# -*- coding: utf-8 -*-
# Copyright (c) Vispy Development Team. All Rights Reserved.
# Distributed under the (new) BSD License. See LICENSE.txt for more info.

"""
Base code for the Qt backends. Note that this is *not* (anymore) a
backend by itself! One has to explicitly use either PySide, PyQt4 or
PySide2, PyQt5 or PyQt6. Note that the automatic backend selection prefers
a GUI toolkit that is already imported.

The _pyside, _pyqt4, _pyside2, _pyqt5 and _pyside6 modules will
import * from this module, and also keep a ref to the module object.
Note that if two of the backends are used, this module is actually
reloaded. This is a sorts of poor mans "subclassing" to get a working
version for both backends using the same code.

Note that it is strongly discouraged to use the
PySide/PyQt4/PySide2/PyQt5/PySide6 backends simultaneously. It is
known to cause unpredictable behavior and segfaults.
"""

from __future__ import division

from time import sleep, time
import math
import os
import sys
import atexit
import ctypes
from packaging.version import Version

from ...util import logger
from ..base import (BaseApplicationBackend, BaseCanvasBackend,
                    BaseTimerBackend)
from ...util import keys
from ... import config
from . import qt_lib

USE_EGL = config['gl_backend'].lower().startswith('es')

# Get platform
IS_LINUX = IS_OSX = IS_WIN = IS_RPI = False
if sys.platform.startswith('linux'):
    if os.uname()[4].startswith('arm'):
        IS_RPI = True
    else:
        IS_LINUX = True
elif sys.platform.startswith('darwin'):
    IS_OSX = True
elif sys.platform.startswith('win'):
    IS_WIN = True

# -------------------------------------------------------------------- init ---


def _check_imports(lib):
    # Make sure no conflicting libraries have been imported.
    libs = ['PyQt4', 'PyQt5', 'PyQt6', 'PySide', 'PySide2', 'PySide6']
    libs.remove(lib)
    for lib2 in libs:
        lib2 += '.QtCore'
        if lib2 in sys.modules:
            raise RuntimeError("Refusing to import %s because %s is already "
                               "imported." % (lib, lib2))


def _get_event_xy(ev):
    # QT6 (and the Python bindings like PyQt6, PySide6) report position differently from previous versions
    if hasattr(ev, 'pos'):
        posx, posy = ev.pos().x(), ev.pos().y()
    else:
        # Compatibility for PySide6 / PyQt6
        posx, posy = ev.position().x(), ev.position().y()

    return posx, posy


# Get what qt lib to try. This tells us wheter this module is imported
# via _pyside or _pyqt4 or _pyqt5
QGLWidget = object
QT5_NEW_API = False
PYSIDE6_API = False
PYQT6_API = False
if qt_lib == 'pyqt4':
    _check_imports('PyQt4')
    if not USE_EGL:
        from PyQt4.QtOpenGL import QGLWidget, QGLFormat
    from PyQt4 import QtGui, QtCore, QtTest
    QWidget, QApplication = QtGui.QWidget, QtGui.QApplication  # Compat
elif qt_lib == 'pyqt5':
    _check_imports('PyQt5')
    if not USE_EGL:
        from PyQt5.QtCore import QT_VERSION_STR
        if Version(QT_VERSION_STR) >= Version('5.4.0'):
            from PyQt5.QtWidgets import QOpenGLWidget as QGLWidget
            from PyQt5.QtGui import QSurfaceFormat as QGLFormat
            QT5_NEW_API = True
        else:
            from PyQt5.QtOpenGL import QGLWidget, QGLFormat
    from PyQt5 import QtGui, QtCore, QtWidgets, QtTest
    QWidget, QApplication = QtWidgets.QWidget, QtWidgets.QApplication  # Compat
elif qt_lib == 'pyqt6':
    _check_imports('PyQt6')
    if not USE_EGL:
        from PyQt6.QtCore import QT_VERSION_STR
        if Version(QT_VERSION_STR) >= Version('6.0.0'):
            from PyQt6.QtOpenGLWidgets import QOpenGLWidget as QGLWidget
            from PyQt6.QtGui import QSurfaceFormat as QGLFormat
            PYQT6_API = True
        else:
            from PyQt6.QtOpenGL import QGLWidget, QGLFormat
    from PyQt6 import QtGui, QtCore, QtWidgets, QtTest
    QWidget, QApplication = QtWidgets.QWidget, QtWidgets.QApplication  # Compat
elif qt_lib == 'pyside6':
    _check_imports('PySide6')
    if not USE_EGL:
        from PySide6.QtCore import __version__ as QT_VERSION_STR
        if Version(QT_VERSION_STR) >= Version('6.0.0'):
            from PySide6.QtOpenGLWidgets import QOpenGLWidget as QGLWidget
            from PySide6.QtGui import QSurfaceFormat as QGLFormat
            PYSIDE6_API = True
        else:
            from PySide6.QtOpenGL import QGLWidget, QGLFormat
    from PySide6 import QtGui, QtCore, QtWidgets, QtTest
    QWidget, QApplication = QtWidgets.QWidget, QtWidgets.QApplication  # Compat
elif qt_lib == 'pyside2':
    _check_imports('PySide2')
    if not USE_EGL:
        from PySide2.QtCore import __version__ as QT_VERSION_STR
        if Version(QT_VERSION_STR) >= Version('5.4.0'):
            from PySide2.QtWidgets import QOpenGLWidget as QGLWidget
            from PySide2.QtGui import QSurfaceFormat as QGLFormat
            QT5_NEW_API = True
        else:
            from PySide2.QtOpenGL import QGLWidget, QGLFormat
    from PySide2 import QtGui, QtCore, QtWidgets, QtTest
    QWidget, QApplication = QtWidgets.QWidget, QtWidgets.QApplication  # Compat
elif qt_lib == 'pyside':
    _check_imports('PySide')
    if not USE_EGL:
        from PySide.QtOpenGL import QGLWidget, QGLFormat
    from PySide import QtGui, QtCore, QtTest
    QWidget, QApplication = QtGui.QWidget, QtGui.QApplication  # Compat
elif qt_lib:
    raise RuntimeError("Invalid value for qt_lib %r." % qt_lib)
else:
    raise RuntimeError("Module backends._qt should not be imported directly.")

