PyDevices

Cross-platform User Interface and Event Drivers for *Python

About • Key Features • Getting Started • Running Your First App • API • Roadmap • Contributing • Thanks • Screenshots

@peterhinch's active.py	@russhughes's tiny_toasters.py

About

WARNINGS: PyDevices is currently alpha quality. Every effort has been made to test on as many platforms as possible, but I need your help and feedback to get it to its inital release. A lot has changed and I am working on catching up the documentation. I am in the process of renaming it from MPDisplay to PyDevices.

PyDevices is a universal display, event and device driver framework for multiple flavors of Python, including MicroPython, CircuitPython and CPython (big Python). It may be used as-is to create graphic frontends to your apps, or may be used as a foundation with GUI libraries such as LVGL, MicroPython-touch or maybe even a GUI framework you've been thinking of developing. Its primary purpose is to provide display and touch drivers for MicroPython, but it is equally useful for developers who may never touch MicroPython.

It is important to note that PyDevices is meant to be a foundation for GUI libraries and is not itself a GUI library. It doesn't provide widgets, such as buttons, checkboxes or sliders, and it doesn't provide a timing mechanism. You will need a GUI library to provide those if necessary, although many apps won't need them. (There is a cross-platform repository timer you can use if you want to used scheduled interrupts. It works with CPython and MicroPython, but doesn't work with CircuitPython. You can also use asyncio for timing.)

Key Features

• May be used without additional libraries to add graphics capabilities to MicroPython, CircuitPython and CPython, with a consistent API across them all.
• Enables moving from one platform to another, for example MicroPython on ESP32-S3 to CPython on Windows without changing your code. Do your graphics development on your desktop, laptop or ChromeBook and then move to a microcontroller when you are ready to interface with your sensors and devices. CPython has much better error messages than MicroPython making it easier to troubleshoot when things go wrong!
• Built around devices available on microcontrollers but not necessarily available on desktop operating systems. For instance, rotary encoders and mouse scroll wheels show up as the same device type and yield the same events. Touchscreens on microcontrollers yield the same events as mice on desktops. Likewise with keypads / keyboards.
• Easily extensible. Use the primitives provided by PyDevices and add your own libraries, classes and functions to have even greater functionality.
• Provides several built-in color palettes and a mechanism to generate your own palettes.
• Lots of examples included, whether developed specifically for PyDevices or ported from Russ Hughes's st7789py_mpy. Also works with all of the examples from Peter Hinch's MicroPython GUI libraries MicroPython-Touch and Nano-GUI on MicroPython.
• Support MicroPython on microcontrollers and on Unix(-like) operating systems.
• On MicroPython, can be configured to work with kdschlosser's lvgl_micropython bus drivers, which are very fast bus drivers written in C.
• Works with CircuitPython's FourWire and ParallelBus bus drivers, as well as FrameBufferDisplay based interfaces such as dotclockframebuffer, usb_video and rgbmatrix

Getting Started

This section is under construction. For now, see Getting Started for more information.

Running your first app

You will need to import the path.py file before running any of the examples.

On desktop operating systems, cd into the mp directory (or wherever you have the files staged) and type:

python3 -i path.py

or

micropython -i path.py

On microcontrollers, either add the following to your boot.py (MicroPython) or code.py (CircuitPython), or simply import it at the REPL before importing your desired app:

import path

The examples directory will be on the system path, so to run an app from it, you just need to type:

import calculator  # substitute `calculator` with the file OR directory you want to run, omitting the .py extension

To run any of the examples from MicroPython-Touch (remember, its for MicroPython only) type:

import gui.demos.various  # substitute `various` with the file you want to run, omitting the .py extension

API

Where possible, existing, proven APIs were used.

