下面列出了android.view.VelocityTracker#getYVelocity ( ) 实例代码，或者点击链接到github查看源代码，也可以在右侧发表评论。
public static void velocityTrackerPointerUpCleanUpIfNecessary(MotionEvent ev,
VelocityTracker tracker) {
// Check the dot product of current velocities.
// If the pointer that left was opposing another velocity vector, clear.
tracker.computeCurrentVelocity(1000, mMaximumFlingVelocity);
final int upIndex = ev.getActionIndex();
final int id1 = ev.getPointerId(upIndex);
final float x1 = tracker.getXVelocity(id1);
final float y1 = tracker.getYVelocity(id1);
for (int i = 0, count = ev.getPointerCount(); i < count; i++) {
if (i == upIndex)
continue;
final int id2 = ev.getPointerId(i);
final float x = x1 * tracker.getXVelocity(id2);
final float y = y1 * tracker.getYVelocity(id2);
final float dot = x + y;
if (dot < 0) {
tracker.clear();
break;
}
}
}
public static void velocityTrackerPointerUpCleanUpIfNecessary(MotionEvent ev,
VelocityTracker tracker) {
// Check the dot product of current velocities.
// If the pointer that left was opposing another velocity vector, clear.
tracker.computeCurrentVelocity(1000, mMaximumFlingVelocity);
final int upIndex = ev.getActionIndex();
final int id1 = ev.getPointerId(upIndex);
final float x1 = tracker.getXVelocity(id1);
final float y1 = tracker.getYVelocity(id1);
for (int i = 0, count = ev.getPointerCount(); i < count; i++) {
if (i == upIndex)
continue;
final int id2 = ev.getPointerId(i);
final float x = x1 * tracker.getXVelocity(id2);
final float y = y1 * tracker.getYVelocity(id2);
final float dot = x + y;
if (dot < 0) {
tracker.clear();
break;
}
}
}
public static void velocityTrackerPointerUpCleanUpIfNecessary(MotionEvent ev,
VelocityTracker tracker) {
// Check the dot product of current velocities.
// If the pointer that left was opposing another velocity vector, clear.
tracker.computeCurrentVelocity(1000, mMaximumFlingVelocity);
final int upIndex = ev.getActionIndex();
final int id1 = ev.getPointerId(upIndex);
final float x1 = tracker.getXVelocity(id1);
final float y1 = tracker.getYVelocity(id1);
for (int i = 0, count = ev.getPointerCount(); i < count; i++) {
if (i == upIndex)
continue;
final int id2 = ev.getPointerId(i);
final float x = x1 * tracker.getXVelocity(id2);
final float y = y1 * tracker.getYVelocity(id2);
final float dot = x + y;
if (dot < 0) {
tracker.clear();
break;
}
}
}
@Override
public boolean onInterceptTouchEvent(MotionEvent event) {
if (vTracker == null) {
vTracker = VelocityTracker.obtain();
}
vTracker.addMovement(event);
float currentY = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
downY = event.getY();
downX = event.getX();
resetSpring();
break;
case MotionEvent.ACTION_MOVE:
float distance = Math.abs(currentY - downY);
if (distance > mTouchSlop) {
// 拦截，不向下传递
return true;
}
break;
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
final VelocityTracker tracker = vTracker;
tracker.computeCurrentVelocity(UNIT);
float velocityY = tracker.getYVelocity();
if (vTracker != null) {
vTracker.recycle();
vTracker = null;
}
if (velocityY > FLING_VELOCITY) {
// 拦截，不向下传递
return true;
}
break;
}
return false;
}
protected float getYVelocity(VelocityTracker velocityTracker) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.FROYO) {
return velocityTracker.getYVelocity(mActivePointerId);
}
return velocityTracker.getYVelocity();
}
protected float getYVelocity(VelocityTracker velocityTracker) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.FROYO) {
return velocityTracker.getYVelocity(mActivePointerId);
}
return velocityTracker.getYVelocity();
}
public static float getYVelocity(VelocityTracker tracker, int pointerId) {
return tracker.getYVelocity(pointerId);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if (mLocked) {
return true;
