Add function that swaps two colours.

Swap the black and colour pixels of night weather icons.
Add `DARK_MODE` as environment variable. It swaps black and white
pixels of the final image.
Make weather text scaling and icon positioning based on display height.
Make swap colours False by defualt.
Fix 02d.png and 02n.png position for small screens.
Limit dark mode to weather mode.
Update README.

Change-type: minor
Signed-off-by: Genadi Naydenov <[email protected]>

README.md

@@ -67,7 +67,11 @@ To enable the weather display, set the environment variable `MODE` to `weather`.
 
 Next, use either `LATLONG` (e.g. 39.9199,32.8543) or `WEATHER_LOCATION` (e.g. Ankara, Turkey) environment variables to define the location for weather information. Entering only an empty `WEATHER_LOCATION` is also sufficient and in this case Inkyshot will lookup the latitude and longitude information from device's IP address.
 
-Set `SCALE` environment variable to `F` to display the temperature values in Fahrenheit scale. The default is Celcius scale.
+Set `SCALE` environment variable to `F` to display the temperature values in Fahrenheit scale. The default is Celsius scale.
+
+Set `TEMP_THRESHOLD` environment variable to a desired temperature. All readings above this value will be displayed in colour on colour eInk screens. The default value is 25 Celsius (77 Fahrenheit).
+
+You can use the `WEATHER_DARK_MODE` environment variable if you want to eanble dark mode on the inkyshot.
 
 Use the `WEATHER_FONT` variable to customize the font used in weather display mode.
 

inkyshot/update-display.py

@@ -78,6 +78,24 @@ def create_mask(source):
                 mask_image.putpixel((x, y), 255)
     return mask_image
 
+def swap_two_colours(img, dark_mode=False):
+    """Swap two colours.
+    """
+    black = BLACK  
+    if dark_mode:
+        target = BLACK - 1    
+    else:
+        target = BLACK + 1
+    logging.info(f"Swapping colours {black} and {target}")
+    w, h = img.size
+    for x in range(w):
+        for y in range(h):
+            if img.getpixel((x, y)) == black:
+                img.putpixel((x, y), target)
+            elif img.getpixel((x, y)) == target:
+                img.putpixel((x, y), black)
+    return img
+
 # Declare non pip fonts here ** Note: ttf files need to be in the /fonts dir of application repo
 Grand9KPixel = "/usr/app/fonts/Grand9KPixel.ttf"
 
@@ -104,26 +122,31 @@ def draw_weather(weather, img, scale, fill):
     # Load weather icon
     icon_name = weather['symbol'].split('_')[0]
     time_of_day = ''
+    swap_colours = False
     # Couple of symbols have different icons for day and night. Check if this symbol is one of them.
     if len(weather['symbol'].split('_')) > 1:
         symbol_cycle = weather['symbol'].split('_')[1]
         if symbol_cycle == 'day':
             time_of_day = 'd'
         elif symbol_cycle == 'night':
             time_of_day = 'n'
+            swap_colours = True
     icon_filename = f"{icon_map[icon_name]:02}{time_of_day}.png"
     filepath = Path(__file__).parent / 'weather-icons' / icon_filename
     icon_image = Image.open(filepath)
+    if swap_colours:
+        logging.info("Swapping night weather icon black and colour pixels")
+        icon_image = swap_two_colours(icon_image)
     # Draw the weather icon
     if WEATHER_INVERT and WAVESHARE:
         icon_mask = create_mask(icon_image)
         logging.info("Inverting Weather Icon")
         icon = Image.new('1', (100, 100), 255)
         icon.paste(icon_image, (0,0), icon_mask)
         icon_inverted = ImageOps.invert(icon.convert('RGB'))
-        img.paste(icon_inverted, (120 + X_OFFSET, 3 + Y_OFFSET))
+        img.paste(icon_inverted, (119 + X_OFFSET, 3 + Y_OFFSET))
     else:
-        img.paste(icon_image, (120 + X_OFFSET, 3 + Y_OFFSET))
+        img.paste(icon_image, (119 + X_OFFSET, 3 + Y_OFFSET))
     return img
 
 def get_current_display():
@@ -225,12 +248,12 @@ def set_current_display(val):
         logging.error(f"Failed to set current display to {val}. Error is: {err}")
 
 def temp_to_str(temp, scale):
-    """Prepare the temperature to draw based on the defined scale: Celcius or Fahrenheit"""
+    """Prepare the temperature to draw based on the defined scale: Celsius or Fahrenheit"""
     if scale == 'F':
-        temp = celcius_to_fahrenheit(temp)
+        temp = celsius_to_fahrenheit(temp)
     return f"{temp:.1f}"
 
-def celcius_to_fahrenheit(temp):
+def celsius_to_fahrenheit(temp):
     """Convert Celsius to Fahrenheit"""
     return temp * 9/5 + 32
 
@@ -273,7 +296,7 @@ def celcius_to_fahrenheit(temp):
 SCALE = 'F' if "SCALE" in os.environ and os.environ["SCALE"] == 'F' else 'C'
 
 # Temperature threshold above which T is displayed in colour
-TEMP_THRESHOLD = 25 if SCALE == 'C' else celcius_to_fahrenheit(25)
+TEMP_THRESHOLD = 25 if SCALE == 'C' else celsius_to_fahrenheit(25)
 if "TEMP_THRESHOLD" in os.environ:
     TEMP_THRESHOLD = os.environ['TEMP_THRESHOLD']
 
@@ -315,15 +338,13 @@ def celcius_to_fahrenheit(temp):
     HEIGHT = display.HEIGHT
     BLACK = display.BLACK
     WHITE = display.WHITE
-    if display.colour == "black":
-        COLOUR = BLACK
+    COLOUR = BLACK if display.colour == "black" else display.RED
+    if HEIGHT == 104:
         # Display size: W 212 x H 104
         X_OFFSET = 0
         Y_OFFSET = 0
         WEATHER_FONT_INCREASE = 0
     else:
-        # Both display.RED and display.YELLOW = 2
-        COLOUR = display.RED
         # Display size: W 250 x H 122
         # text margin is 3 + 1/3*X_OFFSET = 10 pixels from left border
         # weather icon is 250 - (120 + 21 + 100) = 9 pixels from right border 
@@ -367,7 +388,7 @@ def celcius_to_fahrenheit(temp):
     os.environ['LATLONG'] = f"{LAT},{LONG}"
     # If weather is empty dictionary, fall back to drawing quote
     if len(weather) > 0:
-        temperature = weather['temperature'] if SCALE == 'C' else celcius_to_fahrenheit(weather['temperature'])
+        temperature = weather['temperature'] if SCALE == 'C' else celsius_to_fahrenheit(weather['temperature'])
         fill = COLOUR if temperature >= TEMP_THRESHOLD else BLACK
         img = draw_weather(weather, img, SCALE, fill)
     else:
@@ -444,6 +465,12 @@ def celcius_to_fahrenheit(temp):
 if "ROTATE" in os.environ:
     img = img.rotate(180)
 
+# Enable dark mode 
+# #(it swaps the colour of the first two pixels in the palette)
+if "WEATHER_DARK_MODE" in os.environ and target_display == 'weather':
+    logging.info("Switching to dark mode")
+    img = swap_two_colours(img, dark_mode=True)
+
 if WAVESHARE:
     # epd does not have a set_image method.
     display.display(display.getbuffer(img))