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phoenix_title wx.lib.agw.knobctrl

KnobCtrl lets the user select a numerical value by rotating it.


KnobCtrl lets the user select a numerical value by rotating it. It works like a scrollbar: just set the ticks range property and read the value property in the associated EVT_KC_ANGLE_CHANGING/EVT_KC_ANGLE_CHANGED events. Simple but effective.

It can be easily used if you want to simulate the volume knob of a music player or similar functionalities.


Usage example:

import wx
import wx.lib.agw.knobctrl as KC

class MyFrame(wx.Frame):

    def __init__(self, parent):

        wx.Frame.__init__(self, parent, -1, "KnobCtrl Demo")

        panel = wx.Panel(self)

        knob1 = KC.KnobCtrl(panel, -1, size=(100, 100))
        knob2 = KC.KnobCtrl(panel, -1, size=(100, 100))

        knob1.SetTags(range(0, 151, 10))
        knob1.SetAngularRange(-45, 225)

        knob2.SetTags(range(0, 151, 10))
        knob2.SetAngularRange(0, 270)

        main_sizer = wx.BoxSizer(wx.VERTICAL)
        main_sizer.Add(knob1, 0, wx.EXPAND | wx.ALL, 20)
        main_sizer.Add(knob2, 0, wx.EXPAND | wx.ALL, 20)


# our normal wxApp-derived class, as usual

app = wx.App(0)

frame = MyFrame(None)



KnobCtrl implements two events that can be intercepted by the user:


The first one can be “vetoed” by eliminating the event.Skip() at the end of the event handler.

Supported Platforms

KnobCtrl has been tested on the following platforms:
  • Windows (Windows XP);
  • Linux Ubuntu (Dapper 6.06)

Window Styles

This class supports the following window styles:

Window Styles Hex Value Description
KC_BUFFERED_DC 0x1 Flag to use double buffering (recommendeded = 1).

Events Processing

This class processes the following events:

Event Name Description
EVT_KC_ANGLE_CHANGED Notify the client that the knob has changed its value.
EVT_KC_ANGLE_CHANGING Notify the client that the knob is changing its value.

License And Version

KnobCtrl is distributed under the wxPython license.

Latest Revision: Andrea Gavana @ 27 Dec 2012, 21.00 GMT

Version 0.4

class_summary Classes Summary

BufferedWindow A Buffered window class.
KnobCtrl This class can be used to simulate a knob volume control often found in
KnobCtrlEvent Represent details of the events that the KnobCtrl object sends.