}
if (mTracking) {
mVelocityTracker.addMovement(event);
final int action = event.getAction();
switch (action) {
case MotionEvent.ACTION_MOVE:
moveHandle((int) (mVertical ? event.getY() : event.getX()) - mTouchDelta);
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL: {
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(mVelocityUnits);
float yVelocity = velocityTracker.getYVelocity();
float xVelocity = velocityTracker.getXVelocity();
boolean negative;
final boolean vertical = mVertical;
if (vertical) {
negative = yVelocity < 0;
if (xVelocity < 0) {
xVelocity = -xVelocity;
}
if (xVelocity > mMaximumMinorVelocity) {
xVelocity = mMaximumMinorVelocity;
}
} else {
negative = xVelocity < 0;
if (yVelocity < 0) {
yVelocity = -yVelocity;
}
if (yVelocity > mMaximumMinorVelocity) {
yVelocity = mMaximumMinorVelocity;
}
}
float velocity = (float) Math.hypot(xVelocity, yVelocity);
if (negative) {
velocity = -velocity;
}
final int top = mHandle.getTop();
final int left = mHandle.getLeft();
if (Math.abs(velocity) < mMaximumTapVelocity) {
if (vertical ? (mExpanded && top < mTapThreshold + mTopOffset) ||
(!mExpanded && top > mBottomOffset + mBottom - mTop -
mHandleHeight - mTapThreshold) :
(mExpanded && left < mTapThreshold + mTopOffset) ||
(!mExpanded && left > mBottomOffset + mRight - mLeft -
mHandleWidth - mTapThreshold)) {
if (mAllowSingleTap) {
playSoundEffect(SoundEffectConstants.CLICK);
if (mExpanded) {
animateClose(vertical ? top : left, true);
} else {
animateOpen(vertical ? top : left, true);
}
} else {
performFling(vertical ? top : left, velocity, false, true);
}
} else {
performFling(vertical ? top : left, velocity, false, true);
}
} else {
performFling(vertical ? top : left, velocity, false, true);
}
}
break;
}
}
return mTracking || mAnimating || super.onTouchEvent(event);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if (vTracker == null) {
vTracker = VelocityTracker.obtain();
}
vTracker.addMovement(event);
float currentY = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
downY = event.getY();
downX = event.getX();
if (!currentViewRect.contains((int) downX, (int) downY)) {
return false;
}
break;
case MotionEvent.ACTION_MOVE:
distanceY = currentY - downY;
if (Math.abs(distanceY) > mTouchSlop) {
if (pageChangeListener != null) {
pageChangeListener.onPageScrolled(currentItem, (int) Math.abs(distanceY) / getHeight(), (int) distanceY);
pageChangeListener.onPageScrollStateChanged(SCROLL_STATE_DRAGGING);
}
tranSpring.setEndValue(distanceY);
float degree = MAX_DEGREE * distanceY / mHeight;
if (downX < mWidth / 2) {
degree = -degree;
}
rotateSpring.setEndValue(degree);
}
break;
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
if (Math.abs(distanceY) > mTouchSlop) {
if (pageChangeListener != null) {
pageChangeListener.onPageScrollStateChanged(SCROLL_STATE_SETTLING);
}
final VelocityTracker tracker = vTracker;
tracker.computeCurrentVelocity(UNIT);
float velocityY = tracker.getYVelocity();
animOutIfNeeded(currentY - downY, velocityY);
if (vTracker != null) {
vTracker.recycle();
vTracker = null;
}
}
break;
}
return true;
}
private void onTouchUp(MotionEvent ev) {
switch (mTouchMode) {
case TOUCH_MODE_DOWN:
case TOUCH_MODE_TAP:
case TOUCH_MODE_DONE_WAITING:
final int motionPosition = mMotionPosition;
final View child =
getChildCount() == 0 ? null : getChildAt(motionPosition - mFirstPosition);
if (child != null) {
if (mTouchMode != TOUCH_MODE_DOWN) {
child.setPressed(false);
}
final float x = ev.getX();
final boolean inList = x > mListPadding.left && x < getWidth() - mListPadding.right;
if (inList && !child.hasFocusable()) {
if (mPerformClick == null) {
mPerformClick = new PerformClick();
}
final PerformClick performClick = mPerformClick;
performClick.mClickMotionPosition = motionPosition;
