gp_interpolate/interpolate_strokes/properties.py

import bpy
from bpy.types import PropertyGroup
from bpy.props import (EnumProperty,
                        IntProperty,
                        FloatProperty,
                        BoolProperty,
                        PointerProperty,
                        StringProperty)

class GP_PG_interpolate_settings(PropertyGroup):

    # check_only : BoolProperty(
    #     name="Dry run mode (Check only)",
    #     description="Do not change anything, just print the messages", 
    #     default=False, options={'HIDDEN'})
    
    method : EnumProperty(
        name='Method',
        items= (
            ('BONE', 'Bone', 'Pick an armature bone and follow it', 0),
            ('GEOMETRY', 'Geometry', 'Directly follow underlying geometry', 1)   ,
        ),
        default='BONE',
        description='Select method for interpolating strokes'
    )

    search_range : FloatProperty(
        name="Search Range",
        description="Search range size when points are out of mesh", 
        default=0.05, precision=2, step=3, options={'HIDDEN'})


    mode : EnumProperty(
        name='Mode',
        # Combined ?markers ?
        items= (
            ('FRAME', 'Frame', 'prev/next scene frame depending on the padding options', 0),
            ('GPKEY', 'GP Key', 'prev/next Grease pencil key', 1)   ,
            ('RIGKEY', 'Rig Key', 'prev/next armatures keys in targeted collection', 2),
        ),
        default='FRAME',
        description='Select how the previous or next frame should be chosen'
    )

    padding : IntProperty(name='Padding',
        description='Number of frame to jump backward or forward',
        default=2,
        min=1)

    target_collection : PointerProperty(
        name='Collection',
        type=bpy.types.Collection, 
        description='Target collection to check armature keyframes from',
        # placeholder='Collection'
        )
    
    target_rig : PointerProperty(
        name='Rig',
        description='Rig to use as target',
        type=bpy.types.Object)
    
    # target_rig : StringProperty(
    #     name='Rig',
    #     description='Rig to use as target')

    target_bone : StringProperty(
        name='Bone',
        description='Bone of the rig to follow when interpolating') # Bone

    use_bone_rotation : BoolProperty(
        name='Use Bone Rotation',
        default=True,
        description='Apply rotation of the bone') # Bone

classes = (
    GP_PG_interpolate_settings,
)

def register():
    for c in classes:
        bpy.utils.register_class(c)
    bpy.types.Scene.gp_interpo_settings = bpy.props.PointerProperty(type=GP_PG_interpolate_settings)
    
        
def unregister():
    for c in reversed(classes):
        bpy.utils.unregister_class(c)
    del bpy.types.Scene.gp_interpo_settings

if __name__ == "__main__":
    register()