Mark,
I have found that the object actually exists but when I make two subsequent
calls, it fails on the seconds. Look at this:
// not working
MouseArea {
anchors.fill: parent
onClicked: {
console.log("controller: " + controller);
console.log("here1");
controller.kernel.setParameter(DRCSynthEngine.KeyboardScale, 22)
console.log("here2");
controller.kernel.setParameter(DRCSynthEngine.KeyboardScaleCustom,
controller.kernel.keyboard.toggleKey(index))
console.log("here3");
}
}
// ouput
qml: controller: DRCController(0x7fff5c1f99f0)
qml: here1
qml: here2
qrc:/qml/PanelPerform.qml:131: ReferenceError: controller is not defined
// working
MouseArea {
anchors.fill: parent
onClicked: {
console.log("controller: " + controller);
var obj = {};
obj[DRCSynthEngine.KeyboardScale]=22;
obj[DRCSynthEngine.KeyboardScaleCustom]=controller.kernel.keyboard.toggleKey(index);
console.log("here1");
controller.kernel.setParameters(obj)
console.log("here2");
}
}
// outputqml:
qml: controller: DRCController(0x7fff5b96a9f0)
qml: here1
qml: here2
So, the workaround was to have a method to set two parameters at one, using
only one call to controller instance.
Sometimes I find awkward behaviours on qml which I don’t how to explain…
Regards,
Nuno
> On 30 Nov 2017, at 11:11, Mark Tucker <[email protected]> wrote:
>
> Hi Nuno,
>
> Are you attempting to access this "controller" property within a
> "Component.onCompleted" block of code?
>
> With Loaders I've found from experience that there's a brief period of time
> where the component has been created (and therefore its Component.onCompleted
> signal fires), but it has not yet been fully added to the object heirarchy,
> so attempting to access anything outside of that object's own scope fails.
>
> The only way I've ever found to get around this limitation is to instead
> figure out a way of using the onLoaded signal from the Loader, which seems to
> be emitted at a point where the QML object is correctly placed within the
> object heirarchy and can actually correctly access things outside of its own
> scope.
>
> The above is my own observations from a number of years of writing QML code -
> it may be what you're seeing here. I don't know anywhere near enough about
> how the C++ side of things or how the internals of Qt works to be able to
> provide any more detail.
>
> Perhaps you can change the point at which you run this code?
>
> Mark T
>
> From: Interest
> [mailto:[email protected]] On Behalf
> Of Nuno Santos
> Sent: 30 November 2017 10:11
> To: Qt Project MailingList <[email protected]>
> Subject: [Interest] Awkward Javascript problem
>
> Hi,
>
> I usually register a controller property that points to a Controller classe
> when I start my Qt apps. I can then access the controller from any point of
> the code in Javascript:
>
> quickView->rootContext()->setContextProperty("controller", &controller);
>
> Curiously, I’m having an issue in which inside a MouseArea onClick event,
> controller is not defined:
>
> ReferenceError: controller is not defined
>
> This MouseArea lives inside a Loader component that is one of the children of
> a SplitView.
>
> Maybe this be the cause for such ReferenceError? How can I workaround this?
> Any ideas?
>
> Thanks!
>
> Regards,
>
> Nuno
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