Slot not invoked when sending signal with enum values

Subbu

Hi, I have a C++ enum (backend code) that I am passing to a QML (front end) using signal/Slot connection. My post is a bit lengthy. But here is my code. For some reason, the slot is not executing. Am I missing anything here? There is no build errors. No run time error either.

File: FileEnum.h: Here is the C++ enum

namespace BatteryChargeLevel {

Q_NAMESPACE

enum class BattLvl {
 INSUFFICIENT = 1,
 LOW,
 MODERATE,
 FULL,
};

Q_ENUM_NS(BattLvl)

}

File: File2.cpp: This is my main entry function

qRegisterMetaType<BatteryChargeLevel::BattLvl>("BatteryLvl");

qmlRegisterUncreatableMetaObject(BatteryChargeLevel::staticMetaObject, 
    "com.mmt.components",   
    1, 0,                                          
    "BatteryChargeLevel",         
    "Error: only enums");

QObject *topBar = hmi->findChild<QObject *>("topBarObject");
if (!topBar) {
    qDebug("Couldn't find top bar object");
}

:
:
QObject::connect(Obj1, SIGNAL(BatterySoC(BatteryChargeLevel::BattLvl)), topBar, SLOT(onBatterySoC(BatteryChargeLevel::BattLvl)));

File3: StatusBar.qml

import com.mmt.components

id: bar
objectName: "topBarObject"

function onBatterySoC(BTSoC) {
    if(BTSoC === BatteryChargeLevel.INSUFFICIENT) {
        batteryIcon.source = "/Images/battery_icon_1.png"
    } else if (BTSoC === BatteryChargeLevel.LOW) {
        batteryIcon.source = "/Images/battery_icon_2.png"
    } else if (BTSoC === BatteryChargeLevel.MODERATE) {
        batteryIcon.source = "/Images/battery_icon_3.png"
    } else if (BTSoC === BatteryChargeLevel.FULL) {
        batteryIcon.source = "/Images/battery_icon_4.png"
    }

sierdzio

QObject::connect(Obj1, SIGNAL(BatterySoC(BatteryChargeLevel::BattLvl)), topBar, SLOT(onBatterySoC(BatteryChargeLevel::BattLvl)));

Use functor-based connect syntax if possilble. It will catch more errors during compilation time.

Is topBar and id: bar the same object? Does it have onBatterySoC signal or slot?

J.Hilk

@sierdzio said in Slot not invoked when sending signal with enum values:

Use functor-based connect syntax if possilble. It will catch more errors during compilation time.

not possible in the way @Subbu is building his program. The Slot does not exist yet at compile time

sierdzio

@J-Hilk said in Slot not invoked when sending signal with enum values:

@sierdzio said in Slot not invoked when sending signal with enum values:

Use functor-based connect syntax if possilble. It will catch more errors during compilation time.

not possible in the way @Subbu is building his program. The Slot does not exist yet at compile time

You mean the JS function is the slot? I doubt something like this will work at all.

J.Hilk

@sierdzio said in Slot not invoked when sending signal with enum values:

You mean the JS function is the slot

yes.

I doubt something like this will work at all

I think it can, but it's highly discourage to do it this way. Can't remember the reason.
I'll try to look it up. https://doc.qt.io/qt-6/qtqml-cppintegration-interactqmlfromcpp.html#accessing-loaded-qml-objects-by-object-name

accidentally found the issue of the op:
function onBatterySoC(BTSoC)
BTSoC is of type var -> the c++ signal argument must be of type QVariant

https://doc.qt.io/qt-6/qtqml-cppintegration-interactqmlfromcpp.html#invoking-qml-methods