Minor refactoring before starting on velocity tracker changes.
Bug: 6413587
Change-Id: I5eba2bb57193bff78cb3740de5f87aca0b31d154
diff --git a/libs/androidfw/VelocityControl.cpp b/libs/androidfw/VelocityControl.cpp
new file mode 100644
index 0000000..cde2b76
--- /dev/null
+++ b/libs/androidfw/VelocityControl.cpp
@@ -0,0 +1,110 @@
+/*
+ * Copyright (C) 2012 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.
+ */
+
+#define LOG_TAG "VelocityControl"
+//#define LOG_NDEBUG 0
+
+// Log debug messages about acceleration.
+#define DEBUG_ACCELERATION 0
+
+#include <math.h>
+#include <limits.h>
+
+#include <androidfw/VelocityControl.h>
+#include <utils/BitSet.h>
+#include <utils/Timers.h>
+
+namespace android {
+
+// --- VelocityControl ---
+
+const nsecs_t VelocityControl::STOP_TIME;
+
+VelocityControl::VelocityControl() {
+ reset();
+}
+
+void VelocityControl::setParameters(const VelocityControlParameters& parameters) {
+ mParameters = parameters;
+ reset();
+}
+
+void VelocityControl::reset() {
+ mLastMovementTime = LLONG_MIN;
+ mRawPosition.x = 0;
+ mRawPosition.y = 0;
+ mVelocityTracker.clear();
+}
+
+void VelocityControl::move(nsecs_t eventTime, float* deltaX, float* deltaY) {
+ if ((deltaX && *deltaX) || (deltaY && *deltaY)) {
+ if (eventTime >= mLastMovementTime + STOP_TIME) {
+#if DEBUG_ACCELERATION
+ ALOGD("VelocityControl: stopped, last movement was %0.3fms ago",
+ (eventTime - mLastMovementTime) * 0.000001f);
+#endif
+ reset();
+ }
+
+ mLastMovementTime = eventTime;
+ if (deltaX) {
+ mRawPosition.x += *deltaX;
+ }
+ if (deltaY) {
+ mRawPosition.y += *deltaY;
+ }
+ mVelocityTracker.addMovement(eventTime, BitSet32(BitSet32::valueForBit(0)), &mRawPosition);
+
+ float vx, vy;
+ float scale = mParameters.scale;
+ if (mVelocityTracker.getVelocity(0, &vx, &vy)) {
+ float speed = hypotf(vx, vy) * scale;
+ if (speed >= mParameters.highThreshold) {
+ // Apply full acceleration above the high speed threshold.
+ scale *= mParameters.acceleration;
+ } else if (speed > mParameters.lowThreshold) {
+ // Linearly interpolate the acceleration to apply between the low and high
+ // speed thresholds.
+ scale *= 1 + (speed - mParameters.lowThreshold)
+ / (mParameters.highThreshold - mParameters.lowThreshold)
+ * (mParameters.acceleration - 1);
+ }
+
+#if DEBUG_ACCELERATION
+ ALOGD("VelocityControl(%0.3f, %0.3f, %0.3f, %0.3f): "
+ "vx=%0.3f, vy=%0.3f, speed=%0.3f, accel=%0.3f",
+ mParameters.scale, mParameters.lowThreshold, mParameters.highThreshold,
+ mParameters.acceleration,
+ vx, vy, speed, scale / mParameters.scale);
+#endif
+ } else {
+#if DEBUG_ACCELERATION
+ ALOGD("VelocityControl(%0.3f, %0.3f, %0.3f, %0.3f): unknown velocity",
+ mParameters.scale, mParameters.lowThreshold, mParameters.highThreshold,
+ mParameters.acceleration);
+#endif
+ }
+
+ if (deltaX) {
+ *deltaX *= scale;
+ }
+ if (deltaY) {
+ *deltaY *= scale;
+ }
+ }
+}
+
+} // namespace android