Add SCROLL_LONG_FILENAMES option

Marlin/src/lcd/ultralcd.cpp

@@ -76,12 +76,16 @@ int16_t lcd_preheat_hotend_temp[2], lcd_preheat_bed_temp[2], lcd_preheat_fan_spe
   #endif
 #endif
 
-uint8_t lcd_status_message_level;
+uint8_t lcd_status_update_delay = 1, // First update one loop delayed
+        lcd_status_message_level;    // Higher level overrides lower
 char lcd_status_message[3 * (LCD_WIDTH) + 1] = WELCOME_MSG; // worst case is kana with up to 3*LCD_WIDTH+1
 
 #if ENABLED(STATUS_MESSAGE_SCROLLING)
   uint8_t status_scroll_pos = 0;
 #endif
+#if ENABLED(SCROLL_LONG_FILENAMES)
+  uint8_t filename_scroll_pos, filename_scroll_max, filename_scroll_hash;
+#endif
 
 #if ENABLED(LCD_SET_PROGRESS_MANUALLY)
   uint8_t progress_bar_percent;
@@ -4665,7 +4669,6 @@ void lcd_update() {
 
     // We arrive here every ~100ms when idling often enough.
     // Instead of tracking the changes simply redraw the Info Screen ~1 time a second.
-    static int8_t lcd_status_update_delay = 1; // first update one loop delayed
     if (
       #if ENABLED(ULTIPANEL)
         currentScreen == lcd_status_screen &&
@@ -4681,6 +4684,17 @@ void lcd_update() {
       lcdDrawUpdate = LCDVIEW_REDRAW_NOW;
     }
 
+    #if ENABLED(SCROLL_LONG_FILENAMES)
+      // If scrolling of long file names is enabled and we are in the sd card menu,
+      // cause a refresh to occur until all the text has scrolled into view.
+      if (currentScreen == lcd_sdcard_menu && filename_scroll_pos < filename_scroll_max && !lcd_status_update_delay--) {
+        lcd_status_update_delay = 6;
+        lcdDrawUpdate = LCDVIEW_REDRAW_NOW;
+        filename_scroll_pos++;
+        return_to_status_ms = ms + LCD_TIMEOUT_TO_STATUS;
+      }
+    #endif
+
     // then we want to use 1/2 of the time only.
     uint16_t bbr2 = planner.block_buffer_runtime() >> 1;
 
@@ -4765,7 +4779,7 @@ void lcd_update() {
   } // ELAPSED(ms, next_lcd_update_ms)
 }
 
-void pad_message_string() {
+inline void pad_message_string() {
   uint8_t i = 0, j = 0;
   char c;
   while ((c = lcd_status_message[i]) && j < LCD_WIDTH) {

Marlin/src/lcd/ultralcd_impl_DOGM.h

@@ -935,19 +935,36 @@ static void lcd_implementation_status_screen() {
 
       if (!PAGE_CONTAINS(row_y1, row_y2)) return;
 
-      uint8_t n = LCD_WIDTH - (START_COL) - 1;
+      constexpr uint8_t maxlen = LCD_WIDTH - (START_COL) - 1;
+      const char *outstr = longFilename[0] ? longFilename : filename;
       if (longFilename[0]) {
-        filename = longFilename;
-        longFilename[n] = '\0'; // cutoff at screen edge
+        #if ENABLED(SCROLL_LONG_FILENAMES)
+          if (isSelected) {
+            uint8_t name_hash = row;
+            for (uint8_t l = FILENAME_LENGTH; l--;)
+              name_hash = ((name_hash << 1) | (name_hash >> 7)) ^ filename[l];  // rotate, xor
+            if (filename_scroll_hash != name_hash) {                            // If the hash changed...
+              filename_scroll_hash = name_hash;                                 // Save the new hash
+              filename_scroll_max = max(0, lcd_strlen(longFilename) - maxlen);  // Update the scroll limit
+              filename_scroll_pos = 0;                                          // Reset scroll to the start
+              lcd_status_update_delay = 8;                                      // Don't scroll right away
+            }
+            outstr += filename_scroll_pos;
+          }
+        #else
+          longFilename[maxlen] = '\0'; // cutoff at screen edge
+        #endif
       }
 
       if (isDir) lcd_print(LCD_STR_FOLDER[0]);
 
-      while (char c = *filename) {
+      char c;
+      uint8_t n = maxlen;
+      while (n && (c = *outstr)) {
         n -= lcd_print_and_count(c);
-        filename++;
+        ++outstr;
       }
-      while (n--) u8g.print(' ');
+      while (n) { --n; u8g.print(' '); }
     }
 
     #define lcd_implementation_drawmenu_sdfile(sel, row, pstr, filename, longFilename) _drawmenu_sd(sel, row, pstr, filename, longFilename, false)

Marlin/src/lcd/ultralcd_impl_HD44780.h

@@ -991,18 +991,37 @@ static void lcd_implementation_status_screen() {
 
     static void lcd_implementation_drawmenu_sd(const bool sel, const uint8_t row, const char* const pstr, const char* filename, char* const longFilename, const uint8_t concat, const char post_char) {
       UNUSED(pstr);
-      uint8_t n = LCD_WIDTH - concat;
       lcd.setCursor(0, row);
       lcd.print(sel ? '>' : ' ');
+
+      uint8_t n = LCD_WIDTH - concat;
+      const char *outstr = longFilename[0] ? longFilename : filename;
       if (longFilename[0]) {
-        filename = longFilename;
-        longFilename[n] = '\0';
+        #if ENABLED(SCROLL_LONG_FILENAMES)
+          if (sel) {
+            uint8_t name_hash = row;
+            for (uint8_t l = FILENAME_LENGTH; l--;)
+              name_hash = ((name_hash << 1) | (name_hash >> 7)) ^ filename[l];  // rotate, xor
+            if (filename_scroll_hash != name_hash) {                            // If the hash changed...
+              filename_scroll_hash = name_hash;                                 // Save the new hash
+              filename_scroll_max = max(0, lcd_strlen(longFilename) - n);  // Update the scroll limit
+              filename_scroll_pos = 0;                                          // Reset scroll to the start
+              lcd_status_update_delay = 8;                                      // Don't scroll right away
+            }
+            outstr += filename_scroll_pos;
+          }
+        #else
+          longFilename[n] = '\0'; // cutoff at screen edge
+        #endif
       }
-      while (char c = *filename) {
+
+      char c;
+      while (n && (c = *outstr)) {
         n -= charset_mapper(c);
-        filename++;
+        ++outstr;
       }
-      while (n--) lcd.write(' ');
+      while (n) { --n; lcd.write(' '); }
+
       lcd.print(post_char);
     }