reference/pyqtref.txt

# pyqt reference

# qt base development files
$ doas apt-get install qtbase5-dev      # qt 5 base development file
$ doas apt-get install qt6-base-dev     # qt 6 base development file


qt.qpa.plugin: From 6.5.0, xcb-cursor0 or libxcb-cursor0 is needed to load the Qt xcb platform plugin.
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: wayland-egl, vkkhrdisplay, vnc, eglfs, minimalegl, linuxfb, xcb, offscreen, wayland, minimal.

Aborted

$ doas apt-get install libxcb-cursor0


# pyqtgraph
https://pyqtgraph.readthedocs.io/en/latest/getting_started/how_to_use.html
https://www.pythonguis.com/tutorials/plotting-pyqtgraph/


from PyQt5.QtWidgets import QApplication, QWidget

QApplication - the application handler
QWidget - a basic empty GUI widget

The main modules for Qt are QtWidgets, QtGui and QtCore.

Next we create an instance of QApplication, passing in sys.argv, which is python
list containing the command line arguments passed to the application.

app = QApplication(sys.argv)

If you won't be using command line arguments to control Qt you can pass in an
empty list instead.

app = QApplication([])

Next we create an instance of a QWidget using the variable name window.
window = QWidget()
window.show()

In Qt all top level widgets are windows - that is, they don't have a parent and
are not nested within another widget or layout.

Note: Widgets without a parent are invisible by default. So, after creating the
window object, we must always call .show() to make it visible. You can remove
the .show() and run the app, but you'll have no way to quit it!

Window holds the user-interface of your application. Every application needs at
least one (...but can have more). Application will (by default) exit when last
window is closed.

Finally, we call app.exec() to start up the event loop.

The QApplication class - QApplication holds the Qt event loop - One QApplication
instance required - Your application sits waiting in the event loop until an
action is taken - There is only one event loop running at any time.

The core Qt widgets are always imported from the QtWidgets namespace, as are the
QMainWindow and QApplication classes.

Note: When you subclass a Qt class you must always call the super __init__
function to allow Qt to set up the object.

QWidget documentation:
https://doc.qt.io/qt-5/widget-classes.html#basic-widget-classes

Sizing windows and widgets:
In Qt sizes are defined using a QSize object. This accepts width and height
parameters in that order. For example, the following will create a fixed size
window of 400x300 pixels.

window.setFixedSize(QtCore.QSize(400, 300))

As well as .setFixedSize() you can also call .setMinimumSize() and
.setMaximumSize() to set the minimum and maximum sizes respectively.