Is it possible write a python code in a text input?

Question

I would like to add a simple python code here (like when I type 1+1, it shows 2. Or like encoding some text or whatever). Is it possible?

Answer 1

You can't :-(

Typically, you can right-click any field and choose "Add Driver" or just type an expression with a hashtag in front, but here the hashtag is just being displayed and there's no driver related options in the context menu. Trying that from the script doesn't work either:

>>> car = bpy.data.scenes["Scene"].sequence_editor.sequences_all["Text"]
>>> curve = car.driver_add("text")
Traceback (most recent call last):
  File "<blender_console>", line 1, in <module>
TypeError: bpy_struct.driver_add(): property "text" not animatable

---

But... :-)

Someone like Will Chen would probably hack his way through this problem using a driver that updates this field as a side-effect, something like setting the Size to #[40,setattr(bpy.data.scenes["Scene"].sequence_editor.sequences_all["Text"], "text", str(frame))][0] -where the # is there only if you input the script for the first time (when the field is not purple) to tell Blender to turn it to a driver, and 40 at the very beginning is the actual size - the rest is the nasty hack to update your text to current frame.

Perhaps a more elegant solution is to run a script like so:

import bpy
def frame_change_post_text_update(scene):
    scene.sequence_editor.sequences_all["Text"].text = str(scene.frame_current)
name = frame_change_post_text_update.name
listeners = bpy.app.handlers.frame_change_post 
for l in [l for l in listeners if l.name == name]: 
    # this is here so you can change the script and run it again without having
    # multiple listeners stacking - make sure the function name is unique
    listeners.remove(l)
listeners.append(frame_change_post_text_update)