mesh_looptools.py

        items=(("project", "Project", "Project vertices onto the stroke, "
                 "using vertex normals and connected edges"),
                ("irregular", "Spread", "Distribute vertices along the full "
                "stroke, retaining relative distances between the vertices"),
                ("regular", "Spread evenly", "Distribute vertices at regular "
                "distances along the full stroke")),
        description="Method of distributing the vertices over the "
                    "stroke",
        default='regular'
        )

    @classmethod
    def poll(cls, context):
        ob = context.active_object
        return(ob and ob.type == 'MESH' and context.mode == 'EDIT_MESH')

    def draw(self, context):
        looptools =  context.window_manager.looptools
        layout = self.layout
        col = layout.column()

        col.prop(self, "method")
        col.separator()

        col_conv = col.column(align=True)
        col_conv.prop(self, "conversion", text="")
        if self.conversion == 'distance':
            col_conv.prop(self, "conversion_distance")
        elif self.conversion == 'limit_vertices':
            row = col_conv.row(align=True)
            row.prop(self, "conversion_min", text="Min")
            row.prop(self, "conversion_max", text="Max")
        elif self.conversion == 'vertices':
            col_conv.prop(self, "conversion_vertices")
        col.separator()

        col_move = col.column(align=True)
        row = col_move.row(align=True)
        if self.lock_x:
            row.prop(self, "lock_x", text="X", icon='LOCKED')
        else:
            row.prop(self, "lock_x", text="X", icon='UNLOCKED')
        if self.lock_y:
            row.prop(self, "lock_y", text="Y", icon='LOCKED')
        else:
            row.prop(self, "lock_y", text="Y", icon='UNLOCKED')
        if self.lock_z:
            row.prop(self, "lock_z", text="Z", icon='LOCKED')
        else:
            row.prop(self, "lock_z", text="Z", icon='UNLOCKED')
        col_move.prop(self, "influence")
        col.separator()
        if looptools.gstretch_use_guide == "Annotation":
            col.operator("remove.annotation", text="Delete annotation strokes")
        if looptools.gstretch_use_guide == "GPencil":
            col.operator("remove.gp", text="Delete GPencil strokes")

    def invoke(self, context, event):
        # flush cached strokes
        if 'Gstretch' in looptools_cache:
            looptools_cache['Gstretch']['single_loops'] = []
        # load custom settings
        settings_load(self)
        return self.execute(context)

    def execute(self, context):
        # initialise
        object, bm = initialise()
        settings_write(self)

        # check cache to see if we can save time
        cached, safe_strokes, loops, derived, mapping = cache_read("Gstretch",
            object, bm, False, False)
        if cached:
            straightening = False
            if safe_strokes:
                strokes = gstretch_safe_to_true_strokes(safe_strokes)
            # cached strokes were flushed (see operator's invoke function)
            elif get_strokes(self, context):
                strokes = gstretch_get_strokes(self, context)
            else:
                # straightening function (no GP) -> loops ignore modifiers
                straightening = True
                derived = False
                bm_mod = bm.copy()
                bm_mod.verts.ensure_lookup_table()
                bm_mod.edges.ensure_lookup_table()
                bm_mod.faces.ensure_lookup_table()
                strokes = gstretch_get_fake_strokes(object, bm_mod, loops)
            if not straightening:
                derived, bm_mod = get_derived_bmesh(object, bm, False)
        else:
            # get loops and strokes
            if get_strokes(self, context):
                # find loops
                derived, bm_mod, loops = get_connected_input(object, bm, False, input='selected')
                mapping = get_mapping(derived, bm, bm_mod, False, False, loops)
                loops = check_loops(loops, mapping, bm_mod)
                # get strokes
                strokes = gstretch_get_strokes(self, context)
            else:
                # straightening function (no GP) -> loops ignore modifiers
                derived = False
                mapping = False
                bm_mod = bm.copy()
                bm_mod.verts.ensure_lookup_table()
                bm_mod.edges.ensure_lookup_table()
                bm_mod.faces.ensure_lookup_table()
                edge_keys = [
                    edgekey(edge) for edge in bm_mod.edges if
                    edge.select and not edge.hide
                    ]
                loops = get_connected_selections(edge_keys)
                loops = check_loops(loops, mapping, bm_mod)
                # create fake strokes
                strokes = gstretch_get_fake_strokes(object, bm_mod, loops)

