op_island_centralize.py

import bpy
import bmesh

from . import utilities_uv
from .utilities_bbox import BBox
from mathutils import Vector



class op(bpy.types.Operator):
    bl_idname = "uv.textools_island_centralize"
    bl_label = "Centralize"
    bl_description = "Move the selected faces the closest possible to the 0-1 UV area without changes in the textured object"
    bl_options = {'REGISTER', 'UNDO'}
    
    @classmethod
    def poll(cls, context):
        if not bpy.context.active_object:
            return False
        if bpy.context.active_object.mode != 'EDIT':
            return False
        return True

    def execute(self, context):
        _, column, row = utilities_uv.get_UDIM_tile_coords(bpy.context.active_object)
        return self.centralize(column, row)

    @staticmethod
    def centralize(column, row):
        selected_objs = utilities_uv.selected_unique_objects_in_mode_with_uv()
        update_obj = []
        for obj in selected_objs:
            bm = bmesh.from_edit_mesh(obj.data)
            uv_layer = bm.loops.layers.uv.verify()
            islands = utilities_uv.get_selected_islands(bm, uv_layer)

            if not islands:
                continue

            changed = False
            for island in islands:
                center = BBox.calc_bbox_uv(island, uv_layer).center
                delta = Vector((round(-center.x + 0.5) + column, round(-center.y + 0.5) + row))
                if delta != Vector((0, 0)):
                    changed = True
                    utilities_uv.translate_island(island, uv_layer, delta)
            if changed:
                update_obj.append(obj)
                
        if not update_obj:
            return {'CANCELLED'}

        for obj in update_obj:
            bmesh.update_edit_mesh(obj.data)

        return {'FINISHED'}