Added basic theming engine.

This theming engine uses a bytestring (but supports anything indexable,
as long as the index results are a byte long),
stored as `wasp.system._theme`.
It has a default value, which should not change anything about the way this looks currently.

The theme can be set via `wasp.system.set_theme`,
but this should *ONLY* be used in `main.py`.
`wasp.system.set_theme` will return True if it was successful,
or False if the theme is of an old format.
Using an old format theme will *not* crash the watch,
but will use the default theme instead.

To theme this, one has to use tools/themer.py (use flag -h for complete explanation)
to generate a bytestring that's added in main.py (see diff).

The bytestring is then loaded into 'wasp.system._theme'.
Theme values can be looked up by apps by using `wasp.system.theme("theme-key")`.
Theme keys appear in the function body of `wasp.system.theme()`.

I've took the liberty of converting existing apps to use this method,
and it seems to work well.

A test theme is provided in `tools/test_theme.py`

Signed-off-by: kozova1 <mug66kk@gmail.com>

3 files changed, 66 insertions, 23 deletions

diff --git a/wasp/apps/clock.py b/wasp/apps/clock.py
index 106e712..c062d3e 100644
--- a/wasp/apps/clock.py
+++ b/wasp/apps/clock.py
@@ -76,7 +76,8 @@ class ClockApp():
 
             # Clear the display and draw that static parts of the watch face
             draw.fill()
-            draw.rleblit(digits.clock_colon, pos=(2*48, 80), fg=0xb5b6)
+            draw.rleblit(digits.clock_colon, pos=(2*48, 80),
+                         fg=wasp.system.theme('accent-mid'))
 
             # Redraw the status bar
             wasp.system.bar.draw()
@@ -95,10 +96,14 @@ class ClockApp():
         month = MONTH[month*3:(month+1)*3]
 
         # Draw the changeable parts of the watch face
-        draw.rleblit(DIGITS[now[4]  % 10], pos=(4*48, 80))
-        draw.rleblit(DIGITS[now[4] // 10], pos=(3*48, 80), fg=0xbdb6)
-        draw.rleblit(DIGITS[now[3]  % 10], pos=(1*48, 80))
-        draw.rleblit(DIGITS[now[3] // 10], pos=(0*48, 80), fg=0xbdb6)
+        draw.rleblit(DIGITS[now[4]  % 10], pos=(4*48, 80),
+                     fg=wasp.system.theme('accent-hi'))
+        draw.rleblit(DIGITS[now[4] // 10], pos=(3*48, 80),
+                     fg=wasp.system.theme('accent-lo'))
+        draw.rleblit(DIGITS[now[3]  % 10], pos=(1*48, 80),
+                     fg=wasp.system.theme('accent-hi'))
+        draw.rleblit(DIGITS[now[3] // 10], pos=(0*48, 80),
+                     fg=wasp.system.theme('accent-lo'))
         draw.string('{} {} {}'.format(now[2], month, now[0]),
                 0, 180, width=240)
 
diff --git a/wasp/wasp.py b/wasp/wasp.py
index 7cf2883..4837e12 100644
--- a/wasp/wasp.py
+++ b/wasp/wasp.py
@@ -14,7 +14,6 @@
     wasp.watch is an import of :py:mod:`watch` and is simply provided as a
     shortcut (and to reduce memory by keeping it out of other namespaces).
 """
-
 import gc
 import machine
 import micropython
@@ -118,6 +117,8 @@ class Manager():
         self.musicstate = {}
         self.musicinfo = {}
 
+        self._theme = b'\xef{\xef{\xef{<\xe7\xef{\xb6\xb5\xb6\xbd\xff\xff\xff9'
+
         self.blank_after = 15
 
         self._alarms = []
@@ -514,4 +515,30 @@ class Manager():
 
         self._scheduling = enable
 
+    def set_theme(self, new_theme) -> bool:
+        """Sets the system theme.
+
+        Accepts anything that supports indexing,
+        and has a len() equivalent to the default theme."""
+        if len(self._theme) != len(new_theme):
+            return False
+        self._theme = new_theme
+        return True
+
+    def theme(self, theme_part: str) -> int:
+        """Returns the relevant part of theme. For more see ../tools/themer.py"""
+        theme_parts = ("ble",
+                       "scroll-indicator",
+                       "battery-charging",
+                       "status-clock",
+                       "notify-icon",
+                       "accent-mid",
+                       "accent-lo",
+                       "accent-hi",
+                       "slider-default")
+        if theme_part not in theme_parts:
+            raise IndexError('Theme part {} does not exist'.format(theme_part))
+        idx = theme_parts.index(theme_part) * 2
+        return self._theme[idx] | (self._theme[idx+1] << 8)
+
 system = Manager()
diff --git a/wasp/widgets.py b/wasp/widgets.py
index d5abd16..1d79e22 100644
--- a/wasp/widgets.py
+++ b/wasp/widgets.py
@@ -39,7 +39,8 @@ class BatteryMeter:
 
