QML Python中的自定义对象引用

Question

QML Python中的自定义对象引用

3

我试图使用qmlRegisterType扩展QML。我有一个python类 - PyQml.py，main.qml文件以及与之相关的样板代码。

问题在于我无法在main.qml文件中引用（导入）PyQml对象，我得到一个错误 --> QML模块未找到（PyQml）。

到目前为止，我已确定了QML_IMPORT_PATH变量路径。由于我很绝望，我在其中一个路径下创建了名为PyQml的文件夹，并将PyQml.py放入其中，但仍然没有成功。此外，在Qt Creator项目中，我找不到*.pro文件。我想我应该将另一个路径添加到自定义对象中。

PyQml.py

class PyQml(QObject):
    def __init__(self, parent=None):
        super().__init__(parent)
        # Initialise the value of the properties.
        self._name = ''
        self._shoeSize = 0

    # Define the getter of the 'name' property.  The C++ type of the
    # property is QString which Python will convert to and from a string.
    @Property('str')
    def name(self):
        return self._name

    # Define the setter of the 'name' property.
    @name.setter
    def name(self, name):
        self._name = name

    # Define the getter of the 'shoeSize' property.  The C++ type and
    # Python type of the property is int.
    @Property(int)
    def shoeSize(self):
        return self._shoeSize

    # Define the setter of the 'shoeSize' property.
    @shoeSize.setter
    def shoeSize(self, shoeSize):
        self._shoeSize = shoeSize

qmlengine.py

import sys
import sqlite3
from PySide2 import QtCore, QtGui, QtWidgets, QtQuick
from PySide2.QtCore import Qt,QUrl
from PySide2.QtQml import QQmlApplicationEngine,qmlRegisterType
from PySide2.QtGui import QGuiApplication
from ViewModel import PyQml

if __name__ == '__main__':
    app = QGuiApplication(sys.argv)
    engine = QQmlApplicationEngine()
    print(QQmlApplicationEngine.importPathList(engine))
    ctx = engine.rootContext()
    ctx.setContextProperty("qmlapp", engine) #the string can be anything
    qmlRegisterType(PyQml.PyQml, 'People', 1, 0, 'Person');
    engine.load('Documents/ctmd/Qml/main.qml')
    win = engine.rootObjects()[0]
    win.show()
    sys.exit(app.exec_())

main.qml

import QtQuick 2.0
import QtQuick.Controls 1.4
import PyQml 1.0 ---- Error QML module not found ( PyQml)
ApplicationWindow {

    menuBar: MenuBar {
        Menu {
            title: "File"
            MenuItem { text: "Open..." }
            MenuItem { text: "Close" }
        }

        Menu {
            title: "Edit"
            MenuItem { text: "Cut" }
            MenuItem { text: "Copy" }
            MenuItem { text: "Paste" }
        }
    }
    Grid {
        columns: 3
        spacing: 2
        Rectangle { color: "red"; width: 50; height: 50 }
        Rectangle { color: "green"; width: 20; height: 50 }
        Rectangle { color: "blue"; width: 50; height: 20 }
        Rectangle { color: "cyan"; width: 50; height: 50 }
        Rectangle { color: "magenta"; width: 10; height: 10 }
    }

}

项目文件夹树

Qml
   -main.qml
PyQml.py
qmlengine.py

PyQml只是一个示例类，在一天的结束时，我想通过qml传递我在python中计算的自定义数据（x，y坐标），并用qml绘制这些数据。

- user2727167

对我来说，当调用setter时无法更新屏幕上的getter，有什么问题吗？ - kei nagae

2个回答

0

我发现如果我简单地忽略这个错误

在 QML 窗口中一切都正常工作。我甚至尝试重新安装 IDE，但错误仍然存在。感谢您的澄清。

- user2727167

对我来说，这个错误不能被忽视。当我尝试打开QML表单编辑器时，会出现以下错误（见下图），然后点击“确定”会将我带回到QML文本编辑器。因此，每次我想使用所见即所得的QML编辑器时，我都必须在QML代码中注释导入语句。`行：7：找不到QML模块（<module>）。导入路径： <path>对于qmake项目，请使用QML_IMPORT_PATH变量添加导入路径。对于Qbs项目，请在产品中声明并设置qmlImportPaths属性以添加导入路径。 [...]` - yzokras

