Revert "Use a circular buffer in VelocityTracker" (20bebe01) · Commits · e / os / android_frameworks_base

core/java/android/view/VelocityTracker.java

+55 −33

Original line number	Diff line number	Diff line
		@@ -59,8 +59,6 @@ public final class VelocityTracker implements Poolable<VelocityTracker> {
		final float mPastY[] = new float[NUM_PAST];
		final long mPastTime[] = new long[NUM_PAST];

		int mLastTouch;

		float mYVelocity;
		float mXVelocity;

		@@ -107,10 +105,7 @@ public final class VelocityTracker implements Poolable<VelocityTracker> {
		* Reset the velocity tracker back to its initial state.
		*/
		public void clear() {
		final long[] pastTime = mPastTime;
		for (int i = 0; i < NUM_PAST; i++) {
		pastTime[i] = 0;
		}
		mPastTime[0] = 0;
		}

		/**
		@@ -133,11 +128,42 @@ public final class VelocityTracker implements Poolable<VelocityTracker> {
		}

		private void addPoint(float x, float y, long time) {
		final int lastTouch = (mLastTouch + 1) % NUM_PAST;
		mPastX[lastTouch] = x;
		mPastY[lastTouch] = y;
		mPastTime[lastTouch] = time;
		mLastTouch = lastTouch;
		int drop = -1;
		int i;
		if (localLOGV) Log.v(TAG, "Adding past y=" + y + " time=" + time);
		final long[] pastTime = mPastTime;
		for (i=0; i<NUM_PAST; i++) {
		if (pastTime[i] == 0) {
		break;
		} else if (pastTime[i] < time-LONGEST_PAST_TIME) {
		if (localLOGV) Log.v(TAG, "Dropping past too old at "
		+ i + " time=" + pastTime[i]);
		drop = i;
		}
		}
		if (localLOGV) Log.v(TAG, "Add index: " + i);
		if (i == NUM_PAST && drop < 0) {
		drop = 0;
		}
		if (drop == i) drop--;
		final float[] pastX = mPastX;
		final float[] pastY = mPastY;
		if (drop >= 0) {
		if (localLOGV) Log.v(TAG, "Dropping up to #" + drop);
		final int start = drop+1;
		final int count = NUM_PAST-drop-1;
		System.arraycopy(pastX, start, pastX, 0, count);
		System.arraycopy(pastY, start, pastY, 0, count);
		System.arraycopy(pastTime, start, pastTime, 0, count);
		i -= (drop+1);
		}
		pastX[i] = x;
		pastY[i] = y;
		pastTime[i] = time;
		i++;
		if (i < NUM_PAST) {
		pastTime[i] = 0;
		}
		}

		/**
		@@ -167,39 +193,35 @@ public final class VelocityTracker implements Poolable<VelocityTracker> {
		final float[] pastX = mPastX;
		final float[] pastY = mPastY;
		final long[] pastTime = mPastTime;
		final int lastTouch = mLastTouch;

		// find oldest acceptable time
		int oldestTouch = lastTouch;
		if (pastTime[lastTouch] > 0) { // cleared ?
		oldestTouch = (lastTouch + 1) % NUM_PAST;
		final float acceptableTime = pastTime[lastTouch] - LONGEST_PAST_TIME;
		while (pastTime[oldestTouch] < acceptableTime) {
		oldestTouch = (oldestTouch + 1) % NUM_PAST;
		}
		}

		// Kind-of stupid.
		final float oldestX = pastX[oldestTouch];
		final float oldestY = pastY[oldestTouch];
		final long oldestTime = pastTime[oldestTouch];
		final float oldestX = pastX[0];
		final float oldestY = pastY[0];
		final long oldestTime = pastTime[0];
		float accumX = 0;
		float accumY = 0;
		float N = (lastTouch - oldestTouch + NUM_PAST) % NUM_PAST + 1;
		int N=0;
		while (N < NUM_PAST) {
		if (pastTime[N] == 0) {
		break;
		}
		N++;
		}
		// Skip the last received event, since it is probably pretty noisy.
		if (N > 3) N--;

		for (int i=1; i < N; i++) {
		final int j = (oldestTouch + i) % NUM_PAST;
		final int dur = (int)(pastTime[j] - oldestTime);
		final int dur = (int)(pastTime[i] - oldestTime);
		if (dur == 0) continue;
		float dist = pastX[j] - oldestX;
		float dist = pastX[i] - oldestX;
		float vel = (dist/dur) * units; // pixels/frame.
		accumX = (accumX == 0) ? vel : (accumX + vel) * .5f;
		if (accumX == 0) accumX = vel;
		else accumX = (accumX + vel) * .5f;

		dist = pastY[j] - oldestY;
		dist = pastY[i] - oldestY;
		vel = (dist/dur) * units; // pixels/frame.
		accumY = (accumY == 0) ? vel : (accumY + vel) * .5f;
		if (accumY == 0) accumY = vel;
		else accumY = (accumY + vel) * .5f;
		}
		mXVelocity = accumX < 0.0f ? Math.max(accumX, -maxVelocity) : Math.min(accumX, maxVelocity);
		mYVelocity = accumY < 0.0f ? Math.max(accumY, -maxVelocity) : Math.min(accumY, maxVelocity);