op_select_islands_outline.py

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

from . import utilities_uv
from . import utilities_ui

class op(bpy.types.Operator):
    bl_idname = "uv.textools_select_islands_outline"
    bl_label = "Select Overlap"
    bl_description = "Select island edge bounds"
    bl_options = {'REGISTER', 'UNDO'}

    @classmethod
    def poll(cls, context):
        if not bpy.context.active_object:
            return False
        
        if bpy.context.active_object.type != 'MESH':
            return False

        #Requires UV map
        if not bpy.context.object.data.uv_layers:
            return False 

        return True


    def execute(self, context):
        select_outline(context)
        return {'FINISHED'}


def select_outline(context):

    #Only in Edit mode
    if bpy.context.active_object.mode != 'EDIT':
        bpy.ops.object.mode_set(mode='EDIT')


    bpy.context.scene.tool_settings.use_uv_select_sync = False

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

    bpy.ops.mesh.select_mode(use_extend=False, use_expand=False, type='EDGE')
    bpy.ops.mesh.select_all(action='DESELECT')

    # Store previous edge seams
    edges_seam = [edge for edge in bm.edges if edge.seam]
    

    contextViewUV = utilities_ui.GetContextViewUV()
    if not contextViewUV:
        self.report({'ERROR_INVALID_INPUT'}, "This tool requires an available UV/Image view.")
        return

    # Create seams from islands
    bpy.ops.uv.seams_from_islands(contextViewUV)
    edges_islands = [edge for edge in bm.edges if edge.seam]

    # Clear seams
    for edge in edges_islands:
        edge.seam = False

    # Select island edges
    bpy.ops.mesh.select_all(action='DESELECT')
    for edge in edges_islands:
        edge.select = True

    # Restore seam selection
    for edge in edges_seam:
        edge.seam = True

bpy.utils.register_class(op)