Using one property from a qml file in another qml file

JennyAug13

I have a property called width in button.qml. I have to use this property width inside my component called control inside my multiControl.qml file. How can i use this property width in another qml file? Should i use property alias?

LeLev

@JennyAug13 Hello,
first of all you should not use reserved keywords if you create a property, and is't also better to don't call your button 'Button.qml' because QML has already Type named Button.

//MyButton.qml

Item{
  property real m_width : 0 
  
  Rectangle{
  width : m_width 
  }
}

use : MyButton{ m_width : 50 }

or

Item{
  property alias m_rec : rec
  
  Rectangle{
id:rec
  width : 10
  }
}

MyButton{ m_rec.width : 50 }

JennyAug13

Oh, it is not working, bit more complicated. I have the following lines of code in button.qml

sliderHandle{
id:button
...

...
}

I have my control.qml file as follows:

Item{

id: Control


Item{

}

button{

}

}

I have multiControl.qml as follows:

Item{
id:multiControl


Control{


}

}

Now, how can i use width property from button.qml file inside multiControl.qml.

J.Hilk

Hi @JennyAug13
to use a property outside of your QML file, it has to be defined in the root element

The usual way to foward a property is indeed a property alias in the root item

dheerendra

You can't use width property of button in MultiControl directly & you should not. If you want to access, you define another property inside the Control.qml which is alias to width property of Button.

Item{
id: Control
    property alias jwidth : b1.width. 
    Item{
    }
    Button{
     id : b1
    }
}

You can access jwidth inside the multi control.qml

JennyAug13

@dheerendra Yes, solved it, but how can i access mouseX from my button.qml in multiControl.qml...
Can i use something like button.MouseArea.mouseX??
Ah.. many interlinks and complications. I will try to solve it.

dheerendra

many interlinks and complications.

Its is not many interlinks & complications. Framework is designed so beautifully such that you don't end in mess. In general as object oriented principles details of inner modules are not directly exposed outside. Now you should consider button as inner module. So from outside no body should directly access button. If you want to expose, expose what is required explicitly. Hope it clarifies.

JennyAug13

@dheerendra Oh ya..woww. if i want to expose from inner modules, is only way through properties? How can i expose the mouseX from the innner most button.qml to upper qmls. The mouseX is inside my onPressed signal handler of MouseArea of the button and has to be drawn to multiControls.qml level. Can i just take another property with the name startX or something like that and use it in multiControls.qml?

dheerendra

You can define your own signals or expose it like property.