performClick.rememberWindowAttachCount();
if (mTouchMode == TOUCH_MODE_DOWN || mTouchMode == TOUCH_MODE_TAP) {
mLayoutMode = LAYOUT_NORMAL;
if (!mDataChanged && mAdapter.isEnabled(motionPosition)) {
mTouchMode = TOUCH_MODE_TAP;
child.setPressed(true);
positionSelector(mMotionPosition, child);
setPressed(true);
if (mSelector != null) {
Drawable d = mSelector.getCurrent();
if (d != null && d instanceof TransitionDrawable) {
((TransitionDrawable) d).resetTransition();
}
}
if (mTouchModeReset != null) {
removeCallbacks(mTouchModeReset);
}
mTouchModeReset = new Runnable() {
@Override
public void run() {
mTouchModeReset = null;
mTouchMode = TOUCH_MODE_REST;
child.setPressed(false);
setPressed(false);
invalidate();
if (!mDataChanged && mIsAttached) {
performClick.run();
}
}
};
postDelayed(mTouchModeReset,
ViewConfiguration.getPressedStateDuration());
} else {
mTouchMode = TOUCH_MODE_REST;
updateSelectorState();
}
return;
} else if (!mDataChanged && mAdapter.isEnabled(motionPosition)) {
performClick.run();
}
}
}
mTouchMode = TOUCH_MODE_REST;
updateSelectorState();
break;
case TOUCH_MODE_SCROLL:
if (mFlingRunnable == null) {
mFlingRunnable = new FlingRunnable();
}
if (!mFlingRunnable.scrollToAdjustViewsUpOrDown()) {
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
final int initialVelocity =
(int) (velocityTracker.getYVelocity(mActivePointerId) * mVelocityScale);
if (Math.abs(initialVelocity) > mMinimumVelocity) {
if (mFlingRunnable == null) {
mFlingRunnable = new FlingRunnable();
}
reportScrollStateChange(ZrcListView.OnScrollListener.SCROLL_STATE_FLING);
mFlingRunnable.start(-initialVelocity);
} else {
mTouchMode = TOUCH_MODE_REST;
reportScrollStateChange(ZrcListView.OnScrollListener.SCROLL_STATE_IDLE);
if (mFlingRunnable != null) {
mFlingRunnable.endFling();
}
}
}
break;
}
setPressed(false);
invalidate();
recycleVelocityTracker();
mActivePointerId = INVALID_POINTER;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if (isEmpty())
return super.onTouchEvent(event);
initVelocityTrackerIfNotExists();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
//add event into velocity tracker.
mVelocityTracker.clear();
//stop fling and reset fling direction
flingDirection = 0;
mOverScroller.forceFinished(true);
if (animator != null && animator.isRunning()) {
isAnimatorCanceledForwardly = true;
animator.cancel();
}
lastX = event.getX();
lastY = event.getY();
//Make it as a click event when touch down,
//and record touch down time stamp.
touchDownTimeStamp = System.currentTimeMillis();
break;
case MotionEvent.ACTION_MOVE:
//add event into velocity tracker and compute velocity.
mVelocityTracker.addMovement(event);
float currentX = event.getX();
float currentY = event.getY();
int distance = (int) (currentY - lastY);
int direction = 0;
if (distance == 0)
break;
//if moved, cancel click event
touchDownTimeStamp = 0;
direction = distance / Math.abs(distance);
//initialize touch area
rectF.set(0, 0, getWidth(), getHeight());
if (rectF.contains(currentX, currentY)) {
//inside touch area, execute move event.
lastX = currentX;
lastY = currentY;
updateByTotalMoveY(totalMoveY + distance, direction);
}
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
if (System.currentTimeMillis() - touchDownTimeStamp <= CLICK_EVENT_INTERNAL_TIME) {
//it's a click event, do it
executeClickEvent(event.getX(), event.getY());
break;
}
//calculate current velocity
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(velocityUnits, mMaximumVelocity);
float currentVelocity = velocityTracker.getYVelocity();
recycleVelocityTracker();
final int tempFlingDirection = currentVelocity == 0 ? 0 : (currentVelocity < 0 ? -1 : 1);
if (Math.abs(currentVelocity) >= mMinimumVelocity) {
//it's a fling event.
