Adding a Resistor Colour code watch face.

Signed-off-by: Tony Robinson <tony@tonyRobinson.com>

README.rst

@@ -173,6 +173,10 @@ Watch faces:
    :alt: Shows a time as words in the wasp-os simulator
    :width: 179
 
+.. image:: res/screenshots/ResistorClockApp.png
+   :alt: Resistor colour code clock application running in the wasp-os simulator
+   :width: 179
+
 Games:
 
 .. image:: res/screenshots/Play2048App.png

docs/apps.rst

@@ -23,6 +23,8 @@ Watch faces
 
 .. automodule:: word_clock
 
+.. automodule:: resistor_clock
+
 Built-in
 --------
 

watch_faces/resistor_clock.py

@@ -0,0 +1,86 @@
+# SPDX-License-Identifier: LGPL-3.0-or-later
+# Copyright (C) 2023 Tony Robinson based on the other WASP-OS clock faces
+"""Resistor Clock Face
+~~~~~~~~~~~~~~~~~~~~~~
+
+Following https://hackaday.com/2021/07/15/a-perfect-clock-for-any-hackers-ohm
+display the time as HHMMSS DDMMYYY in 6+8 bands using the resistor colour code.
+
+Colours taken from https://people.duke.edu/~ng46/topics/color-code.htm (grey moved from CCCCCC to C0C0C0)
+
+Code adapted from fibonacci_clock.py by Johannes Wache
+Display the time in using the resistor colour codes
+
+.. figure:: res/screenshots/ResistorClockApp.png
+    :width: 179
+"""
+
+import wasp
+
+_COLOR = [ 0x0000, 0x9B26, 0xF800, 0xFCC0, 0xFFE0, 0x07E0, 0x001F, 0xF81F, 0xC618, 0xFFFF ]
+_TIMEX = bytearray([0, 40, 83, 123, 166, 206])
+_DATEX = bytearray([0, 30, 63, 93, 126, 156, 186, 216])
+
+class ResistorClockApp():
+    NAME = 'Resist'
+
+    def foreground(self):
+        """Activate the application.
+
+        Configure the status bar, redraw the display and request a periodic
+        tick callback every second.
+        """
+        wasp.system.bar.clock = False
+        self._draw(True)
+        wasp.system.request_tick(1000)
+
+    def sleep(self):
+        """Prepare to enter the low power mode.
+
+        :returns: True, which tells the system manager not to automatically
+                  switch to the default application before sleeping.
+        """
+        return True
+
+    def wake(self):
+        """Return from low power mode.
+
+        Time will have changes whilst we have been asleep so we must
+        udpate the display (but there is no need for a full redraw because
+        the display RAM is preserved during a sleep.
+        """
+        self._draw()
+
+    def tick(self, ticks):
+        """Periodic callback to update the display."""
+        self._draw()
+
+    def preview(self):
+        """Provide a preview for the watch face selection."""
+        wasp.system.bar.clock = False
+        self._draw(True)
+
+    def _draw(self, redraw=False):
+        """Draw or lazily update the display."""
+
+        draw = wasp.watch.drawable
+
+        if redraw:
+            now = wasp.watch.rtc.get_localtime()
+            draw.fill()
+            wasp.system.bar.draw()
+        else:
+            now = wasp.system.bar.update()
+            if not now:  # or self._sec == now[5]:
+                return
+
+        # draw time
+        for i, c in enumerate('%02d%02d%02d' % now[3:6]):
+          draw.fill(x=_TIMEX[i],y=60,w=34,h=80,bg=_COLOR[int(c)])
+
+        # draw date
+        for i, c in enumerate('%02d%02d%04d' % (now[2], now[1], now[0])):
+          draw.fill(x=_DATEX[i],y=180,w=24,h=60,bg=_COLOR[int(c)])
+          
+        # Record the second that is currently being displayed
+        # self._sec = now[5]