        # saving cache for faster execution next time
        if not cached:
            if strokes:
                safe_strokes = gstretch_true_to_safe_strokes(strokes)
            else:
                safe_strokes = []
            cache_write("Gstretch", object, bm, False, False,
                safe_strokes, loops, derived, mapping)

        # pair loops and strokes
        ls_pairs = gstretch_match_loops_strokes(loops, strokes, object, bm_mod)
        ls_pairs = gstretch_align_pairs(ls_pairs, object, bm_mod, self.method)

        move = []
        if not loops:
            # no selected geometry, convert GP to verts
            if strokes:
                move.append(gstretch_create_verts(object, bm, strokes,
                    self.method, self.conversion, self.conversion_distance,
                    self.conversion_max, self.conversion_min,
                    self.conversion_vertices))
                for stroke in strokes:
                    gstretch_erase_stroke(stroke, context)
        elif ls_pairs:
            for (loop, stroke) in ls_pairs:
                move.append(gstretch_calculate_verts(loop, stroke, object,
                    bm_mod, self.method))
                if self.delete_strokes:
                    if type(stroke) != bpy.types.GPencilStroke:
                        # in case of cached fake stroke, get the real one
                        if get_strokes(self, context):
                            strokes = gstretch_get_strokes(self, context)
                            if loops and strokes:
                                ls_pairs = gstretch_match_loops_strokes(loops,
                                    strokes, object, bm_mod)
                                ls_pairs = gstretch_align_pairs(ls_pairs,
                                    object, bm_mod, self.method)
                                for (l, s) in ls_pairs:
                                    if l == loop:
                                        stroke = s
                                        break
                    gstretch_erase_stroke(stroke, context)

        # move vertices to new locations
        if self.lock_x or self.lock_y or self.lock_z:
            lock = [self.lock_x, self.lock_y, self.lock_z]
        else:
            lock = False
        bmesh.update_edit_mesh(object.data, loop_triangles=True, destructive=True)
        move_verts(object, bm, mapping, move, lock, self.influence)

        # cleaning up
        if derived:
            bm_mod.free()
        terminate()

        return{'FINISHED'}


# relax operator
class Relax(Operator):
    bl_idname = "mesh.looptools_relax"
    bl_label = "Relax"
    bl_description = "Relax the loop, so it is smoother"
    bl_options = {'REGISTER', 'UNDO'}

    input: EnumProperty(
        name="Input",
        items=(("all", "Parallel (all)", "Also use non-selected "
               "parallel loops as input"),
               ("selected", "Selection", "Only use selected vertices as input")),
        description="Loops that are relaxed",
        default='selected'
        )
    interpolation: EnumProperty(
        name="Interpolation",
        items=(("cubic", "Cubic", "Natural cubic spline, smooth results"),
               ("linear", "Linear", "Simple and fast linear algorithm")),
        description="Algorithm used for interpolation",
        default='cubic'
        )
    iterations: EnumProperty(
        name="Iterations",
        items=(("1", "1", "One"),
               ("3", "3", "Three"),
               ("5", "5", "Five"),
               ("10", "10", "Ten"),
              ("25", "25", "Twenty-five")),
        description="Number of times the loop is relaxed",
        default="1"
        )
    regular: BoolProperty(
        name="Regular",
        description="Distribute vertices at constant distances along the loop",
        default=True
        )

    @classmethod
    def poll(cls, context):
        ob = context.active_object
        return(ob and ob.type == 'MESH' and context.mode == 'EDIT_MESH')

    def draw(self, context):
        layout = self.layout
        col = layout.column()

        col.prop(self, "interpolation")
        col.prop(self, "input")
        col.prop(self, "iterations")
        col.prop(self, "regular")

    def invoke(self, context, event):
        # load custom settings
        settings_load(self)
        return self.execute(context)

    def execute(self, context):
        # initialise
        object, bm = initialise()
        settings_write(self)
        # check cache to see if we can save time
        cached, single_loops, loops, derived, mapping = cache_read("Relax",
            object, bm, self.input, False)
        if cached:
            derived, bm_mod = get_derived_bmesh(object, bm, False)
        else:
            # find loops
            derived, bm_mod, loops = get_connected_input(object, bm, False, self.input)
            mapping = get_mapping(derived, bm, bm_mod, False, False, loops)
            loops = check_loops(loops, mapping, bm_mod)
        knots, points = relax_calculate_knots(loops)

