[PATCH evdev] add button debouncing
Peter Hutterer
peter.hutterer at who-t.net
Wed Aug 22 23:40:45 PDT 2012
Hi Matt,
sorry about the delay, bit swamped here.
On Mon, Aug 13, 2012 at 05:47:12PM -0400, Matt Whitlock wrote:
> This patch adds one configuration option, "DebounceDelay", and one XInput
> property, "Evdev Debounce Delay". They refer to the amount of time to wait
> after receiving a mouse button release event from the kernel before posting
> the event to the X server. If a mouse button pressed event is received before
> the delay expires, then the release/press pair is forgotten. This allows to
> deal with mice whose button switches are worn out or dirty. Each mouse button
> is debounced independently.
Just reading the description, I think this is the wrong way round. Why not
let the first event through unconditionally and then discard the second one
if it arrives within the time frame. This wouldn't require a timer, instead
you could note the time the last event arrived and then act on that.
Having said that, I'm really hesitant on this feature. The reason you
stated is "mice whose button switches are worn out or dirty". Is the cost of
replacing (or cleaning) said device not a lot less than writing the code and
maintaining it? How many devices are actually affected by this?
Cheers,
Peter
> ---
> include/evdev-properties.h | 3 +
> src/Makefile.am | 1 +
> src/debounce.c | 198 ++++++++++++++++++++++++++++++++++++++++++++
> src/evdev.c | 6 ++
> src/evdev.h | 17 ++++
> 5 files changed, 225 insertions(+), 0 deletions(-)
> create mode 100644 src/debounce.c
>
> diff --git a/include/evdev-properties.h b/include/evdev-properties.h
> index 745a1ba..4c169c3 100644
> --- a/include/evdev-properties.h
> +++ b/include/evdev-properties.h
> @@ -87,4 +87,7 @@
> */
> #define EVDEV_PROP_FUNCTION_KEYS "Evdev Function Keys"
>
> +/* CARD32 */
> +#define EVDEV_PROP_DEBOUNCE_DELAY "Evdev Debounce Delay"
> +
> #endif
> diff --git a/src/Makefile.am b/src/Makefile.am
> index da76540..4f51e8f 100644
> --- a/src/Makefile.am
> +++ b/src/Makefile.am
> @@ -39,6 +39,7 @@ AM_CPPFLAGS =-I$(top_srcdir)/include
> emuThird.c \
> emuWheel.c \
> draglock.c \
> + debounce.c \
> apple.c \
> axis_labels.h
>
> diff --git a/src/debounce.c b/src/debounce.c
> new file mode 100644
> index 0000000..cda703d
> --- /dev/null
> +++ b/src/debounce.c
> @@ -0,0 +1,198 @@
> +/*
> + * Permission to use, copy, modify, distribute, and sell this software
> + * and its documentation for any purpose is hereby granted without
> + * fee, provided that the above copyright notice appear in all copies
> + * and that both that copyright notice and this permission notice
> + * appear in supporting documentation, and that the name of the authors
> + * not be used in advertising or publicity pertaining to distribution of the
> + * software without specific, written prior permission. The authors make no
> + * representations about the suitability of this software for any
> + * purpose. It is provided "as is" without express or implied
> + * warranty.
> + *
> + * THE AUTHORS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
> + * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN
> + * NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
> + * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
> + * OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
> + * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
> + * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
> + *
> + */
> +
> +#ifdef HAVE_CONFIG_H
> +#include "config.h"
> +#endif
> +
> +#include "evdev.h"
> +
> +#include <X11/Xatom.h>
> +#include <xf86.h>
> +#include <xf86Xinput.h>
> +#include <exevents.h>
> +
> +#include <evdev-properties.h>
> +
> +/* how many milliseconds to wait for buttons to settle */
> +static Atom prop_dbdelay;
> +
> +struct ButtonTime {
> + unsigned int button;
> + Time time;
> +};
> +
> +static int
> +EvdevDBCompareButtonTimes(const void *bt1, const void *bt2)
> +{
> + return ((const struct ButtonTime *) bt1)->time -
> + ((const struct ButtonTime *) bt2)->time;
> +}
> +
> +/**
> + * Timer callback for debouncing buttons.
