Merge "Make velocity tracker strategy configurable." into jb-dev

Author: Jeff Brown

core/java/android/view/VelocityTracker.java

@@ -35,7 +35,7 @@ public final class VelocityTracker implements Poolable<VelocityTracker> {
     private static final Pool<VelocityTracker> sPool = Pools.synchronizedPool(
             Pools.finitePool(new PoolableManager<VelocityTracker>() {
                 public VelocityTracker newInstance() {
-                    return new VelocityTracker();
+                    return new VelocityTracker(null);
                 }
 
                 public void onAcquired(VelocityTracker element) {
@@ -50,10 +50,12 @@ public void onReleased(VelocityTracker element) {
     private static final int ACTIVE_POINTER_ID = -1;
 
     private int mPtr;
+    private final String mStrategy;
+
     private VelocityTracker mNext;
     private boolean mIsPooled;
 
-    private static native int nativeInitialize();
+    private static native int nativeInitialize(String strategy);
     private static native void nativeDispose(int ptr);
     private static native void nativeClear(int ptr);
     private static native void nativeAddMovement(int ptr, MotionEvent event);
@@ -74,12 +76,30 @@ static public VelocityTracker obtain() {
         return sPool.acquire();
     }
 
+    /**
+     * Obtains a velocity tracker with the specified strategy.
+     * For testing and comparison purposes only.
+     *
+     * @param strategy The strategy, or null to use the default.
+     * @return The velocity tracker.
+     *
+     * @hide
+     */
+    public static VelocityTracker obtain(String strategy) {
+        if (strategy == null) {
+            return obtain();
+        }
+        return new VelocityTracker(strategy);
+    }
+
     /**
      * Return a VelocityTracker object back to be re-used by others.  You must
      * not touch the object after calling this function.
      */
     public void recycle() {
-        sPool.release(this);
+        if (mStrategy == null) {
+            sPool.release(this);
+        }
     }
 
     /**
@@ -110,8 +130,9 @@ public void setPooled(boolean isPooled) {
         mIsPooled = isPooled;
     }
 
-    private VelocityTracker() {
-        mPtr = nativeInitialize();
+    private VelocityTracker(String strategy) {
+        mPtr = nativeInitialize(strategy);
+        mStrategy = strategy;
     }
 
     @Override
@@ -253,7 +274,7 @@ public boolean getEstimator(int id, Estimator outEstimator) {
      */
     public static final class Estimator {
         // Must match VelocityTracker::Estimator::MAX_DEGREE
-        private static final int MAX_DEGREE = 2;
+        private static final int MAX_DEGREE = 4;
 
         /**
          * Polynomial coefficients describing motion in X.

core/java/com/android/internal/widget/PointerLocationView.java

@@ -23,6 +23,7 @@
 import android.graphics.Paint.FontMetricsInt;
 import android.hardware.input.InputManager;
 import android.hardware.input.InputManager.InputDeviceListener;
+import android.os.SystemProperties;
 import android.util.Log;
 import android.view.InputDevice;
 import android.view.KeyEvent;
@@ -36,7 +37,11 @@
 
 public class PointerLocationView extends View implements InputDeviceListener {
     private static final String TAG = "Pointer";
-    
+
+    // The system property key used to specify an alternate velocity tracker strategy
+    // to plot alongside the default one.  Useful for testing and comparison purposes.
+    private static final String ALT_STRATEGY_PROPERY_KEY = "debug.velocitytracker.alt";
+
     public static class PointerState {
         // Trace of previous points.
         private float[] mTraceX = new float[32];
@@ -53,9 +58,12 @@ public static class PointerState {
         // Most recent velocity.
         private float mXVelocity;
         private float mYVelocity;
+        private float mAltXVelocity;
+        private float mAltYVelocity;
 
