The file path that the interface definition is saved to. The file must be writeable by Houdini for changes to be saved correctly. If the path is not writeable then an error message is displayed when attempting to apply changes to the interface. The file path can be typed manually or selected using the file browser on the right of the field.

The internal name of the interface. This must be unique across all loaded Python interfaces. That is, at most one interface is loaded into for a given internal name. The name must start with a letter and can contain letters, numbers, and/or underscores.

The human-readable name of the interface. The label is used in the Python Panel pane tab and in the menu interfaces menu. Multiple interfaces may share the same Label.

Internal name, file path, or URL of the icon to use for the interface.

Click the chooser button at the right end of the field to choose a file. Note that you can choose a file contained in a digital asset (click opdef: on the left side of the file chooser).

If you don’t supply an absolute path or URL, Houdini will look for the icon using the path in the $HOUDINI_UI_ICON_PATH environment variable.

You can use an SVG file or any image format Houdini supports (such as PNG or .pic). The icon image should be square.

Houdini ships with a number of stock SVG icons. You can see bitmap representations of these icons in $HFS/houdini/help/icons/large. To specify a stock icon, use the form ‹dirname›_‹filename›, where…

• ‹dirname› is the directory name under $HFS/houdini/help/icons/large, such as OBJ, SHELF, or MISC, and

• ‹filename› is the icon’s filename minus any extension. For example, OBJ_sticky specifies the standard icon for the Sticky object.

When checked on, the pane tab containing the Python Panel interface will show the controls for navigating around the Houdini network.

When no menu definition is loaded from disk then the interface menu hints are used to instruct Houdini on whether to include the interface in the menu and where to insert the interface into the menu.

The script definition for the Python interface. This is where PySide2 or PyQt5 code is written to build the interface. When the interface is loaded in a Python Panel, the script is executed and the root widget returned by the onCreateInterface() function is embedded into the panel.

Python Panels recognize and execute the following functions when certain events occur:

• onCreateInterface() → PySide2.QWidget or PyQt5.QWidget

  Executed when the Python Panel creates the Qt interface. The function must return the root Qt widget of the interface.

• onDestroyInterface()

  Executed when the Python Panel is about to destroy the Qt interface. This can happen when the Python Panel pane tab is closed or if the interface is reloaded.

• onActivateInterface()

  Executed when the interface becomes active and visible.

• onDeactivateInterface()

  Executed when the interface becomes inactive and hidden.

• onHipFileBeforeClear()

  Executed before the hip file clear operation is performed.

• onHipFileAfterClear()

  Executed after the hip file clear operation is performed.

• onHipFileBeforeLoad()

  Executed before the hip file load operation is performed.

• onHipFileAfterLoad()

  Executed after the hip file load operation is performed.

• onHipFileBeforeMerge()

  Executed before the hip file merge operation is performed.

• onHipFileAfterMerge()

  Executed after the hip file merge operation is performed.

• onHipFileBeforeSave()

  Executed before the hip file save operation is performed.

• onHipFileAfterSave()

  Executed after the hip file save operation is performed.

• onNodePathChanged(node)

  Executed when Houdini has changed the current node. This function hook is useful for when your Python Panel interface is interested in following navigation around the Houdini node network.

  node is the current node and is a hou.OpNode object. If there is no current node then node is set to None.

  Note that this function hook is also called when the Python Panel interface is first loaded.

Only the onCreateInterface() function is required by the interface. The other functions are optional.

from PySide2 import QtWidgets

def onCreateInterface():
    panetab = kwargs["paneTab"]

    label = QtWidgets.QLabel()
    label.setText("Running in pane tab '%s'" % panetab.name())
    return label