# todo: add support for distinguishing left and right shift/ctrl/alt keys.
# Linux scan codes:  (left, right)
#   Shift  50, 62
#   Ctrl   37, 105
#   Alt    64, 108
qt_keys = QtCore.Qt.Key if qt_lib == 'pyqt6' else QtCore.Qt
KEYMAP = {
    qt_keys.Key_Shift: keys.SHIFT,
    qt_keys.Key_Control: keys.CONTROL,
    qt_keys.Key_Alt: keys.ALT,
    qt_keys.Key_AltGr: keys.ALT,
    qt_keys.Key_Meta: keys.META,

    qt_keys.Key_Left: keys.LEFT,
    qt_keys.Key_Up: keys.UP,
    qt_keys.Key_Right: keys.RIGHT,
    qt_keys.Key_Down: keys.DOWN,
    qt_keys.Key_PageUp: keys.PAGEUP,
    qt_keys.Key_PageDown: keys.PAGEDOWN,

    qt_keys.Key_Insert: keys.INSERT,
    qt_keys.Key_Delete: keys.DELETE,
    qt_keys.Key_Home: keys.HOME,
    qt_keys.Key_End: keys.END,

    qt_keys.Key_Escape: keys.ESCAPE,
    qt_keys.Key_Backspace: keys.BACKSPACE,

    qt_keys.Key_F1: keys.F1,
    qt_keys.Key_F2: keys.F2,
    qt_keys.Key_F3: keys.F3,
    qt_keys.Key_F4: keys.F4,
    qt_keys.Key_F5: keys.F5,
    qt_keys.Key_F6: keys.F6,
    qt_keys.Key_F7: keys.F7,
    qt_keys.Key_F8: keys.F8,
    qt_keys.Key_F9: keys.F9,
    qt_keys.Key_F10: keys.F10,
    qt_keys.Key_F11: keys.F11,
    qt_keys.Key_F12: keys.F12,

    qt_keys.Key_Space: keys.SPACE,
    qt_keys.Key_Enter: keys.ENTER,
    qt_keys.Key_Return: keys.ENTER,
    qt_keys.Key_Tab: keys.TAB,
}
if PYQT6_API or PYSIDE6_API:
    BUTTONMAP = {
        QtCore.Qt.MouseButton.NoButton: 0,
        QtCore.Qt.MouseButton.LeftButton: 1,
        QtCore.Qt.MouseButton.RightButton: 2,
        QtCore.Qt.MouseButton.MiddleButton: 3,
        QtCore.Qt.MouseButton.BackButton: 4,
        QtCore.Qt.MouseButton.ForwardButton: 5
    }
else:
    BUTTONMAP = {0: 0, 1: 1, 2: 2, 4: 3, 8: 4, 16: 5}


# Properly log Qt messages
def message_handler(*args):

    if qt_lib in ("pyqt4", "pyside"):
        msg_type, msg = args
    elif qt_lib in ("pyqt5", "pyqt6", "pyside2", "pyside6"):  # Is this correct for pyside2?
        msg_type, context, msg = args
    elif qt_lib:
        raise RuntimeError("Invalid value for qt_lib %r." % qt_lib)
    else:
        raise RuntimeError("Module backends._qt ",
                           "should not be imported directly.")