         if watch.battery.charging():
             if self.level != -1:
-                draw.rleblit(icon, pos=(239-icon[0], 0), fg=0x7bef)
+                draw.rleblit(icon, pos=(239-icon[0], 0),
+                             fg=wasp.system.theme('battery-charging'))
                 self.level = -1
         else:
             level = watch.battery.level()
@@ -108,7 +109,7 @@ class Clock:
 
             draw = wasp.watch.drawable
             draw.set_font(fonts.sans28)
-            draw.set_color(0xe73c)
+            draw.set_color(wasp.system.theme('status-clock'))
             draw.string(t1, 52, 12, 138)
 
         self.on_screen = now
@@ -137,13 +138,15 @@ class NotificationBar:
         (x, y) = self._pos
 
         if wasp.watch.connected():
-            draw.blit(icons.blestatus, x, y, fg=0x7bef)
+            draw.blit(icons.blestatus, x, y, fg=wasp.system.theme('ble'))
             if wasp.system.notifications:
-                draw.blit(icons.notification, x+22, y, fg=0x7bef)
+                draw.blit(icons.notification, x+22, y,
+                          fg=wasp.system.theme('notify-icon'))
             else:
                 draw.fill(0, x+22, y, 30, 32)
         elif wasp.system.notifications:
-            draw.blit(icons.notification, x, y, fg=0x7bef)
+            draw.blit(icons.notification, x, y,
+                      fg=wasp.system.theme('notify-icon'))
             draw.fill(0, x+30, y, 22, 32)
         else:
             draw.fill(0, x, y, 52, 32)
@@ -206,10 +209,13 @@ class ScrollIndicator:
     def update(self):
         """Update from scrolling indicator."""
         draw = watch.drawable
+        color = wasp.system.theme('scroll-indicator')
+
         if self.up:
-            draw.rleblit(icons.up_arrow, pos=self._pos, fg=0x7bef)
+            draw.rleblit(icons.up_arrow, pos=self._pos, fg=color)
         if self.down:
-            draw.rleblit(icons.down_arrow, pos=(self._pos[0], self._pos[1] + 13), fg=0x7bef)
+            draw.rleblit(icons.down_arrow, pos=(self._pos[0], self._pos[1] + 13),
+                         fg=color)
 
 _SLIDER_KNOB_DIAMETER = const(40)
 _SLIDER_KNOB_RADIUS = const(_SLIDER_KNOB_DIAMETER // 2)
@@ -221,22 +227,14 @@ _SLIDER_TRACK_Y2 = const(_SLIDER_TRACK_Y1 + _SLIDER_TRACK_HEIGHT)
 
 class Slider():
     """A slider to select values."""
-    def __init__(self, steps, x=10, y=90, color=0x39ff):
+    def __init__(self, steps, x=10, y=90, color=None):
         self.value = 0
         self._steps = steps
         self._stepsize = _SLIDER_TRACK / (steps-1)
         self._x = x
         self._y = y
         self._color = color
-
-        # Automatically generate a lowlight color
-        if color < 0b10110_000000_00000:
-            color = (color | 0b10110_000000_00000) & 0b10110_111111_11111
-        if (color & 0b111111_00000) < 0b101100_00000:
-            color = (color | 0b101100_00000) & 0b11111_101100_11111
-        if (color & 0b11111) < 0b10110:
-            color = (color | 0b11000) & 0b11111_111111_10110
-        self._lowlight = color
+        self._lowlight = None
 
     def draw(self):
         """Draw the slider."""
@@ -244,6 +242,19 @@ class Slider():
         x = self._x
         y = self._y
         color = self._color
+        if self._color is None:
+            self._color = wasp.system.theme('slider-default')
+            color = self._color
+        if self._lowlight is None:
+            # Automatically generate a lowlight color
+            if color < 0b10110_000000_00000:
+                color = (color | 0b10110_000000_00000) & 0b10110_111111_11111
+            if (color & 0b111111_00000) < 0b101100_00000:
+                color = (color | 0b101100_00000) & 0b11111_101100_11111
+            if (color & 0b11111) < 0b10110:
+                color = (color | 0b11000) & 0b11111_111111_10110
+            self._lowlight = color
+            color = self._color
         light = self._lowlight
 
         knob_x = x + ((_SLIDER_TRACK * self.value) // (self._steps-1))