qt - QML : Prevent snap back to bounds on touch event for flickable

Question

我正在 QML 中构建缩放功能。出于性能原因，pinchArea 是轻弹项的子项。

下面的代码是这样设置的，如果用户在操作后双击图像，图像会重新居中并且比例会重置为 1。

不需要的行为是:轻弹项目有一个功能，如果用户在缩放/移动图像后点击屏幕中的某处，该项目会重新居中。我不希望图像在点击屏幕后重新居中，而是想通过双击来控制行为

我可以半解决这个问题的一种方法是使用鼠标区域，但是鼠标区域会在可轻弹项目移动时移动，并且在鼠标区域外部单击会使项目重新居中。关于如何修改鼠标区域以阻止此操作，或关闭点击可轻弹项目并在捏合和缩放后它自行居中的行为的任何想法？

感谢您的帮助/建议!

import QtQuick 2.0

Rectangle {
    width: 640
    height: 360
    color: "gray"

    Flickable {
        id: flick
        anchors.fill: parent
        contentWidth: 500
        contentHeight: 500

        Rectangle {
            width: flick.contentWidth
            height: flick.contentHeight
            id: imageFlick

            gradient: Gradient {
                GradientStop { position: 0.0; color: "red" }
                GradientStop { position: 1.0; color: "white" }
            }
        }

        PinchArea {
            width: Math.max(flick.contentWidth, flick.width)
            height: Math.max(flick.contentHeight, flick.height)

            pinch.minimumScale: 1
            pinch.maximumScale: 10
            pinch.dragAxis: Pinch.XAndYAxis
            pinch.target: imageFlick

            property real initialWidth
            property real initialHeight

            onPinchStarted: {
                initialWidth = flick.contentWidth
                initialHeight = flick.contentHeight
                flick.interactive = false
            }

            onPinchUpdated: {
                flick.contentX += pinch.previousCenter.x - pinch.center.x
                flick.contentY += pinch.previousCenter.y - pinch.center.y
            }

            onPinchFinished: {
                flick.interactive = true
            }

            MouseArea {
                anchors.fill: flick
                width: flick.width
                height: flick.height

                //Prevents behaivor of recentering on tap within mouse area
                //                onClicked: {
                //                    flick.cancelFlick()
                //                }

                //For debugging - if tap inside area, recentering doesn't happen. If you tap
                // outside of area, recentering happens
                //                Rectangle {
                //                    anchors.fill:parent
                //                    color: "blue"
                //                }

                onDoubleClicked: {
                    flick.contentX = 0
                    flick.contentY = 0
                    imageFlick.scale = 1
                }
            }
        }
    }
}

Answer 1

我设法自己回答了这个问题。对于 onPinchUpdated，flick.contentX 和 flick.contentY 需要更改为 flick.x 和 flick.y。我还更改了一些元素的顺序以及它们的嵌套方式。

现在不再发生点击时矩形重新居中的不良行为。

        Rectangle {
            width: 900
            height: parent.height

            Rectangle { // pinch area
                id: test
                width: 800
                height: 500
                anchors.centerIn: parent
                color: "grey"
                clip: true

                Flickable {
                    id: flick
                    anchors.fill: parent
                    contentWidth: imageFlick.width
                    contentHeight: imageFlick.height

                    PinchArea {
                        id: pinchROI
                        width: Math.max(flick.contentWidth, flick.width)
                        height: Math.max(flick.contentHeight, flick.height)

                        pinch.minimumScale: 1
                        pinch.maximumScale: 10
                        pinch.dragAxis: Pinch.XAndYAxis
                        pinch.target: imageFlick

                        property real initialWidth
                        property real initialHeight

                        onPinchStarted: {
                            initialWidth = flick.contentWidth
                            initialHeight = flick.contentHeight
                            flick.interactive = false
                        }

                        onPinchUpdated: {
                            flick.x = pinch.previousCenter.x - pinch.center.x
                            flick.y = pinch.previousCenter.y - pinch.center.y
                        }

                        onPinchFinished: {
                            flick.interactive = true
                        }

                        MouseArea {
                            anchors.fill: parent

                            Rectangle {
                                id: imageFlick
                                width: 800
                                height: 500

                                gradient: Gradient {
                                    GradientStop { position: 0.0; color: "red" }
                                    GradientStop { position: 1.0; color: "yellow" }
                                }
                            }

                            onDoubleClicked: {
                                imageFlick.scale = 1
                                imageFlick.x = 0
                                imageFlick.y = 0
                            }
                        }
                    }
                }
            }
        }