    BLACKLIST = [
        # Ignore spam about tablet input
        'QCocoaView handleTabletEvent: This tablet device is unknown',
        # Not too sure why this warning is emitted when using
        #   Spyder + PyQt5 + Vispy
        #   https://github.com/vispy/vispy/issues/1787
        # In either case, it is really annoying. We should filter it away
        'QSocketNotifier: Multiple socket notifiers for same',
    ]
    for item in BLACKLIST:
        if msg.startswith(item):
            return

    msg = msg.decode() if not isinstance(msg, str) else msg
    logger.warning(msg)


def use_shared_contexts():
    """Enable context sharing for PyQt5 5.4+ API applications.

    This is disabled by default for PyQt5 5.4+ due to occasional segmentation
    faults and other issues when contexts are shared.

    """
    forced_env_var = os.getenv('VISPY_PYQT5_SHARE_CONTEXT', 'false').lower() == 'true'
    return not (QT5_NEW_API or PYSIDE6_API or PYQT6_API) or forced_env_var


try:
    QtCore.qInstallMsgHandler(message_handler)
except AttributeError:
    QtCore.qInstallMessageHandler(message_handler)  # PyQt5, PyQt6


# -------------------------------------------------------------- capability ---

capability = dict(  # things that can be set by the backend
    title=True,
    size=True,
    position=True,
    show=True,
    vsync=True,
    resizable=True,
    decorate=True,
    fullscreen=True,
    context=use_shared_contexts(),
    multi_window=True,
    scroll=True,
    parent=True,
    always_on_top=True,
)


# ------------------------------------------------------- set_configuration ---
def _set_config(c):
    """Set the OpenGL configuration"""
    glformat = QGLFormat()
    glformat.setRedBufferSize(c['red_size'])
    glformat.setGreenBufferSize(c['green_size'])
    glformat.setBlueBufferSize(c['blue_size'])
    glformat.setAlphaBufferSize(c['alpha_size'])
    if QT5_NEW_API:
        # Qt5 >= 5.4.0 - below options automatically enabled if nonzero.
        glformat.setSwapBehavior(glformat.DoubleBuffer if c['double_buffer']
                                 else glformat.SingleBuffer)
    elif PYQT6_API or PYSIDE6_API:
        glformat.setSwapBehavior(glformat.SwapBehavior.DoubleBuffer if c['double_buffer']
                                 else glformat.SwapBehavior.SingleBuffer)
    else:
        # Qt4 and Qt5 < 5.4.0 - buffers must be explicitly requested.
        glformat.setAccum(False)
        glformat.setRgba(True)
        glformat.setDoubleBuffer(True if c['double_buffer'] else False)
        glformat.setDepth(True if c['depth_size'] else False)
        glformat.setStencil(True if c['stencil_size'] else False)
        glformat.setSampleBuffers(True if c['samples'] else False)
    glformat.setDepthBufferSize(c['depth_size'] if c['depth_size'] else 0)
    glformat.setStencilBufferSize(c['stencil_size'] if c['stencil_size']
                                  else 0)
    glformat.setSamples(c['samples'] if c['samples'] else 0)
    glformat.setStereo(c['stereo'])
    return glformat


# ------------------------------------------------------------- application ---

class ApplicationBackend(BaseApplicationBackend):

    def __init__(self):
        BaseApplicationBackend.__init__(self)
        # sharing is currently buggy and causes segmentation faults for tests with PyQt 5.6
        if (QT5_NEW_API or PYSIDE6_API) and use_shared_contexts():
            # For Qt5 >= 5.4.0 - Enable sharing of context between windows.
            QApplication.setAttribute(QtCore.Qt.AA_ShareOpenGLContexts, True)
        elif PYQT6_API and use_shared_contexts():
            QApplication.setAttribute(QtCore.Qt.ApplicationAttribute.AA_ShareOpenGLContexts, True)

    def _vispy_get_backend_name(self):
        name = QtCore.__name__.split('.')[0]
        return name

    def _vispy_process_events(self):
        app = self._vispy_get_native_app()
        # sendPostedEvents replaces flush which has been removed from Qt6.0+
        # This should be compatible with Qt4.x and Qt5.x
        app.sendPostedEvents()
        app.processEvents()

