op_island_rotate_90.py

import bpy
import bmesh
import operator
import math
from mathutils import Vector
from collections import defaultdict
from math import pi

from . import utilities_uv

class op(bpy.types.Operator):
    bl_idname = "uv.textools_island_rotate_90"
    bl_label = "Rotate 90 degrees"
    bl_description = "Rotate the selected UV island 90 degrees left or right"
    bl_options = {'REGISTER', 'UNDO'}
    
    angle : bpy.props.FloatProperty(name="Angle")


    @classmethod
    def poll(cls, context):
        #Only in UV editor mode
        if bpy.context.area.type != 'IMAGE_EDITOR':
            return False

        if not bpy.context.active_object:
            return False

        if bpy.context.active_object.type != 'MESH':
            return False

        #Only in Edit mode
        if bpy.context.active_object.mode != 'EDIT':
            return False

        #Requires UV map
        if not bpy.context.object.data.uv_layers:
            return False
            
        # Not in Synced mode
        if bpy.context.scene.tool_settings.use_uv_select_sync:
            return False

        return True


    def execute(self, context):

        main(context, self.angle)
        return {'FINISHED'}


def main(context, angle):
    
    #Store selection
    utilities_uv.selection_store()

    bm = bmesh.from_edit_mesh(bpy.context.active_object.data)
    uv_layers = bm.loops.layers.uv.verify()
    
    bpy.ops.uv.select_linked()

    #Bounds
    bounds_initial = utilities_uv.getSelectionBBox()
    bpy.ops.transform.rotate(value=angle, orient_axis='Z', constraint_axis=(False, False, False), use_proportional_edit=False)

    #Align rotation to top left|right
    bounds_post = utilities_uv.getSelectionBBox()
    dy = bounds_post['max'].y - bounds_initial['max'].y
    dx = 0
    if angle > 0:
        dx = bounds_post['max'].x - bounds_initial['max'].x
    else:
        dx = bounds_post['min'].x - bounds_initial['min'].x
    bpy.ops.transform.translate(value=(-dx, -dy, 0), constraint_axis=(False, False, False), use_proportional_edit=False)


    #Restore selection
    utilities_uv.selection_restore()

bpy.utils.register_class(op)