qt - QML ItemDelegate 突出显示的属性不起作用

Question

我想在 ItemDelegate 中自定义突出显示颜色。如果我使用默认的 ItemDelegate 和 Material 主题，那么当我将鼠标悬停在该项目上时，一切正常并且颜色会发生变化，但是当我重新定义背景时，它会崩溃并且颜色不再改变。

MyItemDelegate.qml:

import QtQuick 2.11
import QtQuick.Controls.Material 2.4
import QtQuick.Controls 2.4
import QtQuick.Templates 2.4 as T

T.ItemDelegate {
    id: myItemDelegate
    height: 40     
    anchors.left: parent.left
    anchors.right: parent.right

    contentItem: Text {
            text: "Hello"
            anchors.fill: parent
            verticalAlignment: Text.AlignVCenter
            horizontalAlignment: Text.AlignHCenter
        }
    }

    background: Rectangle {
        anchors.fill: myItemDelegate
        color: myItemDelegate.highlighted ? "blue" : "transparent"
    }
}

为什么highlighted属性不起作用？我如何定制这种颜色？

Answer 1

问题很简单，高亮属性不是从头创建的，必须激活它，而且最常见的是它与ListView.isCurrentItem有绑定(bind)，所以必须更新当前项目:

MyItemDelegate.qml

import QtQuick 2.11
import QtQuick.Controls.Material 2.4
import QtQuick.Controls 2.4
import QtQuick.Templates 2.4 as T

T.ItemDelegate {
    id: myItemDelegate
    height: 40
    anchors.left: parent.left
    anchors.right: parent.right
    highlighted: ListView.isCurrentItem // <---
    contentItem: Text {
        text: "Hello"
        anchors.fill: parent
        verticalAlignment: Text.AlignVCenter
        horizontalAlignment: Text.AlignHCenter
    }
    background: Rectangle {
        anchors.fill: myItemDelegate
        color: myItemDelegate.highlighted ? "blue" : "transparent"
    }
}

ma​​in.qml

import QtQuick 2.9
import QtQuick.Controls 2.2

ApplicationWindow {
    visible: true
    width: 640
    height: 480
    title: qsTr("Scroll")
    ListView {
        id: listView
        anchors.fill: parent
        model: 20
        delegate: MyItemDelegate {
            MouseArea{
                anchors.fill: parent
                hoverEnabled: true
                onHoveredChanged: listView.currentIndex = index
            }
        }
    }
}