Unable to assign [undefined] to int during customizing ScrollBar

[Kamichanw]

@Lahearle I've tried to define width, but it still didn't work. In fact, even I just set an empty rectangle as contentItem of ScrollBar, like this:

contentItem: Rectangle {}

The error occurred still occurred when I hovered the ScrollBar.

[LS-KS]

@Kamichanw ScrollView is a Layout. So please try

Layout.preferredWidth

instead of width

[Kamichanw]

@LS-KS I cannot understand... The width we discussed earlier is the width of ScrollBar. And ScrollBar is assigned to ScrollBar.vertical which is a attached property of ScrollView. It shouldn't be a child item of ScrollView.

What's more, when the Rectangle is assigned to contentItem, it doesn't have attached property named Layout.

[sierdzio]

@Kamichanw said in Unable to assign [undefined] to int during customizing ScrollBar:

@sierdzio I don't know. As you can see, the error message shows that error occurred in qrc:/qt-project.org/imports/QtQuick/Controls/Windows/ScrollBar.qml which is a qt internal file.

Well, but looking at it will tell you which property assignment has failed. Then you will know which object in your code is undefined.

[JonB]

@Kamichanw
If you cannot track down which item it is in your code, maybe try commenting each one out till you find out?

[LS-KS]

@Kamichanw
I never used that ScrollBar Item so I may be wrong.
In general when you place something into a Layout object (like ScrollView) you can't use width and height but must use Layout -properties like preferredWidth etc.
You used width in your calculations.

[Kamichanw]

@JonB Of course, I have tried this strategy. However, even I commented all code in Rectangle, the problem persists.

[Kamichanw]

@LS-KS As you can see in qt doc, it uses width as well.

[Kamichanw]

@sierdzio Yes, I hope to open that file as well, but when I click the hyperlink in QML debugger console, it shows that

I also tried to search ScrollBar.qml in qt source directory, but there are too many file named ScrollBar.qml so that I don't know where to start.

[JonB]

@Kamichanw
Is there a directory something like QtQuick\Controls\Windows in the source tree? If so, how many ScrollBar.qml files are there in that directory?

[Kamichanw]

Hey guys, I opened C:\Qt\6.4.2\Src\qtdeclarative\src\quickcontrols2\windows\ScrollBar.qml . I think it might be the correct ScrollBar.qml. The line 33 uses contentITem.transitionDuration. But I cannot set in my file directly.

NativeStyle.ScrollBar {
        // Fade a hovered-looking version of the handle
        // on top of the default handle when hovering it
        x: contentItem.x
        y: contentItem.y
        z: 1
        width: contentItem.width
        height: contentItem.height
        control: controlRoot
        subControl: NativeStyle.ScrollBar.Handle
        overrideState: NativeStyle.StyleItem.AlwaysHovered
        opacity: controlRoot.hovered || control.pressed ? 1 : 0
        visible: contentItem instanceof NativeStyle.StyleItem--
        Behavior on opacity { NumberAnimation { duration: contentItem.transitionDuration } } // line 33
    }

[GrecKo]

@Kamichanw You should not customize native styles.
https://www.youtube.com/watch?v=mImptIBmWW0&t=1179s

[Kamichanw]

@GrecKo But how can I customize ScrollBar of ScrollView? Should I have to implement my own ScrollView?