         // Position estimator.
         private VelocityTracker.Estimator mEstimator = new VelocityTracker.Estimator();
+        private VelocityTracker.Estimator mAltEstimator = new VelocityTracker.Estimator();
 
         public void clearTrace() {
             mTraceCount = 0;
@@ -103,7 +111,8 @@ public void addTrace(float x, float y) {
     private final PointerCoords mTempCoords = new PointerCoords();
 
     private final VelocityTracker mVelocity;
-    
+    private final VelocityTracker mAltVelocity;
+
     private final FasterStringBuilder mText = new FasterStringBuilder();
 
     private boolean mPrintCoords = true;
@@ -145,6 +154,14 @@ public PointerLocationView(Context c) {
         mActivePointerId = 0;
 
         mVelocity = VelocityTracker.obtain();
+
+        String altStrategy = SystemProperties.get(ALT_STRATEGY_PROPERY_KEY);
+        if (altStrategy.length() != 0) {
+            Log.d(TAG, "Comparing default velocity tracker strategy with " + altStrategy);
+            mAltVelocity = VelocityTracker.obtain(altStrategy);
+        } else {
+            mAltVelocity = null;
+        }
     }
 
     public void setPrintCoords(boolean state) {
@@ -296,6 +313,25 @@ protected void onDraw(Canvas canvas) {
                 float xVel = ps.mXVelocity * (1000 / 60);
                 float yVel = ps.mYVelocity * (1000 / 60);
                 canvas.drawLine(lastX, lastY, lastX + xVel, lastY + yVel, mPaint);
+
+                // Draw alternate estimate.
+                if (mAltVelocity != null) {
+                    mPaint.setARGB(128, 0, 128, 128);
+                    lx = ps.mAltEstimator.estimateX(-ESTIMATE_PAST_POINTS * ESTIMATE_INTERVAL);
+                    ly = ps.mAltEstimator.estimateY(-ESTIMATE_PAST_POINTS * ESTIMATE_INTERVAL);
+                    for (int i = -ESTIMATE_PAST_POINTS + 1; i <= ESTIMATE_FUTURE_POINTS; i++) {
+                        float x = ps.mAltEstimator.estimateX(i * ESTIMATE_INTERVAL);
+                        float y = ps.mAltEstimator.estimateY(i * ESTIMATE_INTERVAL);
+                        canvas.drawLine(lx, ly, x, y, mPaint);
+                        lx = x;
+                        ly = y;
+                    }
+
+                    mPaint.setARGB(255, 64, 255, 128);
+                    xVel = ps.mAltXVelocity * (1000 / 60);
+                    yVel = ps.mAltYVelocity * (1000 / 60);
+                    canvas.drawLine(lastX, lastY, lastX + xVel, lastY + yVel, mPaint);
+                }
             }
 
             if (mCurDown && ps.mCurDown) {
@@ -470,6 +506,9 @@ public void addPointerEvent(MotionEvent event) {
                 mCurNumPointers = 0;
                 mMaxNumPointers = 0;
                 mVelocity.clear();
+                if (mAltVelocity != null) {
+                    mAltVelocity.clear();
+                }
             }
 
             mCurNumPointers += 1;
@@ -497,6 +536,10 @@ public void addPointerEvent(MotionEvent event) {
 
         mVelocity.addMovement(event);
         mVelocity.computeCurrentVelocity(1);
+        if (mAltVelocity != null) {
+            mAltVelocity.addMovement(event);
+            mAltVelocity.computeCurrentVelocity(1);
+        }
 
         final int N = event.getHistorySize();
         for (int historyPos = 0; historyPos < N; historyPos++) {
@@ -528,6 +571,11 @@ public void addPointerEvent(MotionEvent event) {
                 ps.mXVelocity = mVelocity.getXVelocity(id);
                 ps.mYVelocity = mVelocity.getYVelocity(id);
                 mVelocity.getEstimator(id, ps.mEstimator);
+                if (mAltVelocity != null) {
+                    ps.mAltXVelocity = mAltVelocity.getXVelocity(id);
+                    ps.mAltYVelocity = mAltVelocity.getYVelocity(id);
+                    mAltVelocity.getEstimator(id, ps.mAltEstimator);
+                }
                 ps.mToolType = event.getToolType(i);
             }
         }

core/jni/android_view_VelocityTracker.cpp

@@ -24,6 +24,8 @@
 #include <androidfw/VelocityTracker.h>
 #include "android_view_MotionEvent.h"
 
+#include <ScopedUtfChars.h>
+
 
 namespace android {
 
@@ -42,7 +44,7 @@ static struct {
 
 class VelocityTrackerState {
 public:
-    VelocityTrackerState();
+    VelocityTrackerState(const char* strategy);
 
     void clear();
     void addMovement(const MotionEvent* event);
@@ -61,7 +63,8 @@ class VelocityTrackerState {
     Velocity mCalculatedVelocity[MAX_POINTERS];
 };
 