• There are currently 5 display classes, and hopefully another EPaperDisplay display class will be added soon, although I will need help from the community for this.
  • BusDisplay is for microcontrollers, both on MicroPython and CircuitPython. CircuitPython provides the required bus drivers, as mentioned elsewhere in this README, but MicroPython doesn't have display bus drivers. The buses packages are included with the installer. It is my hope that community members will create other C bus drivers similar to @kdschlosser's bus drivers in lvgl_micropython.
  • DTDisplay is a superclass containing:
    • SDL2Display - the preferred class for desktop operating systems as it is faster than PGDisplay. It uses an SDL texture in place of an LCD's Graphics RAM (GRAM).
    • PGDisplay - an optional class for desktop operating systems. It uses a pygame surface in place of an LCD's GRAM. It can be benificial in a couple of instances:
      • SDL2Display "glitches" on my ChromeBook, but PGDisplay doesn't
      • On Windows, it is easier to install PyGame than SDL2
  • FBDisplay works with CircuitPython framebufferio.FramebufferDisplay objects, such as dotclockframebuffer (RGB displays), usb_video and rgbmatrix. (usb_video may be the coolest thing you can do with PyDevices, although I'm not sure how practical or useful it is. It allows your board to function as a webcam, even without a camera, and to render the display through USB to any application on your host PC that can open a webcam! My Windows machine sees it as an unsupported device, so it will not work, but it does work on my ChromeBook. Currently it is limited to RP2040 only and is hardcoded to a 128 x 96 resolution, but that likely will change. See the screen capture and the board_config.py for more details.)
  • JNDisplay for Jupyter Notebooks. No input devices are currently supported.
  • PSDisplay for PyScript. Only touchscreens are currently supported.
• Names of Events and Devices in eventsys are taken from PyGame and/or SDL2 to keep the API consistent.
• All drawing targets, sometimes referred to as canvas in the code, may be written to using the API from MicroPython's framebuf.FrameBuffer API (except .blit())
  • CPython and CircuitPython don't have a framebuf module that is API compliant with MicroPython's framebuf, so framebuf.py has been modified from Adafruit CircuitPython framebuf and is provided for those platforms. It is not used in MicroPython.
  • A framebuf_plus module is provided that subclasses FrameBuffer (either built-in or from framebuf.py) and provides additional drawing tools, such as round_rect. All methods in framebuf_plus return an Area object with x, y, w and h attributes describing a bounding box of what was changed. This can be used by applications to only update the part of the display that needs it. That functionality is implemented in DisplayBuffer and will likely be required by EPaperDisplay when it is implemented.
  • Canvases include, but are not limited to, the display itself, framebuf bytearrays, bmp565 (16-bit Windows Bitmap files) and displaybuf.DisplayBuffer objects.
  • displaybuf.DisplayBuffer implements @peterhinch's API that represents the full display as a framebuffer and allows for 4-, 8- and 16-bit bytearrays while still drawing to the screen as 16-bit. It is required for MicroPython-Touch and is very useful outside of that library as well, especially when memory is constrained.
• Display drivers for MicroPython BusDisplay use the constructor API of CircuitPython's DisplayIO drivers. This includes rotation = 0, 90, 180, 270 instead of 0, 1, 2, 3.
• BusDisplay can communicate with the underlying bus driver using either CircuitPython's DisplayIO method calls or @kdschlosser's [lvgl_micropython] method calls.
• There are 3 primary mechanism's for fonts: the binfont.BinFont class, tft_text.text() and tft_write.write() methods. All 3 of these return an Area object as mentioned earlier. A fourth font mechanism called EZFont is included in the utils folder, but it doesn't return an Area object, which is why it isn't in the lib folder.
  • BinFont is derived from Tony DiCola's 5x7 font class and reads 8x8, 8x14 and 8x16 .bin files from @spaceraces romfont repo
  • .text() is written by @russhughes and uses fonts generated by his text_font_converter It reads 8 and 16bit wide fonts in heights that are multiples of 8.
  • .write() is written by @russhughes and uses fonts generated by his write_font_converter
  • EZFont is a subclass of @easytarget's microPyEZfonts which uses fonts generated from @peterhinch's font-to-py.
  • NOTE: @peterhinch's Writer class is inlcuded in MicroPyton-Touch and may be used on MicroPython platforms, but, like EZFont, it doesn't return an Area object.
• Graphics files may be used by 3 mechanisms:
  • bmp565.BM565 is a class that can read and write Windows Bitmap files saved with RGB565 color encoding. GIMP supports exporting RGB565 .BMPs. The BMP565 class can open a file and read it's entire contents into memory, or with the streamed = True flag, it will only read the slice requested, allowing progressive rendering of files much too large to fit into memory. The slice can be 2 dimensional (BMP565[1:5, 6:10] gets pixels 1 through 5 on rows 6 through 10) or 1 dimensional (BMP565[6:10] gets all pixels in rows 6 through 10). This slicing mechanism is very useful when rendering sprites. It can reverse the order of pixels in a row with mirrored = False, which is needed when rendering a background image when rotation is 90 or 270 and (horizontal) scrolling is desired. Finally, it can use an existing bytearray as its buffer instead of reading from a file, which allows saving screenshots from existing canvases such as a FrameBuffer or DisplayBuffer.
  • .bitmap() is written by @russhughes and reads .py graphics files encoded with his image_converter.py utiliity or his sprite_converter.py utility. It renders the entire image to a buffer, and then copies that buffer to the display.
  • .pbitmap() is also written by @russhughes and renders the same fonts as .bitmap(), but it does it progressively, one line at a time using a one line buffer.
• Config files - All files that are intended for you to edit to customize your configuration are in the configs directory. They are:
  • board_config.py - required in all circumstances. Feel free to add your own setup code here, such as for real-time clocks, wifi, sensors, etc.
  • path.py - required in all circumstances
  • color_setup.py - required for Nano-GUI
  • hardware_setup.py - required for MicroPython-Touch
  • lv_config.py - required for LVGL
  • tft_config.py - required for @russhughes's examples. I had to do some search and replace to get those examples to work.

