为什么在点击“运行"时有时不会反映 QML 代码的更改以及如何解决它? [英] Why are changes to the QML code sometimes not reflected when hitting 'Run' and how to solve it?

问题描述

在这个 Qt Quick 简单示例中，我希望当我向上移动 Racked 时，我们在 console.log 上有一条消息显示该移动，而当 Racket 向下移动时，我们有另一条消息.我为此编写了此代码:

In this Qt Quick simple example, I want that when I move a Racked upwards, we have a message on console.log showing that movement and another message when the Racket is moved downwards. I've written this code for that:

Racket.qml:

import QtQuick 2.8

Rectangle {
    id: root
    width: 15; height: 50
    x: 400; y: 100
    color: "red"

    property int oldY: 100
    property bool yUwards: false
    property bool yDwards: false

        onYChanged: {
           if( y > oldY) {
              yDwards = true
              yUwards = false
              console.log("Racket moved downwards.\n")
            }

           else if( y < oldY) {
               yDwards = false
               yUwards = true
               console.log("Racket moved upwards.\n")
             }
            oldY = y
        }

    MouseArea {
        anchors.fill: parent
        drag.target: root
        drag.axis: Drag.YAxis
        drag.minimumY: 10
        drag.maximumY: 440
    }
}

main.qml:

import QtQuick 2.8
import QtQuick.Window 2.2

Window {
    visible: true
    width: 800
    height: 600

    Rectangle {
        id: table
        width: 700; height: 500
        border.width: 10
        border.color: "black"
        color: "white"

   Racket {
       id: redRacket
       x: 630; y: 100
       color: "red"
    }
  }
}

当我第一次点击Run时，代码不起作用，所以我点击clean all，run qmake然后全部重建，然后就成功了！
像我这样的 QML 新程序员是如何发现代码没问题的，但是成功运行程序需要这个过程?

When I at the first time hit Run, the code didn't work, so I hit clean all, run qmake and then rebuild all, then it worked!
How does a new QML programmer like me figure out that the code is fine but this process is needed to successfully run the program?

推荐答案

这确实是 QMake 中的一个错误.正如@Mitch 在他的评论中发布的那样，已经提交了一个错误报告:bugreports.qt.io/browse/QTBUG-13334

This is indeed a bug in QMake. As @Mitch posted in his comment, a bug report was already filed: bugreports.qt.io/browse/QTBUG-13334

如果您通读了该错误报告中的评论，则会发布该问题的解决方法.已经使用它几个月了，它似乎解决了这个问题.您所要做的就是将其粘贴到您的专业文件的末尾.

If you read through the comments in that bug report, a workaround for the problem was posted. Have been using it for a couple of months now and it seems to fix the issue. All you have to do is paste this at the end of your pro file.

#update qml
qml_scenes.depends = $$PWD/resources/scene1.qml $$PWD/resources/scene2.qml ...
qml_scenes.commands =
QMAKE_EXTRA_TARGETS += qml_scenes

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