Using Qt in Plugins¶

MCA Editor runs on PySide6 (Qt6) inside Maya 2025+. Plugins can build full Qt UIs using the mca_qt.qt_compat compatibility layer, which abstracts away version differences.

Importing Qt¶

Always import Qt inside activate(), not at module level. The plugin discovery system imports your module before Qt is guaranteed to be available.

def activate(self, api):
    self._api = api

    # Safe — Qt is available by the time activate() is called.
    from mca_qt.qt_compat import (
        QWidget, QLabel, QVBoxLayout, QHBoxLayout,
        QPushButton, QLineEdit, QTextEdit, QCheckBox,
        QComboBox, QSpinBox, QTimer, QIcon
    )

Available Classes¶

These classes are safe to import from mca_qt.qt_compat:

Class	Notes
`QWidget`	Base class for all panels
`QLabel`	Static text
`QVBoxLayout`, `QHBoxLayout`, `QGridLayout`	Layout managers
`QPushButton`	Clickable button
`QLineEdit`	Single-line text input
`QTextEdit`	Multi-line text area
`QCheckBox`	Boolean toggle
`QComboBox`	Dropdown selector
`QSpinBox`, `QDoubleSpinBox`	Numeric inputs
`QTimer`	Periodic callbacks
`QIcon`	Icons for panels and actions
`QSizePolicy`	Widget sizing hints
`Qt`	Namespace for flags (e.g., `Qt.AlignTop`)

For anything not in this list, import directly from PySide6.QtWidgets or PySide6.QtCore — MCA Editor targets Maya 2025+ which ships PySide6.

Building a Panel¶

Panels are registered with api.add_panel() and displayed in the right sidebar. They must be QWidget instances.

from mca_qt.qt_compat import QWidget, QVBoxLayout, QLabel, QPushButton

panel = QWidget()
layout = QVBoxLayout(panel)
layout.setContentsMargins(8, 8, 8, 8)
layout.setSpacing(6)

layout.addWidget(QLabel("My Plugin"))
layout.addWidget(QPushButton("Run"))
layout.addStretch()  # Push widgets to the top

api.add_panel("my-plugin", "My Plugin", panel)

Timer-Based Updates¶

Use QTimer for periodic refreshes. Always stop timers in deactivate().

from mca_qt.qt_compat import QTimer

def activate(self, api):
    self._api = api
    # ... build UI ...

    self._timer = QTimer()
    self._timer.timeout.connect(self._refresh)
    self._timer.start(5000)  # Refresh every 5 seconds

def deactivate(self):
    self._timer.stop()
    self._timer = None
    self._api.remove_panel("my-plugin")
    self._api = None

Maya Version Notes¶

Maya Version	Qt Version	Import
Maya 2024	Qt5 / PySide2	Not supported by plugin API
Maya 2025	Qt6 / PySide6	Fully supported
Maya 2026	Qt6 / PySide6	Fully supported

MCA Editor's plugin system requires Maya 2025 or later. PySide2 is not supported.