From c06618193d3c58521e45a0c2241278268664030e Mon Sep 17 00:00:00 2001
From: Kevin O'Connor <kevin@koconnor.net>
Date: Sun, 24 Nov 2019 19:43:50 -0500
Subject: [PATCH] extruder: Add an ACTIVATE_EXTRUDER command

Add support for an extended g-code command to change the currently
active extruder.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
---
 docs/G-Codes.md               |  3 +++
 klippy/gcode.py               |  6 ++++++
 klippy/kinematics/extruder.py | 13 +++++++++++++
 3 files changed, 22 insertions(+)

diff --git a/docs/G-Codes.md b/docs/G-Codes.md
index 029c9ae0..a7d1adcd 100644
--- a/docs/G-Codes.md
+++ b/docs/G-Codes.md
@@ -153,6 +153,9 @@ The following standard commands are supported:
 - `SET_HEATER_TEMPERATURE HEATER=<heater_name> [TARGET=<target_temperature>]`:
   Sets the target temperature for a heater. If a target temperature is
   not supplied, the target is 0.
+- `ACTIVATE_EXTRUDER EXTRUDER=<config_name>`: In a printer with
+  multiple extruders this command is used to change the active
+  extruder.
 - `SET_PRESSURE_ADVANCE [EXTRUDER=<config_name>] [ADVANCE=<pressure_advance>]
   [SMOOTH_TIME=<pressure_advance_smooth_time>]`: Set pressure advance
   parameters. If EXTRUDER is not specified, it defaults to the active
diff --git a/klippy/gcode.py b/klippy/gcode.py
index 93e97ec7..9ac7ddda 100644
--- a/klippy/gcode.py
+++ b/klippy/gcode.py
@@ -17,6 +17,8 @@ class GCodeParser:
         printer.register_event_handler("klippy:shutdown", self._handle_shutdown)
         printer.register_event_handler("klippy:disconnect",
                                        self._handle_disconnect)
+        printer.register_event_handler("extruder:activate_extruder",
+                                       self._handle_activate_extruder)
         # Input handling
         self.reactor = printer.get_reactor()
         self.is_processing_data = False
@@ -175,6 +177,10 @@ class GCodeParser:
             self.fd_handle = self.reactor.register_fd(self.fd,
                                                       self._process_data)
         self._respond_state("Ready")
+    def _handle_activate_extruder(self):
+        self.reset_last_position()
+        self.extrude_factor = 1.
+        self.base_position[3] = self.last_position[3]
     def reset_last_position(self):
         self.last_position = self.position_with_transform()
     def _dump_debug(self):
diff --git a/klippy/kinematics/extruder.py b/klippy/kinematics/extruder.py
index b55e6f0e..78e8dc10 100644
--- a/klippy/kinematics/extruder.py
+++ b/klippy/kinematics/extruder.py
@@ -73,6 +73,9 @@ class PrinterExtruder:
         gcode.register_mux_command("SET_PRESSURE_ADVANCE", "EXTRUDER",
                                    self.name, self.cmd_SET_PRESSURE_ADVANCE,
                                    desc=self.cmd_SET_PRESSURE_ADVANCE_help)
+        gcode.register_mux_command("ACTIVATE_EXTRUDER", "EXTRUDER",
+                                   self.name, self.cmd_ACTIVATE_EXTRUDER,
+                                   desc=self.cmd_ACTIVATE_EXTRUDER_help)
     def update_move_time(self, flush_time):
         self.trapq_free_moves(self.trapq, flush_time)
     def _set_pressure_advance(self, pressure_advance, smooth_time):
@@ -168,6 +171,16 @@ class PrinterExtruder:
                    pressure_advance, smooth_time))
         self.printer.set_rollover_info(self.name, "%s: %s" % (self.name, msg))
         gcode.respond_info(msg, log=False)
+    cmd_ACTIVATE_EXTRUDER_help = "Change the active extruder"
+    def cmd_ACTIVATE_EXTRUDER(self, params):
+        gcode = self.printer.lookup_object('gcode')
+        toolhead = self.printer.lookup_object('toolhead')
+        if toolhead.get_extruder() is self:
+            gcode.respond_info("Extruder %s already active" % (self.name))
+            return
+        gcode.respond_info("Activating extruder %s" % (self.name))
+        toolhead.set_extruder(self, self.extrude_pos)
+        self.printer.send_event("extruder:activate_extruder")
 
 # Dummy extruder class used when a printer has no extruder at all
 class DummyExtruder: