PySide6.QtUiTools.QUiLoader¶

class QUiLoader¶

Loads and instantiates Qt Widgets Designer forms at runtime. More…

Synopsis¶

Methods¶

def __init__()
def addPluginPath()
def availableLayouts()
def availableWidgets()
def clearPluginPaths()
def errorString()
def isLanguageChangeEnabled()
def isTranslationEnabled()
def load()
def pluginPaths()
def registerCustomWidget()
def setLanguageChangeEnabled()
def setTranslationEnabled()
def setWorkingDirectory()
def workingDirectory()

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

Detailed Description¶

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Use QUiLoader to dynamically create QWidget-based user interfaces based on the information stored in UI files (created with Qt Widgets Designer).

The load() function reads the content of a UI file, instantiates the widgets described in the file, and returns a pointer to the top-level QWidget. This widget can then be shown:

def __init__(self, parent):
    super().__init__(parent)

    file = QFile(":/forms/myform.ui")
    if not file.open(QFile.OpenModeFlag.ReadOnly):
        qFatal("Cannot open resource file")
    loader = QUiLoader()
    myWidget = loader.load(file, self)
    layout = QVBoxLayout()
    layout.addWidget(myWidget)
    setLayout(layout)

If the instantiation fails, the function returns a nullptr; use the errorString() function to retrieve a human-readable description of the error that occurred.

If the UI file contains custom widgets implemented in a Qt Widgets Designer plugin, loading will fail by default. To work around this, you can subclass QUiLoader and override the createWidget() function. If this is not possible, you can also let the module load Qt Widgets Designer plugins by adding their locations via addPluginPath() or the QT_PLUGIN_PATH environment variable. See the Creating Custom Widgets for Qt Widgets Designer page for more details.

def loadCustomWidget(className,parent):

    loader = QUiLoader()
    availableWidgets = loader.availableWidgets()
    if not availableWidgets.contains(className):
        qWarning() << "Cannot create widget" << className
        return None

    return loader.createWidget(className, parent)

For a complete example using the QUiLoader class, see the Calculator Builder.

See also

Qt-UI-Tools QFormBuilder

__init__([parent=None])¶

Parameters:: parent – QObject

Creates a form loader with the given parent.

addPluginPath(path)¶

Parameters:: path – str

Adds the given path to the list of paths in which the loader will search when locating plugins.

Warning

Only set paths that you trust. Allowing untrusted users to create or add content in a specified path may lead to security vulnerabilities.

See also

createWidget() errorString()

pluginPaths()¶

Return type:: list of strings

Returns a list naming the paths in which the loader will search when locating custom widget plugins.

See also

addPluginPath() clearPluginPaths()

registerCustomWidget(customWidgetType)¶

Parameters:: customWidgetType – object

Registers a Python created custom widget to QUiLoader, so it can be recognized when loading a .ui file. The custom widget type is passed via the customWidgetType argument. This is needed when you want to override a virtual method of some widget in the interface, since duck punching will not work with widgets created by QUiLoader based on the contents of the .ui file.

(Remember that duck punching virtual methods is an invitation for your own demise!)

Let’s see an obvious example. If you want to create a new widget it’s probable you’ll end up overriding QWidget’s paintEvent() method.

class Circle(QWidget):
    def paintEvent(self, event):
        with QPainter(self) as painter:
            painter.setPen(self.pen)
            painter.setBrush(QBrush(self.color))
            painter.drawEllipse(event.rect().center(), 20, 20)

# ...

loader = QUiLoader()
loader.registerCustomWidget(Circle)
circle = loader.load('circle.ui')
circle.show()

# ...

setLanguageChangeEnabled(enabled)¶

Parameters:: enabled – bool

If enabled is true, user interfaces loaded by this loader will automatically retranslate themselves upon receiving a language change event. Otherwise, the user interfaces will not be retranslated.

See also

isLanguageChangeEnabled()

setTranslationEnabled(enabled)¶

Parameters:: enabled – bool

setWorkingDirectory(dir)¶

Parameters:: dir – QDir

Sets the working directory of the loader to dir. The loader will look for other resources, such as icons and resource files, in paths relative to this directory.

Warning

Only set a directory that you trust. Allowing untrusted users to create or add content in the working directory may lead to security vulnerabilities.