197 lines
7.2 KiB
Plaintext
197 lines
7.2 KiB
Plaintext
This file tells how to use gpm and X with a Gunze touchscreen.
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It is pretty similar to README.microtouch, and I plan to unify them as
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soon as I port the two implementation to offer a consistent look and
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feel. Currently the Gunze implementation is more configurable but has
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a worse calibration management (it must write to
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/etc/gpm-calibration).
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DEVICE CONFIGURATION
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--------------------
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The gpm decoder requires the Gunze device to be in Gunze Mode (not in
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Elo Emulation Mode). The supported serial speeds are 9600 and 19200
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baud, the latter being the default speed (in other words, to decode
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data at 9600 you must use the "-b 9600" option of gpm; no "-b" option
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selects 19200 baud). Currently, the only device supported is the
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10-bit one.
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USER INTERFACE
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--------------
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The decoder currently implemented in gpm is quite simple: it only
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supports mouse motion and button-1 events. This will soon change: I
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plan to implement corner-taps for button-2 and button-3, as well as a
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different "mode" where motion is not supported and any touch event is
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converted to a button-1 click.
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In the default (and only) mode, when a user touches the screen, the
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decoder generates mouse motion events. Tapping on the screen generates
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button-press (as well as drag and release) events.
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A "tap" is a finger-down (or pen-down) event generated quickly after a
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finger-up. A touch event is considered a "tap" if the lapse since the
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last finger-up is less than or equal to the double-click interval (the
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default is 250ms, and the value is chosen by specifying the "-i"
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option of gpm). This means that you'll usually move the pointer to the
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desired position and then tap on it.
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Double-and triple clicks are easily generated by repeated tapping.
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Since tapping is usually accompanied by a small movement, the decoder
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will use the coordinates of the finger-up event for the button-press.
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Further dragging will be relative to the tapping position (i.e., the
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finger-up position). Moreover, the last coordinate pair received on
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finger-up is discarded, because it usually is slightly offset (due to
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the non-negligible area of the fingertip).
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My own experience with the Gunze device, revealed that sometimes the
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finger bounces, generating very fast finger-up/finger-down pairs. The
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gpm decoder, therefore, ignores any quick succession of finger-up and
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finger-down events. The default is to ignore any release-press pair if
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the time lapse is less than 100ms (note, however, that this time lapse
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is configurable).
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GPM OPERATION
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-------------
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In order to run the touchscreen with gpm, you need to update the
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/dev/mouse symbolic link to point to the right serial port; then
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invoke gpm with a command line like
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gpm -t gunze
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If /dev/mouse is not updated to point to the touchscreen serial port,
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use
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gpm -t gunze -m /dev/ttyS0
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or an equivalent command.
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Unfortunately, there is currently no way to paste text, but I'll
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implement corner-tapping to achieve that.
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Gunze-specific Configuration
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----------------------------
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It is possible to specify device-specific options to gpm in order to
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customize the behaviour of the Gunze decoder. The options are passed
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as argument to the "-o" command line (reminiscent of the mount
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command).
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The following options are recognized:
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smooth=
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The decoder smooths mouse movements, to prevent the jumpy
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behaviour that usually results from finger movement. The
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default smoothin factor is 9, you can specify a different
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value if you wish: "gpm -t gunze -o smooth=3" gives faster
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(and more jumpy) motion, while "gpm -t gunze -o smooth=30"
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gives a very slow feeling.x
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debounce=
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The option is used to specify the minimum time lapse, in
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milliseconds between finger-up and finger-down events. Smaller
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time intervals are discarded to achieve debouncing. Note that
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the maximum time lapse is the one used for double-click
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detection, and is specified with the "-i" command-line option,
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common to every other mouse type.
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Please note that more than one option can be specified, by using the
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comma ``,'' as a separator. For example:
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gpm -t gunze -o smooth=5,debounce=150
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Calibration
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-----------
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To calibrate the touchscreen, use the program "gunze-setup" found in
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the source tree of gpm. The gpm daemon must already be running in
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order for the program to work flawlessly, as the program stops and
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restarts gpm internally (it depends on gpm for correct serial port
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initialization).
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The calibration program uses either /dev/touchscreen (if available) or
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/dev/mouse (otherwise) as the serial port to communicate with the
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touchscreen. You'll need therefore to create a symlink for one of
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those names before running "gunze-setup".
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After calibration, the calibration values can be found in the file
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/etc/gpm-calibration, but gpm must be restarted in order to be able to
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read them. This can be construed as a bug, and avoiding to stop the
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program is in my TODO list.
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X OPERATION
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-----------
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In order to use the touchscreen in X, you should install in your
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system the "Summa" module, as modified by Frank Holtz (the driver is
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available from http://www.hof-berlin.de/tablet/tablet.html, as well as
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in the gpm CVS tree and from gpm-1.18.2 in the gpm release as well).
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The compiled module (xf86Summa.so) should go in the module directory
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of your X server, usually /usr/X11/lib/modules, when it sits in the
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right place, a proper XF86Config will arrange for its loading.
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Gpm must run in repeater mode, with a command line like:
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gpm -t gunze -Rsumma
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, which instructs gpm to repeat packets according to the Summa protocol.
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Then, you need to add the following sections to your XF86config:
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Section "module"
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Load "xf86Summa.so"
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EndSection
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Section "Xinput"
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Subsection "SummaSketch"
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Port "/dev/gpmdata"
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DeviceName "touchscreen"
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Mode Absolute
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AlwaysCore
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EndSubSection
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EndSection
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Moreover, you should disable the "Pointer" section. I used a trick
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like this one:
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Section "Pointer"
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Protocol "MouseSystems"
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Device "/dev/fifo"
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EndSection
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Where /dev/fifo is just a plain unused fifo ("mknod /dev/fifo p")
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If, when calling ``startx'', it won't work with a message of ``Invalid
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Subsection Name'', please check the previous error lines, as they
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explain what is wrong. They usually look like:
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(--) no ModulePath specified using default: /usr/X11R6/lib/modules
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xf86Summa.so: Unknown error loading module
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It is pretty clear, if your are careful in reading the messages (I am
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not that careful, and lose half an hour in trying to figure out what
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was wrong).
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Calibration
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-----------
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To calibrate the touchscreen, use the program "gunze-setup" found in
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the source tree of gpm (yes, it is the same program used for the text
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mode). The gpm daemon must already be running in order for the
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program to work flawlessly, as the program stops and restarts gpm
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internally (it depends on gpm for correct serial port initialization).
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The calibration program uses either /dev/touchscreen (if available) or
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/dev/mouse (otherwise) as the serial port to communicate with the
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touchscreen. You'll need therefore to create a symlink for one of
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those names before running "gunze-setup".
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