EpdLib is a library for creating dynamically scaled screen layouts for frame-buffered devices such as e-paper/e-ink displays.
Project description
epdlib v0.5
EpdLib is a library for creating dynamically scaled screen layouts for frame-buffered devices such as e-paper/e-ink displays. Complex layouts are defined as image, drawing or text blocks. Using epdlib blocks makes it trivial to develop for different disiplay resolutions as layouts are aware of thier resolution and scale the blocks dynamically to match the available area.
Changes
See the ChangeLog for details
v0.5
- Add support for Block type "DrawBlock"
- Add support for adding borders to all Block types
v0.4
- Add support for IT8951 panels with 8bit gray scale and partial refresh
- Assigning EPD object to screen has changed from directy assignment to using a the string that corresponds to the name.
Dependencies
Python Modules:
- Pillow
- System dependencies for Pillow:
- libopenjp2-7
- libtiff5
- System dependencies for Pillow:
- RPi.GPIO
- spidev
- ensure SPI is enabled on the pi
- waveshare-epd (Non IT8951 based panels)
- this is for interacting with waveshare epaper displays and is not strictly needed to use the Block and Layout objects.
- see notes below for installation instructions
- IT8951 (IT8951 based panels)
- see notes below for installation instructions
Modules:
- Block - image and text blocks that can be assembed into a final layout
- Layout - generate dynamic layouts from Blocks
- Screen - simple interface for waking and writing to WaveShare EPD devices
Block Module
Block
objects are containers for text and images. Block
objects are aware of their dimensions and can be made aware of their position within a larger layout. Block
objects can also handle wrapping text and resizing images to fit within their borders.
Class Block(area, hcenter=False, vcenter=False, rand=False, inverse=False, abs_coordinates=(0, 0), padding=0, border_config={})
Properties
Parent class for other types of blocks
Args [default value]:
area
(list/tuple): x and y integer values for dimensions of block areahcenter
(bool): True: horizontally center contents [False]vcenter
(bool): True: vertically center contents [False]rand
(bool): True: randomly place contents in area [False]inverse
(bool): True: invert pixel values [False]abs_coordinates
(list/tuple): x, y integer coordinates of this block area within a larger image [(0, 0)]padding
(int): number of pixels to pad around edge of contents [0]fill
(int): 0-255 8 bit value for fill color for text/images [0 black]bkground
(int): 0-255 8 bit value for background color [255 white]mode
(str): '1': 1 bit color, 'L': 8 bit grayscale ['1']border_config
(dict): dictonary containing kwargs configuration for adding border to image see help(add_border)
Properties:
image
: None - overridden in child classes'''
Methods
update(update)
Place holder method for child classes.
Functions
Function add_border(img, fill, width, outline=None, outline_width=1, sides=['all'])
add a border around an image
Args:
img
(PIL.Image): image to add border tofill
(int): border fill color 0..255 8bit gray shadewidth
(int): number of pixels to use for borderoutline
(int): 0..255 8bit gray shade for outline of border regionoutline_width
(int): width in pixels of outlinesides
(list of str): sides to add border: "all", "left", "right", "bottom", "top"
Returns: PIL.Image
Block.DrawBlock
Child class of Block
that contains pillow.ImageDraw
drawing objects. DrawBlock
objects can contain ellipses, rounded_rectangles or rectangles. These are useful for creating horizontal and vertical rules and separators. DrawBlock objects can be aligned horizontally ('center', 'left', 'right' or vertically ('center', 'top', 'bottom') within the block area.
Class Block.DrawBlock(area, *args, shape=None, abs_x=None, abs_y=None, scale_x=1, scale_y=1, halign='center', valign='center', draw_format={}, no_clip=True, **kwargs)
DrawBlock
objects that are fully initizlized with area
and shape
will automatically generate an image. No further updates are necessary. When using DrawBlock
in a Layout
layout, it is not necessary to send an update when the block is refreshed unless the properties have been changed. The generated image will remain in memory until the program is termindated.
Properties
area
(tuple of int): area of block in pixelsshape
(str): shape to draw (see DrawBlock.list_shapes())abs_x
(int): absolute x dimension in pixels of drawing (overrides scale_x)abs_y
(int): absolute y dimension in pixels of drawing (overrides scale_y)scale_x
(float): percentage of total x area (0..1) (abs_x overrides)scale_y
(float): percentage of total y area (0..1) (abs_y overrides)halign
(str): horizontal alignment of drawing; 'center', 'left', 'right'valign
(str): vertical alignment of drawing; 'center', 'top', 'bottom'draw_format
(dict): dict of kwargs for shape drawing functionno_clip
(bool): when True fit shapes completely within areaimage
(PIL:Image): rendered shape
Methods
list_shapes()
: list supported shapes that can be drawn -- Static Methoddraw_help()
: print help docstring for the currentshape
update(update=True)
: whenTrue
update the image. This is only necessary if the object properties have been changed or the object was not created with ashape
valuedraw_image()
: update the image
Block.TextBlock
Child class of Block
that contains formatted text. TextBlock
objects can do basic formatting of strings. Text is always rendered as a 1 bit image (black on white or white on black). Text can be horizontally justified and centered and vertically centered within the area of the block.
