am 87da8606: Manually merged VelocityTracker changes
Merge commit '87da860616009a86e260e49bbefffe12c1a06607'
* commit '87da860616009a86e260e49bbefffe12c1a06607':
Use a circular buffer in VelocityTracker
diff --git a/core/java/android/view/VelocityTracker.java b/core/java/android/view/VelocityTracker.java
index 9581080..9a8ee02 100644
--- a/core/java/android/view/VelocityTracker.java
+++ b/core/java/android/view/VelocityTracker.java
@@ -61,6 +61,7 @@
float mYVelocity[] = new float[MotionEvent.BASE_AVAIL_POINTERS];
float mXVelocity[] = new float[MotionEvent.BASE_AVAIL_POINTERS];
+ int mLastTouch;
private VelocityTracker mNext;
@@ -105,8 +106,11 @@
* Reset the velocity tracker back to its initial state.
*/
public void clear() {
- for (int i = 0; i < MotionEvent.BASE_AVAIL_POINTERS; i++) {
- mPastTime[i][0] = 0;
+ final long[][] pastTime = mPastTime;
+ for (int p = 0; p < MotionEvent.BASE_AVAIL_POINTERS; p++) {
+ for (int i = 0; i < NUM_PAST; i++) {
+ pastTime[p][i] = 0;
+ }
}
}
@@ -133,42 +137,11 @@
}
private void addPoint(int pos, float x, float y, long time) {
- int drop = -1;
- int i;
- if (localLOGV) Log.v(TAG, "Adding past y=" + y + " time=" + time);
- final long[] pastTime = mPastTime[pos];
- 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[pos];
- final float[] pastY = mPastY[pos];
- 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;
- }
+ final int lastTouch = (mLastTouch + 1) % NUM_PAST;
+ mPastX[pos][lastTouch] = x;
+ mPastY[pos][lastTouch] = y;
+ mPastTime[pos][lastTouch] = time;
+ mLastTouch = lastTouch;
}
/**
@@ -199,36 +172,41 @@
final float[] pastX = mPastX[pos];
final float[] pastY = mPastY[pos];
final long[] pastTime = mPastTime[pos];
-
+ 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[0];
- final float oldestY = pastY[0];
- final long oldestTime = pastTime[0];
+ final float oldestX = pastX[oldestTouch];
+ final float oldestY = pastY[oldestTouch];
+ final long oldestTime = pastTime[oldestTouch];
float accumX = 0;
float accumY = 0;
- int N=0;
- while (N < NUM_PAST) {
- if (pastTime[N] == 0) {
- break;
- }
- N++;
- }
+ float N = (lastTouch - oldestTouch + NUM_PAST) % NUM_PAST + 1;
// Skip the last received event, since it is probably pretty noisy.
if (N > 3) N--;
for (int i=1; i < N; i++) {
- final int dur = (int)(pastTime[i] - oldestTime);
+ final int j = (oldestTouch + i) % NUM_PAST;
+ final int dur = (int)(pastTime[j] - oldestTime);
if (dur == 0) continue;
- float dist = pastX[i] - oldestX;
+ float dist = pastX[j] - oldestX;
float vel = (dist/dur) * units; // pixels/frame.
- if (accumX == 0) accumX = vel;
- else accumX = (accumX + vel) * .5f;
-
- dist = pastY[i] - oldestY;
+ accumX = (accumX == 0) ? vel : (accumX + vel) * .5f;
+
+ dist = pastY[j] - oldestY;
vel = (dist/dur) * units; // pixels/frame.
- if (accumY == 0) accumY = vel;
- else accumY = (accumY + vel) * .5f;
+ accumY = (accumY == 0) ? vel : (accumY + vel) * .5f;
}
+
mXVelocity[pos] = accumX < 0.0f ? Math.max(accumX, -maxVelocity)
: Math.min(accumX, maxVelocity);
mYVelocity[pos] = accumY < 0.0f ? Math.max(accumY, -maxVelocity)