diff options
Diffstat (limited to 'core/java/android/view/VelocityTracker.java')
| -rw-r--r-- | core/java/android/view/VelocityTracker.java | 335 |
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); } } |