All properties of the parent class are inherited.
Class Block.TextBlock(font, area, text='NONE', font_size=0, max_lines=1, maxchar=None, chardist=None)
TextBlock
objects will attempt to calculate the appropriate number of characters to render on each line given an area, font face and character distribution. Each font face renders characters at a different width and each TTF character uses a different X width (excluding fixed-width fonts). Each language favors certain characters over others.
Properties
font
(str): path to TTF font face - relative paths are acceptablearea
(2-tuple of int): area of block in pixles - requiredtext
(str): string to format- Default: 'NONE'
font_size
(int): font size in points- Default: 0
max_lines
(int): maximum number of lines to use when wrapping text- Default: 1
maxchar
(int): maximum number of characters to fit on a line- if set to
None
, the text block will calculate this value based on the font face and specifiedchardist
- Default: None
- if set to
chardist
(dict): statistical character distribution for a supported language to use for a specified font- dictionary of letter and float representing fractional distribution (see
print_chardist
)
- dictionary of letter and float representing fractional distribution (see
image
(PIL.Image): resultant image generated of formatted textalign
(str): 'left', 'right', 'center' justify text (default: left)
Functions
print_chardist(chardist=None)
- print supported character distrubtions- chardist (str)
chardist='USA_CHARDIST'
print the character distribution for USA English
- chardist (str)
Methods
update(update=None)
- Update the text string with a new string and setsimage
property- update (str)
Block.ImageBlock
Child class of Block
that contains formated images. ImageBlock
objects do basic formatting of color, centering and scaling. All ImageBlock
images are 8 bit grayscale Pillow.Image(mode='L')
. Images that are too large for the area are rescaled using the Pillow.Image.thumbnail()
strageies to limit distortion. Images that are smaller than the set area will not be resized.
All properties of the parent class are inherited.
Class Block.ImageBlock(area, image=None)
Properties
image
(:obj:PIL.Image or :obj:str) -Pillow
image or path provided as astr
to an image file; relative paths are acceptableremove_alpha(bool)
: true: remove alpha chanel of PNG or similar files; see: https://stackoverflow.com/a/35859141/5530152
Methods
update(update=None)
- Update the image with a new image and setsimage
property- update(image)
remove_transparency(im, bg_colour=(255, 255, 255))
- Static method for removing transparency from PNG and similar images- im(PIL image)
- bg_color(background) color to replace alpha/transparenncy
Layout Module
Layout
objects support scaling images and dynamically scaling TTF font-size for different screen sizes.
Font sizes are set based on each individual font and scaled to fit within text blocks using the maximum number of lines specified in the layout. Text is line-broken using the python textwrap logic.
Class Layout(resolution, layout=None, force_onebit=False)
Scaling Example
epdlib Layout
objects can be scaled to any (reasonable) resolution while maintaining internally consistent ratios.
500x500 Layout
300x200 Layout
Properties
resolution
(2-tuple of int): resolution of the entire screen in pixleslayout
(dict): dictionary containing layout paramaters for each block- see example below in Quick-Start Recipe
image
(Pil.Image): concatination of all blocks into single imageforce_onebit
(bool): force all blocks within a layout tomode='1'
Methods
concat()
: join all blocks into a single image- sets
image
property
- sets
update_contents(updates=None)
- update the contents of each block- updates (dict)
- dictionary in the format
{'text_section': 'text to use', 'image_section': '/path/to/img', 'pil_img_section': PIL.Image}
- dictionary in the format
- updates (dict)
Screen Module
Screen
objects provide a method for waking and writing to a WaveShare E-Paper Display (EPD). Screen
objects are aware of their resolution and when they were last updated (stored in monotonic time).
