Run ModalOperatorTimer automatically on animation playback

I have the following script. It updates a MixRGB node's factor input to itself to solve some issues with GLSL viewport in textured mode. Anyways, I was wondering if there is a way to attach this script, so that it runs automatically when I click on the "Play" button or press Alt-A and stop automatically as well when the playback is suspended? What would be the easiest way to go about doing this? Is creating an addon a feasible solution?

import bpy

class ModalTimerOperator(bpy.types.Operator):
"""Operator which runs its self from a timer"""
bl_idname = "wm.modal_timer_operator"
bl_label = "Modal Timer Operator"

_timer = None

def modal(self, context, event):
#        if event.type in {'RIGHTMOUSE', 'ESC'}:
#            self.cancel(context)
#            return {'CANCELLED'}

if event.type == 'TIMER':
mat = bpy.data.materials['Material']
nodes = mat.node_tree.nodes
mix = nodes["Mix"].inputs[0]
mix.default_value = mix.default_value
print('Current Frame:')

return {'PASS_THROUGH'}

def execute(self, context):
wm = context.window_manager
return {'RUNNING_MODAL'}

def cancel(self, context):
wm = context.window_manager
wm.event_timer_remove(self._timer)

def register():
bpy.utils.register_class(ModalTimerOperator)

def unregister():
bpy.utils.unregister_class(ModalTimerOperator)

if __name__ == "__main__":
register()

# test call
bpy.ops.wm.modal_timer_operator()


I'm aware of Handlers in Blender. However I tried the below script with no luck:

import bpy

def refreshNow(val):
mat = bpy.data.materials['Material']
nodes = mat.node_tree.nodes
nodes["Mix"].inputs[0].default_value = nodes["Mix"].inputs[0].default_value
return val

refreshNow(0)

bpy.app.driver_namespace['refresh'] = refreshNow

def my_handler():
refreshNow(0)

def register():
bpy.app.handlers.frame_change_post.append(my_handler)

• instead of the timer attach the main function to the handler bpy.app.handlers.frame_change_pre and it will run before the frame change. see handlers Feb 9 '16 at 8:14
• I have commented on the other question try it out please Feb 9 '16 at 10:15
• if not working you can : attach the modal Op to the handler ( just to trigger it at the start ) and inside the handler detach the Op from the handler ( so it won't be called while running ) , have a counter inside the Op and check if frame don't change for long time stop the Op Feb 9 '16 at 10:18
• just call it inside a function ( appended to handler ) and to detach remove this function from the handler Feb 9 '16 at 10:28
• now you have all the ingredients, I'll get back to you later Feb 9 '16 at 10:49

Solution to the above problem is to use Handler rather than a Modal Operator. Thanks to @Chebhou for his help in this thread and here.

Below is a working solution to execute on playback using handlers:

import bpy

def refreshNow(val):
mat = bpy.data.materials['Material']
nodes = mat.node_tree.nodes
nodes["Mix"].inputs[0].default_value = nodes["Mix"].inputs[0].default_value
bpy.context.scene.update()
return val

refreshNow(0)

bpy.app.driver_namespace['refresh'] = refreshNow
def my_handler(scene):
refreshNow(0)

def register():
bpy.app.handlers.frame_change_post.append(my_handler)

if __name__ == "__main__":
register()