Index: ui/events/ozone/evdev/touch_noise/single_position_touch_noise_filter.cc |
diff --git a/ui/events/ozone/evdev/touch_noise/single_position_touch_noise_filter.cc b/ui/events/ozone/evdev/touch_noise/single_position_touch_noise_filter.cc |
new file mode 100644 |
index 0000000000000000000000000000000000000000..bd389e292a9fecd35733e72d3c3d19ed7702b0fb |
--- /dev/null |
+++ b/ui/events/ozone/evdev/touch_noise/single_position_touch_noise_filter.cc |
@@ -0,0 +1,151 @@ |
+// Copyright 2015 The Chromium Authors. All rights reserved. |
+// Use of this source code is governed by a BSD-style license that can be |
+// found in the LICENSE file. |
+ |
+#include "ui/events/ozone/evdev/touch_noise/single_position_touch_noise_filter.h" |
+ |
+#include "base/logging.h" |
+#include "base/strings/stringprintf.h" |
+ |
+namespace ui { |
+ |
+namespace { |
+ |
+// Max squared distance between fingers for the fingers to be considered in the |
+// same position. |
+const int kSamePositionMaxDistance2 = 2 * 2; |
+ |
+// Max squared movement of a finger before it's no longer considered noise. |
+const int kNoiseMaxMovement2 = 2 * 2; |
+ |
+// Min duration in milliseconds after which touches in the same position are |
+// considered noise. |
+const int kMinDurationMs = 2000; |
+ |
+// Max duration in milliseconds to check for common positions with previous |
+// touches. |
+const int kMaxDurationMs = 4000; |
+ |
+// Returns the squared distance between (|x1|, |y1|) and (|x2|, |y2|) |
+int Distance2(int x1, int y1, int x2, int y2) { |
+ int offset_x = x2 - x1; |
+ int offset_y = y2 - y1; |
+ return offset_x * offset_x + offset_y * offset_y; |
+} |
+ |
+} // namespace |
+ |
+SinglePositionTouchNoiseFilter::SinglePositionTouchNoiseFilter() |
+ : tracked_touches_start_(0), tracked_touches_end_(0) { |
+ for (size_t i = 0; i < kNumTouchEvdevSlots; ++i) |
+ tracked_slots_[i] = kNumTrackedTouches; |
+} |
+ |
+void SinglePositionTouchNoiseFilter::Filter( |
+ const std::vector<InProgressTouchEvdev>& touches, |
+ base::TimeDelta time, |
+ std::bitset<kNumTouchEvdevSlots>* slots_with_noise) { |
+ // Forget old touches which will no longer be considered for overlap. |
+ base::TimeDelta touch_cutoff = |
+ time - base::TimeDelta::FromMilliseconds(kMaxDurationMs); |
+ for (size_t i = tracked_touches_start_; i != tracked_touches_end_; |
+ i = (i + 1) % kNumTrackedTouches) { |
+ if (!tracked_touches_[i].valid) |
+ continue; |
+ if (tracked_touches_[i].end < touch_cutoff) |
+ StopTrackingTouch(i); |
+ } |
+ |
+ for (const InProgressTouchEvdev& touch : touches) { |
+ size_t slot = touch.slot; |
+ |
+ bool arrived = touch.touching && !touch.was_touching; |
+ bool departed = !touch.touching && touch.was_touching; |
+ if (departed) |
+ tracked_slots_[slot] = kNumTrackedTouches; |
+ if (!touch.touching) |
+ continue; |
+ |
+ // Track all new touches until they move too far. |
+ if (arrived) |
+ TrackTouch(touch, time); |
+ |
+ size_t t_ind = tracked_slots_[slot]; |
+ if (t_ind != kNumTrackedTouches) { |
+ tracked_touches_[t_ind].end = time; |
+ // Stop tracking if touch moves more than sqrt(kNoiseMaxMovement2). |
+ if (Distance2(touch.x, touch.y, tracked_touches_[t_ind].x, |
+ tracked_touches_[t_ind].y) > kNoiseMaxMovement2) { |
+ StopTrackingTouch(t_ind); |
+ } else { |
+ // Determine duration over which touches have been occuring in this |
+ // position. |
+ base::TimeDelta max_duration; |
+ for (size_t i = tracked_touches_start_; i != tracked_touches_end_; |
+ i = (i + 1) % kNumTrackedTouches) { |
+ TrackedTouch* tracked_touch = &tracked_touches_[i]; |
+ if (!tracked_touch->valid) |
+ continue; |
+ if (Distance2(touch.x, touch.y, tracked_touch->x, tracked_touch->y) <= |
+ kSamePositionMaxDistance2) { |
+ base::TimeDelta duration = time - tracked_touch->begin; |
+ if (duration > max_duration) |
+ max_duration = duration; |
+ } |
+ } |
+ |
+ if (max_duration.InMilliseconds() > kMinDurationMs) { |
+ VLOG(2) << base::StringPrintf( |
+ "Cancel tracking id %d, in position occurring for %ldms", |
+ touch.tracking_id, max_duration.InMilliseconds()); |
+ slots_with_noise->set(slot); |
+ } |
+ } |
+ } |
+ } |
+} |
+ |
+void SinglePositionTouchNoiseFilter::StopTrackingTouch(size_t index) { |
+ size_t slot = tracked_touches_[index].slot; |
+ if (tracked_slots_[slot] == index) |
+ tracked_slots_[slot] = kNumTrackedTouches; |
+ tracked_touches_[index].valid = false; |
+ |
+ // If first touch is canceled, remove all dead touches. |
+ if (index == tracked_touches_start_) { |
+ while (!tracked_touches_[tracked_touches_start_].valid && |
+ tracked_touches_start_ != tracked_touches_end_) { |
+ tracked_touches_start_ = |
+ (tracked_touches_start_ + 1) % kNumTrackedTouches; |
+ } |
+ } |
+} |
+ |
+void SinglePositionTouchNoiseFilter::TrackTouch( |
+ const InProgressTouchEvdev& touch, |
+ base::TimeDelta time) { |
+ size_t index = (tracked_touches_end_ + 1) % kNumTrackedTouches; |
+ // If we would reach the start touch index, we cannot track any more touches. |
+ if (index == tracked_touches_start_) |
+ return; |
+ |
+ tracked_touches_end_ = index; |
+ tracked_touches_[index].valid = true; |
+ tracked_touches_[index].slot = touch.slot; |
+ tracked_touches_[index].x = touch.x; |
+ tracked_touches_[index].y = touch.y; |
+ tracked_touches_[index].begin = time; |
+ tracked_touches_[index].end = time; |
+ tracked_slots_[touch.slot] = index; |
+} |
+ |
+SinglePositionTouchNoiseFilter::SinglePositionTouchNoiseFilter::TrackedTouch:: |
+ TrackedTouch() |
+ : valid(false), slot(0), x(0), y(0) { |
+} |
+ |
+SinglePositionTouchNoiseFilter::SinglePositionTouchNoiseFilter::TrackedTouch:: |
+ ~TrackedTouch() { |
+} |
+ |
+} // namespace ui |