v.0.9.1 DigitalClock: optimzed update the display

app/utils/digital_clock.py

@@ -1,26 +1,58 @@
 from app.display.neopixel_64x64 import NeoPixel_64x64
-from app.utils import get_datetime_string
+from app.utils import get_datetime_string, text_width, find_first_mismatch
 from app.utils import colors
 
 
 class DigitalClock:
-    CLOCK_WIDTH = 38
+    stored_time_str: str = "99:99:99"
+    text_color: tuple[int[3]] = colors.NEON_YELLOW
+    clear_color: tuple[int[3]] = colors.BLACK
 
     def __init__(self, display: NeoPixel_64x64, xpos: int, ypos: int):
         self.display = display
         self.xpos = xpos
         self.ypos = ypos
 
+    def _toggle_clear_color(self) -> tuple[int]:
+        self.clear_color = (
+            colors.BLACK if self.clear_color != colors.BLACK else colors.MAGENTA
+        )
+        return self.clear_color
+
+    def _text_width(self, text: str) -> int:
+        return text_width(text, self.display.selected_font)
+
     async def tick(self):
-        time_str: str = get_datetime_string("time")
+        time_str: str = get_datetime_string("time")[:8]
+
+        # ab welcher Position malen wir den String neu
+        mismatch_pos: int = find_first_mismatch(self.stored_time_str, time_str)
+
+        untouched_part: str = time_str[:mismatch_pos]
+        fresh_part: str = time_str[mismatch_pos:]
+        part_to_clear: str = self.stored_time_str[mismatch_pos:]
+
+        print(f"untouched_part: {untouched_part}[{part_to_clear}-->{fresh_part}] ")
+
+        textwidth: int = self._text_width(self.stored_time_str)
+        print(f"{self.stored_time_str}: #{textwidth}")
+
+        textwidth_untouched_part: int = self._text_width(untouched_part)
+        clear_x_start_pos: int = self.xpos + textwidth_untouched_part + 1
+
+        textwidth_part_to_clear: int = self._text_width(part_to_clear)
+        clear_x_end_pos: int = clear_x_start_pos + textwidth_part_to_clear - 1
+
         self.display.clear_box(
             self.ypos,
-            self.xpos,
+            clear_x_start_pos,
             self.ypos + self.display.font_height,
-            self.xpos + self.CLOCK_WIDTH,
-            color=colors.MAGENTA,
+            clear_x_end_pos,
+            color=self.clear_color,
         )
 
         self.display.write_text(
-            time_str[:8], self.xpos, self.ypos, color=colors.NEON_YELLOW
+            fresh_part, clear_x_start_pos, self.ypos, color=self.text_color
         )
+
+        self.stored_time_str = time_str