touch_keyboard: Reject taps with unusual pressure
Previously pressure values were collected for tapping fingers on the
keyboard, but nothing was really done with it. Checking pressure values
is a an easy way to reject some bad taps, such as palms and accidentally
brushing the key with a finger. This CL adds in the ability to check
that the maximum pressure value during a tap is within an acceptable
range.
BUG=b:36279311
TEST=emerged onto my Pbody. Typing normally on they keyboard still
works, but pressing with my palm doesn't produce key events anymore
nor do very light taps/brushes.
Change-Id: I2b3fb71944a0b3a50b0229a6c65c8881acd02963
Signed-off-by: Charlie Mooney <charliemooney@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/456044
Reviewed-by: Jingkui Wang <jkwang@google.com>
diff --git a/touch_keyboard/fakekeyboard.cc b/touch_keyboard/fakekeyboard.cc
index 7a2c25a..a215a27 100644
--- a/touch_keyboard/fakekeyboard.cc
+++ b/touch_keyboard/fakekeyboard.cc
@@ -44,6 +44,9 @@
constexpr float kTabWidth = 27.0 * kWidthPitch;
constexpr float kBackspaceWidth = 27.0 * kWidthPitch;
+constexpr int kMinTapPressure = 50;
+constexpr int kMaxTapPressure = 110;
+
FakeKeyboard::FakeKeyboard() : ff_manager_(kInputWidth) {
SetUpLayout();
}
@@ -442,10 +445,21 @@
std::unordered_map<int, FingerData>::iterator it;
it = finger_data_.find(next_event.tid_);
if (it != finger_data_.end()) {
- // TODO(charliemooney): See if this event is still valid! Currently,
- // this just assumes they are valid because there are no invalidating
- // conditions at the deadline yet. Something like "pressure never
- // exceeded a threshold" would be a good check to add here later.
+ // Here we check to see if this event is still valid before firing it
+ // off to the OS. Currently there is only a pressure check here, but
+ // more could easily be added later.
+
+ // This checks if the maximum pressure a finger reported is within
+ // range. An exception is made for the spacebar since it is often
+ // pressed by a user's thumb, which may have unusually high pressure.
+ if (it->second.max_pressure_ < kMinTapPressure ||
+ (layout_[it->second.starting_key_number_].event_code_ !=
+ KEY_SPACE && it->second.max_pressure_ > kMaxTapPressure)) {
+ LOG(INFO) << "Tap rejected! Pressure of " <<
+ it->second.max_pressure_ << " is out of range " <<
+ kMinTapPressure << "->" << kMaxTapPressure;
+ continue;
+ }
} else {
// The finger has already left -- that's OK as long as it is
// "guaranteed" to fire.