> + */
> +static CARD32
> +EvdevDBTimer(OsTimerPtr timer, CARD32 time, pointer arg)
> +{
> + InputInfoPtr pInfo = arg;
> + EvdevPtr pEvdev = pInfo->private;
> + struct debounce *db = &pEvdev->debounce;
> + struct ButtonTime release[EVDEV_MAXBUTTONS];
> + size_t nRelease = 0;
> + int sigstate = xf86BlockSIGIO();
> +
> + if (db->bouncing) {
> + BOOL bouncing = FALSE;
> + Time next_expiry = ~0;
> + for (size_t button = 0; button < EVDEV_MAXBUTTONS; ++button) {
> + if (db->state[button].bouncing) {
> + Time expiry = db->state[button].expiry;
> + if (expiry <= time) {
> + db->state[button].pressed = FALSE;
> + db->state[button].bouncing = FALSE;
> + release[nRelease].button = button;
> + release[nRelease].time = expiry;
> + ++nRelease;
> + }
> + else if (expiry < next_expiry) {
> + bouncing = TRUE;
> + next_expiry = expiry;
> + }
> + }
> + }
> + if (nRelease > 0) {
> + if (nRelease > 1) {
> + qsort(release, nRelease, sizeof *release,
> + EvdevDBCompareButtonTimes);
> + }
> + for (size_t i = 0; i < nRelease; ++i) {
> + EvdevPostButtonEvent(pInfo, release[i].button, BUTTON_RELEASE);
> + }
> + }
> + if (bouncing) {
> + db->timer = TimerSet(db->timer, 0, next_expiry - GetTimeInMillis(),
> + EvdevDBTimer, pInfo);
> + }
> + else {
> + db->bouncing = FALSE;
> + }
> + }
> +
> + xf86UnblockSIGIO(sigstate);
> + return 0;
> +}
> +
> +/**
> + * Debounce button states.
> + *
> + * @return TRUE iff event was swallowed by debouncing.
> + */
> +BOOL
> +EvdevDBFilterEvent(InputInfoPtr pInfo, unsigned int button, BOOL pressed)
> +{
> + EvdevPtr pEvdev = pInfo->private;
> + struct debounce *db = &pEvdev->debounce;
> +
> + if (db->delay == 0) {
> + return FALSE;
> + }
> +
> + if (pressed) {
> + if (db->state[button].pressed) {
> + db->state[button].bouncing = FALSE;
> + return TRUE;
> + }
> + db->state[button].pressed = TRUE;
> + return FALSE;
> + }
> +
> + if (db->state[button].pressed) {
> + db->state[button].bouncing = TRUE;
> + db->state[button].expiry = GetTimeInMillis() + db->delay;
> + if (!db->bouncing) {
> + db->bouncing = TRUE;
> + db->timer = TimerSet(db->timer, 0, db->delay, EvdevDBTimer, pInfo);
> + }
> + }
> +
> + return TRUE;
> +}
> +
> +void
> +EvdevDBPreInit(InputInfoPtr pInfo)
> +{
> + EvdevPtr pEvdev = pInfo->private;
> + struct debounce *db = &pEvdev->debounce;
> +
> + db->delay = xf86SetIntOption(pInfo->options, "DebounceDelay", 0);
> + db->timer = TimerSet(NULL, 0, 0, NULL, NULL);
> +}
> +
> +void
> +EvdevDBFinalize(InputInfoPtr pInfo)
> +{
> + EvdevPtr pEvdev = pInfo->private;
> + struct debounce *db = &pEvdev->debounce;
> +
> + TimerFree(db->timer), db->timer = NULL;
> +}
> +
> +static int
> +EvdevDBSetProperty(DeviceIntPtr dev, Atom atom, XIPropertyValuePtr val,
> + BOOL checkonly)
> +{
> + InputInfoPtr pInfo = dev->public.devicePrivate;
> + EvdevPtr pEvdev = pInfo->private;
> + struct debounce *db = &pEvdev->debounce;
> +
> + if (atom == prop_dbdelay) {
> + if (val->format != 32 || val->size != 1 || val->type != XA_INTEGER) {
