Capture Maya viewport to QImage

viewport_to_qimage.py

import ctypes
import maya.OpenMaya as om
import maya.OpenMayaUI as omui
from PySide2 import QtCore, QtGui, QtWidgets

# Capture viewport to MImage 

view = omui.M3dView.active3dView()
mIm = om.MImage()

if view.getRendererName() == view.kViewport2Renderer:      
    mIm.create(view.portWidth(), view.portHeight(), 4, om.MImage.kFloat)
    view.readColorBuffer(mIm)
    mIm.convertPixelFormat(om.MImage.kByte)
else:
    view.readColorBuffer(mIm)

# Prep MImage
mIm.verticalFlip()

# Get the width and height
wUtil = om.MScriptUtil()
wUtil.createFromInt(0)
wPtr = wUtil.asUintPtr()

hUtil = om.MScriptUtil()
hUtil.createFromInt(0)
hPtr = hUtil.asUintPtr()

mIm.getSize(wPtr, hPtr)

width = wUtil.getUint(wPtr)
height = hUtil.getUint(hPtr)

# byte size
imSize = width * height * 4

# pass pointer to QImage
buf = ctypes.c_ubyte * imSize
buf = buf.from_address(long(mIm.pixels()))
qIm = QtGui.QImage(buf, width, height, QtGui.QImage.Format_RGB32).rgbSwapped()
    
# Test
pix = QtGui.QPixmap.fromImage(qIm)
l = QtWidgets.QLabel()
l.setPixmap(pix)
l.setScaledContents(True)
l.resize(640,480)
l.show()