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-rw-r--r--core/java/android/view/VelocityTracker.java335
1 files changed, 44 insertions, 291 deletions
diff --git a/core/java/android/view/VelocityTracker.java b/core/java/android/view/VelocityTracker.java
index 4ab2881..fccef2b 100644
--- a/core/java/android/view/VelocityTracker.java
+++ b/core/java/android/view/VelocityTracker.java
@@ -16,8 +16,6 @@
package android.view;
-import android.util.Config;
-import android.util.Log;
import android.util.Poolable;
import android.util.Pool;
import android.util.Pools;
@@ -25,24 +23,15 @@ import android.util.PoolableManager;
/**
* Helper for tracking the velocity of touch events, for implementing
- * flinging and other such gestures. Use {@link #obtain} to retrieve a
- * new instance of the class when you are going to begin tracking, put
- * the motion events you receive into it with {@link #addMovement(MotionEvent)},
- * and when you want to determine the velocity call
- * {@link #computeCurrentVelocity(int)} and then {@link #getXVelocity()}
- * and {@link #getXVelocity()}.
+ * flinging and other such gestures.
+ *
+ * Use {@link #obtain} to retrieve a new instance of the class when you are going
+ * to begin tracking. Put the motion events you receive into it with
+ * {@link #addMovement(MotionEvent)}. When you want to determine the velocity call
+ * {@link #computeCurrentVelocity(int)} and then call {@link #getXVelocity(int)}
+ * and {@link #getXVelocity(int)} to retrieve the velocity for each pointer id.
*/
public final class VelocityTracker implements Poolable<VelocityTracker> {
- private static final String TAG = "VelocityTracker";
- private static final boolean DEBUG = false;
- private static final boolean localLOGV = DEBUG || Config.LOGV;
-
- private static final int NUM_PAST = 10;
- private static final int MAX_AGE_MILLISECONDS = 200;
-
- private static final int POINTER_POOL_CAPACITY = 20;
- private static final int INVALID_POINTER = -1;
-
private static final Pool<VelocityTracker> sPool = Pools.synchronizedPool(
Pools.finitePool(new PoolableManager<VelocityTracker>() {
public VelocityTracker newInstance() {
@@ -56,31 +45,20 @@ public final class VelocityTracker implements Poolable<VelocityTracker> {
element.clear();
}
}, 2));
-
- private static Pointer sRecycledPointerListHead;
- private static int sRecycledPointerCount;
-
- private static final class Pointer {
- public Pointer next;
-
- public int id;
- public float xVelocity;
- public float yVelocity;
-
- public final float[] pastX = new float[NUM_PAST];
- public final float[] pastY = new float[NUM_PAST];
- public final long[] pastTime = new long[NUM_PAST]; // uses Long.MIN_VALUE as a sentinel
-
- public int generation;
- }
-
- private Pointer mPointerListHead; // sorted by id in increasing order
- private int mLastTouchIndex;
- private int mGeneration;
- private int mActivePointerId;
+ private static final int ACTIVE_POINTER_ID = -1;
+
+ private int mPtr;
private VelocityTracker mNext;
+ private static native int nativeInitialize();
+ private static native void nativeDispose(int ptr);
+ private static native void nativeClear(int ptr);
+ private static native void nativeAddMovement(int ptr, MotionEvent event);
+ private static native void nativeComputeCurrentVelocity(int ptr, int units, float maxVelocity);
+ private static native float nativeGetXVelocity(int ptr, int id);
+ private static native float nativeGetYVelocity(int ptr, int id);
+
/**
* Retrieve a new VelocityTracker object to watch the velocity of a
* motion. Be sure to call {@link #recycle} when done. You should
@@ -116,18 +94,26 @@ public final class VelocityTracker implements Poolable<VelocityTracker> {
}
private VelocityTracker() {
- clear();
+ mPtr = nativeInitialize();
}
-
+
+ @Override
+ protected void finalize() throws Throwable {
+ try {
+ if (mPtr != 0) {
+ nativeDispose(mPtr);
+ mPtr = 0;
+ }
+ } finally {
+ super.finalize();
+ }
+ }
+
/**
* Reset the velocity tracker back to its initial state.
*/
public void clear() {
- releasePointerList(mPointerListHead);
-
- mPointerListHead = null;
- mLastTouchIndex = 0;
- mActivePointerId = INVALID_POINTER;
+ nativeClear(mPtr);
}
/**
@@ -137,110 +123,13 @@ public final class VelocityTracker implements Poolable<VelocityTracker> {
* final {@link MotionEvent#ACTION_UP}. You can, however, call this
* for whichever events you desire.
*
- * @param ev The MotionEvent you received and would like to track.
+ * @param event The MotionEvent you received and would like to track.
*/
- public void addMovement(MotionEvent ev) {
- final int historySize = ev.getHistorySize();
- final int pointerCount = ev.getPointerCount();
- final int lastTouchIndex = mLastTouchIndex;
- final int nextTouchIndex = (lastTouchIndex + 1) % NUM_PAST;
- final int finalTouchIndex = (nextTouchIndex + historySize) % NUM_PAST;
- final int generation = mGeneration++;
-
- mLastTouchIndex = finalTouchIndex;
-
- // Update pointer data.