    def _vispy_run(self):
        app = self._vispy_get_native_app()
        if hasattr(app, '_in_event_loop') and app._in_event_loop:
            pass  # Already in event loop
        else:
            # app.exec_() for PyQt <=5 and app.exec() for PyQt >=5
            exec_func = app.exec if hasattr(app, "exec") else app.exec_
            return exec_func()

    def _vispy_quit(self):
        return self._vispy_get_native_app().quit()

    def _vispy_get_native_app(self):
        # Get native app in save way. Taken from guisupport.py
        app = QApplication.instance()
        if app is None:
            app = QApplication([''])
        # Store so it won't be deleted, but not on a vispy object,
        # or an application may produce error when closed.
        QtGui._qApp = app
        # Return
        return app

    def _vispy_sleep(self, duration_sec):
        QtTest.QTest.qWait(duration_sec * 1000)  # in ms


# ------------------------------------------------------------------ canvas ---

def _get_qpoint_pos(pos):
    """Return the coordinates of a QPointF object."""
    return pos.x(), pos.y()


class QtBaseCanvasBackend(BaseCanvasBackend):
    """Base functionality of Qt backend. No OpenGL Stuff."""

    def __init__(self, vispy_canvas, **kwargs):
        BaseCanvasBackend.__init__(self, vispy_canvas)
        # Maybe to ensure that exactly all arguments are passed?
        p = self._process_backend_kwargs(kwargs)
        self._initialized = False

        # Init in desktop GL or EGL way
        self._init_specific(p, kwargs)
        assert self._initialized

        self.setMouseTracking(True)
        self._vispy_set_title(p.title)
        self._vispy_set_size(*p.size)
        if p.fullscreen is not False:
            if p.fullscreen is not True:
                logger.warning('Cannot specify monitor number for Qt '
                               'fullscreen, using default')
            self._fullscreen = True
        else:
            self._fullscreen = False

        # must set physical size before setting visible or fullscreen
        # operations may make the size invalid
        if hasattr(self, 'devicePixelRatioF'):
            # handle high DPI displays in PyQt5
            ratio = self.devicePixelRatioF()
        else:
            ratio = 1
        self._physical_size = (p.size[0] * ratio, p.size[1] * ratio)

        if not p.resizable:
            self.setFixedSize(self.size())
        if p.position is not None:
            self._vispy_set_position(*p.position)
        if p.show:
            self._vispy_set_visible(True)

        # Qt supports OS double-click events, so we set this here to
        # avoid double events
        self._double_click_supported = True

        try:
            # see screen_changed docstring for more details
            self.window().windowHandle().screenChanged.connect(self.screen_changed)
        except AttributeError:
            # either not PyQt5 backend or no parent window available
            pass

        # QNativeGestureEvent does not keep track of last or total
        # values like QGestureEvent does
        self._native_gesture_scale_values = []
        self._native_gesture_rotation_values = []

    def screen_changed(self, new_screen):
        """Window moved from one display to another, resize canvas.

        If display resolutions are the same this is essentially a no-op except for the redraw.
        If the display resolutions differ (HiDPI versus regular displays) the canvas needs to
        be redrawn to reset the physical size based on the current `devicePixelRatioF()` and
        redrawn with that new size.

        """
        self.resizeGL(*self._vispy_get_size())

    def _vispy_warmup(self):
        etime = time() + 0.25
        while time() < etime:
            sleep(0.01)
            self._vispy_canvas.set_current()
            self._vispy_canvas.app.process_events()

    def _vispy_set_title(self, title):
        # Set the window title. Has no effect for widgets
        if self._vispy_canvas is None:
            return
        self.setWindowTitle(title)

    def _vispy_set_size(self, w, h):
        # Set size of the widget or window
        self.resize(w, h)

    def _vispy_set_physical_size(self, w, h):
        self._physical_size = (w, h)

    def _vispy_get_physical_size(self):
        if self._vispy_canvas is None:
            return
        return self._physical_size

    def _vispy_set_position(self, x, y):
        # Set location of the widget or window. May have no effect for widgets
        self.move(x, y)

    def _vispy_set_visible(self, visible):
        # Show or hide the window or widget
        if visible:
            if self._fullscreen:
                self.showFullScreen()
            else:
                self.showNormal()
        else:
            self.hide()

    def _vispy_set_fullscreen(self, fullscreen):
        self._fullscreen = bool(fullscreen)
        self._vispy_set_visible(True)

    def _vispy_get_fullscreen(self):
        return self._fullscreen

    def _vispy_update(self):
        if self._vispy_canvas is None:
            return
        # Invoke a redraw
        self.update()

    def _vispy_get_position(self):
        g = self.geometry()
        return g.x(), g.y()

