QPainter::begin: Paint device returned engine == 0, type: 1 #194

adam-grant-hendry · 2022-07-09T01:50:25Z

adam-grant-hendry
Jul 9, 2022

When using QtInteractor (Windows 10 with PySide6)

from pyvistaqt import MainWindow, QtInteractor
from qtpy import QtWidgets

class Window(MainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle('Example')

        self.layout_ = QtWidgets.QVBoxLayout()

        self.container = QtWidgets.QFrame()
        self.container.setLayout(self.layout_)
        self.setCentralWidget(self.container)

        self.plotter = QtInteractor(parent=self.container)
        self.layout_.addWidget(self.plotter)
        self.plotter.show()

app = QtWidgets.QApplication([])
window = Window()
window.show()
app.exec_()

I'm seeing the error:

QPainter::begin: Paint device returned engine == 0, type: 1

I know PyQt6 and PySide6 use "QOpenGLWidget" and the others "QGLWidget" in rwi.py.

However, I also know PyQt's sip supports cooperative multiple inheritance, but PySide's Shiboken is still struggling. We first encountered this here.

If I print out the __mro__ of QtInteractor, I get

(<class 'pyvistaqt.plotting.QtInteractor'>, <class 'pyvistaqt.rwi.QVTKRenderWindowInteractor'>, <class 'PySide6.QtOpenGLWidgets.QOpenGLWidget'>, <class 'PySide6.QtWidgets.QWidget'>, <class 'PySide6.QtCore.QObject'>, <class 'PySide6.QtGui.QPaintDevice'>, <class 'Shiboken.Object'>, <class 'pyvista.plotting.plotting.BasePlotter'>, <class 'pyvista.plotting.picking.PickingHelper'>, <class 'pyvista.plotting.widgets.WidgetHelper'>, <class 'object'>)

Does anyone know if this is a QOpenGLWidget vs QGLWidget issue, or a PyQt vs PySide issue? Has anyone else come across this?

UPDATE:

When I close the application, I get a bunch of the following repeated errors:

2022-07-08 18:42:04.838 (  23.428s) [                ]vtkWin32OpenGLRenderWin:267    ERR| vtkWin32OpenGLRenderWindow (00000260D8C8ABD0): wglMakeCurrent failed in MakeCurrent(), error: ☠�ɠ

From the PySide6 docs:

Your widget’s OpenGL rendering context is made current when paintGL() , resizeGL() , or initializeGL() is called. If you need to call the standard OpenGL API functions from other places (e.g. in your widget’s constructor or in your own paint functions), you must call makeCurrent() first.

All rendering happens into an OpenGL framebuffer object. makeCurrent() ensure that it is bound in the context. Keep this in mind when creating and binding additional framebuffer objects in the rendering code in paintGL() . Never re-bind the framebuffer with ID 0. Instead, call defaultFramebufferObject() to get the ID that should be bound.

So I wonder if Shiboken.Object is breaking the inheritance chain during super() calls to __init__?

UPDATE 2:

Python 3.8.10 (tags/v3.8.10:3d8993a, May  3 2021, 11:48:03) [MSC v.1928 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import pyvista
>>> pyvista.Report(gpu=False)

--------------------------------------------------------------------------------
  Date: Fri Jul 08 19:18:53 2022 Pacific Daylight Time

                OS : Windows
            CPU(s) : 96
           Machine : AMD64
      Architecture : 64bit
               RAM : 190.7 GiB
       Environment : Python
       GPU Details : None

  Python 3.8.10 (tags/v3.8.10:3d8993a, May  3 2021, 11:48:03) [MSC v.1928 64
  bit (AMD64)]

           pyvista : 0.35.1
               vtk : 9.1.0
             numpy : 1.23.0
           imageio : 2.19.3
           appdirs : 1.4.4
            scooby : 0.5.12
        matplotlib : 3.5.2
         pyvistaqt : 0.9.0
           IPython : 8.4.0
              tqdm : 4.64.0
            meshio : 5.3.4
--------------------------------------------------------------------------------
>>> pyvista.Report(gpu=True)  

--------------------------------------------------------------------------------
  Date: Fri Jul 08 19:19:21 2022 Pacific Daylight Time

                OS : Windows
            CPU(s) : 96
           Machine : AMD64
      Architecture : 64bit
               RAM : 190.7 GiB
       Environment : Python
        GPU Vendor : NVIDIA Corporation
      GPU Renderer : Quadro RTX 8000/PCIe/SSE2
       GPU Version : 4.5.0 NVIDIA 512.78

  Python 3.8.10 (tags/v3.8.10:3d8993a, May  3 2021, 11:48:03) [MSC v.1928 64
  bit (AMD64)]

           pyvista : 0.35.1
               vtk : 9.1.0
             numpy : 1.23.0
           imageio : 2.19.3
           appdirs : 1.4.4
            scooby : 0.5.12
        matplotlib : 3.5.2
         pyvistaqt : 0.9.0
           IPython : 8.4.0
              tqdm : 4.64.0
            meshio : 5.3.4
--------------------------------------------------------------------------------
>>>

larsoner · 2022-07-09T14:17:27Z

larsoner
Jul 9, 2022
Maintainer

Can you see if you experience the same problem when using BackgroundPlotter? If not then you might be able to look at the BackgroundPlotter code to see how it's avoiding the problem.