-VelocityTrackerState::VelocityTrackerState() : mActivePointerId(-1) {
+VelocityTrackerState::VelocityTrackerState(const char* strategy) :
+        mVelocityTracker(strategy), mActivePointerId(-1) {
 }
 
 void VelocityTrackerState::clear() {
@@ -135,8 +138,13 @@ bool VelocityTrackerState::getEstimator(int32_t id, VelocityTracker::Estimator*
 
 // --- JNI Methods ---
 
-static jint android_view_VelocityTracker_nativeInitialize(JNIEnv* env, jclass clazz) {
-    return reinterpret_cast<jint>(new VelocityTrackerState());
+static jint android_view_VelocityTracker_nativeInitialize(JNIEnv* env, jclass clazz,
+        jstring strategyStr) {
+    if (strategyStr) {
+        ScopedUtfChars strategy(env, strategyStr);
+        return reinterpret_cast<jint>(new VelocityTrackerState(strategy.c_str()));
+    }
+    return reinterpret_cast<jint>(new VelocityTrackerState(NULL));
 }
 
 static void android_view_VelocityTracker_nativeDispose(JNIEnv* env, jclass clazz, jint ptr) {
@@ -209,7 +217,7 @@ static jboolean android_view_VelocityTracker_nativeGetEstimator(JNIEnv* env, jcl
 static JNINativeMethod gVelocityTrackerMethods[] = {
     /* name, signature, funcPtr */
     { "nativeInitialize",
-            "()I",
+            "(Ljava/lang/String;)I",
             (void*)android_view_VelocityTracker_nativeInitialize },
     { "nativeDispose",
             "(I)V",

include/androidfw/VelocityTracker.h

@@ -35,7 +35,7 @@ class VelocityTracker {
     };
 
     struct Estimator {
-        static const size_t MAX_DEGREE = 2;
+        static const size_t MAX_DEGREE = 4;
 
         // Estimator time base.
         nsecs_t time;
@@ -61,7 +61,10 @@ class VelocityTracker {
         }
     };
 
-    VelocityTracker();
+    // Creates a velocity tracker using the specified strategy.
+    // If strategy is NULL, uses the default strategy for the platform.
+    VelocityTracker(const char* strategy = NULL);
+
     ~VelocityTracker();
 
     // Resets the velocity tracker state.
@@ -99,10 +102,16 @@ class VelocityTracker {
     inline BitSet32 getCurrentPointerIdBits() const { return mCurrentPointerIdBits; }
 
 private:
+    static const char* DEFAULT_STRATEGY;
+
     nsecs_t mLastEventTime;
     BitSet32 mCurrentPointerIdBits;
     int32_t mActivePointerId;
     VelocityTrackerStrategy* mStrategy;
+
+    bool configureStrategy(const char* strategy);
+
+    static VelocityTrackerStrategy* createStrategy(const char* strategy);
 };
 
 
@@ -129,7 +138,8 @@ class VelocityTrackerStrategy {
  */
 class LeastSquaresVelocityTrackerStrategy : public VelocityTrackerStrategy {
 public:
-    LeastSquaresVelocityTrackerStrategy();
+    // Degree must be no greater than Estimator::MAX_DEGREE.
+    LeastSquaresVelocityTrackerStrategy(uint32_t degree);
     virtual ~LeastSquaresVelocityTrackerStrategy();
 
     virtual void clear();
@@ -139,9 +149,6 @@ class LeastSquaresVelocityTrackerStrategy : public VelocityTrackerStrategy {
     virtual bool getEstimator(uint32_t id, VelocityTracker::Estimator* outEstimator) const;
 
 private:
-    // Polynomial degree.  Must be less than or equal to Estimator::MAX_DEGREE.
-    static const uint32_t DEGREE = 2;
-
     // Sample horizon.
     // We don't use too much history by default since we want to react to quick
     // changes in direction.
@@ -160,6 +167,7 @@ class LeastSquaresVelocityTrackerStrategy : public VelocityTrackerStrategy {
         }
     };
 
+    const uint32_t mDegree;
     uint32_t mIndex;
     Movement mMovements[HISTORY_SIZE];
 };