Can slot be set in Javascript?

Landy

Hi all,

Here is a question, can slot be set in Javascript?
Code:
@ Rectangle {
id: rootRect

    width: 100
    height: 100

    Rectangle {
        id: subRect

        width: 50
        height: 50
    }
    Component.onCompleted: {
        //something like the following code
        /*
          subRect.onWidthChanged = function () {
          }
          */
    }
}@

Take the code for example, i wanna set subRect's onWidthChanged slot in rootRect's Component.onCompleted, is there any solution for it?

MichK

onWidthChanged is a signal emmited when width property of your subRect changes.
If you want to call function of a qml element after width has changed then you have to do sth like this
or do a property binding.
@
Component.onCompleted: {
subRect.onWidthChanged.connect(otherComponent.doSthing)
}
@

Landy

Hi michal,

I tried as your suggestion.
but it didn't work.
Here is an error information:
TypeError: Result of expression 'subRect.onWidthChanged' [undefined] is not an object.
So, I changed the code as following:
@ function dosth() {
console.log("this is do sth");
}

Component.onCompleted: {
    root.widthChanged.connect(dosth());
}@

There is no error after I modified.
But there is another problem:
The function "dosth()" is called only once, only when the application starts.
after that, however I change the width, dosth() will not be called any more.
Do u have any idea?

[quote author="michal.k" date="1313734376"]onWidthChanged is a signal emmited when width property of your subRect changes.
If you want to call function of a qml element after width has changed then you have to do sth like this
or do a property binding.
@
Component.onCompleted: {
subRect.onWidthChanged.connect(otherComponent.doSthing)
}
@[/quote]

MichK

On the other hand maybe you should write something like this:
@
Rectangle {
id: rootRect

width: 100
height: 100

function writeMe() {
    console.log("subRectWidth changed")
}

Rectangle {
    id: subRect

    width: 50
    height: 50
    onWidthChanged: writeMe()
}
Component.onCompleted: {
    subRect.width = 100
}

}
@
But it all depends what you want to do.
writeMe will be called only when width of subRect changes

Landy

Yes, I know that we can use signal like that.
But, I wanna know if we can connect a slot and a signal in javascript.
For example:
If I create an Rectangle object named "rect" dynamic, and I wanna do sth when rect's width changed.
When the object is static, of course I can implement it very easily. But I don't know how to do it when the object is created dynamically

MichK

Aha, hmm so you mean situation where you create object like this:
@
var rectItem = Qt.createQmlObject('import Qt 4.7; Rect { id: subRect'
+ '}',
parentObject);
@
I don't know how to do it in this kind of situation ;)

Diph

Try if this works.

@Connections {
target: rectItem
onWidthChanged: console.log("width " + width)
}@

Landy

Great! It worked.
Thanks, guys.

Landy

I am sorry to open this thread again.
Thanks for Diph's solution, now I can handle signals out of their senders.
But I met a new problem again.
I found that I couldn't handle a signal dynamically with Diph's solution.
So, I still want to know if there is a way to handle signal dynamically.
Any guy has a solution about this?