    def _vispy_get_size(self):
        g = self.geometry()
        return g.width(), g.height()

    def sizeHint(self):
        return self.size()

    def mousePressEvent(self, ev):
        if self._vispy_canvas is None:
            return
        self._vispy_mouse_press(
            native=ev,
            pos=_get_event_xy(ev),
            button=BUTTONMAP.get(ev.button(), 0),
            modifiers=self._modifiers(ev),
        )

    def mouseReleaseEvent(self, ev):
        if self._vispy_canvas is None:
            return
        self._vispy_mouse_release(
            native=ev,
            pos=_get_event_xy(ev),
            button=BUTTONMAP[ev.button()],
            modifiers=self._modifiers(ev),
        )

    def mouseDoubleClickEvent(self, ev):
        if self._vispy_canvas is None:
            return
        self._vispy_mouse_double_click(
            native=ev,
            pos=_get_event_xy(ev),
            button=BUTTONMAP.get(ev.button(), 0),
            modifiers=self._modifiers(ev),
        )

    def mouseMoveEvent(self, ev):
        if self._vispy_canvas is None:
            return
        self._vispy_mouse_move(
            native=ev,
            pos=_get_event_xy(ev),
            modifiers=self._modifiers(ev),
        )

    def wheelEvent(self, ev):
        if self._vispy_canvas is None:
            return
        # Get scrolling
        deltax, deltay = 0.0, 0.0
        if hasattr(ev, 'orientation'):
            if ev.orientation == QtCore.Qt.Horizontal:
                deltax = ev.delta() / 120.0
            else:
                deltay = ev.delta() / 120.0
        else:
            # PyQt5 / PyQt6
            delta = ev.angleDelta()
            deltax, deltay = delta.x() / 120.0, delta.y() / 120.0
        # Emit event
        self._vispy_canvas.events.mouse_wheel(
            native=ev,
            delta=(deltax, deltay),
            pos=_get_event_xy(ev),
            modifiers=self._modifiers(ev),
        )

    def keyPressEvent(self, ev):
        self._keyEvent(self._vispy_canvas.events.key_press, ev)

    def keyReleaseEvent(self, ev):
        self._keyEvent(self._vispy_canvas.events.key_release, ev)

    def _handle_native_gesture_event(self, ev):
        if self._vispy_canvas is None:
            return
        t = ev.gestureType()
        # this is a workaround for what looks like a Qt bug where
        # QNativeGestureEvent gives the wrong local position.
        # See: https://bugreports.qt.io/browse/QTBUG-59595
        try:
            pos = self.mapFromGlobal(ev.globalPosition().toPoint())
        except AttributeError:
            # globalPos is deprecated in Qt6
            pos = self.mapFromGlobal(ev.globalPos())
        pos = pos.x(), pos.y()

        if t == QtCore.Qt.NativeGestureType.BeginNativeGesture:
            self._vispy_canvas.events.touch(
                type='gesture_begin',
                pos=_get_event_xy(ev),
            )
        elif t == QtCore.Qt.NativeGestureType.EndNativeGesture:
            self._native_touch_total_rotation = []
            self._native_touch_total_scale = []
            self._vispy_canvas.events.touch(
                type='gesture_end',
                pos=_get_event_xy(ev),
            )
        elif t == QtCore.Qt.NativeGestureType.RotateNativeGesture:
            angle = ev.value()
            last_angle = (
                self._native_gesture_rotation_values[-1]
                if self._native_gesture_rotation_values
                else None
            )
            self._native_gesture_rotation_values.append(angle)
            total_rotation_angle = math.fsum(self._native_gesture_rotation_values)
            self._vispy_canvas.events.touch(
                type="gesture_rotate",
                pos=pos,
                rotation=angle,
                last_rotation=last_angle,
                total_rotation_angle=total_rotation_angle,
            )
        elif t == QtCore.Qt.NativeGestureType.ZoomNativeGesture:
            scale = ev.value()
            last_scale = (
                self._native_gesture_scale_values[-1]
                if self._native_gesture_scale_values
                else None
            )
            self._native_gesture_scale_values.append(scale)
            total_scale_factor = math.fsum(self._native_gesture_scale_values)
            self._vispy_canvas.events.touch(
                type="gesture_zoom",
                pos=pos,
                last_scale=last_scale,
                scale=scale,
                total_scale_factor=total_scale_factor,
            )
        # QtCore.Qt.NativeGestureType.PanNativeGesture
        # Qt6 docs seem to imply this is only supported on Wayland but I have
        # not been able to test it.
        # Two finger pan events are anyway converted to scroll/wheel events.
        # On macOS, more fingers are usually swallowed by the OS (by spaces,
        # mission control, etc.).

