drawutils.py

#!/usr/bin/env python
'''
These are some helper routines I wrote for drawing images for a dual-color
128x64 OLED display. The display has a 16-row strip of cyan pixels along the
top, followed by an unaddressable strip of black which is 2 pixels in height,
then the remaining 48 rows are yellow.

https://www.amazon.com/gp/product/B00O2LLT30/

To make it easier to keep drawings in the correct aspect ratio, I preferred to
just draw a 128x66 image and then slice out the black strip before outputting
to the display. The `prepare()` function does this for you.

If you would like to see a rendering of what the image will look like with the
display's colors, use `render()`.

You can use the Adafruit_SSD1306 module to actually send the image to the
display.

https://github.com/adafruit/Adafruit_Python_SSD1306
'''


from PIL import Image, ImageDraw, ImageFont


WHITE = 255
YELLOW = (246, 236, 110)
CYAN = (150, 236, 255)

WIDTH = 128
HEIGHT = 64
GAP_Y = 16
GAP_HEIGHT = 2


def demo_image():
  # Adapted from the Adafruit 'shapes.py' sample code by Tony DiCola
  image = Image.new('1', (WIDTH, HEIGHT+GAP_HEIGHT))
  draw = ImageDraw.Draw(image)
  
  # First define some constants to allow easy resizing of shapes.
  padding = 2
  shape_width = 20
  top = padding
  bottom = HEIGHT+GAP_HEIGHT-padding
  x = padding
  
  # Draw an ellipse
  draw.ellipse((x, top , x+shape_width, bottom), outline=WHITE)
  x += shape_width+padding
  
  # Draw a rectangle
  draw.rectangle((x, top, x+shape_width, bottom), outline=WHITE)
  x += shape_width+padding
  
  # Draw a triangle
  draw.polygon([(x, bottom), (x+shape_width/2, top), (x+shape_width, bottom)],
               outline=WHITE)
  x += shape_width+padding
  
  # Draw an X
  draw.line((x, bottom, x+shape_width, top), fill=WHITE)
  draw.line((x, top, x+shape_width, bottom), fill=WHITE)
  x += shape_width+padding

  # Write some text
  font = ImageFont.load_default()
  draw.text((x, top),    'Hello',  font=font, fill=WHITE)
  draw.text((x, top+20), 'World!', font=font, fill=WHITE)
  return image

def create_bg():
  bg = Image.new('RGB', (WIDTH, HEIGHT+GAP_HEIGHT))
  draw = ImageDraw.Draw(bg)
  draw.rectangle((0, 0, WIDTH, GAP_Y-1), fill=YELLOW)
  draw.rectangle((0, GAP_Y+GAP_HEIGHT, WIDTH, HEIGHT+GAP_HEIGHT), fill=CYAN)
  return bg

def render(image):
  rendered = Image.new('RGB', (WIDTH, HEIGHT+GAP_HEIGHT))
  rendered.paste(create_bg(), image)
  return rendered

def prepare(image):
  output = Image.new('1', (WIDTH, HEIGHT))
  draw = ImageDraw.Draw(output)
  draw.rectangle((0, 0, WIDTH, HEIGHT), fill=WHITE)
  output.paste(image.crop((0, 0, WIDTH, GAP_Y)), (0, 0))
  output.paste(image.crop((0, GAP_Y+GAP_HEIGHT, WIDTH, HEIGHT+GAP_HEIGHT)),
                          (0, GAP_Y))
  return output

if __name__ == '__main__':
  render(demo_image()).show()