Many signals one slot

corruptedsyntax

I have a collection of QML objects (I've defined the same custom type for all of them). I want them all to notify the same instance of parent object upon a user click. What's the easiest way I can achieve this? Will I need to implement a connection for each instantiated item of my type?

ODБOï

Hi,
https://doc.qt.io/archives/qq/qq10-signalmapper.html
Here you have :

The Trivial Solution
The sender() Approach
The Subclass Approach
The Signal Mapper Approach

LA

corruptedsyntax

This post is deleted!

corruptedsyntax

@LeLev I'm looking for a purely QML solution. I'm designing a settings menu and toggling enabled/disabled on panels based on the selection of other menu items.

Eeli K

@corruptedsyntax I can't quite grasp your explanation but maybe something like this:

import QtQuick 2.6
import QtQuick.Layouts 1.3
import QtQuick.Controls 2.1

ApplicationWindow {
    id: window
    width: 360
    height: 520
    visible: true
    Item {
        function onButtonClicked(num_button){
            console.log(num_button)
        }
        ColumnLayout {
            Button {
                text: "1"
                onClicked: parent.parent.onButtonClicked(text)
            }
            Button {
                text: "2"
                onClicked: parent.parent.onButtonClicked(text)
            }
        }
    }
}

where the Button is promoted to your custom component. 'parent' inside a component file should be automatically resolved during runtime. Or you can add the listening object as a property to your component.

corruptedsyntax

I have a custom type for a collapsible menu item containing a label and collapsible panel for a setting. The respective data item panel is toggled visible/invisible based on the user clicking the label item. Only 1 data item may be shown at a time, so my design is:

User clicks label panel to enable data panel and make it visible
All data panels are disabled and made invisible
Selected data panel is made visible and enabled

Step 3 is achieved easily by defining by defining a single signal handler inside my custom type which listens to its parent. However step 2 requires that the parent object listens for signals from ALL children. I may be scaling the number of menu item children objects I am instancing as time goes on, and this will cause a lot of copy/paste code if there's not a better way to manage this. Example of how it's being done now:

//Custom type DoublePanel.qml
Rectangle {
    signal enableBox();
    Rectangle {
        id: leftLabel
        ...
        MouseArea {
            ...
            onClicked: {
                enableBox();
                //code to enable this box after signal to disable all boxes
                ...
            }
        }
    }
    Rectangle {
        id: rightData
        ...
    }
    Connections {
        target: parent.parent
        onDisableAll: {
            //code to disable here
            ...
        }
    }
}

//User context, CollapsibleBar.qml
Rectangle {
    signal disableAll();
    ...
    DoublePanel {
        id: panelSetting1
        Connections {    //Is this Connections code block avoidable with each instance?
            target: panelSetting1
            onEnableBox: {
                disableAll();
            }
        }
    }
    DoublePanel {
        id: panelSetting2
        Connections {    //Is this Connections code block avoidable with each instance?
            target: panelSetting2
            onEnableBox: {
                disableAll();
            }
        }
    }
    DoublePanel {
        id: panelSetting3
        Connections {    //Is this Connections code block avoidable with each instance?
            target: panelSetting3
            onEnableBox: {
                disableAll();
            }
        }
    }
    ...
}

Eeli K

@corruptedsyntax First, why do you use Connections when the target is the same as the parent of that Connections? This should work:

DoublePanel {
        id: panelSetting1
            onEnableBox: {
                disableAll();
            }
        }
    }

Second, you should be able to move it to the component and call parent.disableAll() (assuming that the Rectangle which has disableAll is the direct parent):

//Custom type DoublePanel.qml
Rectangle {
    onEnableBox: {
                parent.disableAll();
            }
...

(Though I haven't tested this.)

corruptedsyntax

@Eeli-K Only been using QML about a week and I've been on a tight timeline. So far it's just been throwing stuff together to make it work. Got a few days to spare, so now it's worth refactoring. Thanks for the tips, I thought I might be considerably over complicating things

Eeli K

@corruptedsyntax Then you've got a good start.

'Connections' is for writing a signal handler in other component than the sender - in C++ a signal and a slot are connected with connect(), in QML all senders can have corresponding onX handlers and any component can handle a signal from any available sender object with Connections.