1. Controlling MXW through Python

Python is used in MXW trough a plugin interface. Specified program paths are searched for plugins which are registered, and then loaded through the user interface.

As of version 7.2., plugins are available in the playlist. There are two paths searched during program startup, the program folder and the user folder:

• (Program folder)/plugins/playlist/python/
• ~.StageDesigner/plugins/playlist/python/ (Unix)
• ~.StageDesigner/plugins/playlist/python/ (Windows)

Each plugin resides in a folder. Inside this folder, two files have to be present,

• mxw_plugin.ini
• mxw_main.py

The file mxw_plugin.ini defines the registration of the plugin. The following fields are valid:

Fields

Tag	Use	Values/Example
plugin_version	Plugin Version	1
plugin_script_language	Plugin Script Language	Python
plugin_action_level	Plugin Activity Switch	disabled = not visible
plugin_menu_parent	Top level parent in playlist menu	"AI", "IO" ..
plugin_menu_name	Playlist menu entry	"Face detection"
plugin_grid_name	Default name in grid (may be completed via script)	"Face detect"
plugin_grid_bg_color	Default color in grid (may be changed via script)	0.95 0.05 0.45 1.00 (RGBA with range 0..1)
plugin_tooltip	Tool tip in grid and panel	"This plugin triggers the playlist when it finds a face"

An example mxw_plugin.ini looks like this:

[mxw_plugin]                            ; must be here
plugin_version = 1                      ; must be V1 (as of V7.2)
plugin_script_language = Python         ; must be Python (as of V7.2)
plugin_menu_parent = AI
plugin_menu_name = NeuronalNet(Dlib) Face Detect Plugin
plugin_grid_name = Face Detect Plugin
plugin_grid_bg_color = 0.950000 0.050000 0.450000 1.000000 ; set plugin color.
plugin_tooltip = This plugin triggers the playlist when it finds a Face using a neuronal net (Dlib)
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The plugins are defined in a mxw_main.py file. This file is loaded, and the main UI calls the provided interface functions. The following interface functions are available for playlist plugins:

Fields

Function Name	Details
onCreate()	Called when the plugin item is created
onDelete()	Called when the plugin item is deleted. Note that this is only called on software shutdown, not called when the plugin is e.g. removed, since items are kept for eventual undo-operations
getColorBG()	Get background color, called each render cycle
onAction()	Called when cue is entered
onPostAction()	Called when the cue is left
onPreparePlayback()	Called when the playlist gets a preloading command (e.g. when the GoToStart button is pressed)
onActivateInUI()	Called when the item is selected in the ui
onNewFrameInPlayoutCue()	Called on each frame when in current active cue
onRenderPanel()	Called on each frame when actvated in UI to render the panel
onActiveCueChange()	Called when the playlist seeks
getDuration()	Get action duration
getText()	Get grid text, called each render cycle (may display some information)
onCleanup()	Called when the playlist aborts or seeks
getTimeSinceOnActionIssued()	Get action duration, called each render cycle (may display a countdown)
onPause()	Called when the playlist goes paused

Note that not all of the interface functions need to be implemented. If a function is not defined, it is probed but not called.

This is a minimal example of video writing and placing the recorded video into the first preload:

import tempfile
import mxw, mxw_imgui	# for mxw interaction, mxw ui interaction
import cv2 	        # image processing
import numpy as np	# math

capture_device=""
videosize = (640,480)
f = object()
out = object()

def onCreate():
	global capture_device
	dev = mxw.media().get_capture_device_names()
	capture_device = dev[1]
	return

def onAction():
	global capture_device, out, f
	f = tempfile.NamedTemporaryFile(suffix='.avi')
	f.close()
	fourcc = cv2.VideoWriter_fourcc('M','P','4','V')
	out = cv2.VideoWriter(f.name, fourcc, mxw.fps, videosize)
	m = mxw.media(capture_device)
	if(m.isvalid()):
		m.reference(True)
	return

def onPostAction():
	global capture_device, out, f
	out.release()
	mxw.preload(1).set_media(f.name)
	m = mxw.media(capture_device)
	if(m.isvalid()):
		m.reference(False)
	return

def onNewFrameInPlayoutCue():
	global capture_device, out, f
	m = mxw.media(capture_device)
	if(m.isvalid()):
		img = m.get_image_sample_cvmat(videosize[0],videosize[1])
		img = np.array(img, copy=False)
		img = cv2.flip(img, 0)
		out.write(img)
	return

# render in panel for settings etc
def onRenderPanel():
	mxw_imgui.text_unformatted("This plugin records a camera")
	return
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