- Pointer previousPointer = null;
- for (int i = 0; i < pointerCount; i++){
- final int pointerId = ev.getPointerId(i);
-
- // Find the pointer data for this pointer id.
- // This loop is optimized for the common case where pointer ids in the event
- // are in sorted order. However, we check for this case explicitly and
- // perform a full linear scan from the start if needed.
- Pointer nextPointer;
- if (previousPointer == null || pointerId < previousPointer.id) {
- previousPointer = null;
- nextPointer = mPointerListHead;
- } else {
- nextPointer = previousPointer.next;
- }
-
- final Pointer pointer;
- for (;;) {
- if (nextPointer != null) {
- final int nextPointerId = nextPointer.id;
- if (nextPointerId == pointerId) {
- pointer = nextPointer;
- break;
- }
- if (nextPointerId < pointerId) {
- nextPointer = nextPointer.next;
- continue;
- }
- }
-
- // Pointer went down. Add it to the list.
- // Write a sentinel at the end of the pastTime trace so we will be able to
- // tell when the trace started.
- if (mActivePointerId == INVALID_POINTER) {
- // Congratulations! You're the new active pointer!
- mActivePointerId = pointerId;
- }
- pointer = obtainPointer();
- pointer.id = pointerId;
- pointer.pastTime[lastTouchIndex] = Long.MIN_VALUE;
- pointer.next = nextPointer;
- if (previousPointer == null) {
- mPointerListHead = pointer;
- } else {
- previousPointer.next = pointer;
- }
- break;
- }
-
- pointer.generation = generation;
- previousPointer = pointer;
-
- final float[] pastX = pointer.pastX;
- final float[] pastY = pointer.pastY;
- final long[] pastTime = pointer.pastTime;
-
- for (int j = 0; j < historySize; j++) {
- final int touchIndex = (nextTouchIndex + j) % NUM_PAST;
- pastX[touchIndex] = ev.getHistoricalX(i, j);
- pastY[touchIndex] = ev.getHistoricalY(i, j);
- pastTime[touchIndex] = ev.getHistoricalEventTime(j);
- }
- pastX[finalTouchIndex] = ev.getX(i);
- pastY[finalTouchIndex] = ev.getY(i);
- pastTime[finalTouchIndex] = ev.getEventTime();
- }
-
- // Find removed pointers.
- previousPointer = null;
- for (Pointer pointer = mPointerListHead; pointer != null; ) {
- final Pointer nextPointer = pointer.next;
- final int pointerId = pointer.id;
- if (pointer.generation != generation) {
- // Pointer went up. Remove it from the list.
- if (previousPointer == null) {
- mPointerListHead = nextPointer;
- } else {
- previousPointer.next = nextPointer;
- }
- releasePointer(pointer);
-
- if (pointerId == mActivePointerId) {
- // Pick a new active pointer. How is arbitrary.
- mActivePointerId = mPointerListHead != null ?
- mPointerListHead.id : INVALID_POINTER;
- }
- } else {
- previousPointer = pointer;
- }
- pointer = nextPointer;
+ public void addMovement(MotionEvent event) {
+ if (event == null) {
+ throw new IllegalArgumentException("event must not be null");
}
+ nativeAddMovement(mPtr, event);
}
/**
@@ -250,7 +139,7 @@ public final class VelocityTracker implements Poolable<VelocityTracker> {
* @see #computeCurrentVelocity(int, float)
*/
public void computeCurrentVelocity(int units) {
- computeCurrentVelocity(units, Float.MAX_VALUE);
+ nativeComputeCurrentVelocity(mPtr, units, Float.MAX_VALUE);
}
/**
@@ -267,78 +156,7 @@ public final class VelocityTracker implements Poolable<VelocityTracker> {
* must be positive.
*/
public void computeCurrentVelocity(int units, float maxVelocity) {
- final int lastTouchIndex = mLastTouchIndex;
-
- for (Pointer pointer = mPointerListHead; pointer != null; pointer = pointer.next) {
- final long[] pastTime = pointer.pastTime;
-
- // Search backwards in time for oldest acceptable time.
- // Stop at the beginning of the trace as indicated by the sentinel time Long.MIN_VALUE.
- int oldestTouchIndex = lastTouchIndex;
- int numTouches = 1;
- final long minTime = pastTime[lastTouchIndex] - MAX_AGE_MILLISECONDS;
- while (numTouches < NUM_PAST) {
- final int nextOldestTouchIndex = (oldestTouchIndex + NUM_PAST - 1) % NUM_PAST;
- final long nextOldestTime = pastTime[nextOldestTouchIndex];
- if (nextOldestTime < minTime) { // also handles end of trace sentinel
- break;
- }
- oldestTouchIndex = nextOldestTouchIndex;
- numTouches += 1;
- }
-
- // If we have a lot of samples, skip the last received sample since it is
- // probably pretty noisy compared to the sum of all of the traces already acquired.
