelessWindowHint) | Qt::Tool);
auto pal = palette();
pal.setColor(QPalette::Background, Qt::cyan);
setAutoFillBackground(true);
setPalette(pal);
setFixedSize(200, 200);
}
qreal alpha() const {
return windowOpacity();
}
void setAlpha(qreal level) {
setWindowOpacity(level);
update();
}
protected:
void closeEvent(QCloseEvent* e) override {
if (opacityAnimation->currentValue().toReal() == 1.0) { // Ignore event + start animation
e->ignore();
startHide();
QObject::connect(opacityAnimation, SIGNAL(finished()), this, SLOT(onAnimationCallBack()), Qt::UniqueConnection);
} else {
e->accept();
if (!isHidden())
hide();
QWidget::close(); // necessary actions
}
}
public Q_SLOTS:
void show() {
startShow();
QWidget::show(); // necessary actions
}
private Q_SLOTS:
void onAnimationCallBack() {
if (opacityAnimation->currentValue().toReal() == 0.0) { // we're finished so let's really close the widget
QCloseEvent ev;
QApplication::sendEvent(this, &ev);
qApp->sendEvent(this, &ev);
}
}
void startHide() {
opacityAnimation->setStartValue(1.0);
opacityAnimation->setEndValue(0.0);
opacityAnimation->setDuration(1500);
opacityAnimation->start();
}
void startShow() {
opacityAnimation->setStartValue(0.0);
opacityAnimation->setEndValue(1.0);
opacityAnimation->setDuration(1500);
opacityAnimation->start();
}
private:
QPropertyAnimation* opacityAnimation = nullptr;
};
class Base : public QWidget {
public:
Base(QWidget* parent = nullptr) :QWidget{ parent }, widget{ new AnimatedWidget{} } {
}
private:
AnimatedWidget* widget;
protected:
void mouseReleaseEvent(QMouseEvent* e) override {
if (widget->isHidden())
widget->show();
else
widget->close();
QWidget::mouseReleaseEvent(e);
}
};
int main(int argc, char *argv[]) {
QApplication app(argc, argv);
Base base;
base.show();
return app.exec();
}
You can override the eventFilter in your widget and check for QEvent::Show and QEvent::Close events.
bool MyWidget::eventFilter(QObject * obj, QEvent * event)
{
if(obj == this && event->type() == QEvent::Show)
{
//about to show
}
else if(obj == this && event->type() == QEvent::Close)
{
//about to close
}
return false;
}
You should also install the event filter in the constructor by:
this->installEventFilter(this);