    def event(self, ev):
        out = super(QtBaseCanvasBackend, self).event(ev)

        # QNativeGestureEvent is Qt 5+
        if (
            (QT5_NEW_API or PYSIDE6_API or PYQT6_API)
            and isinstance(ev, QtGui.QNativeGestureEvent)
        ):
            self._handle_native_gesture_event(ev)

        return out

    def _keyEvent(self, func, ev):
        # evaluates the keycode of qt, and transform to vispy key.
        key = int(ev.key())
        if key in KEYMAP:
            key = KEYMAP[key]
        elif 32 <= key <= 127:
            key = keys.Key(chr(key))
        else:
            key = None
        mod = self._modifiers(ev)
        func(native=ev, key=key, text=str(ev.text()), modifiers=mod)

    def _modifiers(self, event):
        # Convert the QT modifier state into a tuple of active modifier keys.
        mod = ()
        qtmod = event.modifiers()
        qt_keyboard_modifiers = QtCore.Qt.KeyboardModifier if PYQT6_API else QtCore.Qt
        for q, v in ([qt_keyboard_modifiers.ShiftModifier, keys.SHIFT],
                     [qt_keyboard_modifiers.ControlModifier, keys.CONTROL],
                     [qt_keyboard_modifiers.AltModifier, keys.ALT],
                     [qt_keyboard_modifiers.MetaModifier, keys.META]):
            if qtmod & q:
                mod += (v,)
        return mod


_EGL_DISPLAY = None
egl = None

# todo: Make work on Windows
# todo: Make work without readpixels on Linux?
# todo: Make work on OSX?
# todo: Make work on Raspberry Pi!


class CanvasBackendEgl(QtBaseCanvasBackend, QWidget):

    def _init_specific(self, p, kwargs):

        # Initialize egl. Note that we only import egl if needed.
        global _EGL_DISPLAY
        global egl
        if egl is None:
            from ...ext import egl as _egl
            egl = _egl
            # Use MESA driver on Linux
            if IS_LINUX and not IS_RPI:
                os.environ['EGL_SOFTWARE'] = 'true'
            # Create and init display
            _EGL_DISPLAY = egl.eglGetDisplay()
            CanvasBackendEgl._EGL_VERSION = egl.eglInitialize(_EGL_DISPLAY)
            atexit.register(egl.eglTerminate, _EGL_DISPLAY)

        # Deal with context
        p.context.shared.add_ref('qt-egl', self)
        if p.context.shared.ref is self:
            self._native_config = c = egl.eglChooseConfig(_EGL_DISPLAY)[0]
            self._native_context = egl.eglCreateContext(_EGL_DISPLAY, c, None)
        else:
            self._native_config = p.context.shared.ref._native_config
            self._native_context = p.context.shared.ref._native_context

        # Init widget
        qt_window_types = QtCore.Qt.WindowType if PYQT6_API else QtCore.Qt
        if p.always_on_top or not p.decorate:
            hint = 0
            hint |= 0 if p.decorate else qt_window_types.FramelessWindowHint
            hint |= qt_window_types.WindowStaysOnTopHint if p.always_on_top else 0
        else:
            hint = qt_window_types.Widget  # can also be a window type

        QWidget.__init__(self, p.parent, hint)

        qt_window_attributes = QtCore.Qt.WidgetAttribute if PYQT6_API else QtCore.Qt
        if 0:  # IS_LINUX or IS_RPI:
            self.setAutoFillBackground(False)
            self.setAttribute(qt_window_attributes.WA_NoSystemBackground, True)
            self.setAttribute(qt_window_attributes.WA_OpaquePaintEvent, True)
        elif IS_WIN:
            self.setAttribute(qt_window_attributes.WA_PaintOnScreen, True)
            self.setAutoFillBackground(False)

        # Init surface
        w = self.get_window_id()
        self._surface = egl.eglCreateWindowSurface(_EGL_DISPLAY, c, w)
        self.initializeGL()
        self._initialized = True

    def get_window_id(self):
        """Get the window id of a PySide Widget. Might also work for PyQt4."""
        # Get Qt win id
        winid = self.winId()

        # On Linux this is it
        if IS_RPI:
            nw = (ctypes.c_int * 3)(winid, self.width(), self.height())
            return ctypes.pointer(nw)
        elif IS_LINUX:
            return int(winid)  # Is int on PySide, but sip.voidptr on PyQt

