gp_interpolate/ui.py

import bpy

class GP_PT_interpolate(bpy.types.Panel):
    bl_label = "Interpolate"
    bl_category = "Gpencil"
    bl_space_type = 'VIEW_3D'
    bl_region_type = 'UI'

    @classmethod
    def poll(cls, context):
        return context.object # and context.object.type == 'GPENCIL'

    def draw(self, context):
        settings = bpy.context.scene.gp_interpo_settings

        layout = self.layout
        layout.use_property_split = True
        col = layout.column(align=False)

        ## interpolation buttons
        if settings.mode == 'FRAME':
            prev_icon, next_icon = 'FRAME_PREV', 'FRAME_NEXT'
        else:
            prev_icon, next_icon = 'PREV_KEYFRAME', 'NEXT_KEYFRAME'
        row = col.row(align=True)
        row.scale_x = 3
        row.operator("gp.interpolate_stroke", text="", icon=prev_icon).next = False
        row.operator("gp.interpolate_stroke", text="", icon=next_icon).next = True
        # col.separator()


        col.prop(settings, 'method', text='Method')

        if settings.method == 'BONE':
            col = layout.column(align=True)
            col.prop_search(settings, 'target_rig', context.scene, 'objects', text='Rig')
            if settings.target_rig:
                # col.prop_search(ob.rig_picker, 'name', settings.target_rig.pose, 'bones', text='Bone')
                col.prop_search(settings, 'target_bone', settings.target_rig.pose, 'bones', text='Bone')


        elif settings.method == 'GEOMETRY':
            col.prop(settings, 'target_collection', text='Collection')
            col.prop(settings, 'search_range')

        col.separator()
        col = layout.column(align=True)
        row = col.row(align=True)
        row.prop(settings, 'mode', expand=True)

        if settings.mode == 'FRAME':
            col.prop(settings, 'padding')

classes = (
    GP_PT_interpolate,
)

def register():
    for c in classes:
        bpy.utils.register_class(c)

def unregister():
    for c in reversed(classes) :
        bpy.utils.unregister_class(c)