Delay movement after a finger configuration change

The current code responds to finger movement immediately after
a finger has been placed on the trackpad, even if the touch is
accidental. This patch delays the effect of the finger by 70 ms,
resulting in fewer accidental movements.

Signed-off-by: Arturo Castro <arturo@openframeworks.cc>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>

2 files changed, 22 insertions, 8 deletions

diff --git a/src/gestures.c b/src/gestures.c
index e032214..b04c679 100644
--- a/src/gestures.c
+++ b/src/gestures.c
@@ -21,11 +21,14 @@
 
 #include "gestures.h"
 
+/* timer for cursor stability on finger touch/release */
+static const int AFTER_FINGER_CHANGE_MS = 70;
+
 static void extract_movement(struct Gestures *gs, struct MTouch* mt)
 {
         const struct FingerState *prev[DIM_FINGER];
         const struct FingerState *f = mt->state.finger;
-        int same_fingers, i;
+        int same_fingers, i, x = 0, y = 0;
 
         if (mt->state.nfinger == 0)
                 return;
@@ -36,16 +39,25 @@ static void extract_movement(struct Gestures *gs, struct MTouch* mt)
                 same_fingers = same_fingers && prev[i];
         }
 
-        if (!same_fingers)
-                return;
-
         for (i = 0; i < mt->state.nfinger; i++) {
-                gs->dx += f[i].hw.position_x - prev[i]->hw.position_x;
-                gs->dy += f[i].hw.position_y - prev[i]->hw.position_y;
+                x += f[i].hw.position_x;
+                y += f[i].hw.position_y;
+        }
+        x /= mt->state.nfinger;
+        y /= mt->state.nfinger;
+
+        if (!same_fingers) {
+                mt->mem.move_time = mt->state.evtime + AFTER_FINGER_CHANGE_MS;
+        } else if (mt->state.evtime >= mt->mem.move_time) {
+                gs->dx = x - mt->mem.move_x;
+                gs->dy = y - mt->mem.move_y;
+        } else {
+                /* accumulate all movement during delay */
+                return;
         }
 
-        gs->dx /= mt->state.nfinger;
-        gs->dy /= mt->state.nfinger;
+        mt->mem.move_x = x;
+        mt->mem.move_y = y;
 }
 
 static void extract_buttons(struct Gestures *gs, struct MTouch* mt)
diff --git a/src/memory.h b/src/memory.h
index a6c51ec..0ab4d04 100644
--- a/src/memory.h
+++ b/src/memory.h
@@ -26,6 +26,8 @@
 
 struct Memory {
         unsigned btdata;
+        mstime_t move_time;
+        int move_x, move_y;
 };
 
 void init_memory(struct Memory *mem);