qt - 鼠标区域是否由于拖动而中断了?

我想实现项目拖放功能,并在QML文档( https://doc.qt.io/qt-5/qtquick-tutorials-dynamicview-dynamicview2-example.html )中找到了一个良好的开端。

在本教程的第二部分中,开始实际拖动(不拖放)。

当我在自己的项目中应用此实现时,我发现只有PressAndHold事件到达dragArea仅此而已。 保持状态更改为true,但无法拖动。 此外,Release事件未达到dragArea

我使用了教程(在Creator中很容易获得ode)制作了一个最小的工作示例。

我可以通过在文本列上添加MouseArea来重现此行为。 我将propertyComposedEvents设置为true ,并且希望拖动能够正常工作。 但事实并非如此。

颜色变化表示PressAndHold已被显示。 但是从未收到Release事件(颜色保持蓝色)。

同样在添加的MouseAreas onRelease中添加mouse.accept = false并没有帮助。

以为它可能与重寄信有关,但似乎并非如此。

这对我来说似乎很糟糕……我该怎么做才能使其与拖动的项目中的MouseAreas一起使用。

Qt教程中的dynamicview.qml

/****************************************************************************
**
** Copyright (C) 2017 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of The Qt Company Ltd nor the names of its
**     contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/

import QtQuick 2.0

Rectangle {
    id: root

    width: 300; height: 400

//![0]
    Component {
        id: dragDelegate

//![1]
        MouseArea {
            id: dragArea

            property bool held: false

            anchors { left: parent.left; right: parent.right }
            height: content.height

            drag.target: held ? content : undefined
            drag.axis: Drag.YAxis

            onPressAndHold: held = true
            onReleased: held = false

            Rectangle {
                id: content
//![1]
                anchors {
                    horizontalCenter: parent.horizontalCenter
                    verticalCenter: parent.verticalCenter
                }
                width: dragArea.width; height: column.implicitHeight + 4

                border.width: 1
                border.color: "lightsteelblue"
//![3]
                color: dragArea.held ? "lightsteelblue" : "white"
                Behavior on color { ColorAnimation { duration: 100 } }
//![3]
                radius: 2
//![4]
                states: State {
                    when: dragArea.held

                    ParentChange { target: content; parent: root }
                    AnchorChanges {
                        target: content
                        anchors { horizontalCenter: undefined; verticalCenter: undefined }
                    }
                }
//![4]
                Column {
                    id: column
                    anchors { fill: parent; margins: 2 }

                    Text { text: 'Name: ' + name }
                    Text { text: 'Type: ' + type }
                    Text { text: 'Age: ' + age }
                    Text { text: 'Size: ' + size }
                }

                ///////////////// added mouse area
                MouseArea {
                    anchors.fill: parent
                    propagateComposedEvents: true
                    onClicked: {
                        console.log("clicked")
                    }
                    onReleased: {
                        mouse.accepted = false // doesn't help
                    }
                }

//![2]
            }
        }
//![2]
    }
//![0]

    ListView {
        id: view

        anchors { fill: parent; margins: 2 }

        model: PetsModel {}
        delegate: dragDelegate

        spacing: 4
        cacheBuffer: 50
    }
}

来自教程的PetsModel.qml

/****************************************************************************
**
** Copyright (C) 2017 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of The Qt Company Ltd nor the names of its
**     contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/

import QtQuick 2.0

ListModel {
    ListElement {
        name: "Polly"
        type: "Parrot"
        age: 12
        size: "Small"
    }
    ListElement {
        name: "Penny"
        type: "Turtle"
        age: 4
        size: "Small"
    }
    ListElement {
        name: "Warren"
        type: "Rabbit"
        age: 2
        size: "Small"
    }
    ListElement {
        name: "Spot"
        type: "Dog"
        age: 9
        size: "Medium"
    }
    ListElement {
        name: "Schrödinger"
        type: "Cat"
        age: 2
        size: "Medium"
    }
    ListElement {
        name: "Joey"
        type: "Kangaroo"
        age: 1
        size: "Medium"
    }
    ListElement {
        name: "Kimba"
        type: "Bunny"
        age: 65
        size: "Large"
    }
    ListElement {
        name: "Rover"
        type: "Dog"
        age: 5
        size: "Large"
    }
    ListElement {
        name: "Tiny"
        type: "Elephant"
        age: 15
        size: "Large"
    }
}

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