Qt5中QML如何自定义环形菜单/环形选择框

这篇"Qt5中QML如何自定义环形菜单/环形选择框"文章的知识点大部分人都不太理解，所以小编给大家总结了以下内容，内容详细，步骤清晰，具有一定的借鉴价值，希望大家阅读完这篇文章能有所收获，下面我们一起来看看这篇"Qt5中QML如何自定义环形菜单/环形选择框"文章吧。

Qt5 中本身提供了扇形菜单 PieMenu，属于 QtQuick.Extras 模块，这个模块是拓展自 QtQuick.Control1 的，QtQuick.Control1 在 Qt5 高版本被废弃，并在 Qt6 移除。

不过我们也可以用 QtQuick.Control2 的组件自定义样式来实现环形或扇形的菜单和选择框。主要思路就是使用 PathView 来替换默认的 ListView，再改下弹框的背景样式。

ItemDelegate 需要设置给 ComboBox 或者 Menu，而不是 View。最好用 Button 的相关类型（默认是 ItemDelegate 类型），因为组件默认这些小部件是 Button 类型，内部 cast 成按钮来处理的。而且用按钮就不用自己处理下拉框 currentIndex，内部会自己处理，这也避免了我们在这个 delegate 对 currentIndex 赋值后导致其属性绑定失效的问题。

QQuickAction *QQuickMenu::actionAt(int index) const{    Q_D(const QQuickMenu);    QQuickAbstractButton *item = qobject_cast(d->itemAt(index));    if (!item)        return nullptr;     return item->action();}

自定义的时候遇到一点状况，就是 PathView 替代 ListView 作为 Menu 的 contentItem 后，Menu 的 contentData 和 contentModel 始终会多一个表示高亮的 Item，这样环形路径就有个缺口，目前我只能将显示的 Item 个数减去一个来使显示效果正常。

    contentItem: PathView {        model: control.contentModel        //把PathView放Menu，会有一个高亮Item被放到contentModel，减去        pathItemCount: control.count > 0 ? control.count - 1 : 0        //... ...    }

主要代码：

import QtQuick 2.12import QtQuick.Window 2.12import QtQuick.Controls 2.12 Window {    width: 640    height: 480    visible: true    title: qsTr("PathView")     Row {        anchors.centerIn: parent        spacing: 20         MyComboBox {            model: 10        }         Button {            width: 60            height: 30            text: "menu"            background: Rectangle {                radius: 15                color: "red"                border.color: "black"            }            onClicked: {                menu.popup()            }             MyMenu {                id: menu                anchors.centerIn: parent                Action { text: "1" }                Action { text: "2" }                Action { text: "3" }                Action { text: "4" }                Action { text: "5" }                Action { text: "6" }                Action { text: "7" }                Action { text: "8" }                Action { text: "9" }                Action { text: "10" }            }        }    }}

import QtQuick 2.12import QtQuick.Controls 2.12 //环形选择框//龚建波 2022-03-13//note：弹框为pop会被限制在window内ComboBox {    id: control     implicitWidth: 30    implicitHeight: 30    opacity: 0.9999     delegate: ItemDelegate {        width: 30        height: width        padding: 0        background: Rectangle {            radius: width / 2            color: "green"            border.color: "black"        }        contentItem: Text {            text: modelData            padding: 0            verticalAlignment: Text.AlignVCenter            horizontalAlignment: Text.AlignHCenter        }    }    contentItem: Text {        text: control.displayText        padding: 0        verticalAlignment: Text.AlignVCenter        horizontalAlignment: Text.AlignHCenter    }    indicator: null    background: Rectangle {        radius: 15        color: "green"        border.color: "black"    }    popup: Popup {        id: pop        width: 200        height: width        anchors.centerIn: parent        margins: 0        padding: 0        //pathview环形的角度范围和延申半径        property int angle: 1        property int spread: 1        //pop弹出和隐藏时的过渡动画        enter: Transition {            ParallelAnimation {                NumberAnimation { property: "angle"; from: 1; to: 360; duration: 500 }                NumberAnimation { property: "spread"; from: 1; to: 100; duration: 500 }            }        }        exit: Transition {            ParallelAnimation {                NumberAnimation { property: "angle"; from: 360; to: 1; duration: 500 }                NumberAnimation { property: "spread"; from: 100; to: 1; duration: 500 }            }        }        background: Item { }        contentItem: PathView {            model: control.popup.visible ? control.delegateModel : null            //currentIndex: control.highlightedIndex            //highlightRangeMode: PathView.NoHighlightRange            interactive: false            path: Path {                //一个圆环路径                PathAngleArc {                    centerX: 100; centerY: 100                    radiusX: pop.spread; radiusY: pop.spread                    moveToStart: true                    startAngle: 0                    sweepAngle: pop.angle                }            }        }    }}

import QtQuick 2.12import QtQuick.Controls 2.12 //环形菜单//龚建波 2022-03-13//note：弹框为pop会被限制在window内Menu {    id: control     implicitWidth: 250    implicitHeight: 250    margins: 0    padding: 0     //pathview环形的角度范围和延申半径    property int angle: 1    property int spread: 1    //pop弹出和隐藏时的过渡动画    enter: Transition {        ParallelAnimation {            NumberAnimation { property: "angle"; from: 1; to: 360; duration: 500 }            NumberAnimation { property: "spread"; from: 1; to: 100; duration: 500 }        }    }    exit: Transition {        ParallelAnimation {            NumberAnimation { property: "angle"; from: 360; to: 1; duration: 500 }            NumberAnimation { property: "spread"; from: 100; to: 1; duration: 500 }        }    }    delegate: MenuItem {        id: item        width: 30        height: width        padding: 0        spacing: 0        indicator: null        arrow: null        background: Rectangle {            radius: width / 2            color: "red"            border.color: "black"        }        contentItem: Text {            text: item.text            padding: 0            verticalAlignment: Text.AlignVCenter            horizontalAlignment: Text.AlignHCenter        }    }    contentItem: PathView {        implicitWidth: 250        implicitHeight: 250        model: control.contentModel        //把PathView放Menu，会有一个高亮Item被放到contentModel，减去        pathItemCount: control.count > 0 ? control.count - 1 : 0        //currentIndex: control.currentIndex        //highlightRangeMode: PathView.NoHighlightRange        interactive: false        path: Path {            //一个圆环路径            PathAngleArc {                centerX: 125; centerY: 125                radiusX: control.spread; radiusY: control.spread                moveToStart: true                startAngle: 0                sweepAngle: control.angle            }        }    }    background: Item { }}

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