Split the MT state syncing and event generation into two functions

In the near future, we will need to handle slot termination *before* any other
state synchronization. So let's start splitting things up.

This is functionally equivalent though dropping the need_tracking_id_changes
variable means we run through all slots now to check if we need to terminate
one of them. Given the normal number of slots on a device and that this should
only ever run very rarely anyway... meh.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

diff --git a/libevdev/libevdev.c b/libevdev/libevdev.c
index 124e987209b35a1ee5cc2aaf495ce2fe1717e9f5..aa2e964a5f4f811afd4316e456ab1d86024cf617 100644 (file)
--- a/libevdev/libevdev.c
+++ b/libevdev/libevdev.c
@@ -59,7 +59,8 @@ struct slot_change_state {
        unsigned long axes[NLONGS(ABS_CNT)]; /* bitmask for updated axes */
 };
 
-static int sync_mt_state(struct libevdev *dev, int create_events);
+static int sync_mt_state(struct libevdev *dev,
+                        struct slot_change_state *changes_out);
 
 static inline int*
 slot_value(const struct libevdev *dev, int slot, int axis)
@@ -533,8 +534,10 @@ libevdev_set_fd(struct libevdev* dev, int fd)
        if (rc != 0)
                goto out;
 
-       if (dev->num_slots != -1)
-               sync_mt_state(dev, 0);
+       if (dev->num_slots != -1) {
+               struct slot_change_state unused[dev->num_slots];
+               sync_mt_state(dev, unused);
+       }
 
        rc = init_event_queue(dev);
        if (rc < 0) {
@@ -669,13 +672,11 @@ out:
 }
 
 static int
-sync_mt_state(struct libevdev *dev, int create_events)
+sync_mt_state(struct libevdev *dev,
+             struct slot_change_state changes_out[dev->num_slots])
 {
-       struct input_absinfo abs_info;
        int rc;
-       int last_reported_slot = 0;
        struct slot_change_state changes[dev->num_slots];
-       int need_tracking_id_changes = 0;
 
        memset(changes, 0, sizeof(changes));
 
@@ -710,7 +711,6 @@ sync_mt_state(struct libevdev *dev, int create_events)
                                } else if (val_before != -1 && val_after != -1 &&
                                           val_before != val_after) {
                                        changes[slot].state = TOUCH_CHANGED;
-                                       need_tracking_id_changes = 1;
                                } else {
                                        changes[slot].state = TOUCH_OFF;
                                }
@@ -727,25 +727,37 @@ sync_mt_state(struct libevdev *dev, int create_events)
                }
        }
 
-       if (!create_events) {
-               rc = 0;
-               goto out;
-       }
+       memcpy(changes_out, changes, sizeof(changes));
+out:
+       return rc;
+}
 
-       if (need_tracking_id_changes) {
-               for (int slot = 0; slot < dev->num_slots;  slot++) {
-                       if (changes[slot].state != TOUCH_CHANGED)
-                               continue;
+static int
+push_mt_sync_events(struct libevdev *dev,
+                   const struct slot_change_state changes[dev->num_slots])
+{
+       struct input_absinfo abs_info;
+       int last_reported_slot = 0;
+       int rc;
+       bool touches_stopped = false;
 
-                       queue_push_event(dev, EV_ABS, ABS_MT_SLOT, slot);
-                       queue_push_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
+       for (int slot = 0; slot < dev->num_slots;  slot++) {
+               if (changes[slot].state != TOUCH_CHANGED)
+                       continue;
 
-                       last_reported_slot = slot;
-               }
+               queue_push_event(dev, EV_ABS, ABS_MT_SLOT, slot);
+               queue_push_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
 
-               queue_push_event(dev, EV_SYN, SYN_REPORT, 0);
+               last_reported_slot = slot;
+               touches_stopped = true;
        }
 
+       /* If any of the touches stopped, we need to split the sync state
+          into two frames - one with all the stopped touches, one with the
+          new touches starting (if any) */
+       if (touches_stopped)
+               queue_push_event(dev, EV_SYN, SYN_REPORT, 0);
+
        for (int slot = 0; slot < dev->num_slots;  slot++) {
                if (!bit_is_set(changes[slot].axes, ABS_MT_SLOT))
                        continue;
@@ -859,8 +871,13 @@ sync_state(struct libevdev *dev)
        if (rc == 0 && libevdev_has_event_type(dev, EV_ABS))
                rc = sync_abs_state(dev);
        if (rc == 0 && dev->num_slots > -1 &&
-           libevdev_has_event_code(dev, EV_ABS, ABS_MT_SLOT))
-               rc = sync_mt_state(dev, 1);
+           libevdev_has_event_code(dev, EV_ABS, ABS_MT_SLOT)) {
+               struct slot_change_state changes[dev->num_slots];
+
+               rc = sync_mt_state(dev, changes);
+               if (rc == 0)
+                       push_mt_sync_events(dev, changes);
+       }
 
        dev->queue_nsync = queue_num_elements(dev);