Decorators for node tree updation delay

When we create a field on the add-on interface panel, the value of which changes something in the node tree, each time the user changes the field value the node tree recompiles. If the user changes the value in that field by holding and moving the mouse, too frequent node tree recompilation will cause Blender to hangs.

This problem can be solved using decorators for deferred updating of the node tree.

Code by Skarn.

Decorators definition:

import bpy
from functools import partial
from time import time

from ..third_party.boltons.funcutils import wraps

def parametrized(dec):
    def layer(*args, **kwargs):
        def repl(f):
            return dec(f, *args, **kwargs)
        return repl
    return layer

@parametrized
def delay_execution(func, delay_sec=1.0):

    lock = False
    def timer(*args, **kwargs):
        nonlocal lock
        lock = False

        func(*args, **kwargs)

    @wraps(func)
    def wrapped(*args, **kwargs):
        nonlocal lock

        if not lock:
            lock = True
            bpy.app.timers.register(partial(timer, *args, **kwargs), first_interval=delay_sec)

    return wrapped

@parametrized
def on_release(func, delay_sec=1.5):

    exec_time = time()

    def timer(*args, **kwargs):
        nonlocal exec_time
        if not abs(exec_time - time()) < delay_sec:
            func(*args, **kwargs)

    @wraps(func)
    def wrapped(*args, **kwargs):
        nonlocal exec_time
        exec_time = time()

        bpy.app.timers.register(partial(timer, *args, **kwargs), first_interval=max(1.0, delay_sec))

    return wrapped

import bpy

from functools import partial

from time import time

from ..third_party.boltons.funcutils import wraps

def parametrized(dec):

def layer(*args, **kwargs):

def repl(f):

return dec(f, *args, **kwargs)

return repl

return layer

@parametrized

def delay_execution(func, delay_sec=1.0):

lock = False

def timer(*args, **kwargs):

nonlocal lock

lock = False

func(*args, **kwargs)

@wraps(func)

def wrapped(*args, **kwargs):

nonlocal lock

if not lock:

lock = True

bpy.app.timers.register(partial(timer, *args, **kwargs), first_interval=delay_sec)

return wrapped

@parametrized

def on_release(func, delay_sec=1.5):

exec_time = time()

def timer(*args, **kwargs):

nonlocal exec_time

if not abs(exec_time - time()) < delay_sec:

func(*args, **kwargs)

@wraps(func)

def wrapped(*args, **kwargs):

nonlocal exec_time

exec_time = time()

bpy.app.timers.register(partial(timer, *args, **kwargs), first_interval=max(1.0, delay_sec))

return wrapped

The code uses the third-party “Boltons” library, which needs to be included to the add-on for proper work.

This code defines two decorators: “delay_execution” – to delay execution by time, and “on_release” – to delay until the user releases the held mouse button.

In the add-on we can use these decorators:

@on_release()
def update_sun_direction(self, context):
    properties = bpy.data.node_groups.get('MO_Properties')
    if properties:
        properties.nodes['SunDirection'].inputs[1].default_value = self.sun_direction

@on_release()

def update_sun_direction(self, context):

properties = bpy.data.node_groups.get('MO_Properties')

if properties:

properties.nodes['SunDirection'].inputs[1].default_value = self.sun_direction

Here the “sun_direction” node property will update only when the user releases the held mouse button.