Text steps out of line (window) on round rectangle. (Solution without using Qt5Compat.GraphicalEffects and OpacityMask)

I have qml ListView and inside it, I load My ListModel. My delegate component is a rectangle that holds a Text component. the Problem is when I scroll the ListView some alphabet like 'H' step out of the defined Rectangle. My defined rectangle has a round edge (radius), and the alphabet appears on the rounded edge. Is there any solution to it?

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The code sample just is a summary of the main code, imagine the list view is the whole alphabet.

blabla.qml

Rectangle{
    anchors.fill: parent
    color: "#141414"

    // Rect to keep listView component
    Rectangle {
        id: rectList
        anchors.centerIn: parent
        width: 200
        height: 400
        radius: 10
           
        ListModel{
            id: bla
            ListElement{name: "A"} ....}

        Component{
            id: delegateComponent
            Rectangle{
                id: rectListView
                width: rectList.width
                height: 30// txt.implicitHeight //removed implicitHeight
                color: "transparent"
                // radius: 10
                z: -1
                readonly property ListView __lv: ListView.view // read only property for saving model current index
                Text {
                    id: txt
                    property string __longString
                    anchors.fill: rectListView
                    anchors.left: rectListView.left
                    anchors.bottomMargin: 5
                    width: rectListView.width
                    height: rectListView.height
                    text: model.name
                   }
               }

           ListView{
               id: lv
               model: listModel
               delegate: delegateComponent
               anchors.fill: parent
               anchors.centerIn: parent
               focus: true
               clip: true
               cacheBuffer: 5000
               spacing: 15
   }

UPDATE:

Try it online

Solution

I cleaned up your QML:

I put the Rectangle into background properties, e.g. Page and Frame
I eliminated unnecessary sizing parameters and kept the essential ones
Your ListView had both anchors.fill and anchors.centerIn, it should only have one
I added more data to your ListModel
I fixed the indentation and made your snippet runnable

Because we use Frame we give QML a hint that this object will derive it's height from the Text component that's within. The width of the Frame I use the ListView.view.width attached property.

The Text only needs to set width: parent.width to inherit the padding width inside the Frame. I also set wordWrap: Text.WordWrap so that whilst the width is constrained, the height of the Text box will grow if the text needs to be multiline. If the Text does grow, the Frame will automatically grow with it.

[EDIT]

With the new requirements added, I have made the following addition changes:

Use padding: 0 on the Frame
Introduce Qt5Compat.GraphicalEffects and OpacityMask

import QtQuick
import QtQuick.Controls
import Qt5Compat.GraphicalEffects
Page {
    Rectangle {
        id: backgroundRect
        anchors.fill: parent
        color: "#89a"
    }

    Frame {
        id: frame
        anchors.centerIn: parent
        width: 200
        height: 400
        padding: 0
        background: Rectangle {
            radius: 10
        }
        ListView {
            id: listView
            model: SampleListModel { }
            anchors.fill: parent
            clip: true
            delegate: Frame {
                width: ListView.view.width
                background: Rectangle {
                    color: index & 1 ? "#eee" : "#ccc"
                }
                Text {
                    width: parent.width
                    text: model.name
                    wrapMode: Text.WordWrap
                }
            }
            section.property: "group"
            section.delegate: Frame {
                width: ListView.view.width
                background: Rectangle {
                    color: "#60a2b3"
                }
                Text {
                    anchors.centerIn: parent
                    text: section
                }
            }
        }
    }

    Item {
        id: backgroundMask
        anchors.fill: parent
        visible: false
        Rectangle {
            x: frame.x
            y: frame.y
            width: frame.width
            height: frame.height
            radius: 10
         }
    }

    OpacityMask {
        anchors.fill: parent
        source: backgroundRect
        maskSource: backgroundMask
        invert: true
    }
}

// SampleListModel.qml
import QtQuick
import QtQuick.Controls

ListModel {
    id: listModel
    ListElement { name: "A"; group: "Group A" }
    ListElement { name: "B"; group: "Group A" }
    ListElement { name: "C"; group: "Group B" }
    ListElement { name: "D"; group: "Group B" }
    ListElement { name: "E"; group: "Group C" }
    ListElement { name: "F"; group: "Group C" }
    ListElement { name: "G"; group: "Group C" }
    ListElement { name: "H"; group: "Group C" }
    ListElement { name: "01010101001000111010100101010101110010111100011101101001010"; group: "Group D" }
    ListElement { name: "User2"; group: "Group D" }
    ListElement { name: "User3"; group: "Group D" }
    ListElement { name: "User4"; group: "Group D" }
    ListElement { name: "User5"; group: "Group D" }
    ListElement { name: "User6"; group: "Group D" }
    ListElement { name: "User7"; group: "Group D" }
    ListElement { name: "User8"; group: "Group D" }
    ListElement { name: "User9"; group: "Group D" }
    ListElement { name: "User10"; group: "Group D" }
    ListElement { name: "User11"; group: "Group D" }
    ListElement { name: "User12"; group: "Group D" }
    ListElement { name: "User13"; group: "Group D" }
    ListElement { name: "01010101001000111010100101010101110010111100011101101001010"; group: "Group D" }
    ListElement { name: "User2"; group: "Group D" }
    ListElement { name: "User3"; group: "Group D" }
    ListElement { name: "User4"; group: "Group D" }
    ListElement { name: "User5"; group: "Group D" }
    ListElement { name: "User6"; group: "Group D" }
    ListElement { name: "User7"; group: "Group D" }
    ListElement { name: "User8"; group: "Group D" }
    ListElement { name: "User9"; group: "Group D" }
    ListElement { name: "User10"; group: "Group D" }
    ListElement { name: "User11"; group: "Group D" }
    ListElement { name: "User12"; group: "Group D" }
}

You can Try it Online!