Qt : Can't update QQuickWidget from outside MainWindow - c++

Question

I have been trying to fix this issue for 2 days now.I have a gmaps QML project , which I've Integrated into my Qt widgets project using the following code:
gmap locator;
ui->quickWidget->setSource(QUrl::fromLocalFile("/maps/main.qml"));
ui->quickWidget->rootContext()->setContextProperty("gmap",&locator);
ui->quickWidget->show();
When I set the location on the map from the MainWindow using
locator.setData( "28.6082819", "77.0350079");
It works as expected , however , when I add a toolbutton and do the same thing from its slot , it doesn't work.I've connected it to a custom slot in my MainWindow like this:
connect(ui->toolButton_5, SIGNAL(clicked()), this, SLOT(plotmap(QString(ui->lineEdit_3->text()),QString(ui->lineEdit_4->text()),&locator,&ui->quickWidget)));
and here's the custom slot:
void MainWindow::plotmap(QString lat , QString lon, gmap *loc,QQuickWidget *view)
{
loc->setData("02.60","77.04");
view->show();
view->update();
}
Here's my qml files
gmap.cpp
#include "gmap.h"
gmap::gmap()
{
}
void gmap::setData(QString lat,QString lang)
{
qDebug(lat.toLatin1());
emit getLat(lat.toDouble());
emit getLang(lang.toDouble());
}
gmap.h
#ifndef GMAP_H
#define GMAP_H
#include <QObject>
class gmap : public QObject
{
Q_OBJECT
public:
gmap();
signals:
void getLat(double lat);
void getLang(double lang);
public slots:
void setData(QString lat,QString lang);
};
#endif // GMAP_H
main.qml
import QtQuick 2.6
import QtQuick.Window 2.2;
import QtPositioning 5.6;
import QtLocation 5.9
import Qt3D.Input 2.1
import QtQuick.Controls 2.2;
Window {
width: Qt.platform.os == "android" ? Screen.width : 512
height: Qt.platform.os == "android" ? Screen.height : 512
visible: true
Plugin {
id: mapPlugin
name: "osm"
PluginParameter {
name: 'osm.mapping.highdpi_tiles'
value: !!1 }
}
Connections{
target: gmap
onGetLat : mapmarker.center.latitude = lat
}
Connections{
target: gmap
onGetLang : mapmarker.center.longitude = lang
}
Connections{
target: gmap
onGetLang : map.center = QtPositioning.coordinate(mapmarker.center.latitude,mapmarker.center.longitude,150);
}
Map {
id: map
anchors.fill: parent
anchors.rightMargin: -15
anchors.bottomMargin: -10
anchors.leftMargin: 15
anchors.topMargin: 10
plugin: mapPlugin
center: QtPositioning.coordinate() // NSUT
zoomLevel: 14
activeMapType: supportedMapTypes[2]
Button {
x: 389
y: 445
text: "ADD MARKER"
anchors.right: parent.right
anchors.bottom: parent.bottom
anchors.bottomMargin: 27
anchors.rightMargin: 23
padding: 7
onClicked: gmap.setData(textField.text,textField1.text)
}
MapCircle {
id: mapmarker
center {
latitude: 28.6078
longitude: 77.0406
}
radius: 50.0
color: 'green'
border.width: 3
}
TextField {
id: textField
x: 176
y: 397
text: qsTr("")
anchors.right: parent.right
anchors.bottom: parent.bottom
anchors.bottomMargin: 75
anchors.rightMargin: 136
}
TextField {
id: textField1
x: 176
y: 445
anchors.right: parent.right
anchors.bottom: parent.bottom
anchors.bottomMargin: 27
anchors.rightMargin: 136
font.hintingPreference: Font.PreferDefaultHinting
}
}
}
The map in my QQuickWidget doesn't update.What could I be doing wrong , please let me know.

Answer 1

AFAIK your connect syntax is wrong.
Store locator as a member somewhere, in MainWindow for example:
public:
void setLocator(gmap* loc) { m_locator = loc; }
private:
gmap* m_locator;
Add a slot to MainWindow:
private slot:
plotmapFromLineEdits() { plotmap(ui->lineEdit_3->text(), ui->lineEdit_4->text(), m_locator, ui->quickWidget); }
and connect it like this:
connect(ui->toolButton_5, SIGNAL(clicked()), this, SLOT(plotmapFromLineEdits()));
Or in C++11 or above you can connect without defining a slot by using lambda:
connect(ui->toolButton_5, SIGNAL(clicked()), [&](){plotmap(ui->lineEdit_3->text(), ui->lineEdit_4->text(), m_locator, ui->quickWidget);}));
I don't think you have to show and update QQuickWidget every time. Just delete the quickwidget parameter.
Lastly please make sure your class names start with an uppercase letter:
gmap => GMap