        # saving cache for faster execution next time
        if not cached:
            cache_write("Relax", object, bm, self.input, False, False, loops,
                derived, mapping)

        for iteration in range(int(self.iterations)):
            # calculate splines and new positions
            tknots, tpoints = relax_calculate_t(bm_mod, knots, points,
                self.regular)
            splines = []
            for i in range(len(knots)):
                splines.append(calculate_splines(self.interpolation, bm_mod,
                    tknots[i], knots[i]))
            move = [relax_calculate_verts(bm_mod, self.interpolation,
                tknots, knots, tpoints, points, splines)]
            move_verts(object, bm, mapping, move, False, -1)

        # cleaning up
        if derived:
            bm_mod.free()
        terminate()

        return{'FINISHED'}


# space operator
class Space(Operator):
    bl_idname = "mesh.looptools_space"
    bl_label = "Space"
    bl_description = "Space the vertices in a regular distribution on the loop"
    bl_options = {'REGISTER', 'UNDO'}

    influence: FloatProperty(
        name="Influence",
        description="Force of the tool",
        default=100.0,
        min=0.0,
        max=100.0,
        precision=1,
        subtype='PERCENTAGE'
        )
    input: EnumProperty(
        name="Input",
        items=(("all", "Parallel (all)", "Also use non-selected "
                "parallel loops as input"),
              ("selected", "Selection", "Only use selected vertices as input")),
        description="Loops that are spaced",
        default='selected'
        )
    interpolation: EnumProperty(
        name="Interpolation",
        items=(("cubic", "Cubic", "Natural cubic spline, smooth results"),
              ("linear", "Linear", "Vertices are projected on existing edges")),
        description="Algorithm used for interpolation",
        default='cubic'
        )
    lock_x: BoolProperty(
        name="Lock X",
        description="Lock editing of the x-coordinate",
        default=False
        )
    lock_y: BoolProperty(
        name="Lock Y",
        description="Lock editing of the y-coordinate",
        default=False
        )
    lock_z: BoolProperty(
        name="Lock Z",
        description="Lock editing of the z-coordinate",
        default=False
        )

    @classmethod
    def poll(cls, context):
        ob = context.active_object
        return(ob and ob.type == 'MESH' and context.mode == 'EDIT_MESH')

    def draw(self, context):
        layout = self.layout
        col = layout.column()

        col.prop(self, "interpolation")
        col.prop(self, "input")
        col.separator()

        col_move = col.column(align=True)
        row = col_move.row(align=True)
        if self.lock_x:
            row.prop(self, "lock_x", text="X", icon='LOCKED')
        else:
            row.prop(self, "lock_x", text="X", icon='UNLOCKED')
        if self.lock_y:
            row.prop(self, "lock_y", text="Y", icon='LOCKED')
        else:
            row.prop(self, "lock_y", text="Y", icon='UNLOCKED')
        if self.lock_z:
            row.prop(self, "lock_z", text="Z", icon='LOCKED')
        else:
            row.prop(self, "lock_z", text="Z", icon='UNLOCKED')
        col_move.prop(self, "influence")

    def invoke(self, context, event):
        # load custom settings
        settings_load(self)
        return self.execute(context)

    def execute(self, context):
        # initialise
        object, bm = initialise()
        settings_write(self)
        # check cache to see if we can save time
        cached, single_loops, loops, derived, mapping = cache_read("Space",
            object, bm, self.input, False)
        if cached:
            derived, bm_mod = get_derived_bmesh(object, bm, True)
        else:
            # find loops
            derived, bm_mod, loops = get_connected_input(object, bm, True, self.input)
            mapping = get_mapping(derived, bm, bm_mod, False, False, loops)
            loops = check_loops(loops, mapping, bm_mod)

