[clutter/clutter-1.16] evdev: add minimal support for touchpads

[Giovanni Campagna <gcampagna src gnome org>]

commit 89cd3112febbc27a9222623df4f50404934e2fec
Author: Giovanni Campagna <gcampagn redhat com>
Date:   Mon Sep 9 10:51:11 2013 +0200

    evdev: add minimal support for touchpads
    
    The added support is very very basic (single touch, motion only,
    no acceleration, no pressure recognition), but anything more
    complex requires a state machine that will be hopefully provided
    by libinputcommon in the future.
    And at least, with this patch the pointer moves, which will be
    useful for people testing wayland in 3.10 without a physical mouse.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=706494

 clutter/evdev/clutter-device-manager-evdev.c |  101 ++++++++++++++++++++++++--
 1 files changed, 94 insertions(+), 7 deletions(-)
---
diff --git a/clutter/evdev/clutter-device-manager-evdev.c b/clutter/evdev/clutter-device-manager-evdev.c
index 3271b2f..00958c8 100644
--- a/clutter/evdev/clutter-device-manager-evdev.c
+++ b/clutter/evdev/clutter-device-manager-evdev.c
@@ -25,6 +25,7 @@
 #include "config.h"
 #endif
 
+#include <math.h>
 #include <linux/input.h>
 #include <sys/stat.h>
 #include <sys/types.h>
@@ -61,6 +62,12 @@
 
 #define AUTOREPEAT_VALUE 2
 
+/* Taken from weston/src/evdev-touchpad.c
+   In the future, we may want to make this configurable, or
+   delegate everything to loadable input drivers.
+*/
+#define DEFAULT_HYSTERESIS_MARGIN_DENOMINATOR 700.0
+
 struct _ClutterDeviceManagerEvdevPrivate
 {
   GUdevClient *udev_client;
@@ -130,7 +137,14 @@ struct _ClutterEventSource
   GPollFD event_poll_fd;              /* file descriptor of the /dev node */
   struct libevdev *dev;
 
+  /* For mice (and emulated for touchpads) */
   int dx, dy;
+
+  /* For touchpads */
+  gboolean touching;
+  int margin;
+  int last_x, last_y;
+  int cur_x, cur_y;
 };
 
 static gboolean
@@ -448,6 +462,47 @@ notify_button (ClutterEventSource *source,
 }
 
 static void
+process_absolute_motion (ClutterEventSource *source)
+{
+  /* Compute deltas and update absolute positions */
+  if (source->touching)
+    {
+      source->dx = source->cur_x - source->last_x;
+      source->dy = source->cur_y - source->last_y;
+      source->last_x = source->cur_x;
+      source->last_y = source->cur_y;
+    }
+}
+
+static void
+process_relative_motion (ClutterEventSource *source,
+                        guint32             _time)
+{
+  /* Flush accumulated motion deltas */
+  if (source->dx != 0 || source->dy != 0)
+    {
+      notify_relative_motion (source, _time, source->dx, source->dy);
+      source->dx = 0;
+      source->dy = 0;
+    }
+}
+
+static inline int
+hysteresis (int in, int center, int margin)
+{
+  int diff = in - center;
+
+  if (ABS (diff) <= margin)
+    return center;
+
+  if (diff > margin)
+    return center + diff - margin;
+  else if (diff < -margin)
+    return center + diff + margin;
+  return center + diff;
+}
+
+static void
 dispatch_one_event (ClutterEventSource *source,
                    struct input_event *e)
 {
@@ -466,6 +521,15 @@ dispatch_one_event (ClutterEventSource *source,
          if (e->value != AUTOREPEAT_VALUE)
            notify_button (source, _time, e->code, e->value);
        }
+      else if (e->code == BTN_TOOL_FINGER && e->value != AUTOREPEAT_VALUE)
+       {
+         source->touching = e->value;
+         if (e->value)
+           {
+             source->last_x = source->cur_x;
+             source->last_y = source->cur_y;
+           }
+       }
       else
        {
          /* We don't know about this code, ignore */
@@ -475,13 +539,8 @@ dispatch_one_event (ClutterEventSource *source,
     case EV_SYN:
       if (e->code == SYN_REPORT)
        {
-         /* Flush accumulated motion deltas */
-         if (source->dx != 0 || source->dy != 0)
-           {
-             notify_relative_motion (source, _time, source->dx, source->dy);
-             source->dx = 0;
-             source->dy = 0;
-           }
+         process_absolute_motion (source);
+         process_relative_motion (source, _time);
        }
       break;
 
@@ -510,6 +569,17 @@ dispatch_one_event (ClutterEventSource *source,
       break;
 
     case EV_ABS:
+      switch (e->code)
+       {
+       case ABS_X:
+         source->cur_x = hysteresis (e->value, source->cur_x, source->margin);
+         break;
+       case ABS_Y:
+         source->cur_y = hysteresis (e->value, source->cur_y, source->margin);
+         break;
+       }
+      break;
+
     default:
       g_warning ("Unhandled event of type %d", e->type);
       break;
@@ -646,6 +716,7 @@ clutter_event_source_new (ClutterInputDeviceEvdev *input_device)
   const gchar *node_path;
   gint fd, clkid;
   GError *error;
+  ClutterInputDeviceType device_type;
 
   /* grab the udev input device node and open it */
   node_path = _clutter_input_device_evdev_get_device_path (input_device);
@@ -684,6 +755,22 @@ clutter_event_source_new (ClutterInputDeviceEvdev *input_device)
   event_source->event_poll_fd.events = G_IO_IN;
   libevdev_new_from_fd (fd, &event_source->dev);
 
+  device_type = clutter_input_device_get_device_type (CLUTTER_INPUT_DEVICE (input_device));
+  if (device_type == CLUTTER_TOUCHPAD_DEVICE)
+    {
+      const struct input_absinfo *info_x, *info_y;
+      double width, height, diagonal;
+
+      info_x = libevdev_get_abs_info (event_source->dev, ABS_X);
+      info_y = libevdev_get_abs_info (event_source->dev, ABS_Y);
+
+      width = ABS (info_x->maximum - info_x->minimum);
+      height = ABS (info_y->maximum - info_y->minimum);
+      diagonal = sqrt (width * width + height * height);
+
+      event_source->margin = diagonal / DEFAULT_HYSTERESIS_MARGIN_DENOMINATOR;
+    }
+
   /* and finally configure and attach the GSource */
   g_source_set_priority (source, CLUTTER_PRIORITY_EVENTS);
   g_source_add_poll (source, &event_source->event_poll_fd);