Blender Python module (bpy): use integer property with exponential increment [duplicate]

Question

I have an integer property I would like to increment as 2^int property. If that isn't possible, I would alternatively like to just have regular increment, but display the value in the panel as 2^property.

Answer 1

Here's a trick you can use. Incrementing will continue to adjust by ±1, but we'll give the prop a custom setter that snaps it to a power of 2. If the value decreased, we'll snap to the next lower one; if it increased, to the next higher one.

import bpy


def set_prop(self, value):
    cur_value = self.power_of_2_prop
    value = max(value, 1)
    power_of_2 = 1 << (value.bit_length() - 1)  # rounded down to power of 2
    
    if value != power_of_2:
        value = power_of_2 if value < cur_value else 2 * power_of_2

    self["power_of_2_prop"] = value


# Note: This is the default getter, but the setter won't
# work unless we provide it too for some reason.
def get_prop(self):
    return self.get("power_of_2_prop", 1)


bpy.types.Scene.power_of_2_prop = bpy.props.IntProperty(get=get_prop, set=set_prop)


# Add panel in the Properties Editor to test it

class LayoutDemoPanel(bpy.types.Panel):
    """Creates a Panel in the scene context of the properties editor"""
    bl_label = "Test Panel"
    bl_idname = "SCENE_PT_layout"
    bl_space_type = 'PROPERTIES'
    bl_region_type = 'WINDOW'
    bl_context = "scene"

    def draw(self, context):
        layout = self.layout
        scene = context.scene
        layout.prop(scene, "power_of_2_prop")


bpy.utils.register_class(LayoutDemoPanel)

Look for the Test Panel in the Scene tab of the Properties Editor.

Answer 2

@scurest's answer is definitely works as an answer for the first, however I think I'll use this approach because the interaction of setting a number and then it snapping to the nearest power is a bit wonky.

I was able to figure out the second approach, where it just shows 2 to the power of the property alongside the power, using the following expression:

col.prop(Rprops,'resolution', text='Resolution: '+str(2**Rprops.resolution))