> + return BadMatch;
> + }
> + if (!checkonly) {
> + db->delay = *((CARD32 *) val->data);
> + }
> + }
> +
> + return Success;
> +}
> +
> +void
> +EvdevDBInitProperty(DeviceIntPtr dev)
> +{
> + InputInfoPtr pInfo = dev->public.devicePrivate;
> + EvdevPtr pEvdev = pInfo->private;
> + struct debounce *db = &pEvdev->debounce;
> +
> + if (dev->button) {
> + prop_dbdelay = MakeAtom(EVDEV_PROP_DEBOUNCE_DELAY,
> + strlen(EVDEV_PROP_DEBOUNCE_DELAY), TRUE);
> + if (XIChangeDeviceProperty(dev, prop_dbdelay, XA_INTEGER, 32,
> + PropModeReplace, 1, &db->delay, FALSE)
> + != Success) {
> + return;
> + }
> + XISetDevicePropertyDeletable(dev, prop_dbdelay, FALSE);
> + XIRegisterPropertyHandler(dev, EvdevDBSetProperty, NULL, NULL);
> + }
> +}
> diff --git a/src/evdev.c b/src/evdev.c
> index 2aab97f..cd0eb11 100644
> --- a/src/evdev.c
> +++ b/src/evdev.c
> @@ -667,6 +667,9 @@ EvdevProcessButtonEvent(InputInfoPtr pInfo, struct input_event *ev)
> if (EvdevMBEmuFilterEvent(pInfo, button, value))
> return;
>
> + if (EvdevDBFilterEvent(pInfo, button, value))
> + return;
> +
> if (button)
> EvdevQueueButtonEvent(pInfo, button, value);
> else
> @@ -1807,6 +1810,7 @@ EvdevInit(DeviceIntPtr device)
> Evdev3BEmuInitProperty(device);
> EvdevWheelEmuInitProperty(device);
> EvdevDragLockInitProperty(device);
> + EvdevDBInitProperty(device);
> EvdevAppleInitProperty(device);
>
> return Success;
> @@ -1864,6 +1868,7 @@ EvdevProc(DeviceIntPtr device, int what)
> {
> EvdevMBEmuFinalize(pInfo);
> Evdev3BEmuFinalize(pInfo);
> + EvdevDBFinalize(pInfo);
> }
> if (pInfo->fd != -1)
> {
> @@ -2530,6 +2535,7 @@ EvdevPreInit(InputDriverPtr drv, InputInfoPtr pInfo, int flags)
> Evdev3BEmuPreInit(pInfo);
> EvdevWheelEmuPreInit(pInfo);
> EvdevDragLockPreInit(pInfo);
> + EvdevDBPreInit(pInfo);
> }
>
> return Success;
> diff --git a/src/evdev.h b/src/evdev.h
> index 2901886..8243806 100644
> --- a/src/evdev.h
> +++ b/src/evdev.h
> @@ -222,6 +222,17 @@ typedef struct {
> Time expires; /* time of expiry */
> Time timeout;
> } emulateWheel;
> + /* Button debouncing */
> + struct debounce {
> + Time delay;
> + OsTimerPtr timer;
> + BOOL bouncing;
> + struct {
> + BOOL pressed;
> + BOOL bouncing;
> + Time expiry;
> + } state[EVDEV_MAXBUTTONS];
> + } debounce;
> /* run-time calibration */
> struct {
> int min_x;
> @@ -298,6 +309,12 @@ BOOL EvdevWheelEmuFilterMotion(InputInfoPtr pInfo, struct input_event *pEv);
> void EvdevDragLockPreInit(InputInfoPtr pInfo);
> BOOL EvdevDragLockFilterEvent(InputInfoPtr pInfo, unsigned int button, int value);
>
> +/* Button debouncing */
> +BOOL EvdevDBFilterEvent(InputInfoPtr pInfo, unsigned int button, BOOL pressed);
> +void EvdevDBPreInit(InputInfoPtr pInfo);
> +void EvdevDBFinalize(InputInfoPtr pInfo);
> +void EvdevDBInitProperty(DeviceIntPtr dev);
> +
> void EvdevMBEmuInitProperty(DeviceIntPtr);
> void Evdev3BEmuInitProperty(DeviceIntPtr);
> void EvdevWheelEmuInitProperty(DeviceIntPtr);
> --
> 1.7.8.6
>
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