PIE menu inside PIE menu

Question

I want to make in my addon PIE like that (next GIF PIE's made by PME addon), when PIE menu item call another PIE menu.

I have no ideas how PME do this and dig inside not the best option - ton of stuff going on under the hood. I can't find such examples across the internet - 100 500 tutorials for just PIE, but not PIE inside PIE.

When I try to put just menu it gives me menu like this. Not what I looking for.

class FRP_MT_PIE_Menu(bpy.types.Menu):
bl_idname = 'FRP_MT_PIE_Menu'
bl_label = 'FRP_MT_PIE_Menu'

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

    sc_frp = context.scene.frp_props
    an_a = sc_frp.frp_angle_a
    an_b = sc_frp.frp_angle_b
    to = sc_frp.frp_transform

    #LT
    pie.operator("fgt.frp_rotator", text="- 90", icon='LOOP_FORWARDS').R_Angle = -90.0
    #RT
    pie.operator("fgt.frp_rotator", text="90", icon='LOOP_BACK').R_Angle = 90.0
    #TO
    pie.operator("fgt.frp_rotator", text="180", icon='FILE_REFRESH').R_Angle = 180.0
    #BO
    pie.menu("FRP_MT_PIE_SMenu_TO", text="TO - " + to, icon='NONE')
    #LTTO
    pie.operator("fgt.frp_rotator", text='- ' + an_a, icon='LOOP_FORWARDS').R_Angle = -1 * float(an_a)
    #RTTO
    pie.operator("fgt.frp_rotator", text= an_a, icon='LOOP_BACK').R_Angle = float(an_a)
    #LTBO
    pie.operator("fgt.frp_rotator", text='- ' + an_b, icon='LOOP_FORWARDS').R_Angle = -1 * float(an_b)
    #RTBO
    pie.operator("fgt.frp_rotator", text= an_b, icon='LOOP_BACK').R_Angle = float(an_b)

Using some menu_pie or pie instead of just menu give error like this:

layout.menu_pie("FRP_MT_PIE_SMenu_TO", text="TO - " + to, icon='NONE')
TypeError: UILayout.menu_pie(): takes at most 0 arguments, got 3"

Any ideas guys how to make it work as on first GIF - PIE menu inside PIE menu?

Answer 1

Call pie menu operator.

Example using the Text Editor > Templates > Python > UI Menu Pie template.

Calls itself if clicked on and expands as another pie menu.

Note. Does not auto expand as a pie menu.

import bpy
from bpy.types import Menu

# spawn an edit mode selection pie (run while object is in edit mode to get a valid output)


class VIEW3D_MT_PIE_template(Menu):
    # label is displayed at the center of the pie menu.
    bl_label = "Select Mode"

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

        pie = layout.menu_pie()
        # operator_enum will just spread all available options
        # for the type enum of the operator on the pie
        pie.operator_enum("mesh.select_mode", "type")

        # this one expands as a regular menu
        pie.menu('VIEW3D_MT_PIE_template')
        
        # this one when pressed expands as a pie menu (of self)
        op = pie.operator("wm.call_menu_pie")
        op.name = 'VIEW3D_MT_PIE_template'

def register():
    bpy.utils.register_class(VIEW3D_MT_PIE_template)


def unregister():
    bpy.utils.unregister_class(VIEW3D_MT_PIE_template)


if __name__ == "__main__":
    register()

    bpy.ops.wm.call_menu_pie(name="VIEW3D_MT_PIE_template")