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Add support for 4 color grayscale displays (txoof#71)
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@ThomasR
ThomasR authored Feb 1, 2025
1 parent 424c3f4 commit 02bb904
Showing 1 changed file with 89 additions and 59 deletions.
148 changes: 89 additions & 59 deletions epdlib/Screen.py
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,7 @@
import sys
import time
import subprocess
from enum import Enum

# +
import logging
Expand Down Expand Up @@ -200,6 +201,14 @@ def update(self):
self._last_updated = self.now


# + code_folding=[0]
class ScreenType(Enum):

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@txoof

txoof Feb 2, 2025

I like what you're doing here. Can you add some comments to be explicit and make sure to add Enum to the requirements file?
HD = 0
MONOCHROME = 1
FOUR_GRAYS = 2
THREE_COLORS = 3 # black/white and 1 additional color; currently only supported in BW mode
FOUR_COLORS = 4 # black/white/yellow/red
SEVEN_COLORS = 5

# + code_folding=[5, 95]
class Screen():
Expand Down Expand Up @@ -235,7 +244,7 @@ def __init__(self, epd=None, rotation=0, vcom=None, *args, **kwargs):
self.clear_args = kwargs.get('clear_args', {})
self.buffer_no_image = kwargs.get('buffer_no_image', [])
self.constants = kwargs.get('constants', None)
self.mode = kwargs.get('mode', None)
self.screen_type = kwargs.get('screen_type', None)
self.HD = kwargs.get('HD', False)
self.epd = epd
self.rotation = rotation
Expand All @@ -262,7 +271,12 @@ def wrapper(*args, **kwargs):
if not obj.HD:
logging.debug('Non HD display')
try:
obj.epd.init()
if obj.screen_type == ScreenType.FOUR_GRAYS:
# unfortunately, naming is not consistent
initializer = getattr(obj.epd, 'Init_4Gray') or getattr(obj.epd, 'init_4Gray')
else:
initializer = obj.epd.init
initializer()
except FileNotFoundError as e:
raise FileNotFoundError(f'It appears SPI is not enabled on this Pi: {e}')
except Exception as e:
Expand Down Expand Up @@ -317,8 +331,8 @@ def epd(self, epd):
clear_args(dict): arguments required for clearing the screen
constants(namespace): constants required for read/write of IT8951 screens
HD(bool): True for IT8951 based screens
mode(str): "1", "L", "RGB" (note this does not override the mode if already set)'''
screen_type(Enum): type of screen regarding color support'''

if not epd or epd.lower == 'none':
self._epd = None
return
Expand All @@ -340,12 +354,10 @@ def epd(self, epd):
self.resolution = myepd['resolution']
self.clear_args = myepd['clear_args']
self.constants = myepd['constants']
self.one_bit_display = myepd['one_bit_display']
self.mode = myepd['mode']


if not self.one_bit_display and self.mode not in('L', 'RGB'):
logging.debug('setting buffer_no_image for bi-color display')
self.screen_type = myepd['screen_type']

if self.screen_type == ScreenType.THREE_COLORS:
logging.debug('setting buffer_no_image for one-color display')
self.buffer_no_image = self.epd.getbuffer(self.blank_image())

logging.debug(f'epd configuration {myepd}')
Expand Down Expand Up @@ -378,19 +390,17 @@ def rotation(self, rotation):
raise ValueError(f'valid rotation values are {constants.SCREEN_ROTATIONS}')

if rotation in [90, -90, 270]:
resolution = self.resolution
resolution = sorted(self.resolution)
self.resolution = resolution
else:
resolution = self.resolution
resolution = sorted(self.resolution)
resolution.sort(reverse=True)
self.resolution = resolution

# set an image if the epd is defined
if self.epd:
self.image = Image.new(self.mode, self.resolution, 255)
if not self.HD:
if self.epd:
self.image = Image.new(self.mode, self.resolution, 0xff)
if self.screen_type == ScreenType.THREE_COLORS:
self.buffer_no_image = self.epd.getbuffer(self.blank_image())

self._rotation = rotation
Expand Down Expand Up @@ -440,15 +450,14 @@ def _load_hd(self, epd, timeout=20):
resolution.sort(reverse=True)
resolution = resolution
clear_args = {}
one_bit_display = False

return {'epd': myepd,
'resolution': resolution,
'clear_args': clear_args,
'one_bit_display': one_bit_display,
'constants': constants_HD,
'mode': 'L'}

screen_type = ScreenType.HD

return {'epd': myepd,
'resolution': resolution,
'clear_args': clear_args,
'screen_type': screen_type,
'constants': constants_HD}

def _load_non_hd(self, epd):
'''configure non IT8951 SPI epd
Expand Down Expand Up @@ -510,45 +519,63 @@ def _load_non_hd(self, epd):
raise ScreenError(f'"{epd}" has an unsupported `EPD.display()` function and is not usable with this module')

logging.debug(f'args_spec: {display_args_spec.args}')