        # saving cache for faster execution next time
        if not cached:
            cache_write("Space", object, bm, self.input, False, False, loops,
                derived, mapping)

        move = []
        for loop in loops:
            # calculate splines and new positions
            if loop[1]:  # circular
                loop[0].append(loop[0][0])
            tknots, tpoints = space_calculate_t(bm_mod, loop[0][:])
            splines = calculate_splines(self.interpolation, bm_mod,
                tknots, loop[0][:])
            move.append(space_calculate_verts(bm_mod, self.interpolation,
                tknots, tpoints, loop[0][:-1], splines))
        # move vertices to new locations
        if self.lock_x or self.lock_y or self.lock_z:
            lock = [self.lock_x, self.lock_y, self.lock_z]
        else:
            lock = False
        move_verts(object, bm, mapping, move, lock, self.influence)

        # cleaning up
        if derived:
            bm_mod.free()
        terminate()

        cache_delete("Space")

        return{'FINISHED'}


# ########################################
# ##### GUI and registration #############
# ########################################

# menu containing all tools
class VIEW3D_MT_edit_mesh_looptools(Menu):
    bl_label = "LoopTools"

    def draw(self, context):
        layout = self.layout

        layout.operator("mesh.looptools_bridge", text="Bridge").loft = False
        layout.operator("mesh.looptools_circle")
        layout.operator("mesh.looptools_curve")
        layout.operator("mesh.looptools_flatten")
        layout.operator("mesh.looptools_gstretch")
        layout.operator("mesh.looptools_bridge", text="Loft").loft = True
        layout.operator("mesh.looptools_relax")
        layout.operator("mesh.looptools_space")


# panel containing all tools
class VIEW3D_PT_tools_looptools(Panel):
    bl_space_type = 'VIEW_3D'
    bl_region_type = 'UI'
    bl_category = 'Edit'
    bl_context = "mesh_edit"
    bl_label = "LoopTools"
    bl_options = {'DEFAULT_CLOSED'}

    def draw(self, context):
        layout = self.layout
        col = layout.column(align=True)
        lt = context.window_manager.looptools

        # bridge - first line
        split = col.split(factor=0.15, align=True)
        if lt.display_bridge:
            split.prop(lt, "display_bridge", text="", icon='DOWNARROW_HLT')
        else:
            split.prop(lt, "display_bridge", text="", icon='RIGHTARROW')
        split.operator("mesh.looptools_bridge", text="Bridge").loft = False
        # bridge - settings
        if lt.display_bridge:
            box = col.column(align=True).box().column()
            # box.prop(self, "mode")

            # top row
            col_top = box.column(align=True)
            row = col_top.row(align=True)
            col_left = row.column(align=True)
            col_right = row.column(align=True)
            col_right.active = lt.bridge_segments != 1
            col_left.prop(lt, "bridge_segments")
            col_right.prop(lt, "bridge_min_width", text="")
            # bottom row
            bottom_left = col_left.row()
            bottom_left.active = lt.bridge_segments != 1
            bottom_left.prop(lt, "bridge_interpolation", text="")
            bottom_right = col_right.row()
            bottom_right.active = lt.bridge_interpolation == 'cubic'
            bottom_right.prop(lt, "bridge_cubic_strength")
            # boolean properties
            col_top.prop(lt, "bridge_remove_faces")

            # override properties
            col_top.separator()
            row = box.row(align=True)
            row.prop(lt, "bridge_twist")
            row.prop(lt, "bridge_reverse")

        # circle - first line
        split = col.split(factor=0.15, align=True)
        if lt.display_circle:
            split.prop(lt, "display_circle", text="", icon='DOWNARROW_HLT')
        else:
            split.prop(lt, "display_circle", text="", icon='RIGHTARROW')
        split.operator("mesh.looptools_circle")
        # circle - settings
        if lt.display_circle:
            box = col.column(align=True).box().column()
            box.prop(lt, "circle_fit")
            box.separator()

            box.prop(lt, "circle_flatten")
            row = box.row(align=True)
            row.prop(lt, "circle_custom_radius")
            row_right = row.row(align=True)
            row_right.active = lt.circle_custom_radius
            row_right.prop(lt, "circle_radius", text="")
            box.prop(lt, "circle_regular")
            box.separator()

            col_move = box.column(align=True)
            row = col_move.row(align=True)
            if lt.circle_lock_x:
                row.prop(lt, "circle_lock_x", text="X", icon='LOCKED')
            else:
                row.prop(lt, "circle_lock_x", text="X", icon='UNLOCKED')
            if lt.circle_lock_y:
                row.prop(lt, "circle_lock_y", text="Y", icon='LOCKED')
            else:
                row.prop(lt, "circle_lock_y", text="Y", icon='UNLOCKED')
            if lt.circle_lock_z:
                row.prop(lt, "circle_lock_z", text="Z", icon='LOCKED')
            else:
                row.prop(lt, "circle_lock_z", text="Z", icon='UNLOCKED')
            col_move.prop(lt, "circle_influence")

