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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Qt Toolkit - Qt/Embedded Pointer Handling</title><style type="text/css"><!--
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<h1 align=center> Qt/Embedded Pointer Handling</h1><br clear="all">
<p>
Pointer handling in Qt/Embedded works for any mouse-like device such as
a touchpanel, a trackball, or real mouse.
<p>
In a real device, only a small number of pointer devices (usually one)
would be supported, but for demonstration purposes, Qt/Embedded includes
a large number of supported devices.
<p>
<h2>Mouse Protocols</h2>
<p>
Qt/Embedded normally auto-detects the mouse type and device if it is one of
the supported types on <tt>/dev/psaux</tt> or one of the <tt>/dev/ttyS?</tt>
serial lines. If multiple mice are detected, all may be used simultaneously.
<p>
Alternatively, you may set the environment variable QWS_MOUSE_PROTO to
determine which mouse to use. This environment variable may be set to:
<blockquote>
<i><protocol></i><tt>:</tt><i><device></i>
</blockquote>
where <i><protocol></i> is one of:
<ul>
<li>MouseMan
<li>IntelliMouse
<li>Microsoft
</ul>
and <i><device></i> is the mouse device, often <tt>/dev/mouse</tt>.
If no such variable is specified, the built-in default
is <tt>Auto</tt> which enables auto-detection of the mouse protocol
and device.
<p>
To add another protocol, new subclasses of QAutoMouseSubHandler or
QMouseHandler can be written in <tt>kernel/qwsmouse_qws.cpp</tt>.
<p>
<h2>Touch Panels</h2>
<p>
Qt/Embedded ships with support for the NEC Vr41XX touchpanel
and the iPAQ touchpanel.
These are subclasses of QCalibratedMouseHandler which is in turn
a subclass of QMouseHandler in <tt>kernel/qwsmouse_qws.cpp</tt>.
<p>
Writing a custom touch panel handler for Qt/Embedded is not as
hard as the QVrTPanelHandlerPrivate class makes it look.
The Vr41XX touch panel handler is complex; it handles filtering of
noisy input data, and it generates mouse release events by using a
timer.
<p>
Many touch panel devices have a much simpler interface, so a
port to Qt/Embedded can be written in a few minutes, without expert
knowledge of Qt/Embedded.
<p>
The Qt/Embedded release contains an example touch panel handler in the
class QCustomTPanelHandlerPrivate, located in the file
<tt>$QTDIR/src/kernel/qwsmouse_qws.cpp</tt>. It is protected by<tt>#ifdef
QWS_CUSTOMTOUCHPANEL</tt>.
<p>
The example reads data from /dev/ts with the following format:
Each packet consists of 5 bytes.
<ul>
<li>Byte 0 gives status information, in particular, bit 6 (0x40)
is 1 when the stylus is down, 0 if it is released.
<li> Bytes 1 and 2 give the x position;
<li> Bytes 3 and 4 give the y position;
</ul>
<p>
To enable this driver, uncomment the line <tt>#define QWS_CUSTOMTOUCHPANEL</tt>
in the file qwsmouse_qws.cpp.
<p>
Chances are, your touch panel device will not match exactly the
example device. As an example, take a hypothetical device located at
/dev/touchpanel. This device uses 6-byte packets. Byte 0 and 1 give
status and pressure information. In particular, bit 5 (0x20) of byte 1
tells whether the stylus is down or up. Bytes 2 and 3 give x position and
bytes 4 and 5 give y position.
<p>
Pressure information is not necessary for basic Qt/Embedded operation,
so we will ignore that for now. The following shows the modified touch
panel handler for the hypothetical device, with comments marked with
<tt>//***<tt> indicating the changes made. You can also see some printf
calls left over from the (hypothetical) debugging.
<p>
<pre>//*** Modified Trolltech's example handler to handle the
//*** hypothetical touch panel.
QCustomTPanelHandlerPrivate::QCustomTPanelHandlerPrivate( MouseProtocol, QString )
{
//*** changed device name to /dev/touchpanel
if ((mouseFD = open( "/dev/touchpanel", O_RDONLY)) < 0) {
<a href="qapplication.html#290ef4">qWarning</a>( "Cannot open /dev/touchpanel (%s)", strerror(errno));
return;
}
//*** removed the delay since our device does not need it.
//else {
// sleep(1);
//}
<a href="qsocketnotifier.html">QSocketNotifier</a> *mouseNotifier;
mouseNotifier = new <a href="qsocketnotifier.html">QSocketNotifier</a>( mouseFD, QSocketNotifier::Read,
this );
connect(mouseNotifier, SIGNAL(activated(int)),this, SLOT(readMouseData()));
}
QCustomTPanelHandlerPrivate::~QCustomTPanelHandlerPrivate()
{
if (mouseFD >= 0)
close(mouseFD);
}
struct CustomTPdata {
unsigned char status;
unsigned short xpos;
unsigned short ypos;
};
void QCustomTPanelHandlerPrivate::readMouseData()
{
if(!qt_screen)
return;
CustomTPdata data;
//*** changed size to 6 bytes
unsigned char data2[6];
int ret;
//*** read 6 bytes
ret=read(mouseFD,data2,6);
if(ret==6) { //*** change to 6
//*** all the indexes changed:
data.status=data2[1];
data.xpos=(data2[2] << 8) | data2[3];
data.ypos=(data2[4] << 8) | data2[5];
<a href="qpoint.html">QPoint</a> q;
q.<a href="qpoint.html#75b57f">setX</a>(data.xpos);
q.<a href="qpoint.html#c780b4">setY</a>(data.ypos);
mousePos=q;
if(data.status & 0x20) { //*** Changed to 0x20 (bit 5)
emit mouseChanged(mousePos,Qt::LeftButton);
//printf( "Stylus press/move %d,%d\n", data.xpos, data.ypos );
} else {
emit mouseChanged(mousePos,0);
//printf( "Stylus release %d,%d\n", data.xpos, data.ypos );
}
}
if(ret<0) {
<a href="qapplication.html#72e78c">qDebug</a>("Error %s",strerror(errno));
}
}
</pre>
<p>
Once you have your touch panel handler working, you may choose to keep
it like it is. However, if you want to switch between different
mouse/touch panel devices at run time, you will have to modify
QWSServer::newMouseHandler() (also in qwsmouse_qws.cpp) to instantiate
your new handler(s). You will also need to add to the enum
<tt>MouseProtocol</tt> and the table <tt>mouseConfig[]</tt>. Note that
the precise details on how mouse and touch panel drivers are instantiated
may have to be changed in future versions of Qt/Embedded.
<p><address><hr><div align="center">
<table width="100%" cellspacing="0" border="0"><tr>
<td>Copyright 2001 Trolltech<td><a href="http://www.trolltech.com/trademarks.html">Trademarks</a>
<td align="right"><div align="right">Qt version 2.3.2</div>
</table></div></address></body></html>
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