Create Input SlopController
Create a basic input slop controller, and use it for rotary inputs.
Bug: 285957835
Test: atest SlopControllerTest
Change-Id: I0cabfed1f064b849f8151f069e1241292cc374cf
diff --git a/services/inputflinger/reader/mapper/SlopController.cpp b/services/inputflinger/reader/mapper/SlopController.cpp
new file mode 100644
index 0000000..6f31d0e
--- /dev/null
+++ b/services/inputflinger/reader/mapper/SlopController.cpp
@@ -0,0 +1,81 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// clang-format off
+#include "../Macros.h"
+// clang-format on
+
+#include "SlopController.h"
+
+namespace {
+int signOf(float value) {
+ if (value == 0) return 0;
+ if (value > 0) return 1;
+ return -1;
+}
+} // namespace
+
+namespace android {
+
+SlopController::SlopController(float slopThreshold, nsecs_t slopDurationNanos)
+ : mSlopThreshold(slopThreshold), mSlopDurationNanos(slopDurationNanos) {}
+
+SlopController::~SlopController() {}
+
+float SlopController::consumeEvent(nsecs_t eventTimeNanos, float value) {
+ if (mSlopDurationNanos == 0) {
+ return value;
+ }
+
+ if (shouldResetSlopTracking(eventTimeNanos, value)) {
+ mCumulativeValue = 0;
+ mHasSlopBeenMet = false;
+ }
+
+ mLastEventTimeNanos = eventTimeNanos;
+
+ if (mHasSlopBeenMet) {
+ // Since slop has already been met, we know that all of the current value would pass the
+ // slop threshold. So return that, without any further processing.
+ return value;
+ }
+
+ mCumulativeValue += value;
+
+ if (abs(mCumulativeValue) >= mSlopThreshold) {
+ mHasSlopBeenMet = true;
+ // Return the amount of value that exceeds the slop.
+ return signOf(value) * (abs(mCumulativeValue) - mSlopThreshold);
+ }
+
+ return 0;
+}
+
+bool SlopController::shouldResetSlopTracking(nsecs_t eventTimeNanos, float value) {
+ const nsecs_t ageNanos = eventTimeNanos - mLastEventTimeNanos;
+ if (ageNanos >= mSlopDurationNanos) {
+ return true;
+ }
+ if (value == 0) {
+ return false;
+ }
+ if (signOf(mCumulativeValue) != signOf(value)) {
+ return true;
+ }
+ return false;
+}
+
+} // namespace android