Class Screen(resolution=None, epd=None)
Properties
resolution
(2 tuple of int): resolution in pixels- this is overriden by the epd object resolution when it is set
epd
(epd object)- waveshare epd object used for interfacing with the display
update
(obj:Screen.Update): monotonicly aware object that tracks time since last updaterotation
(int): [-90, 0, 90, 180, 270] rotation of screen see note belowmode
(str): '1' for 1 bit screens, 'L' for screens capable of 8 bit grayscalevcom
(float): vcom voltage for HD IT8951 based screens (not needed & ignored for non-HD screens)
NOTE
Screens with cable along long edge
Rotation = 0
┌───────────────┐
│ (__) │
│ `\------(oo) │
│ || (__) │
│ ||w--|| │
└─────┬───┬─────┘
│|||│
Rotation = 180
│|||│
┌─────┴───┴─────┐
│ (__) │
│ `\------(oo) │
│ || (__) │
│ ||w--|| │
└───────────────┘
Screens with cable along short edge
Rotation = 0
┌───────────────┐
│ (__) ├──
│ `\------(oo) │--
│ || (__) │--
│ ||w--|| ├──
└───────────────┘
Rotation = 180
┌───────────────┐
──┤ (__) │
--│ `\------(oo) │
--│ || (__) │
──┤ ||w--|| │
└───────────────┘
Methods
clearScreen()
: Set a blank image screenclearEPD()
: send the clear signal to the EPD to wipe all contents and set to "white"writeEPD(image, sleep=True, partial=False)
: writeimage
to the EPD.- resets update timer
- sleep: put the display to low power mode (default: True)
- partial: update only chaged portions of the screen (faster, but only works with black and white pixles) (default: False)
intiEPD()
- initializes the EPD for writingblank_image():
produces a blank PIL.Image in ofmode
type ofresolution
dimensionslist_compatible_modules()
: print a list of all waveshare_epd panels that are compatible with paperpi
Example
import Screen
import waveshare_epd
myScreen = Screen()
myScreen.epd = "epd5in83"
myScreen.initEPD()
myScreen.writeEPD('./my_image.png')
Screen.Update
Create a monotonically aware object that records the passage of time.
Class Screen.Update()
Properties
age
(float): age in seconds since creationnow
(float): time in CLOCK_MONOTONIC timelast_updated
(float): time in seconds since last updatedupdate
(bool): True - trigger resets last_updated time
Methods
update(update=True)
- reset last_updated timer to zero
Example
import Screen
u = Update()
u.now
>>> 357147.118559987
u.age
>>> 37.449310125026386
u.last_updated
>>> 62.2587232599617
u.update = True
u.last_updated
>>> 0.00021347898291423917
Screen.ScreenShot
Capture a rolling set of screenshots. When the total number of screenshots exceeds n
the oldest is deleted. Images are stored as .png.
This is useful for debugging over time.
Class Screen.ScreenShot(path='./', n=2, prefix=None)
Properties
total
(int): total number of screenshots to keepprefix
(str): prefix to add to filenamestime
(str): time in format: %y-%m-%d_%H%M.%S - 2020-02-29_1456.39img_array
(list): list of files stored inpath
Methods
delete(img)
: deleteimg
filesave(img)
: saveimg
topath
- img: PIL.Image
import Screen
scrnShot = Screen.ScreenShot(path='/temp/', n=20)
spam = PIL.Image.new(mode='L', size=(100, 100), color=0)
scrnShot.save(spam)
Quick-Start Recipes
Quick Demo
The demo creates a very basic layout and displays some text in four orientations. This is an easy way to test your panel and confirm that it is working properly.
python3 -m epdlib.Screen
Creating an Image from a Layout
The following recipe will produce the a layout for a 500x300 pixel display. This image can be passed directly to a WaveShare e-Paper display for writing.
## Sample Layout ##
import epdlib
# create the layout object - adjust the resolution to match the display area
layout_obj = epdlib.Layout(resolution=(500, 300))
l = { # basic two row layout
'tux_img': {
'type': 'ImageBlock', # required as of v0.6
'image': True, # image block
'padding': 10, # pixels to padd around edge
'width': .25, # 1/4 of the entire width
'height': 1/4, # 1/4 of the entire height
'abs_coordinates': (0, 0), # this block is the key block that all other blocks will be defined in terms of
'hcenter': True, # horizontally center image
'vcenter': True, # vertically center image
'relative': False, # this block is not relative to any other. It has an ABSOLUTE position (0, 0)
'mode': 'L', # treat this image as an 8bit gray-scale image
},
'vertical_rule_1' :{
'type': 'DrawBlock', # required as of v0.6
'shape': 'rounded_rectangle',# shape to draw
'abs_x': 5, # absolute x dimension of shape in pixels
'scale_y': .8, # scale shape so it is 80% of available area
'halign': 'center', # horizontally center in area
'valign': 'center', # vertically center in area
'draw_format': {'radius': 5, # any key word args (kwargs) needed for formatting the shpae
'outline': 128,
'width': 2},
'height': 1/4,
'width': .02,
'abs_coordinates': (None, 0), # x value will be calculated from the 'tux_image' block, the y value is "0"
