commit b9fc973905eddc3d380c9a22b9d2e8bd909cfea8
author Che-Liang Chiou <clchiou@chromium.org> Mon Nov 26 15:49:02 2012 -0800
committer Gerrit <chrome-bot@google.com> Wed Nov 28 11:57:48 2012 -0800
tree 04b2f648a3ab0a981239c66e4d74539588d25d3f
parent 1359d8be1e73ae1fbffa079b39e627d76cca4f7e

Add heuristics for determining evdev device class

These heuristics are similar to those of xf86-input-cmt.

BUG=chromium-os:36634
TEST=see it probes device class correctly from debug output

Change-Id: I9e8a2225ff439608621d3760adde7690ded4b61e
Reviewed-on: https://gerrit.chromium.org/gerrit/38695
Commit-Ready: Che-Liang Chiou <clchiou@chromium.org>
Reviewed-by: Che-Liang Chiou <clchiou@chromium.org>
Tested-by: Che-Liang Chiou <clchiou@chromium.org>

include/libevdev/libevdev.h

diff --git a/include/libevdev/libevdev.h b/include/libevdev/libevdev.h
index 891a423..5c41231 100644
--- a/include/libevdev/libevdev.h
+++ b/include/libevdev/libevdev.h
@@ -22,9 +22,20 @@
 typedef void (*log_callback)(void*, int level, const char*, ...)
                 __attribute__((format(printf, 3, 4)));
 
+enum EvdevClass_ {
+  EvdevClassUnknown,
+  EvdevClassKeyboard,
+  EvdevClassMouse,
+  EvdevClassTablet,
+  EvdevClassTouchpad,
+  EvdevClassTouchscreen,
+};
+typedef enum EvdevClass_ EvdevClass, *EvdevClassPtr;
+
 struct EvdevInfo_ {
   struct input_id id;
   char name[1024];
+  EvdevClass evdev_class;
 
   unsigned long bitmask[NLONGS(EV_CNT)];
   unsigned long key_bitmask[NLONGS(KEY_CNT)];

src/libevdev.c

diff --git a/src/libevdev.c b/src/libevdev.c
index 1f1c5e8..fa60550 100644
--- a/src/libevdev.c
+++ b/src/libevdev.c
@@ -30,6 +30,8 @@
 
 static void Absinfo_Print(EvdevPtr device, struct input_absinfo*);
 static const char* Event_Property_To_String(int type);
+static EvdevClass EvdevProbeClass(EvdevInfoPtr info);
+static const char* EvdevClassToString(EvdevClass cls);
 
 int EvdevOpen(EvdevPtr evdev, const char* device) {
   evdev->fd = open(device, O_RDWR | O_NONBLOCK, 0);
@@ -198,6 +200,15 @@
           Absinfo_Print(device, absinfo);
       }
   }
+
+  info->evdev_class = EvdevProbeClass(info);
+  LOG_DEBUG(device, "Has evdev device class = %s\n",
+            EvdevClassToString(info->evdev_class));
+  if (info->evdev_class == EvdevClassUnknown) {
+    LOG_ERROR(device, "Couldn't determine evdev class\n");
+    return !Success;
+  }
+
   return Success;
 }
 
@@ -274,3 +285,55 @@
         LOG_DEBUG(device, "    res = %d\n", absinfo->resolution);
 }
 
+/*
+ * Heuristics for determining evdev device class; similar to those of
+ * xf86-input-evdev.
+ */
+static EvdevClass EvdevProbeClass(EvdevInfoPtr info) {
+  int bit;
+  for (bit = 0; bit < BTN_MISC; bit++)
+    if (TestBit(bit, info->key_bitmask))
+      return EvdevClassKeyboard;
+
+  if (TestBit(REL_X, info->rel_bitmask) &&
+      TestBit(REL_Y, info->rel_bitmask))
+    return EvdevClassMouse;
+
+  if (TestBit(ABS_X, info->abs_bitmask) &&
+      TestBit(ABS_Y, info->abs_bitmask)) {
+
+    if (TestBit(BTN_TOOL_PEN, info->key_bitmask) ||
+        TestBit(BTN_STYLUS, info->key_bitmask) ||
+        TestBit(BTN_STYLUS2, info->key_bitmask))
+      return EvdevClassTablet;
+
+    if (TestBit(ABS_PRESSURE, info->abs_bitmask) ||
+        TestBit(BTN_TOUCH, info->key_bitmask)) {
+      if (TestBit(BTN_LEFT, info->key_bitmask) ||
+          TestBit(BTN_MIDDLE, info->key_bitmask) ||
+          TestBit(BTN_RIGHT, info->key_bitmask) ||
+          TestBit(BTN_TOOL_FINGER, info->key_bitmask))
+        return EvdevClassTouchpad;
+      else
+        return EvdevClassTouchscreen;
+    }
+
+    /* Some touchscreens use BTN_LEFT rather than BTN_TOUCH */
+    if (TestBit(BTN_LEFT, info->key_bitmask))
+      return EvdevClassTouchscreen;
+  }
+
+  return EvdevClassUnknown;
+}
+
+static const char* EvdevClassToString(EvdevClass cls) {
+  switch (cls) {
+    case EvdevClassUnknown:     return "EvdevClassUnknown";
+    case EvdevClassKeyboard:    return "EvdevClassKeyboard";
+    case EvdevClassMouse:       return "EvdevClassMouse";
+    case EvdevClassTablet:      return "EvdevClassTablet";
+    case EvdevClassTouchpad:    return "EvdevClassTouchpad";
+    case EvdevClassTouchscreen: return "EvdevClassTouchscreen";
+  }
+  return "Unhandled Evdev Class";
+}