specifying Button:onClicked via property

mzimmers

Hi all -

I'm implementing an app that will make copious use of customized buttons (really Rectangles with MouseAreas, probably). I need to be able to specify for each of my buttons what behavior to take when clicked. Can I do this using a property? If not, does anyone have a recommendation?

Rectangle {
    id: pill

    // stuff
    
    MouseArea {
        anchors.fill: parent
        onClicked: // what do I put here?
    }
}

Thanks...

JoeCFD

Can not you simply inherit a button for example:

TabButton  {
    id: root
    background: Rectangle {
        width: root.width
        height: root.height
        color: root.checked ? StyleSheet.mainActive : StyleSheet.greyBackground
    }

    onClicked: {
        if ( root.checked ) {
            ----------switch pane----------
        }
    }
}

mzimmers

My custom button is going to have to be fairly "open" when it comes to the onClicked() activity:

push something onto a stack
pop something off of a stack
send a signal of some kind back to the C++ code
etc.

I really need to parameterize the action (if this is possible).

lemons

@mzimmers if you want to add an onClicked signal to your rectangle:

// Pill.qml
Rectangle {
    id: pill
    signal clicked

    MouseArea {
        anchors.fill: parent
        onClicked: pill.clicked()
    }
}

// main.qml
Pill {
    width: 200
    height: 200
    color: "red"
    onClicked: {
        console.debug("pill clicked")
    }
}

if you want to pass an action as parameter to the object:

// Pill.qml
Rectangle {
    id: pill
    property var action: function () {}

    MouseArea {
        anchors.fill: parent
        onClicked: action()
    }
}

// main.qml
Pill {
    width: 200
    height: 200
    color: "red"
    action: function () {
        console.debug("action passed to mousearea of pill")
    }
}

GrecKo

Just customize a QQC2 button, don't recreate your own from scratch.

mzimmers

@GrecKo I don't see how that would solve my problem.

Bob64

@mzimmers if I understand what you want correctly, all you need to do is to expose a property in your root component (or maybe a property alias to the mouse area's onClicked property) that expects to be assigned an on-clicked handler function:

MyButton.qml

Rectangle {
    id: pill
    property var onClickedHandler
    // stuff
    
    MouseArea {
        anchors.fill: parent
        onClicked: pill.onClickedHandler()
    }
}

Usage:

     function handler1() { ... }
     function handler2() { ... }
     ...
     MyButton {
        id: but1
        onClickedHandler: handler1
     }
     MyButton {
        id: but2
        onClickedHandler: handler2
     }

mzimmers

@Bob64 @lemons thanks; this will work. I wonder -- is it possible to avoid using a function for this? No big deal if it isn't; it would just simplify the coding a bit.

Bob64

@mzimmers I think you mean just to use a "Javascript block" (not sure of technical term) like this:

     onClickHandler: {
        // do stuff
     }

and have that passed down to the onClicked property of the MouseArea?

I don't think that would work, though I can't explain the technicalities of it. You can almost get there with an "inline" function of some description though. If you have a later version of Qt than I have, I think you can use JS "arrow functions" like this:

     onClickHandler: () => {
        // do stuff
     }

(If the function had arguments, they would go in the () but here it's an empty arg list.)

The older approach to do something similar is the anonymous function:

     onClickHandler: function() {
        // do stuff
     }

mzimmers

@Bob64 good input. What I was originally thinking of was something like:

Rectangle {
    id: pill
    property var doStuff
    // stuff
    
    MouseArea {
        anchors.fill: parent
        onClicked: doStuff
    }
}

But stepping back, I think I'm trying to do something that will create more work than it will solve.

GrecKo

@mzimmers said in specifying Button:onClicked via property:

@GrecKo I don't see how that would solve my problem.

A Button already has a clicked signal.
If you only want to customize the look of your button, inherit from a base Button and change the contentItem and/or the background property of it.

\\ MyCustomButton.qml
 import QtQuick.Controls
Button {
    id: control
    background: // ...
    contentItem: // ...
}

Then you don't have to do anything special for the click and just use it like so:

MyCustomButton {
   onClicked: doSomething();
}

You don't need more than that. This onClickedHandler is superfluous.
And you still have access to the Qt Quick Controls features like font and style inheriting, padding, inset, clickPolicy, etc..

mzimmers

@GrecKo OK, now I see what you're saying, and I agree that would make things a little easier. I'm wondering how much I can customize the button: can I have multiple lines of text? And, if necessary, use multiple fonts/sizes for the text?

Thanks...

johngod

I know this is marked as solved but just wanted to add my 2 cents.
I did this by adding a property int type and a signal with a argument in my button, then calling the mouse click handler would invoke the signal with the type argument. Then outside on your menu were you have all your buttons, each button click will call another menu signal that receives the button type. Then you just add a bunch of if else's or a switch case to handle every type of button. Something like this:
Pill.qml:

Rectangle {
    id: pill
    property int type
    signal btnClick(btnSignal: int)
    
    MouseArea {
        anchors.fill: parent
        onClicked: btnClick(type)
    }
}

Then on your menu:

signal handlePills(type: int) 

onHandlePills: function(type){
    if (type === stuff1)
        doStuff1()

    if (type === stuff2)
        doStuff2()
.......
}


Pill {
    type: stuff1
    onBtnClick: handlePills(type)
}

Pill {
    type: stuff2
    onBtnClick: handlePills(type)
}

To make this more elegant you can create a qml enum and use it on type. I dont know your use case but to me was less error prone and more elegant code.

Taking another step further, and since I needed a dynamic menu where I could add or remove buttons, I created a listview, a model and button delegate, to create the menu with buttons. Then only took me a line of code to add a button:

function showMenuCommands() {
        menuCommands.modelMenu.clear()
        menuCommands.modelMenu.append({"textName": "copy", "typeName": Commands.Copy})
        menuCommands.modelMenu.append({"textName": "move", "typeName": Commands.Move})
        menuCommands.modelMenu.append({"textName": "scale", "typeName": Commands.Scale})
        ........
    }