Port Chromium OS touch noise filtering to Chromium

ui/events/ozone/evdev/touch_noise/touch_noise_remover.cc

Index: ui/events/ozone/evdev/touch_noise/touch_noise_remover.cc
diff --git a/ui/events/ozone/evdev/touch_noise/touch_noise_remover.cc b/ui/events/ozone/evdev/touch_noise/touch_noise_remover.cc
new file mode 100644
index 0000000000000000000000000000000000000000..da56da7025aefe48b770fdcd87935c2e1612336e
--- /dev/null
+++ b/ui/events/ozone/evdev/touch_noise/touch_noise_remover.cc
@@ -0,0 +1,63 @@
+// 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/touch_noise_remover.h"
+
+#include "base/logging.h"
+#include "base/stl_util.h"
+#include "base/strings/stringprintf.h"
+#include "base/time/time.h"
+#include "ui/events/event.h"
+#include "ui/events/ozone/evdev/device_event_dispatcher_evdev.h"
+#include "ui/events/ozone/evdev/touch_noise/far_apart_taps_touch_noise_filter.h"
+#include "ui/events/ozone/evdev/touch_noise/horizontally_aligned_touch_noise_filter.h"
+#include "ui/events/ozone/evdev/touch_noise/single_position_touch_noise_filter.h"
+
+namespace ui {
+
+TouchNoiseRemover::TouchNoiseRemover() {
+  filters_.push_back(new FarApartTapsTouchNoiseFilter);
+  filters_.push_back(new HorizontallyAlignedTouchNoiseFilter);
+  filters_.push_back(new SinglePositionTouchNoiseFilter);
+}
+
+TouchNoiseRemover::~TouchNoiseRemover() {
+  STLDeleteElements(&filters_);
+}
+
+void TouchNoiseRemover::RemoveNoise(
+    std::vector<ui::TouchEventParams>* touches,
+    base::TimeDelta timestamp) {
+  TouchNoiseFilter::Frame prev_frame = frame_;
+  const int num_slots = static_cast<int>(arraysize(frame_.fingers));
+  frame_.timestamp = timestamp;
+  for (const ui::TouchEventParams& touch : *touches) {
+    int slot = touch.touch_id;
+    if (slot < 0 || slot >= num_slots)

[flackr, 2015/03/10 05:23:40]

Why do we need to check for slot < 0 || slot >= num_slots? Shouldn't all touches
have valid slots?

+      continue;
+
+    DCHECK_EQ(timestamp, touch.timestamp);
+    frame_.fingers[slot].location = touch.location;
+    frame_.fingers[slot].tracking_id =
+        (touch.type == ET_TOUCH_RELEASED) ? -1 : touch.tracking_id;
+
+    if (touch.type == ET_TOUCH_PRESSED)
+      frame_.fingers[slot].canceled = false;
+  }
+
+  for (TouchNoiseFilter* filter : filters_)
+    filter->FilterFrame(&prev_frame, &frame_);
+
+  for (auto it = touches->begin(); it != touches->end();) {
+    int slot = it->touch_id;
+    if (slot < 0 || slot >= num_slots || frame_.fingers[slot].canceled) {

[flackr, 2015/03/10 05:23:40]

ditto

+      VLOG(2) << base::StringPrintf("TrackingID %d cancelled", it->tracking_id);
+      it = touches->erase(it);

[flackr, 2015/03/10 05:23:40]

Should use std::remove_if for linear complexity.

+    } else {
+      ++it;
+    }
+  }
+}
+
+}  // namespace ui