pause_resume: fixes

- When using absolute extrusion the gcode position e-axis position is now captured on PAUSE and restored in RESUME with a call to the G92 handler.
- Add a get_status() function that returns a dictionary with an 'is_paused' key.
- Do not allow consective calls to PAUSE or RESUME to exectue.  Also do not allow a RESUME to executed without a previous PAUSE.

Signed-off-by:  Eric Callahan <arksine.code@gmail.com>

klippy/extras/pause_resume.py

@@ -11,6 +11,7 @@ class PauseResume:
         self.recover_velocity = config.getfloat('recover_velocity', 50.)
         self.captured_position = None
         self.captured_speed = 0.
+        self.captured_epos = None
         self.toolhead = self.v_sd = None
         self.sd_paused = False
         self.printer.register_event_handler("klippy:ready", self.handle_ready)
@@ -19,7 +20,15 @@ class PauseResume:
     def handle_ready(self):
         self.toolhead = self.printer.lookup_object('toolhead')
         self.v_sd = self.printer.lookup_object('virtual_sdcard', None)
+    def get_status(self, eventtime):
+        paused = self.captured_position is not None
+        return {
+            'is_paused': paused
+        }
     def cmd_PAUSE(self, params):
+        if self.captured_position is not None:
+            self.gcode.respond_info("Print already paused")
+            return
         if self.v_sd is not None and self.v_sd.is_active():
             # Printing from virtual sd, run pause command
             self.sd_paused = True
@@ -30,22 +39,29 @@ class PauseResume:
         self.toolhead.wait_moves()
         self.captured_position = self.toolhead.get_position()
         reactor = self.printer.get_reactor()
-        gc_status = self.gcode.get_status(reactor.monotonic())
-        self.captured_speed = gc_status['speed']
+        gcs = self.gcode.get_status(reactor.monotonic())
+        self.captured_speed = gcs['speed']
+        if gcs['abs_extrude']:
+            self.captured_epos = gcs['last_epos'] - gcs['base_epos']
     def cmd_RESUME(self, params):
+        if self.captured_position is None:
+            self.gcode.respond_info("Print is not paused, resume aborted")
+            return
         velocity = self.gcode.get_float(
             'VELOCITY', params, self.recover_velocity)
-        if self.captured_position is not None:
-            # restore previous xyz position
-            cur_pos = self.toolhead.get_position()
-            self.captured_position[3] = cur_pos[3]
-            self.toolhead.move(self.captured_position, velocity)
-            self.toolhead.get_last_move_time()
-            self.gcode.reset_last_position()
-            # restore previous speed
+
+        cur_pos = self.toolhead.get_position()
+        self.captured_position[3] = cur_pos[3]
+        self.toolhead.move(self.captured_position, velocity)
+        self.toolhead.get_last_move_time()
+        self.gcode.reset_last_position()
+        # restore previous speed
+        self.gcode.run_script_from_command(
+            "G1 F%.6f" % (self.captured_speed))
+        if self.captured_epos is not None:
             self.gcode.run_script_from_command(
-                "G1 F%.6f" % (self.captured_speed))
-        self.captured_position = None
+                "G92 E%.6f" % (self.captured_epos))
+        self.captured_position = self.captured_epos = None
         if self.sd_paused:
             # Printing from virtual sd, run pause command
             self.v_sd.cmd_M24({})