        # curve - first line
        split = col.split(factor=0.15, align=True)
        if lt.display_curve:
            split.prop(lt, "display_curve", text="", icon='DOWNARROW_HLT')
        else:
            split.prop(lt, "display_curve", text="", icon='RIGHTARROW')
        split.operator("mesh.looptools_curve")
        # curve - settings
        if lt.display_curve:
            box = col.column(align=True).box().column()
            box.prop(lt, "curve_interpolation")
            box.prop(lt, "curve_restriction")
            box.prop(lt, "curve_boundaries")
            box.prop(lt, "curve_regular")
            box.separator()

            col_move = box.column(align=True)
            row = col_move.row(align=True)
            if lt.curve_lock_x:
                row.prop(lt, "curve_lock_x", text="X", icon='LOCKED')
            else:
                row.prop(lt, "curve_lock_x", text="X", icon='UNLOCKED')
            if lt.curve_lock_y:
                row.prop(lt, "curve_lock_y", text="Y", icon='LOCKED')
            else:
                row.prop(lt, "curve_lock_y", text="Y", icon='UNLOCKED')
            if lt.curve_lock_z:
                row.prop(lt, "curve_lock_z", text="Z", icon='LOCKED')
            else:
                row.prop(lt, "curve_lock_z", text="Z", icon='UNLOCKED')
            col_move.prop(lt, "curve_influence")

        # flatten - first line
        split = col.split(factor=0.15, align=True)
        if lt.display_flatten:
            split.prop(lt, "display_flatten", text="", icon='DOWNARROW_HLT')
        else:
            split.prop(lt, "display_flatten", text="", icon='RIGHTARROW')
        split.operator("mesh.looptools_flatten")
        # flatten - settings
        if lt.display_flatten:
            box = col.column(align=True).box().column()
            box.prop(lt, "flatten_plane")
            # box.prop(lt, "flatten_restriction")
            box.separator()

            col_move = box.column(align=True)
            row = col_move.row(align=True)
            if lt.flatten_lock_x:
                row.prop(lt, "flatten_lock_x", text="X", icon='LOCKED')
            else:
                row.prop(lt, "flatten_lock_x", text="X", icon='UNLOCKED')
            if lt.flatten_lock_y:
                row.prop(lt, "flatten_lock_y", text="Y", icon='LOCKED')
            else:
                row.prop(lt, "flatten_lock_y", text="Y", icon='UNLOCKED')
            if lt.flatten_lock_z:
                row.prop(lt, "flatten_lock_z", text="Z", icon='LOCKED')
            else:
                row.prop(lt, "flatten_lock_z", text="Z", icon='UNLOCKED')
            col_move.prop(lt, "flatten_influence")

        # gstretch - first line
        split = col.split(factor=0.15, align=True)
        if lt.display_gstretch:
            split.prop(lt, "display_gstretch", text="", icon='DOWNARROW_HLT')
        else:
            split.prop(lt, "display_gstretch", text="", icon='RIGHTARROW')
        split.operator("mesh.looptools_gstretch")
        # gstretch settings
        if lt.display_gstretch:
            box = col.column(align=True).box().column()
            box.prop(lt, "gstretch_use_guide")
            if lt.gstretch_use_guide == "GPencil":
                box.prop(lt, "gstretch_guide")
            box.prop(lt, "gstretch_method")

            col_conv = box.column(align=True)
            col_conv.prop(lt, "gstretch_conversion", text="")
            if lt.gstretch_conversion == 'distance':
                col_conv.prop(lt, "gstretch_conversion_distance")
            elif lt.gstretch_conversion == 'limit_vertices':
                row = col_conv.row(align=True)
                row.prop(lt, "gstretch_conversion_min", text="Min")
                row.prop(lt, "gstretch_conversion_max", text="Max")
            elif lt.gstretch_conversion == 'vertices':
                col_conv.prop(lt, "gstretch_conversion_vertices")
            box.separator()

            col_move = box.column(align=True)
            row = col_move.row(align=True)
            if lt.gstretch_lock_x:
                row.prop(lt, "gstretch_lock_x", text="X", icon='LOCKED')
            else:
                row.prop(lt, "gstretch_lock_x", text="X", icon='UNLOCKED')
            if lt.gstretch_lock_y:
                row.prop(lt, "gstretch_lock_y", text="Y", icon='LOCKED')
            else:
                row.prop(lt, "gstretch_lock_y", text="Y", icon='UNLOCKED')
            if lt.gstretch_lock_z:
                row.prop(lt, "gstretch_lock_z", text="Z", icon='LOCKED')
            else:
                row.prop(lt, "gstretch_lock_z", text="Z", icon='UNLOCKED')
            col_move.prop(lt, "gstretch_influence")
            if lt.gstretch_use_guide == "Annotation":
                box.operator("remove.annotation", text="Delete Annotation Strokes")
            if lt.gstretch_use_guide == "GPencil":
                box.operator("remove.gp", text="Delete GPencil Strokes")

        # loft - first line
        split = col.split(factor=0.15, align=True)
        if lt.display_loft:
            split.prop(lt, "display_loft", text="", icon='DOWNARROW_HLT')
        else:
            split.prop(lt, "display_loft", text="", icon='RIGHTARROW')
        split.operator("mesh.looptools_bridge", text="Loft").loft = True
        # loft - settings
        if lt.display_loft:
            box = col.column(align=True).box().column()
            # box.prop(self, "mode")

            # top row
            col_top = box.column(align=True)
            row = col_top.row(align=True)
            col_left = row.column(align=True)
            col_right = row.column(align=True)
            col_right.active = lt.bridge_segments != 1
            col_left.prop(lt, "bridge_segments")
            col_right.prop(lt, "bridge_min_width", text="")
            # bottom row
            bottom_left = col_left.row()
            bottom_left.active = lt.bridge_segments != 1
            bottom_left.prop(lt, "bridge_interpolation", text="")
            bottom_right = col_right.row()
            bottom_right.active = lt.bridge_interpolation == 'cubic'
            bottom_right.prop(lt, "bridge_cubic_strength")
            # boolean properties
            col_top.prop(lt, "bridge_remove_faces")
            col_top.prop(lt, "bridge_loft_loop")

            # override properties
            col_top.separator()
            row = box.row(align=True)
            row.prop(lt, "bridge_twist")
            row.prop(lt, "bridge_reverse")

        # relax - first line
        split = col.split(factor=0.15, align=True)
        if lt.display_relax:
            split.prop(lt, "display_relax", text="", icon='DOWNARROW_HLT')
        else:
            split.prop(lt, "display_relax", text="", icon='RIGHTARROW')
        split.operator("mesh.looptools_relax")
        # relax - settings
        if lt.display_relax:
            box = col.column(align=True).box().column()
            box.prop(lt, "relax_interpolation")
            box.prop(lt, "relax_input")
            box.prop(lt, "relax_iterations")
            box.prop(lt, "relax_regular")

        # space - first line
        split = col.split(factor=0.15, align=True)
        if lt.display_space:
            split.prop(lt, "display_space", text="", icon='DOWNARROW_HLT')
        else:
            split.prop(lt, "display_space", text="", icon='RIGHTARROW')
        split.operator("mesh.looptools_space")
        # space - settings
        if lt.display_space:
            box = col.column(align=True).box().column()
            box.prop(lt, "space_interpolation")
            box.prop(lt, "space_input")
            box.separator()

            col_move = box.column(align=True)
            row = col_move.row(align=True)
            if lt.space_lock_x:
                row.prop(lt, "space_lock_x", text="X", icon='LOCKED')
            else:
                row.prop(lt, "space_lock_x", text="X", icon='UNLOCKED')
            if lt.space_lock_y:
                row.prop(lt, "space_lock_y", text="Y", icon='LOCKED')
            else:
                row.prop(lt, "space_lock_y", text="Y", icon='UNLOCKED')
            if lt.space_lock_z:
                row.prop(lt, "space_lock_z", text="Z", icon='LOCKED')
            else:
                row.prop(lt, "space_lock_z", text="Z", icon='UNLOCKED')
            col_move.prop(lt, "space_influence")