# 2 and 3 color displays have >= 2 args
if len(display_args_spec.args) <= 2:
one_bit_display = True
mode = '1'
else:
one_bit_display = False
mode = 'L'


# use the presence of `BLUE` and `ORANGE` properties as evidence that this is a color display
if vars(myepd.EPD()).get('BLUE', False) and vars(myepd.EPD()).get('ORANGE', False):
one_bit_display = False
mode = 'RGB'
# 7 colors

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@txoof

txoof Feb 2, 2025

Oh wow! This looks really great! Does the three color mode work as expected?
screen_type = ScreenType.SEVEN_COLORS
elif vars(myepd.EPD()).get('YELLOW', False):
if vars(myepd.EPD()).get('RED', False):
# B/W/Y/R
screen_type = ScreenType.FOUR_COLORS
else:
# B/W/Y
screen_type = ScreenType.THREE_COLORS
elif vars(myepd.EPD()).get('RED', False):
# B/W/R
screen_type = ScreenType.THREE_COLORS
elif hasattr(myepd.EPD(), 'display_4Gray'):
# B/W with grayscale (4 shades)
screen_type = ScreenType.FOUR_GRAYS
else:
mode = '1'

# default to B/W
screen_type = ScreenType.MONOCHROME

if screen_type == ScreenType.THREE_COLORS:
assert len(display_args_spec.args) == 3
else:
assert len(display_args_spec.args) == 2

resolution = [myepd.EPD_HEIGHT, myepd.EPD_WIDTH]
resolution.sort(reverse=True)

return {'epd': myepd.EPD(),
'resolution': resolution,
'clear_args': clear_args,
'one_bit_display': one_bit_display,
'constants': None,
'mode': mode}

'screen_type': screen_type,
'constants': None}

def initEPD(self, *args, **kwargs):
'''**DEPRICATED** init EPD for wirting
'''**DEPRECATED** init EPD for wirting
For non IT8951 boards use `epd.init()` at your own risk -- SPI file handles are NOT automatically closed
'''
logging.warning('this method is depricated and does nothing. If you really know what you are doing, use `epd.init()` at your own risk')
logging.warning('this method is deprecated and does nothing. If you really know what you are doing, use `epd.init()` at your own risk')

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@txoof

txoof Feb 2, 2025

Thanks for the spell check.

def blank_image(self):
'''retrun a PIL image that is entirely blank that matches the resolution of the screen'''
return Image.new(self.mode, self.resolution, 255)



'''return a PIL image that is entirely blank that matches the resolution of the screen'''
return Image.new('1', self.resolution, 0xff)

@property
def mode(self):
'''determine the internal color mode, depending on the screen type'''
if self.screen_type == ScreenType.HD or self.screen_type == ScreenType.FOUR_GRAYS:
return 'L' # grayscale
if self.screen_type == ScreenType.SEVEN_COLORS:
return 'RGB'
return '1' # monochrome


@_spi_handler
def clearEPD(self):
'''wipe epd screen entirely'''
Expand Down Expand Up @@ -638,19 +665,22 @@ def _full_writeEPD_hd(self, image):

def _full_writeEPD_non_hd(self, image):
'''wipe screen and write an image'''
image_buffer = self.epd.getbuffer(image)

if self.screen_type == ScreenType.FOUR_GRAYS:
image_buffer = self.epd.getbuffer_4Gray(image)
else:
image_buffer = self.epd.getbuffer(image)

try:
if self.one_bit_display: # one bit displays
if self.screen_type == ScreenType.FOUR_GRAYS:
logging.debug('one-bit display')
self.epd.display(image_buffer)
elif self.one_bit_display == False and self.mode != '1': # 7 color displays
logging.debug('seven-color display')
self.epd.display(image_buffer)
else: # bi-color displays that require multiple images
self.epd.display_4Gray(image_buffer)
elif self.screen_type == ScreenType.THREE_COLORS: # displays that require multiple images
logging.debug('bi-color display')
self.epd.display(image_buffer, self.buffer_no_image)

else: # 7 color displays
logging.debug('seven-color or monochrome display')
self.epd.display(image_buffer)

except Exception as e:
raise ScreenError(f'failed to write image to display: {e}')

Expand Down

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