Variable tool change purge (#14618)

Marlin/src/gcode/config/M217.cpp

   #if ENABLED(TOOLCHANGE_FILAMENT_SWAP)
     serialprintPGM(eeprom ? PSTR("  M217") : PSTR("Toolchange:"));
     SERIAL_ECHOPAIR(" S", LINEAR_UNIT(toolchange_settings.swap_length));
+    SERIAL_ECHOPAIR(" E", LINEAR_UNIT(toolchange_settings.extra_prime));
     SERIAL_ECHOPAIR(" P", LINEAR_UNIT(toolchange_settings.prime_speed));
     SERIAL_ECHOPAIR(" R", LINEAR_UNIT(toolchange_settings.retract_speed));
 
  * M217 - Set SINGLENOZZLE toolchange parameters
  *
  *  S[linear]   Swap length
+ *  E[linear]   Purge length
  *  P[linear/m] Prime speed
  *  R[linear/m] Retract speed
  *  X[linear]   Park X (Requires TOOLCHANGE_PARK)
   #if ENABLED(TOOLCHANGE_FILAMENT_SWAP)
 
     #undef SPR_PARAM
-    #define SPR_PARAM "SPR"
-
-    if (parser.seenval('S')) { const float v = parser.value_linear_units(); toolchange_settings.swap_length = constrain(v, 0, 500); }
+    #define SPR_PARAM "SPRE"
+
+    static constexpr float max_extrude =
+      #if ENABLED(PREVENT_LENGTHY_EXTRUDE)
+        EXTRUDE_MAXLENGTH
+      #else
+        500
+      #endif
+    ;
+
+    if (parser.seenval('S')) { const float v = parser.value_linear_units(); toolchange_settings.swap_length = constrain(v, 0, max_extrude); }
+    if (parser.seenval('E')) { const float v = parser.value_linear_units(); toolchange_settings.extra_prime = constrain(v, 0, max_extrude); }
     if (parser.seenval('P')) { const int16_t v = parser.value_linear_units(); toolchange_settings.prime_speed = constrain(v, 10, 5400); }
     if (parser.seenval('R')) { const int16_t v = parser.value_linear_units(); toolchange_settings.retract_speed = constrain(v, 10, 5400); }
   #endif
+
   #if ENABLED(TOOLCHANGE_PARK)
     #undef XY_PARAM
     #define XY_PARAM "XY"
     if (parser.seenval('X')) { toolchange_settings.change_point.x = parser.value_linear_units(); }
     if (parser.seenval('Y')) { toolchange_settings.change_point.y = parser.value_linear_units(); }
   #endif
+
   if (parser.seenval('Z')) { toolchange_settings.z_raise = parser.value_linear_units(); }
 
   if (!parser.seen(SPR_PARAM XY_PARAM "Z")) M217_report();

Marlin/src/lcd/language/language_en.h

   #define MSG_AUTORETRACT                     _UxGT("AutoRetr.")
 #endif
 #ifndef MSG_FILAMENT_SWAP_LENGTH
-  #define MSG_FILAMENT_SWAP_LENGTH            _UxGT("Retract Distance")
+  #define MSG_FILAMENT_SWAP_LENGTH            _UxGT("Swap Length")
+#endif
+#ifndef MSG_FILAMENT_PURGE_LENGTH
+  #define MSG_FILAMENT_PURGE_LENGTH           _UxGT("Purge Length")
 #endif
 #ifndef MSG_TOOL_CHANGE
-  #define MSG_TOOL_CHANGE                      _UxGT("Tool Change")
+  #define MSG_TOOL_CHANGE                     _UxGT("Tool Change")
 #endif
 #ifndef MSG_TOOL_CHANGE_ZLIFT
-  #define MSG_TOOL_CHANGE_ZLIFT                _UxGT("Z Raise")
+  #define MSG_TOOL_CHANGE_ZLIFT               _UxGT("Z Raise")
 #endif
 #ifndef MSG_SINGLENOZZLE_PRIME_SPD
   #define MSG_SINGLENOZZLE_PRIME_SPD          _UxGT("Prime Speed")