        # Get window id from stupid capsule thingy
        # http://translate.google.com/translate?hl=en&sl=zh-CN&u=http://www.cnb
        # logs.com/Shiren-Y/archive/2011/04/06/2007288.html&prev=/search%3Fq%3Dp
        # yside%2Bdirectx%26client%3Dfirefox-a%26hs%3DIsJ%26rls%3Dorg.mozilla:n
        # l:official%26channel%3Dfflb%26biw%3D1366%26bih%3D614
        # Prepare
        ctypes.pythonapi.PyCapsule_GetName.restype = ctypes.c_char_p
        ctypes.pythonapi.PyCapsule_GetName.argtypes = [ctypes.py_object]
        ctypes.pythonapi.PyCapsule_GetPointer.restype = ctypes.c_void_p
        ctypes.pythonapi.PyCapsule_GetPointer.argtypes = [ctypes.py_object,
                                                          ctypes.c_char_p]
        # Extract handle from capsule thingy
        name = ctypes.pythonapi.PyCapsule_GetName(winid)
        handle = ctypes.pythonapi.PyCapsule_GetPointer(winid, name)
        return handle

    def _vispy_close(self):
        # Destroy EGL surface
        if self._surface is not None:
            egl.eglDestroySurface(_EGL_DISPLAY, self._surface)
            self._surface = None
        # Force the window or widget to shut down
        self.close()

    def _vispy_set_current(self):
        egl.eglMakeCurrent(_EGL_DISPLAY, self._surface,
                           self._surface, self._native_context)

    def _vispy_swap_buffers(self):
        egl.eglSwapBuffers(_EGL_DISPLAY, self._surface)

    def initializeGL(self):
        self._vispy_canvas.set_current()
        self._vispy_canvas.events.initialize()

    def resizeEvent(self, event):
        w, h = event.size().width(), event.size().height()
        self._vispy_canvas.events.resize(size=(w, h))

    def paintEvent(self, event):
        self._vispy_canvas.events.draw(region=None)

        if IS_LINUX or IS_RPI:
            # Arg, cannot get GL to draw to the widget, so we take a
            # screenshot and draw that for now ...
            # Further, QImage keeps a ref to the data that we pass, so
            # we need to use a static buffer to prevent memory leakage
            from ... import gloo
            import numpy as np
            if not hasattr(self, '_gl_buffer'):
                self._gl_buffer = np.ones((3000 * 3000 * 4), np.uint8) * 255
            # Take screenshot and turn into RGB QImage
            im = gloo.read_pixels()
            sze = im.shape[0] * im.shape[1]
            self._gl_buffer[0:0+sze*4:4] = im[:, :, 2].ravel()
            self._gl_buffer[1:0+sze*4:4] = im[:, :, 1].ravel()
            self._gl_buffer[2:2+sze*4:4] = im[:, :, 0].ravel()
            img = QtGui.QImage(self._gl_buffer, im.shape[1], im.shape[0],
                               QtGui.QImage.Format_RGB32)
            # Paint the image
            painter = QtGui.QPainter()
            painter.begin(self)
            rect = QtCore.QRect(0, 0, self.width(), self.height())
            painter.drawImage(rect, img)
            painter.end()

    def paintEngine(self):
        if IS_LINUX and not IS_RPI:
            # For now we are drawing a screenshot
            return QWidget.paintEngine(self)
        else:
            return None  # Disable Qt's native drawing system


class CanvasBackendDesktop(QtBaseCanvasBackend, QGLWidget):

    def _init_specific(self, p, kwargs):

        # Deal with config
        glformat = _set_config(p.context.config)
        glformat.setSwapInterval(1 if p.vsync else 0)
        # Deal with context
        widget = kwargs.pop('shareWidget', None) or self
        p.context.shared.add_ref('qt', widget)
        if p.context.shared.ref is widget:
            if widget is self:
                widget = None  # QGLWidget does not accept self ;)
        else:
            widget = p.context.shared.ref
            if 'shareWidget' in kwargs:
                raise RuntimeError('Cannot use vispy to share context and '
                                   'use built-in shareWidget.')

        qt_window_types = QtCore.Qt.WindowType if PYQT6_API else QtCore.Qt
        if p.always_on_top or not p.decorate:
            hint = 0
            hint |= 0 if p.decorate else qt_window_types.FramelessWindowHint
            hint |= qt_window_types.WindowStaysOnTopHint if p.always_on_top else 0
        else:
            hint = qt_window_types.Widget  # can also be a window type

        if QT5_NEW_API or PYSIDE6_API or PYQT6_API:
            # Qt5 >= 5.4.0 - sharing is automatic
            QGLWidget.__init__(self, p.parent, hint)

