olegv142 / pygamets

Touch screen support for pygame frame-buffer applications

pygamets

GUI micro-framework with touch screen support for Pygame frame-buffer applications. Designed for building simple GUI in embedded applications with focus on multi-threading.

The demo application main screen

Pie chart progress indicator

Another progress indicator

Data plotting window

Log view window

What it does

The touch screen events seen in /dev/input/mouse has incorrect position information so the touch screen support in pygame seems to be broken unless running under x-windows. We have implemented separate input events handler reading them from /dev/input/event raw events pipe. It is installed in place of pygame.event.get routine so any pygame application reading events from there will be able to work with touch screen flawlessly.

The existing touch screen calibration applications are available for x-windows only. We created our own calibration tool which should be executed before using aforementioned event reading engine.

The event reading hook is quite convenient place for adding additional functionality to event loop based GUI applications. We added 2 useful facilities there:

• timers for scheduling callbacks after some time interval in one shot or periodic mode
• jobs for scheduling actions that must be executed ASAP in the context of the event loop

We provided GUI base classes to serve as generic building blocks for applications as well as several ready to use GUI elements such as buttons, labels, progress and battery charge indicators, graph plotter and log viewer.

The styles framework serves as a convenient way of setting various parameters in CSS-like manner. It separates parameters storage from the code using them which leads to cleaner code and simplify visual appearance tuning.

The textual elements rely on the global text translation table for the sake of GUI localization. You can see the localized START button label on the above screenshot.

The log viewer widget is collecting last log records using standard logging module. So the application developer can get all necessary debugging information right on the screen without using remote terminal access to the target system. The data plotter widget helps to visualize arbitrary data represented as array of (x, y) samples.

The demo application is provided as working example of building simple GUI in multi-threaded application.

Environment

Tested on Raspberry Pi zero W with Stretch lite installed equipped with 4inch 320×480 LCD screen. Also works on windows without any modifications.

Running demo

You have to install pygame first

pip install pygame

On Raspberry Pi you should calibrate screen before first use of this GUI framework.

cd tool
sudo ./calibrate.py

Then you will be able to launch demo application

cd demo
sudo ./demo.py

To have demo running automatically on boot install systemd service demo/pygame-ts-demo.service

cd demo
sudo cp pygame-ts-demo.service /etc/systemd/system/
sudo systemctl enable pygame-ts-demo
sudo systemctl start  pygame-ts-demo

On windows there is no need to calibrate anything. Just execute

python demo.py

from the demo directory.

Author

Oleg Volkov ([e-mail])