My guess is that your call to plotter.show() before you've done mainwindow.show() is a problem

3 replies

adam-grant-hendry Jul 9, 2022
Author

I get the same error if I use BackgroundPlotter or if I switch to show the plotter after the mainwindow.show()

adam-grant-hendry Jul 9, 2022
Author

@larsoner So there are 2 errors occurring. The first is

QPainter::begin: Paint device returned engine == 0, type: 1

issuing when the window is made and on every update.

The second is

2022-07-08 18:42:04.838 (  23.428s) [                ]vtkWin32OpenGLRenderWin:267    ERR| vtkWin32OpenGLRenderWindow (00000260D8C8ABD0): wglMakeCurrent failed in MakeCurrent(), error: ☠�ɠ

1st Error

From the PySide6 QPaintEngine docs, this error is saying that Qt thinks I am on X11 (i.e. Linux; constant QPaintEngine.X11 == 0), but I am really on Windows (constant QPaintEngine.Windows == 1)

There is a widget attribute set in pyvistaqt.rwi::QVTKRenderWindowInteractor.__init__():

self.setAttribute(WidgetAttribute.WA_PaintOnScreen)

The PySide6.QtCore.Qt docs state:

**Note:** This flag is only supported on X11 and it disables double buffering.

I believe this is the source of the error, so QVTKRenderWindowInteractor.py will need to be modified accordingly.

There is a posted Qt bug that may interest you and the developers regarding offscreen rendering:

2nd Error

I found I get the second error because plotter isn't getting closed when MainWindow is . (BackgroundPlotter does not have this problem.)

To fix this error with QtInteractor, simply connect the pyvistaqt.MainWindow.signal_close signal to plotter.close:

from pyvistaqt import MainWindow, QtInteractor
from qtpy import QtWidgets

class Window(MainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle('Example')

        self.layout_ = QtWidgets.QVBoxLayout()

        self.container = QtWidgets.QFrame()
        self.container.setLayout(self.layout_)
        self.setCentralWidget(self.container)

        self.plotter = QtInteractor(parent=self.container)
        self.layout_.addWidget(self.plotter)
        self.plotter.show()

        self.signal_close.connect(self.plotter.close)  # Fixes 2nd problem


app = QtWidgets.QApplication([])
window = Window()
window.show()
app.exec_()

This fix is consistent with several other posts I found on the same topic:

This may be purely a Window issue (as I suspect since vtkWin32OpenGLRenderWin issues the error). There's a now dead link that claimed this was due to the fact that

if the thread calling makeCurrent() is not equal to the thread that retrieved the device context, GetDC() is called. As stated in the linked thread, the problem was that ReleaseDC() was not called accordingly, causing the handle to leak and at some point triggering Windows to return NULL on the call to GetDC(), which made wglMakeCurrent() fail.

I believe the same conclusion is alluded to here and here.

adam-grant-hendry Jul 9, 2022
Author

@larsoner This appeared almost 2 years ago in a related issue on mayavi Problem when using QGLWidget

After debugging in VSCode with the following launch.json so it will go into packages:

{
    "configurations": [
        {
            "name": "Python: Current File",
            "type": "python",
            "request": "launch",
            "program": "${file}",
            "console": "integratedTerminal",
            "justMyCode": false
        }
    ],
}

the culprit is rwi.py::QVTKRenderWindowInteractor.paintEngine() getting called when a Paint event occurs:

def paintEngine(self):
    return None

My guess is paintEngine was overriden to return None (NULL in C++) to avoid the error:

QWidget::paintEngine: Should no longer be called

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QPainter::begin: Paint device returned engine == 0, type: 1 #194

adam-grant-hendry Jul 9, 2022

Replies: 1 comment · 3 replies

larsoner Jul 9, 2022 Maintainer

adam-grant-hendry Jul 9, 2022 Author

adam-grant-hendry Jul 9, 2022 Author

1st Error

2nd Error

adam-grant-hendry Jul 9, 2022 Author

adam-grant-hendry
Jul 9, 2022

Replies: 1 comment 3 replies

larsoner
Jul 9, 2022
Maintainer

adam-grant-hendry Jul 9, 2022
Author

adam-grant-hendry Jul 9, 2022
Author

adam-grant-hendry Jul 9, 2022
Author