            # Need to create an offscreen surface so we can get GL parameters
            # without opening/showing the Widget. PyQt5 >= 5.4 will create the
            # valid context later when the widget is shown.
            self._secondary_context = QtGui.QOpenGLContext()
            self._secondary_context.setShareContext(self.context())
            self._secondary_context.setFormat(glformat)
            self._secondary_context.create()

            self._surface = QtGui.QOffscreenSurface()
            self._surface.setFormat(glformat)
            self._surface.create()
            self._secondary_context.makeCurrent(self._surface)
        else:
            # Qt4 and Qt5 < 5.4.0 - sharing is explicitly requested
            QGLWidget.__init__(self, p.parent, widget, hint)
            # unused with this API
            self._secondary_context = None
            self._surface = None

        self.setFormat(glformat)
        self._initialized = True
        if not QT5_NEW_API and not PYSIDE6_API and not PYQT6_API and not self.isValid():
            # On Qt5 >= 5.4.0, isValid is only true once the widget is shown
            raise RuntimeError('context could not be created')
        if not QT5_NEW_API and not PYSIDE6_API and not PYQT6_API:
            # to make consistent with other backends
            self.setAutoBufferSwap(False)
        qt_focus_policies = QtCore.Qt.FocusPolicy if PYQT6_API else QtCore.Qt
        self.setFocusPolicy(qt_focus_policies.WheelFocus)

    def _vispy_close(self):
        # Force the window or widget to shut down
        self.close()
        self.doneCurrent()
        if not QT5_NEW_API and not PYSIDE6_API and not PYQT6_API:
            self.context().reset()
        if self._vispy_canvas is not None:
            self._vispy_canvas.app.process_events()
            self._vispy_canvas.app.process_events()

    def _vispy_set_current(self):
        if self._vispy_canvas is None:
            return  # todo: can we get rid of this now?
        if self.isValid():
            self.makeCurrent()

    def _vispy_swap_buffers(self):
        # Swap front and back buffer
        if self._vispy_canvas is None:
            return
        if QT5_NEW_API or PYSIDE6_API or PYQT6_API:
            ctx = self.context()
            ctx.swapBuffers(ctx.surface())
        else:
            self.swapBuffers()

    def _vispy_get_fb_bind_location(self):
        if QT5_NEW_API or PYSIDE6_API or PYQT6_API:
            return self.defaultFramebufferObject()
        else:
            return QtBaseCanvasBackend._vispy_get_fb_bind_location(self)

    def initializeGL(self):
        if self._vispy_canvas is None:
            return
        self._vispy_canvas.events.initialize()

    def resizeGL(self, w, h):
        if self._vispy_canvas is None:
            return
        if hasattr(self, 'devicePixelRatioF'):
            # We take into account devicePixelRatioF, which is non-unity on
            # e.g HiDPI displays.
            # self.devicePixelRatioF() is a float and should have been in Qt5 according to the documentation
            ratio = self.devicePixelRatioF()
            w = int(w * ratio)
            h = int(h * ratio)
        self._vispy_set_physical_size(w, h)
        self._vispy_canvas.events.resize(size=(self.width(), self.height()),
                                         physical_size=(w, h))

    def paintGL(self):
        if self._vispy_canvas is None:
            return
        # (0, 0, self.width(), self.height()))
        self._vispy_canvas.set_current()
        self._vispy_canvas.events.draw(region=None)

        # Clear the alpha channel with QOpenGLWidget (Qt >= 5.4), otherwise the
        # window is translucent behind non-opaque objects.
        # Reference:  MRtrix3/mrtrix3#266
        if QT5_NEW_API or PYSIDE6_API or PYQT6_API:
            context = self._vispy_canvas.context
            context.set_color_mask(False, False, False, True)
            context.clear(color=True, depth=False, stencil=False)
            context.set_color_mask(True, True, True, True)
            context.flush()


# Select CanvasBackend
if USE_EGL:
    CanvasBackend = CanvasBackendEgl
else:
    CanvasBackend = CanvasBackendDesktop


# ------------------------------------------------------------------- timer ---

class TimerBackend(BaseTimerBackend, QtCore.QTimer):

    def __init__(self, vispy_timer):
        # Make sure there is an app
        app = ApplicationBackend()
        app._vispy_get_native_app()
        # Init
        BaseTimerBackend.__init__(self, vispy_timer)
        QtCore.QTimer.__init__(self)
        self.timeout.connect(self._vispy_timeout)

    def _vispy_start(self, interval):
        self.start(int(interval * 1000))

    def _vispy_stop(self):
        self.stop()

    def _vispy_timeout(self):
        self._vispy_timer._timeout()