Roadmap

• Much more documentation on Github
• Document the files to produce output for ReadTheDocs
• Implement EPaperDisplay
• Optimize with more Numpy and Viper code
• Decrease the memory footprint where possible
• Test with frozen modules
• On MicroPython on Unix, the screen gets cleared when the display is rotated. Microcontroller displays don't do this. It's not an issue unless you want to draw to the display, rotate it, then draw more on top. This functionality allow drawing text in all four 90 degree orientations.
• Scrolling vertically on desktop operating sytems works correctly, but not when rotated. When rotated, it show scroll horizontally, but continues to scroll vertically.
• Scrolling on microcontrollers has issues when trying to write spanning the cutoff line. For instance, if drawing a 16 pixel high image at the 8th line from the cutoff line, the bottom 8 lines don't end up where you expect. See the bmp565_sprite example.
• Ensure multiple displays work at the same time
• Implement color depths other than 16 bit
• Add a Joystick class to eventsys
• Test with CircuitPython Blinka on SBC's such as Raspberry Pi 4
• Need C bus drivers from the community, especially for STM32H7 and MIMXRT

Contributing

This is a community project and I need your help! If you have a suggestion that would make this better, please fork the repo and create a pull request. Don't forget to give the project a star! Thanks again!

1. Fork the project
2. Clone it open the repository in command line
3. Create your feature branch (git checkout -b feature/amazing-feature)
4. Commit your changes (git commit -m 'Add some amazing feature')
5. Push to the branch (git push origin feature/amazing-feature)
6. Open a pull request from your feature branch from your repository into this repository main branch, and provide a description of your changes

Thanks

I very much appreciate @peterhinch, @russhughes and the team at Adafruit for their contributions to the Python on microcontrollers community.

Why

I started out just wanting to create drivers that worked with MicroPython the way DisplayIO drivers work for CircuitPython, except without DisplayIO and instead usable by any GUI framework like, but not limited to, LVGL. That snowballed into adding more platforms and then adding drawing primitives, font classes, palettes, an event system, a barebones SDL2 library, a Bitmap 565 reader/writer and supporting as many platforms as possible. I stopped short of creating a full fledged GUI and plan to leave it as a very capable graphics library. I think this is a great foundation for building a GUI framework with widgets and a task scheduler, although it is very usable and useful without one. @peterhinch has a great GUI for MicroPython that works on top of PyDevices, and I'm hoping someone will make a GUI that works across platforms.