6. A simple GUI appΒΆ

In this part of the tutorial you will build an application to custom function generator GUI:

Start the simulated instrument running the following command:

$ lantz-sim fungen tcp

Using Qt Designer, create a window like this:


and save it as fungen.ui in the folder in which you have created the driver (Building your own drivers). For the example, we have labeled each control as corresponding label in lower caps (amplitude, offset, waveform). The button is named scan. You can also download the ui file if you prefer.

Notice that the amplitude and offset don’t show units and that the waveform combobox is not populated. These widgets will be connected to the corresponding Feats of the drivers and Lantz will take care of setting the right values, items, etc.

Create a python file named fungen-gui.py with the following content:

import sys

# Import from a lantz the start_gui helper function
from lantz.ui.app import start_gui

with LantzSignalGenerator('TCPIP::localhost::5678::SOCKET') as inst:
    start_gui('fungen.ui', inst)

Run it and enjoy:

$ python scanfrequency-gui.py


In Windows, you can use pythonw instead of python to suppress the terminal window.

:func:start_gui take at leas two arguments. First, the fullpath of an QtDesigner ui file. As a second argument, an instrument instance.

Under the hood, start_gui is creating a Qt Application and loading the ui file. Then it matches by name Widgets to Feats and then connects them. Under the hood, for each match it:

1.- Wraps the widget to make it Lantz compatible.

2.- If applicable, configures minimum, maximum, steps and units.

3.- Add a handler such as when the widget value is changed, the Feat is updated.

4.- Add a handler such as when the Feat value is changed, the widget is updated.

You can learn more fine grained alternatives in Connecting a custom UI to a driver.

Learn how in the next part of the tutorial: A simple GUI app.