# property group containing all properties for the gui in the panel
class LoopToolsProps(PropertyGroup):
    """
    Fake module like class
    bpy.context.window_manager.looptools
    """
    # general display properties
    display_bridge: BoolProperty(
        name="Bridge settings",
        description="Display settings of the Bridge tool",
        default=False
        )
    display_circle: BoolProperty(
        name="Circle settings",
        description="Display settings of the Circle tool",
        default=False
        )
    display_curve: BoolProperty(
        name="Curve settings",
        description="Display settings of the Curve tool",
        default=False
        )
    display_flatten: BoolProperty(
        name="Flatten settings",
        description="Display settings of the Flatten tool",
        default=False
        )
    display_gstretch: BoolProperty(
        name="Gstretch settings",
        description="Display settings of the Gstretch tool",
        default=False
        )
    display_loft: BoolProperty(
        name="Loft settings",
        description="Display settings of the Loft tool",
        default=False
        )
    display_relax: BoolProperty(
        name="Relax settings",
        description="Display settings of the Relax tool",
        default=False
        )
    display_space: BoolProperty(
        name="Space settings",
        description="Display settings of the Space tool",
        default=False
        )

    # bridge properties
    bridge_cubic_strength: FloatProperty(
        name="Strength",
        description="Higher strength results in more fluid curves",
        default=1.0,
        soft_min=-3.0,
        soft_max=3.0
        )
    bridge_interpolation: EnumProperty(
        name="Interpolation mode",
        items=(('cubic', "Cubic", "Gives curved results"),
                ('linear', "Linear", "Basic, fast, straight interpolation")),
        description="Interpolation mode: algorithm used when creating segments",
        default='cubic'
        )
    bridge_loft: BoolProperty(
        name="Loft",
        description="Loft multiple loops, instead of considering them as "
                    "a multi-input for bridging",
        default=False
        )
    bridge_loft_loop: BoolProperty(
        name="Loop",
        description="Connect the first and the last loop with each other",
        default=False
        )
    bridge_min_width: IntProperty(
        name="Minimum width",
        description="Segments with an edge smaller than this are merged "
                    "(compared to base edge)",
        default=0,
        min=0,
        max=100,
        subtype='PERCENTAGE'
        )
    bridge_mode: EnumProperty(
        name="Mode",
        items=(('basic', "Basic", "Fast algorithm"),
                 ('shortest', "Shortest edge", "Slower algorithm with "
                                               "better vertex matching")),
        description="Algorithm used for bridging",
        default='shortest'
        )
    bridge_remove_faces: BoolProperty(
        name="Remove faces",
        description="Remove faces that are internal after bridging",
        default=True
        )
    bridge_reverse: BoolProperty(
        name="Reverse",
        description="Manually override the direction in which the loops "
                    "are bridged. Only use if the tool gives the wrong result",
        default=False
        )
    bridge_segments: IntProperty(
        name="Segments",
        description="Number of segments used to bridge the gap (0=automatic)",
        default=1,
        min=0,
        soft_max=20
        )
    bridge_twist: IntProperty(
        name="Twist",
        description="Twist what vertices are connected to each other",
        default=0
        )

