Quick and easy with PySimpleGUI
Simple Is Good
Use the same code for your Python GUI and web apps.
The PySimpleGUI project has two main goals: a simpler method for creating graphical user interfaces (GUIs), and common code for Tkinter, QT, Wx, and web graphics. Although I feel comfortable doing my own Python Tkinter and web interfaces, having common code for both local GUI and web apps could be extremely useful, especially for Raspberry Pi projects. In this article, I introduce PySimpleGUI and create both a local GUI and a web interface to control a Raspberry Pi rover, all in less than 60 lines of code.
Getting Started
The Python PySimpleGUI [1] project has a number of "ports" or versions. The main full-featured version is for Tkinter-based graphics. The versions for Qt, Wx, and web graphics are still in development, so some testing will be required if you are hoping for full code compatibility between the different libraries.
Although you probably won't encounter a lot of cases in which you would want to flip between Qt, Wx, and Tkinter graphic engines, the possibility exists. Figure 1 shows examples of the same code applied to the different graphic libraries.
To install the default version of PySimpleGUI for Tkinter enter:
pip install pysimpleGUI
PySimpleGUI has a wide range of graphic widgets or elements. Graphic presentations are built by creating a layout variable, and elements are placed in separate rows defined by enclosing square brackets. A row can have a single element or multiple elements. Figure 2 is a graphic GUI example with three rows.
A Button Interface
The rover project I create in this article uses a five-row layout (Listing 1; Figure 3). The first row contains feedback text, and rows 2-5 contain buttons.
Listing 1
PySimpleGUI Button
01 # Create a simple graphic interface 02 # 03 import PySimpleGUI as sg 04 05 layout = [ [sg.Text("the feedback" , key="feedback")], 06 [sg.Button("FORWARD")], 07 [sg.Button("LEFT"),sg.Button("RIGHT")], 08 [sg.Button("STOP")], 09 [sg.Button("QUIT")] 10 ] 11 # Create the Window 12 window = sg.Window('My First App', layout) 13 # Event Loop to process "events" 14 while True: 15 event, values = window.read() 16 window['feedback'].Update(event) # show the button in the feedback text 17 print(event,values) 18 if event in (None, 'QUIT'): 19 break 20 window.close()
The PySimpleGUI sg.window()
method displays a window with the title and a layout definition (line 12). The window.read()
method returns events and values that have changed (line 15). The feedback text element (line 5) is given the key name feedback
, which is used by the Update
method to indicate which button is pressed (line 16).
Standalone Web Apps
The PySimpleGUIWeb library is excellent for creating a lightweight standalone web interface. The real beauty in PySimpleGUIWeb is that no HTML, style sheets, Ajax, or JavaScript code is required. PySimpleGUIWeb is ideal for small, single-user web interfaces, and it supports features like a tabbed interface, tables, and graphics; however, it would not be a good fit if you need a multipage-multiuser web environment.
To install PySimpleGUIWeb enter:
pip install remi pip install pysimpleGUIweb
If I use my earlier button example, but this time use the PySimpleGUIWeb library, the code is identical, except for some added window options (Figure 4). If you are working locally on a Raspberry Pi, you can use the default sg.window
settings; however, if you want to work remotely, you need to define a web server address (web_ip
) and port (web_port
) and to disable the auto launching of the a web browser (web_start_browser = False
).
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