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git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@25082 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
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Robin Dunn
2004-01-07 18:46:54 +00:00
parent 7c2ba9a1e1
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wxPython/demo/Joystick.py
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@@ -969,8 +969,100 @@ def runTest(frame, nb, log):
#----------------------------------------------------------------------------
overview = """\
<html>
<body>
<h1>wx.Joystick</h1>
This demo illustrates the use of the wx.Joystick class, which is an interface to
one or more joysticks attached to your system.
<p>The data that can be retrieved from the joystick comes in four basic flavors.
All of these are illustrated in the demo. In fact, this demo illustrates everything
you <b>can</b> get from the wx.Joystick control.
<ul>
<li>Static information such as Manufacturer ID and model name,
<li>Analog input from up to six axes, including X and Y for the actual stick,
<li>Button input from the fire button and any other buttons that the stick has,
<li>and the POV control (a kind of mini-joystick on top of the joystick) that many sticks come with.
</ul>
<p>Getting data from the joystick can be event-driven thanks to four event types associated
with wx.JoystickEvent, or the joystick can be polled programatically to get data on
a regular basis.
<h2>Data types</h2>
Data from the joystick comes in two flavors: that which defines the boundaries, and that
which defines the current state of the stick. Thus, we have Get*Max() and Get*Min()
methods for all axes, the max number of axes, the max number of buttons, and so on. In
general, this data can be read once and stored to speed computation up.
<h3>Analog Input</h3>
Analog input (the axes) is delivered as a whole, positive number. If you need to know
if the axis is at zero (centered) or not, you will first have to calculate that center
based on the max and min values. The demo shows a bar graph for each axis expressed
in native numerical format, plus a 'centered' X-Y axis compas showing the relationship
of that input to the calculcated stick position.
Analog input may be jumpy and spurious, so the control has a means of 'smoothing' the
analog data by setting a movement threshold. This demo sets the threshold to 10, but
you can set it at any valid value between the min and max.
<h3>Button Input</h3>
Button state is retrieved as one int that contains each button state mapped to a bit.
You get the state of a button by AND-ing its bit against the returned value, in the form
<pre>
# assume buttonState is what the stick returned, and buttonBit
# is the bit you want to examine
if (buttonState & ( 1 &lt;&lt; buttonBit )) :
# button pressed, do something with it
</pre>
<p>The problem here is that some OSs return a 32-bit value for up to 32 buttons
(imagine <i>that</i> stick!). Python V2.3 will generate an exception for bit
values over 30. For that reason, this demo is limited to 16 buttons.
<p>Note that more than one button can be pressed at a time, so be sure to check all of them!
<h3>POV Input</h3>
POV hats come in two flavors: four-way, and continuous. four-way POVs are restricted to
the cardinal points of the compass; continuous, or CTS POV hats can deliver input in
.01 degree increments, theoreticaly. The data is returned as a whole number; the last
two digits are to the right of the decimal point, so in order to use this information,
you need to divide by 100 right off the bat.
<p>Different methods are provided to retrieve the POV data for a CTS hat
versus a four-way hat.
<h2>Caveats</h2>
The wx.Joystick control is in many ways incomplete at the C++ library level, but it is
not insurmountable. In short, while the joystick interface <i>can</i> be event-driven,
the wx.JoystickEvent class lacks event binders for all event types. Thus, you cannot
rely on wx.JoystickEvents to tell you when something has changed, necessarilly.
<ul>
<li>There are no events associated with the POV control.
<li>There are no events associated with the Rudder
<li>There are no events associated with the U and V axes.
</ul>
<p>Fortunately, there is an easy workaround. In the top level frame, create a wx.Timer
that will poll the stick at a set interval. Of course, if you do this, you might as
well forgo catching wxEVT_JOYSTICK_* events at all and rely on the timer to do the
polling.
<p>Ideally, the timer should be a one-shot; after it fires, collect and process data as
needed, then re-start the timer, possibly using wx.CallAfter().
</body>
</html>
"""
#----------------------------------------------------------------------------