Reimplement Chromium's OneEuroFilter to InputConsumer
Reimplemented Chromium's OneEuroFilter usage to InputConsumerNoResampling.
There are a few differences between Chromium's work and this CL. We
reimplemented One Euro filter an adaptive cutoff frequency low pass
made in this implementation as in the Chromium's implementation. The
class FilteredResampler filters the output of LegacyResampler using the
One Euro filter approach.
Here's the link to Chromium's to One Euro filter:
https://source.chromium.org/chromium/chromium/src/+/main:ui/base/prediction/one_euro_filter.h
Bug: 297226446
Flag: EXEMPT bugfix
Test: TEST=libinput_tests; m $TEST && $ANDROID_HOST_OUT/nativetest64/$TEST/$TEST
Change-Id: I0316cb1e81c73b1dc28dc809f55dee3a1cc0ebd2
diff --git a/include/input/Resampler.h b/include/input/Resampler.h
index 6d95ca7..1550977 100644
--- a/include/input/Resampler.h
+++ b/include/input/Resampler.h
@@ -19,11 +19,13 @@
#include <array>
#include <chrono>
#include <iterator>
+#include <map>
#include <optional>
#include <vector>
#include <android-base/logging.h>
#include <ftl/mixins.h>
+#include <input/CoordinateFilter.h>
#include <input/Input.h>
#include <input/InputTransport.h>
#include <input/RingBuffer.h>
@@ -293,4 +295,43 @@
inline static void addSampleToMotionEvent(const Sample& sample, MotionEvent& motionEvent);
};
+/**
+ * Resampler that first applies the LegacyResampler resampling algorithm, then independently filters
+ * the X and Y coordinates with a pair of One Euro filters.
+ */
+class FilteredLegacyResampler final : public Resampler {
+public:
+ /**
+ * Creates a resampler, using the given minCutoffFreq and beta to instantiate its One Euro
+ * filters.
+ */
+ explicit FilteredLegacyResampler(float minCutoffFreq, float beta);
+
+ void resampleMotionEvent(std::chrono::nanoseconds requestedFrameTime, MotionEvent& motionEvent,
+ const InputMessage* futureMessage) override;
+
+ std::chrono::nanoseconds getResampleLatency() const override;
+
+private:
+ LegacyResampler mResampler;
+
+ /**
+ * Minimum cutoff frequency of the value's low pass filter. Refer to OneEuroFilter class for a
+ * more detailed explanation.
+ */
+ const float mMinCutoffFreq;
+
+ /**
+ * Scaling factor of the adaptive cutoff frequency criterion. Refer to OneEuroFilter class for a
+ * more detailed explanation.
+ */
+ const float mBeta;
+
+ /*
+ * Note: an associative array with constant insertion and lookup times would be more efficient.
+ * When this was implemented, there was no container with these properties.
+ */
+ std::map<int32_t /*pointerId*/, CoordinateFilter> mFilteredPointers;
+};
+
} // namespace android