Skip to content

Latest commit

 

History

History
172 lines (122 loc) · 5.55 KB

REFERENCE.md

File metadata and controls

172 lines (122 loc) · 5.55 KB
Raw

Scroll pHAT HD Function Reference

Scroll pHAT HD uses white LEDs which can be brightness controlled. Note that when you set a pixel it will not immediately display on Scroll pHAT HD, you must call scrollphathd.show().

Set A Single Pixel In Buffer

scrollphathd.set_pixel(x, y, brightness)

Parameters:
x – Position of pixel from left of buffer
y – Position of pixel from top of buffer
brightness – Intensity of the pixel, from 0.0 to 1.0 or 0 to 255

Write A Text String

scrollphathd.write_string(string, x=0, y=0, font=None, letter_spacing=1, brightness=1.0)

Parameters:
string – The string to display
x – Offset x - distance of the string from the left of the buffer
y – Offset y - distance of the string from the top of the buffer
font – Font to use, default is to use the one specified with set_font
brightness – Brightness of the pixels that compromise the text, from 0.0 to 1.0

Draw A Single Char

scrollphathd.draw_char(x, y, char, font=None, brightness=1.0)

Parameters:
x – Offset x - distance of the char from the left of the buffer
y – Offset y - distance of the char from the top of the buffer
char – Char to display- either an integer ordinal or a single letter
font – Font to use, default is to use one specified with set_font
brightness – Brightness of the pixels that compromise the char, from 0.0 to 1.0

Display A Graph

scrollphathd.set_graph(values, low=None, high=None, brightness=1.0, x=0, y=0, width=None, height=None)

Parameters:
values – A list of numerical values to display
low – The lowest possible value (default min(values))
high – The highest possible value (default max(values))
brightness – Maximum graph brightness (from 0.0 to 1.0)
x – x position of graph in display buffer (default 0)
y – y position of graph in display buffer (default 0)
width – width of graph in display buffer (default 17)
height – height of graph in display buffer (default 7)
Returns: None

Fill An Area

scrollphathd.fill(brightness, x=0, y=0, width=0, height=0)

Parameters:
brightness – Brightness of pixels
x – Offset x - distance of the area from the left of the buffer
y – Offset y - distance of the area from the top of the buffer
width – Width of the area (default is 17)
height – Height of the area (default is 7)

Clear An Area

scrollphathd.clear_rect(x, y, width, height)

Parameters:
x – Offset x - distance of the area from the left of the buffer
y – Offset y - distance of the area from the top of the buffer
width – Width of the area (default is 17)
height – Height of the area (default is 7)

Display Buffer

All of your changes to Scroll pHAT HD are stored in a Python buffer. To display them on Scroll pHAT HD you must call scrollphthd.show().

scrollphathd.show()

The buffer is copied, then scrolling, rotation and flip y/x transforms applied before taking a 17x7 slice and displaying.

Clear Buffer

scrollphathd.clear()

You must call show after clearing the buffer to update the display.

Scroll The Buffer

scrollphathd.scroll(x=0, y=0)

Scroll pHAT HD displays an 17x7 pixel window into the buffer, which starts at the left offset and wraps around. The x and y values are added to the internal scroll offset. If called with no arguments, a horizontal right to left scroll is used.

Parameters:
x – Amount to scroll on x-axis
y – Amount to scroll on y-axis

Scroll To A Position

scrollphathd.scroll_to(x=0, y=0)

Scroll pHAT HD displays a 17x7 pixel window into the buffer, which starts at the left offset and wraps around. The x and y values set the internal scroll offset. If called with no arguments, the scroll offset is reset to 0,0

Parameters:
x – Position to scroll to on x-axis
y – Position to scroll to on y-axis

Rotate The Display

scrollphathd.rotate(degrees=0)

Parameters: degrees – Amount to rotate- will snap to the nearest 90 degrees

Flip The Display

scrollphathd.flip(x=False, y=False)

Parameters:
x – Flip horizontally left to right
y – Flip vertically up to down

Run a http API

flask must be installed before the api bluerint can be imported. To build up a flask api using the blueprint you can use the following and add your own blueprints to the api as you choose:

from scrollphathd.api.http import scrollphathd_blueprint
from flask import Flask


app = Flask(__name__)
app.register_blueprint(scrollphathd_blueprint, url_prefix='/scrollphathd')
app.run()

Alternatively, with the module installed you should be able to run python -m scrollphathd.api.http and optionally supply -p|--port and -H|--host which will start the same api as described above.

Both options will start a http flask server with the endpoints:

  • /scrollphathd/show - post {"text": "helloworld"} with the content type of the post request set to application/json
  • /scrollphathd/clear - post to clear the screen
  • /scrollphathd/scroll - post {"x": 1,"y": 1} to move it 1 in each direction. Content type must be set to application/json
  • /scrollphathd/flip - post {"x": "true||false", "y": "true||false"} to flip either, both or none of the directions.

If any data is formatted incorrectly, the blueprint api will respond with 422 (unprocessable entity) with a JSON response containing an indication of how the data was unprocessable, in the format {"error": <string>}.

If all was ok, you'll get a 200 response with no data.