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原文链接

- eyllanesc · Accepted Answer

简介; 由于QtCreator和Qt for Python的限制，无法消除错误消息，因此没有解决方案。但是，QtCreator只是一个IDE，因此不需要在其中工作，相反，您只需要从控制台/CMD运行代码即可：

python /path/of/script.py

您有以下错误：

当您使用qmlRegisterType向QObject注册“People”时，“People”是QML中的包名称，“Person”是组件名称，因此除非更改注册表参数，否则不应在导入中使用PyQml。
QtCreator/QtQuickDesigner对Python支持仍然存在限制，因此“Qml模块未找到（FooPackage）”的消息就是一个例子。如Qt for Python/PySide2的开发人员指出，在将来的版本中他们将添加新功能，但目前还无法实现。
我看到您在发布中指定的结构与您的项目不匹配，例如，您指示主要的.qml位于与qmlengine.py同级的QML文件夹中，但在加载中却使用“Documents/ctmd/Qml/main.qml”。
PySide2在Property修饰符及其setter方面存在限制，因为它不被QML识别，而是使用广泛声明：name_of_property = Property(type_of_property, fget=getter_of_property, ...)
如果一个具有setter的Qt属性，则必须有一个关联的信号。

考虑上述问题，解决方案如下：

├── PyQml.py
├── Qml
│   └── main.qml
└── qmlengine.py

qmlengine.py

import os
import sys

from PySide2.QtCore import QUrl
from PySide2.QtGui import QGuiApplication
from PySide2.QtQml import QQmlApplicationEngine, qmlRegisterType

import PyQml

if __name__ == "__main__":
    app = QGuiApplication(sys.argv)
    qmlRegisterType(PyQml.PyQml, "People", 1, 0, "Person")
    engine = QQmlApplicationEngine()

    ctx = engine.rootContext()
    ctx.setContextProperty("qmlapp", engine)  # the string can be anything

    current_dir = os.path.dirname(os.path.realpath(__file__))
    filename = os.path.join(current_dir, "Qml/main.qml")

    engine.load(QUrl.fromLocalFile(filename))
    if not engine.rootObjects():
        sys.exit(-1)
    sys.exit(app.exec_())

PyQml.py

from PySide2.QtCore import Property, Signal, QObject


class PyQml(QObject):
    nameChanged = Signal(str)
    shoeSizeChanged = Signal(int)

    def __init__(self, parent=None):
        super().__init__(parent)
        # Initialise the value of the properties.
        self._name = ""
        self._shoeSize = 0

    # Define the getter of the 'name' property.  The C++ type of the
    # property is QString which Python will convert to and from a string.
    def get_name(self):
        return self._name

    # Define the setter of the 'name' property.
    def set_name(self, name):
        if self._name != name:
            self._name = name
            self.nameChanged.emit(name)

    name = Property(str, fget=get_name, fset=set_name, notify=nameChanged)

    # Define the getter of the 'shoeSize' property.  The C++ type and
    # Python type of the property is int.
    def get_shoeSize(self):
        return self._shoeSize

    # Define the setter of the 'shoeSize' property.
    def set_shoeSize(self, shoeSize):
        if self._shoeSize != shoeSize:
            self._shoeSize = shoeSize
            self.shoeSizeChanged.emit(shoeSize)

    shoeSize = Property(
        int, fget=get_shoeSize, fset=set_shoeSize, notify=shoeSizeChanged
    )

main.qml

import QtQuick 2.0
import QtQuick.Controls 1.4
import People 1.0

ApplicationWindow {
    visible: true

    Person{
        name: "foo"
        shoeSize: 10
    }

    menuBar: MenuBar {
        Menu {
            title: "File"
            MenuItem { text: "Open..." }
            MenuItem { text: "Close" }
        }

        Menu {
            title: "Edit"
            MenuItem { text: "Cut" }
            MenuItem { text: "Copy" }
            MenuItem { text: "Paste" }
        }
    }
    Grid {
        columns: 3
        spacing: 2
        Rectangle { color: "red"; width: 50; height: 50 }
        Rectangle { color: "green"; width: 20; height: 50 }
        Rectangle { color: "blue"; width: 50; height: 20 }
        Rectangle { color: "cyan"; width: 50; height: 50 }
        Rectangle { color: "magenta"; width: 10; height: 10 }
    }
}