Add screen state to gcode_M600()

- Allowing resume after M600 via on screen button:

- Adding check for TFT state status
- Setting flag when print was started via TFT

Marlin/AnycubicTFT.h

@@ -55,6 +55,9 @@ class AnycubicTFTClass {
   void HeatingStart();
   void FilamentRunout();
   void KillTFT();
+  char TFTstate=ANYCUBIC_TFT_STATE_IDLE;
+  bool PausedByRunout=false;
+  bool PausedByFilamentChange=false;
 
 private:
   char TFTcmdbuffer[TFTBUFSIZE][TFT_MAX_CMD_SIZE];
@@ -64,16 +67,13 @@ class AnycubicTFTClass {
   char serial3_char;
   int serial3_count = 0;
   char *TFTstrchr_pointer;
-  char TFTstate=ANYCUBIC_TFT_STATE_IDLE;
   char FlagResumFromOutage=0;
   uint16_t filenumber=0;
   unsigned long starttime=0;
   unsigned long stoptime=0;
   uint8_t tmp_extruder=0;
   char LastSDstatus=0;
   uint16_t HeaterCheckCount=0;
-  bool PausedByRunout=false;
-  bool PausedByFilamentChange=false;
 
   struct OutageDataStruct {
     char OutageDataVersion;

Marlin/Marlin_main.cpp

@@ -10992,6 +10992,12 @@ inline void gcode_M502() {
    *  Default values are used for omitted arguments.
    */
   inline void gcode_M600() {
+    #ifdef SDSUPPORT
+        if ((AnycubicTFT.TFTstate==ANYCUBIC_TFT_STATE_SDPRINT)){
+        AnycubicTFT.TFTstate=ANYCUBIC_TFT_STATE_SDPAUSE_REQ;
+        AnycubicTFT.PausedByFilamentChange=true;
+        }
+    #endif
     point_t park_point = NOZZLE_PARK_POINT;
 
     if (get_target_extruder_from_command(600)) return;