Forums Technical Discussion 456.py and hou.qt.mainWindow() returns None when Houdini first starts

456.py and hou.qt.mainWindow() returns None when Houdini first starts

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ragnoru
Member
5 posts
Joined: April 2008
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HI,
we have a pyside window that we want to parent to the hou.qt.mainWindow(), like in the docs I am doing something along these lines
from hutil.Qt import QtCore
dialog = MyDialog()
print (hou.qt.mainWindow()) #this returns None on first houdini start so no parenting happens
dialog.setParent(hou.qt.mainWindow(), QtCore.Qt.Window)
dialog.show()

So the question is
How to create a PySide window that is parented to the hou.qt.mainWindow() on start up?
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rvinluan
Staff
1296 posts
Joined: July 2005
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Hello,

The Houdini UI probably hasn't opened yet which explains why hou.qt.mainWindow() is None. You could try deferring the code until Houdini's UI is ready.

Using the hdefereval module like so might work:
import hdefereval
from hutil.Qt import QtCore

theDialog = None
def openDialog():
    global theDialog
    theDialog = MyDialog()
    theDialog.setParent(hou.qt.mainWindow(), QtCore.Qt.Window)
    theDialog.show()

hdefereval.executeDeferred(openDialog)

Note that the script variable, theDialog, is needed to keep the dialog alive past the scope of the openDialog() function. If you use just a regular function variable then the dialog will most likely close and disappear when the function finishes execution.

Also, 456.py is called whenever a .hip file is opened. This means openDialog() can be called multiple times. If you just want the function to be called once at Houdini startup then try placing the code in pythonrc.py instead of 456.py.

Lastly, hutil.Qt was intended to be used by only Houdini internals. Feel free to use the module but be aware that the behaviour of this module can change in future Houdini releases.

Cheers,
Rob
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