Merge pull request #1966 from thinkyhead/g4_dwell_message

G4 shows status message only if no message is set already

Marlin/Marlin_main.cpp

 }
 
 bool code_has_value() {
-  char c = strchr_pointer[1];
-  return (c >= '0' && c <= '9') || c == '-' || c == '+' || c == '.';
+  int i = 1;
+  char c = strchr_pointer[i];
+  if (c == '-' || c == '+') c = strchr_pointer[++i];
+  if (c == '.') c = strchr_pointer[++i];
+  return (c >= '0' && c <= '9');
 }
 
 float code_value() {
 inline void gcode_G4() {
   millis_t codenum = 0;
 
-  LCD_MESSAGEPGM(MSG_DWELL);
-
   if (code_seen('P')) codenum = code_value_long(); // milliseconds to wait
   if (code_seen('S')) codenum = code_value_long() * 1000; // seconds to wait
 
   st_synchronize();
   refresh_cmd_timeout();
   codenum += previous_cmd_ms;  // keep track of when we started waiting
+
+  if (!lcd_hasstatus()) LCD_MESSAGEPGM(MSG_DWELL);
+
   while (millis() < codenum) {
     manage_heater();
     manage_inactivity();

Marlin/ultralcd.cpp

     #endif
     #if PROGRESS_MSG_EXPIRE > 0
       // Handle message expire
-      if (expireStatusMillis > 0) {
+      if (expire_status_ms > 0) {
         if (card.isFileOpen()) {
           // Expire the message when printing is active
           if (IS_SD_PRINTING) {
             // Expire the message when printing is active
-            if (ms >= expireStatusMillis) {
+            if (ms >= expire_status_ms) {
               lcd_status_message[0] = '\0';
-              expireStatusMillis = 0;
+              expire_status_ms = 0;
             }
           }
           else {
-            expireStatusMillis += LCD_UPDATE_INTERVAL;
+            expire_status_ms += LCD_UPDATE_INTERVAL;
           }
         }
         else {
-          expireStatusMillis = 0;
+          expire_status_ms = 0;
         }
       }
     #endif
   #ifdef LCD_PROGRESS_BAR
     progressBarTick = millis();
     #if PROGRESS_MSG_EXPIRE > 0
-      expireStatusMillis = persist ? 0 : progressBarTick + PROGRESS_MSG_EXPIRE;
+      expire_status_ms = persist ? 0 : progressBarTick + PROGRESS_MSG_EXPIRE;
     #endif
   #endif
   lcdDrawUpdate = 2;
 }
 
 #if defined(LCD_PROGRESS_BAR) && PROGRESS_MSG_EXPIRE > 0
-  void dontExpireStatus() { expireStatusMillis = 0; }
+  void dontExpireStatus() { expire_status_ms = 0; }
 #endif
 
 void set_utf_strlen(char *s, uint8_t n) {
   s[i] = 0;
 }
 
+bool lcd_hasstatus() { return (lcd_status_message[0] != '\0'); }
+
 void lcd_setstatus(const char* message, bool persist) {
   if (lcd_status_message_level > 0) return;
   strncpy(lcd_status_message, message, 3*LCD_WIDTH);

Marlin/ultralcd.h

   int lcd_strlen_P(const char *s);
   void lcd_update();
   void lcd_init();
+  bool lcd_hasstatus();
   void lcd_setstatus(const char* message, const bool persist=false);
   void lcd_setstatuspgm(const char* message, const uint8_t level=0);
   void lcd_setalertstatuspgm(const char* message);
 #else //no LCD
   FORCE_INLINE void lcd_update() {}
   FORCE_INLINE void lcd_init() {}
+  FORCE_INLINE bool lcd_hasstatus() { return false; }
   FORCE_INLINE void lcd_setstatus(const char* message, const bool persist=false) {}
   FORCE_INLINE void lcd_setstatuspgm(const char* message, const uint8_t level=0) {}
   FORCE_INLINE void lcd_buttons_update() {}
   FORCE_INLINE void lcd_buzz(long duration,uint16_t freq) {}
   FORCE_INLINE bool lcd_detected(void) { return true; }
 
-  #define LCD_MESSAGEPGM(x) 
-  #define LCD_ALERTMESSAGEPGM(x) 
+  #define LCD_MESSAGEPGM(x) do{}while(0)
+  #define LCD_ALERTMESSAGEPGM(x) do{}while(0)
 
 #endif //ULTRA_LCD
 

Marlin/ultralcd_implementation_hitachi_HD44780.h

 #ifdef LCD_PROGRESS_BAR
   static uint16_t progressBarTick = 0;
   #if PROGRESS_MSG_EXPIRE > 0
-    static uint16_t expireStatusMillis = 0;
+    static uint16_t expire_status_ms = 0;
   #endif
   #define LCD_STR_PROGRESS  "\x03\x04\x05"
 #endif