Marlin/src/lcd/menu/menu_configuration.cpp

     START_MENU();
     MENU_BACK(MSG_CONFIGURATION);
     #if ENABLED(TOOLCHANGE_FILAMENT_SWAP)
-      MENU_ITEM_EDIT(float3, MSG_FILAMENT_SWAP_LENGTH, &toolchange_settings.swap_length, 0, 200);
+      static constexpr float max_extrude =
+        #if ENABLED(PREVENT_LENGTHY_EXTRUDE)
+          EXTRUDE_MAXLENGTH
+        #else
+          500
+        #endif
+      ;
+      MENU_ITEM_EDIT(float3, MSG_FILAMENT_SWAP_LENGTH, &toolchange_settings.swap_length, 0, max_extrude);
+      MENU_ITEM_EDIT(float3, MSG_FILAMENT_PURGE_LENGTH, &toolchange_settings.extra_prime, 0, max_extrude);
       MENU_MULTIPLIER_ITEM_EDIT(int4, MSG_SINGLENOZZLE_RETRACT_SPD, &toolchange_settings.retract_speed, 10, 5400);
       MENU_MULTIPLIER_ITEM_EDIT(int4, MSG_SINGLENOZZLE_PRIME_SPD, &toolchange_settings.prime_speed, 10, 5400);
     #endif

Marlin/src/module/configuration_store.cpp

  */
 
 // Change EEPROM version if the structure changes
-#define EEPROM_VERSION "V67"
+#define EEPROM_VERSION "V68"
 #define EEPROM_OFFSET 100
 
 // Check the integrity of data offsets.
   #if EXTRUDERS > 1
     #if ENABLED(TOOLCHANGE_FILAMENT_SWAP)
       toolchange_settings.swap_length = TOOLCHANGE_FIL_SWAP_LENGTH;
+      toolchange_settings.extra_prime = TOOLCHANGE_FIL_EXTRA_PRIME;
       toolchange_settings.prime_speed = TOOLCHANGE_FIL_SWAP_PRIME_SPEED;
       toolchange_settings.retract_speed = TOOLCHANGE_FIL_SWAP_RETRACT_SPEED;
     #endif

Marlin/src/module/tool_change.cpp

         #if ENABLED(TOOLCHANGE_FILAMENT_SWAP)
           if (should_swap && !too_cold) {
             #if ENABLED(ADVANCED_PAUSE_FEATURE)
-              do_pause_e_move(toolchange_settings.swap_length + TOOLCHANGE_FIL_EXTRA_PRIME, MMM_TO_MMS(toolchange_settings.prime_speed));
+              do_pause_e_move(toolchange_settings.swap_length + toolchange_settings.extra_prime, MMM_TO_MMS(toolchange_settings.prime_speed));
             #else
-              current_position[E_AXIS] += (toolchange_settings.swap_length + TOOLCHANGE_FIL_EXTRA_PRIME) / planner.e_factor[tmp_extruder];
+              current_position[E_AXIS] += (toolchange_settings.swap_length + toolchange_settings.extra_prime) / planner.e_factor[tmp_extruder];
               planner.buffer_line(current_position, MMM_TO_MMS(toolchange_settings.prime_speed), tmp_extruder);
             #endif
             planner.synchronize();
-
-            #if TOOLCHANGE_FIL_EXTRA_PRIME
-              planner.set_e_position_mm((destination[E_AXIS] = current_position[E_AXIS] = current_position[E_AXIS] - (TOOLCHANGE_FIL_EXTRA_PRIME)));
-            #endif
+            planner.set_e_position_mm((destination[E_AXIS] = current_position[E_AXIS] = current_position[E_AXIS] - (TOOLCHANGE_FIL_EXTRA_PRIME)));
           }
         #endif
 

Marlin/src/module/tool_change.h

 
   typedef struct {
     #if ENABLED(TOOLCHANGE_FILAMENT_SWAP)
-      float swap_length;
+      float swap_length, extra_prime;
       int16_t prime_speed, retract_speed;
     #endif
     #if ENABLED(TOOLCHANGE_PARK)