Only extract movement from identical finger configurations

The current code would extract movement from a rapid change
from one finger to the next, resulting in unwanted jumps. This
patch first checks that the finger configuration is the same
before attempting to extract movement.

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

1 files changed, 21 insertions, 16 deletions

diff --git a/src/gestures.c b/src/gestures.c
index f26aba8..c837d6c 100644
--- a/src/gestures.c
+++ b/src/gestures.c
@@ -23,24 +23,29 @@
 
 static void extract_movement(struct Gestures *gs, struct MTouch* mt)
 {
-        const struct FingerState *b = mt->state.finger;
-        const struct FingerState *e = b + mt->state.nfinger;
-        const struct FingerState *p, *fs;
-        int dn = 0, i;
-        if (mt->state.nfinger == mt->prev_state.nfinger) {
-                for (p = b; p != e; p++) {
-                        fs = find_finger(&mt->prev_state, p->id);
-                        if (fs) {
-                                gs->dx += p->hw.position_x - fs->hw.position_x;
-                                gs->dy += p->hw.position_y - fs->hw.position_y;
-                                dn++;
-                        }
-                }
+        const struct FingerState *prev[DIM_FINGER];
+        const struct FingerState *f = mt->state.finger;
+        int same_fingers, i;
+
+        if (mt->state.nfinger == 0)
+                return;
+
+        same_fingers = mt->state.nfinger == mt->prev_state.nfinger;
+        for (i = 0; i < mt->state.nfinger; i++) {
+                prev[i] = find_finger(&mt->prev_state, mt->state.finger[i].id);
+                same_fingers = same_fingers && prev[i];
         }
-        if (dn) {
-                gs->dx /= dn;
-                gs->dy /= dn;
+
+        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;
         }
+
+        gs->dx /= mt->state.nfinger;
+        gs->dy /= mt->state.nfinger;
 }
 
 static void extract_buttons(struct Gestures *gs, struct MTouch* mt)