- if (numTouches > 3) {
- numTouches -= 1;
- }
-
- // Kind-of stupid.
- final float[] pastX = pointer.pastX;
- final float[] pastY = pointer.pastY;
-
- final float oldestX = pastX[oldestTouchIndex];
- final float oldestY = pastY[oldestTouchIndex];
- final long oldestTime = pastTime[oldestTouchIndex];
-
- float accumX = 0;
- float accumY = 0;
-
- for (int i = 1; i < numTouches; i++) {
- final int touchIndex = (oldestTouchIndex + i) % NUM_PAST;
- final int duration = (int)(pastTime[touchIndex] - oldestTime);
-
- if (duration == 0) continue;
-
- float delta = pastX[touchIndex] - oldestX;
- float velocity = (delta / duration) * units; // pixels/frame.
- accumX = (accumX == 0) ? velocity : (accumX + velocity) * .5f;
-
- delta = pastY[touchIndex] - oldestY;
- velocity = (delta / duration) * units; // pixels/frame.
- accumY = (accumY == 0) ? velocity : (accumY + velocity) * .5f;
- }
-
- if (accumX < -maxVelocity) {
- accumX = - maxVelocity;
- } else if (accumX > maxVelocity) {
- accumX = maxVelocity;
- }
-
- if (accumY < -maxVelocity) {
- accumY = - maxVelocity;
- } else if (accumY > maxVelocity) {
- accumY = maxVelocity;
- }
-
- pointer.xVelocity = accumX;
- pointer.yVelocity = accumY;
-
- if (localLOGV) {
- Log.v(TAG, "Pointer " + pointer.id
- + ": Y velocity=" + accumX +" X velocity=" + accumY + " N=" + numTouches);
- }
- }
+ nativeComputeCurrentVelocity(mPtr, units, maxVelocity);
}
/**
@@ -348,8 +166,7 @@ public final class VelocityTracker implements Poolable<VelocityTracker> {
* @return The previously computed X velocity.
*/
public float getXVelocity() {
- Pointer pointer = getPointer(mActivePointerId);
- return pointer != null ? pointer.xVelocity : 0;
+ return nativeGetXVelocity(mPtr, ACTIVE_POINTER_ID);
}
/**
@@ -359,8 +176,7 @@ public final class VelocityTracker implements Poolable<VelocityTracker> {
* @return The previously computed Y velocity.
*/
public float getYVelocity() {
- Pointer pointer = getPointer(mActivePointerId);
- return pointer != null ? pointer.yVelocity : 0;
+ return nativeGetYVelocity(mPtr, ACTIVE_POINTER_ID);
}
/**
@@ -371,8 +187,7 @@ public final class VelocityTracker implements Poolable<VelocityTracker> {
* @return The previously computed X velocity.
*/
public float getXVelocity(int id) {
- Pointer pointer = getPointer(id);
- return pointer != null ? pointer.xVelocity : 0;
+ return nativeGetXVelocity(mPtr, id);
}
/**
@@ -383,68 +198,6 @@ public final class VelocityTracker implements Poolable<VelocityTracker> {
* @return The previously computed Y velocity.
*/
public float getYVelocity(int id) {
- Pointer pointer = getPointer(id);
- return pointer != null ? pointer.yVelocity : 0;
- }
-
- private Pointer getPointer(int id) {
- for (Pointer pointer = mPointerListHead; pointer != null; pointer = pointer.next) {
- if (pointer.id == id) {
- return pointer;
- }
- }
- return null;
- }
-
- private static Pointer obtainPointer() {
- synchronized (sPool) {
- if (sRecycledPointerCount != 0) {
- Pointer element = sRecycledPointerListHead;
- sRecycledPointerCount -= 1;
- sRecycledPointerListHead = element.next;
- element.next = null;
- return element;
- }
- }
- return new Pointer();
- }
-
- private static void releasePointer(Pointer pointer) {
- synchronized (sPool) {
- if (sRecycledPointerCount < POINTER_POOL_CAPACITY) {
- pointer.next = sRecycledPointerListHead;
- sRecycledPointerCount += 1;
- sRecycledPointerListHead = pointer;
- }
- }
- }
-
- private static void releasePointerList(Pointer pointer) {
- if (pointer != null) {
- synchronized (sPool) {
- int count = sRecycledPointerCount;
- if (count >= POINTER_POOL_CAPACITY) {
- return;
- }
-
- Pointer tail = pointer;
- for (;;) {
- count += 1;
- if (count >= POINTER_POOL_CAPACITY) {
- break;
- }
-
- Pointer next = tail.next;
- if (next == null) {
- break;
- }
- tail = next;
- }
-
- tail.next = sRecycledPointerListHead;
- sRecycledPointerCount = count;
- sRecycledPointerListHead = pointer;
- }
- }
+ return nativeGetYVelocity(mPtr, id);
}
}
generated by cgit v1.1 at 2025-08-16 05:00:17 +0000