QT QML切换页面时隐藏button_1按钮失效问题求助

需求：从第一页导航到第二页时隐藏button_1，但添加button_1.visible: false语句后未生效。相关代码如下：

main.qml #

import QtQuick 2.15
import QtMultimedia 5.0
import QtQuick.Controls 2.15
import QtQuick.Dialogs 1.0
import QtQuick.Layouts 1.2
import Qt.labs.folderlistmodel 2.1
ApplicationWindow{
    title : qsTr("Swipe view")
    visible: true
    width : 800
    height: 480
    color: "black"
    /*------------------------- Swipe View -------------------------*/ 
    SwipeView {
        id: swipeView
        currentIndex: swipeView.currentIndex
        anchors.fill: parent

        Item {
            id: id_page_1
            Text {
                color: "white"
                text: qsTr("Page_1")
            }
        }
        Item {
            id: id_page_2
            Text {
                color: "white"
                text: qsTr("Page_2")
            }
            visible: id_page_2.visible
            
            button_1.visible: false
        }
    }
    /*------------------------- BOTTOM BAR-------------------------*/   
    Rectangle{
        id: id_toolButton
        width : parent.height/1.2
        height: 80
        x: parent.width/4
        y: parent.height-height
        color: "white"
        visible: true
        opacity: 0.5
        Row {
            id: rowToolButton
            anchors.left: parent.left
            anchors.verticalCenter: parent.verticalCenter
            Button {
                id: button_1
                visible : button_1.visible
                width: 60
                height: 60
                background: Rectangle {
                    color: "transparent"
                }
                Image {
                    anchors.centerIn: parent;
                    width: parent.width/1.25
                    height: parent.height/1.25
                    source: "icons/image_1.png"
                }
            }
        }
    }
}

main.py #

import sys
import os
from PySide2.QtQml import *
from PySide2.QtGui import *
from PySide2 import QtCore

def qt_message_handler(mode, context, message):
    if mode == QtCore.QtInfoMsg:
        mode = 'Info'
    elif mode == QtCore.QtWarningMsg:
        mode = 'Warning'
    elif mode == QtCore.QtCriticalMsg:
        mode = 'critical'
    elif mode == QtCore.QtFatalMsg:
        mode = 'fatal'
    else:
        mode = 'Debug'
    print("%s: %s (%s:%d, %s)" % (mode, message, context.file, context.line, context.file))


if __name__ == "__main__":
    os.environ["QT_QUICK_BACKEND"] = "software"
    QtCore.qInstallMessageHandler(qt_message_handler)
    application = QGuiApplication(sys.argv)
    engine = QQmlApplicationEngine()
    engine.load(os.path.join(os.path.dirname(__file__),"application.qml"))
    if not engine.rootContext():
        sys.exit(-1)
    try :
        sys.exit(application.exex_())
    except:
        pass

问题根源 #

1. 作用域错误：button_1属于底部栏控件，不在id_page_2的作用域内，直接在id_page_2里修改button_1.visible不符合QML规则，完全无效。
2. 循环绑定：button_1的visible: button_1.visible是自引用循环绑定，会导致属性值无法正常更新。
3. 无效代码：id_page_2中的visible: id_page_2.visible同样是无意义的循环绑定。

修改后的main.qml #

import QtQuick 2.15
import QtMultimedia 5.0
import QtQuick.Controls 2.15
import QtQuick.Dialogs 1.0
import QtQuick.Layouts 1.2
import Qt.labs.folderlistmodel 2.1
ApplicationWindow{
    title : qsTr("Swipe view")
    visible: true
    width : 800
    height: 480
    color: "black"
    /*------------------------- Swipe View -------------------------*/ 
    SwipeView {
        id: swipeView
        anchors.fill: parent

        Item {
            id: id_page_1
            Text {
                color: "white"
                text: qsTr("Page_1")
            }
        }
        Item {
            id: id_page_2
            Text {
                color: "white"
                text: qsTr("Page_2")
            }
        }
    }
    /*------------------------- BOTTOM BAR-------------------------*/   
    Rectangle{
        id: id_toolButton
        width : parent.height/1.2
        height: 80
        x: parent.width/4
        y: parent.height-height
        color: "white"
        visible: true
        opacity: 0.5
        Row {
            id: rowToolButton
            anchors.left: parent.left
            anchors.verticalCenter: parent.verticalCenter
            Button {
                id: button_1
                // 绑定SwipeView索引：第二页（索引1）时隐藏按钮
                visible : swipeView.currentIndex !== 1
                width: 60
                height: 60
                background: Rectangle {
                    color: "transparent"
                }
                Image {
                    anchors.centerIn: parent;
                    width: parent.width/1.25
                    height: parent.height/1.25
                    source: "icons/image_1.png"
                }
            }
        }
    }
}

关键修改说明 #

• 移除所有循环绑定的无效代码，比如swipeView.currentIndex: swipeView.currentIndex、visible: id_page_2.visible等。
• 给button_1的visible属性添加正确绑定：swipeView.currentIndex !== 1，当SwipeView切换到第二页时自动隐藏按钮，其他页面显示。
• 删除id_page_2内试图修改button_1的无效代码，控件属性控制应该直接在目标控件上通过全局可访问对象（如swipeView）实现。

另外，main.py中有一处笔误：application.exex_()需改为application.exec_()，否则会导致运行报错。

内容的提问来源于stack exchange，提问作者RACHID BEN ABDELMALEK