Python Qt Signals And Slots
Therefore it is not usually necessary to use QtCore.SLOT for Qt slots. However, doing so is more efficient as it avoids a conversion to Python and back to C. Qt allows a signal to be connected to a slot that requires fewer arguments than the signal passes. The extra arguments are quietly discarded. PyQt slots can be used in the same way. We connect the standard finished and terminated signals from the thread to the same slot in the widget. This will reset the user interface when the thread stops running. The custom output (QRect, QImage) signal is connected to the addImage slot so that we can update the viewer label every time a new star is drawn.
Graphical applications (GUI) are event-driven, unlike console or terminal applications. A users action like clicks a button or selecting an item in a list is called an event.
If an event takes place, each PyQt5 widget can emit a signal. A signal does not execute any action, that is done by a slot.
Related course:
Create GUI Apps with PyQt5
Python Qt Signal Slot Example
Signals and slot introduction
Consider this example:
The button click (signal) is connected to the action (slot). In this example, the method slot_method will be called if the signal emits.
This principle of connecting slots methods or function to a widget, applies to all widgets,
or we can explicitly define the signal:
PyQt supports many type of signals, not just clicks.
Example
We can create a method (slot) that is connected to a widget. A slot is any callable function or method.
On running the application, we can click the button to execute the action (slot).
Python Qt Signals And Slots Free Play
If you are new to programming Python PyQt, I highly recommend this book.