'relative': ['tux_img', 'vertical_rule_1'] # use 'tux_image' X value, use 'vertical_rule_1' for Y value
},
'pangram_a': {
'type': 'TextBlock', # required as ov v0.6
'image': None, # set to None if this is a text block
'max_lines': 3, # maximum lines of text to use when wrapping text
'padding': 10, # padding around all edges (in pixles)
'width': .73, # proportion of the entire width
'height': 1/4, # proprtion of the entire height
'abs_coordinates': (None, 0), # absolute coordinates within the final image (use None for those
# coordinates that are relative to other blocks and will be calculated
'hcenter': False, # horizontal-center the text and the resulting image
'vcenter': True, # vertically-center the text within the block
'relative': ['vertical_rule_1', 'pangram_a'], # blocks to which THIS block's coordinates are relative to
# -- in this case X: `weather_img` and Y: `temperature`
# the width of the block `weather` will be used to
# to calculate the X value of this block and the Y value
# specified within the `temperature` block will be used
'font': './fonts/Open_Sans/OpenSans-Regular.ttf', # TTF Font face to use; relative paths are OK
'font_size': None, # set this to None to automatically scale the font to the size of the block
'mode': 'L' # set text blocks to "mode": L" to enable anti-aliasing on HD screens (automatically disabled on non HD)
},
'pangram_b': {
'type': 'TextBlock',
'image': None,
'max_lines': 3,
'padding': 8,
'width': 1,
'height': 1/4,
'abs_coordinates': (0, None),
'hcenter': True,
'vcenter': True,
'relative': ['pangram_b', 'tux_img'],
'font': './fonts/Open_Sans/OpenSans-Regular.ttf',
'font_size': None,
'inverse': False,
'mode': 'L',
'border_config': {'fill': 0, # add a border to the top and bottom of this text block
'width': 3,
'sides': ['top', 'bottom']}
},
'pangram_c': {
'type': 'TextBlock',
'image': None,
'max_lines': 2,
'padding': 0,
'width': 1,
'height': 1/4,
'abs_coordinates': (0, None),
'hcenter': True,
'vcenter': True,
'relative': ['pangram_c', 'pangram_b'],
'font': './fonts/Open_Sans/OpenSans-BoldItalic.ttf',
'font_size': None,
'inverse': False,
'mode': 'L'
},
'text': {
'type': 'TextBlock',
'image': None,
'max_lines': 4,
'padding': 10,
'width': 1,
'height': 1/4,
'abs_coordinates': (0, None),
'hcenter': True,
'vcenter': True,
'relative': ['text', 'pangram_c'],
'font': './fonts/Open_Sans/OpenSans-Regular.ttf',
'font_size': None,
'inverse': True
}
}
# apply the layout instructions to the layout object
layout_obj.layout = l
# create a dictionary with the values that will be pushed to each block
# note that is is not necessary to update the DrawBlocks if they are fully configured
update = {
'tux_img': './images/tux.png',
'pangram_a': 'The quick brown fox jumps over the lazy dog.',
'pangram_b': 'Pack my box with five jugs of liquor. This block has a top & bottom border',
'pangram_c': 'Jackdaws love my big sphinx of quartz.',
'text': 'A pangram or holoalphabetic sentence is a sentence using every letter of a given alphabet at least once. This text is not anti-aliased.'}
# update the layout with the data in the dictionary and send each item to the proper block
layout_obj.update_contents(update)
# join all the sub images into one complete image
myImg = layout_obj.concat()
# write the image out to a file
myImg.save('sample.jpg')
Write an image to a Screen
The following code will create an interface for writing images to the EPD Requirements
- Waveshare EPD module or IT8951 library (see Notes below)
from epdlib import Screen
from PIL import Image
## non IT8951 screens
my_epd = "epd2in7"
my_vcom = None
## IT8951 screens
# my_epd = "HD"
# my_vcom = -1.8
# create screen object
my_screen = Screen(epd=my_epd, vcom=my_vcom)
my_resolution = my_screen.resolution
# open image, convert to 1 bit and scale
my_img = Image.open('path/to/image.jpg')
my_img = my_img.convert("1")
my_img.thumbail(my_resolution)
# write image to screen
my_screen.writeEPD(my_img)
# clear screen
my_screen.clearEPD()
Notes
WaveShare non-IT8951 Screens The waveshare-epd library is required for non-IT8951 screens and can be installed from the Git repo:
pip install -e "git+https://github.com/waveshare/e-Paper.git#egg=waveshare_epd&subdirectory=RaspberryPi_JetsonNano/python"
IT8951 basee Screens The Broadcom BCM 2835 library is required by the IT8951 module. Download and install the BCM2835 library according to the directions found on Mike McCauley's site
Greg D Meyer's IT8951 library is also required and can be installed from the Git repo:
pip install -e "git+https://github.com/GregDMeyer/IT8951#egg=IT8951"
getting ready for pypi: https://medium.com/@joel.barmettler/how-to-upload-your-python-package-to-pypi-65edc5fe9c56
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