Support palm detection for trackpads without width support

The Magic Trackpad does not report both touch and width of a finger,
making thumb/palm detection less reliable. Approximate thumb detection
as a large oval object, restoring some of the thumb functionality.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>

1 files changed, 7 insertions, 3 deletions

diff --git a/src/mtstate.c b/src/mtstate.c
index 313550b..771048d 100644
--- a/src/mtstate.c
+++ b/src/mtstate.c
@@ -25,6 +25,7 @@
 #define TOUCH_SCALE(caps) (0.05 * caps->abs[MTDEV_TOUCH_MAJOR].maximum)
 
 #define THUMB_TOUCH(hw) (1.2 * hw->touch_minor)
+#define THUMB_TOUCH_SIZE(hw, caps) (0.14 * get_cap_xsize(caps))
 #define THUMB_WIDTH_TOUCH(hw) (4 * hw->touch_major)
 #define THUMB_WIDTH_WIDTH(hw) (1.2 * hw->width_minor)
 #define THUMB_WIDTH_SIZE(hw, caps) (0.25 * get_cap_xsize(caps))
@@ -56,10 +57,13 @@ static int is_thumb(const struct FingerState *hw,
                     const struct Capabilities *caps)
 {
         if (!caps->has_abs[MTDEV_TOUCH_MAJOR] ||
-            !caps->has_abs[MTDEV_TOUCH_MINOR] ||
-            !caps->has_abs[MTDEV_WIDTH_MAJOR] ||
-            !caps->has_abs[MTDEV_WIDTH_MINOR])
+            !caps->has_abs[MTDEV_TOUCH_MINOR])
                 return 0;
+        if (!caps->has_abs[MTDEV_WIDTH_MAJOR] ||
+            !caps->has_abs[MTDEV_WIDTH_MINOR]) {
+                return  hw->touch_major > THUMB_TOUCH(hw) &&
+                        hw->touch_major > THUMB_TOUCH_SIZE(hw, caps);
+        }
         return  hw->touch_major > THUMB_TOUCH(hw) &&
                 hw->width_major > THUMB_WIDTH_TOUCH(hw) &&
                 hw->width_major > THUMB_WIDTH_WIDTH(hw) &&