    # circle properties
    circle_custom_radius: BoolProperty(
        name="Radius",
        description="Force a custom radius",
        default=False
        )
    circle_fit: EnumProperty(
        name="Method",
        items=(("best", "Best fit", "Non-linear least squares"),
            ("inside", "Fit inside", "Only move vertices towards the center")),
        description="Method used for fitting a circle to the vertices",
        default='best'
        )
    circle_flatten: BoolProperty(
        name="Flatten",
        description="Flatten the circle, instead of projecting it on the mesh",
        default=True
        )
    circle_influence: FloatProperty(
        name="Influence",
        description="Force of the tool",
        default=100.0,
        min=0.0,
        max=100.0,
        precision=1,
        subtype='PERCENTAGE'
        )
    circle_lock_x: BoolProperty(
        name="Lock X",
        description="Lock editing of the x-coordinate",
        default=False
        )
    circle_lock_y: BoolProperty(
        name="Lock Y",
        description="Lock editing of the y-coordinate",
        default=False
        )
    circle_lock_z: BoolProperty(
        name="Lock Z",
        description="Lock editing of the z-coordinate",
        default=False
        )
    circle_radius: FloatProperty(
        name="Radius",
        description="Custom radius for circle",
        default=1.0,
        min=0.0,
        soft_max=1000.0
        )
    circle_regular: BoolProperty(
        name="Regular",
        description="Distribute vertices at constant distances along the circle",
        default=True
        )
    circle_angle: FloatProperty(
        name="Angle",
        description="Rotate a circle by an angle",
        unit='ROTATION',
        default=math.radians(0.0),
        soft_min=math.radians(-360.0),
        soft_max=math.radians(360.0)
        )
    # curve properties
    curve_boundaries: BoolProperty(
        name="Boundaries",
        description="Limit the tool to work within the boundaries of the "
                    "selected vertices",
        default=False
        )
    curve_influence: FloatProperty(
        name="Influence",
        description="Force of the tool",
        default=100.0,
        min=0.0,
        max=100.0,
        precision=1,
        subtype='PERCENTAGE'
        )
    curve_interpolation: EnumProperty(
        name="Interpolation",
        items=(("cubic", "Cubic", "Natural cubic spline, smooth results"),
            ("linear", "Linear", "Simple and fast linear algorithm")),
        description="Algorithm used for interpolation",
        default='cubic'
        )
    curve_lock_x: BoolProperty(
        name="Lock X",
        description="Lock editing of the x-coordinate",
        default=False
        )
    curve_lock_y: BoolProperty(
        name="Lock Y",
        description="Lock editing of the y-coordinate",
        default=False
        )
    curve_lock_z: BoolProperty(
        name="Lock Z",
        description="Lock editing of the z-coordinate",
        default=False
        )
    curve_regular: BoolProperty(
        name="Regular",
        description="Distribute vertices at constant distances along the curve",
        default=True
        )
    curve_restriction: EnumProperty(
        name="Restriction",
        items=(("none", "None", "No restrictions on vertex movement"),
            ("extrude", "Extrude only", "Only allow extrusions (no indentations)"),
            ("indent", "Indent only", "Only allow indentation (no extrusions)")),
        description="Restrictions on how the vertices can be moved",
        default='none'
        )

    # flatten properties
    flatten_influence: FloatProperty(
        name="Influence",
        description="Force of the tool",
        default=100.0,
        min=0.0,
        max=100.0,
        precision=1,
        subtype='PERCENTAGE'
        )
    flatten_lock_x: BoolProperty(
        name="Lock X",
        description="Lock editing of the x-coordinate",
        default=False)
    flatten_lock_y: BoolProperty(name="Lock Y",
        description="Lock editing of the y-coordinate",
        default=False
        )
    flatten_lock_z: BoolProperty(
        name="Lock Z",
        description="Lock editing of the z-coordinate",
        default=False
        )
    flatten_plane: EnumProperty(
        name="Plane",
        items=(("best_fit", "Best fit", "Calculate a best fitting plane"),
            ("normal", "Normal", "Derive plane from averaging vertex "
            "normals"),
            ("view", "View", "Flatten on a plane perpendicular to the "
            "viewing angle")),
        description="Plane on which vertices are flattened",
        default='best_fit'
        )
    flatten_restriction: EnumProperty(
        name="Restriction",
        items=(("none", "None", "No restrictions on vertex movement"),
            ("bounding_box", "Bounding box", "Vertices are restricted to "
            "movement inside the bounding box of the selection")),
        description="Restrictions on how the vertices can be moved",
        default='none'
        )

    # gstretch properties
    gstretch_conversion: EnumProperty(
        name="Conversion",
        items=(("distance", "Distance", "Set the distance between vertices "
            "of the converted stroke"),
            ("limit_vertices", "Limit vertices", "Set the minimum and maximum "
            "number of vertices that converted GP strokes will have"),
            ("vertices", "Exact vertices", "Set the exact number of vertices "
            "that converted strokes will have. Short strokes "
            "with few points may contain less vertices than this number."),
            ("none", "No simplification", "Convert each point "
            "to a vertex")),
        description="If strokes are converted to geometry, "
                    "use this simplification method",
        default='limit_vertices'
        )
    gstretch_conversion_distance: FloatProperty(
        name="Distance",
        description="Absolute distance between vertices along the converted "
                    "stroke",
        default=0.1,
        min=0.000001,
        soft_min=0.01,
        soft_max=100
        )
    gstretch_conversion_max: IntProperty(