flingDirection = tempFlingDirection;
mOverScroller.fling(
0, totalMoveY,
0, (int) currentVelocity,
0, 0,
-(getItemCount() + showCount / 2) * itemHeight, (showCount / 2) * itemHeight,
0, 0
);
invalidate();
} else {
calculateSelectedIndex(totalMoveY, tempFlingDirection);
selectedIndex = calculateResult[0];
offsetY = calculateResult[1];
//execute rebound animation
executeAnimation(
totalMoveY,
0 - selectedIndex * itemHeight
);
}
break;
}
return true;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if (mLocked) {
return true;
}
if (mTracking) {
mVelocityTracker.addMovement(event);
final int action = event.getAction();
switch (action) {
case MotionEvent.ACTION_MOVE:
moveHandle((int) (mVertical ? event.getY() : event.getX()) - mTouchDelta);
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL: {
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(mVelocityUnits);
float yVelocity = velocityTracker.getYVelocity();
float xVelocity = velocityTracker.getXVelocity();
boolean negative;
final boolean vertical = mVertical;
if (vertical) {
negative = yVelocity < 0;
if (xVelocity < 0) {
xVelocity = -xVelocity;
}
if (xVelocity > mMaximumMinorVelocity) {
xVelocity = mMaximumMinorVelocity;
}
} else {
negative = xVelocity < 0;
if (yVelocity < 0) {
yVelocity = -yVelocity;
}
if (yVelocity > mMaximumMinorVelocity) {
yVelocity = mMaximumMinorVelocity;
}
}
float velocity = (float) Math.hypot(xVelocity, yVelocity);
if (negative) {
velocity = -velocity;
}
final int top = mHandle.getTop();
final int left = mHandle.getLeft();
if (Math.abs(velocity) < mMaximumTapVelocity) {
if (vertical ? (mExpanded && top < mTapThreshold + mTopOffset) ||
(!mExpanded && top > mBottomOffset + getBottom() - getTop() -
mHandleHeight - mTapThreshold) :
(mExpanded && left < mTapThreshold + mTopOffset) ||
(!mExpanded && left > mBottomOffset + getRight() - getLeft() -
mHandleWidth - mTapThreshold)) {
if (mAllowSingleTap) {
playSoundEffect(SoundEffectConstants.CLICK);
if (mExpanded) {
animateClose(vertical ? top : left);
} else {
animateOpen(vertical ? top : left);
}
} else {
performFling(vertical ? top : left, velocity, false);
}
} else {
performFling(vertical ? top : left, velocity, false);
}
} else {
performFling(vertical ? top : left, velocity, false);
}
}
break;
}
}
return mTracking || mAnimating || super.onTouchEvent(event);
}
@Override
public float getYVelocity(VelocityTracker tracker, int pointerId) {
return tracker.getYVelocity();
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if(mItemHeight == 0) return true;
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(event);
currY = event.getY();
switch(event.getAction()){
case MotionEvent.ACTION_DOWN:
mFlagMayPress = true;
mHandlerInNewThread.removeMessages(HANDLER_WHAT_REFRESH);
stopScrolling();
downY = currY;
downYGlobal = mCurrDrawGlobalY;
onScrollStateChange(OnScrollListener.SCROLL_STATE_IDLE);
getParent().requestDisallowInterceptTouchEvent(true);
break;
case MotionEvent.ACTION_MOVE:
float spanY = downY - currY;
if(mFlagMayPress && (-mScaledTouchSlop < spanY && spanY < mScaledTouchSlop)){
}else{
mFlagMayPress = false;
mCurrDrawGlobalY = limitY((int)(downYGlobal + spanY));
calculateFirstItemParameterByGlobalY();
invalidate();
}
onScrollStateChange(OnScrollListener.SCROLL_STATE_TOUCH_SCROLL);
break;
case MotionEvent.ACTION_UP:
if(mFlagMayPress){
click(event);
}else {
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(1000);
int velocityY = (int) (velocityTracker.getYVelocity() * mFriction);
if (Math.abs(velocityY) > mMiniVelocityFling) {
mScroller.fling(0, mCurrDrawGlobalY, 0, -velocityY,
Integer.MIN_VALUE, Integer.MAX_VALUE, limitY(Integer.MIN_VALUE), limitY(Integer.MAX_VALUE));
invalidate();
onScrollStateChange(OnScrollListener.SCROLL_STATE_FLING);
}
mHandlerInNewThread.sendMessageDelayed(getMsg(HANDLER_WHAT_REFRESH), 0);
releaseVelocityTracker();
}
break;
case MotionEvent.ACTION_CANCEL:
downYGlobal = mCurrDrawGlobalY;
stopScrolling();
mHandlerInNewThread.sendMessageDelayed(getMsg(HANDLER_WHAT_REFRESH), 0);
break;
}
return true ;
}
@Override
public float getYVelocity(VelocityTracker tracker, int pointerId) {
return tracker.getYVelocity();
}
@Override
public float getYVelocity(VelocityTracker tracker, int pointerId) {
return tracker.getYVelocity();
}
private float getVelocity(VelocityTracker vt) {
return mSwipeDirection == X ? vt.getXVelocity() :
vt.getYVelocity();
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if (mLocked) {
return true;
}
if (mTracking) {
mVelocityTracker.addMovement(event);
final int action = event.getAction();
switch (action) {
case MotionEvent.ACTION_MOVE:
moveHandle((int) (mVertical ? event.getY() : event.getX()) - mTouchDelta);
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL: {
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(mVelocityUnits);
float yVelocity = velocityTracker.getYVelocity();
float xVelocity = velocityTracker.getXVelocity();
boolean negative;
final boolean vertical = mVertical;
if (vertical) {
negative = yVelocity < 0;
if (xVelocity < 0) {
xVelocity = -xVelocity;
}
if (xVelocity > mMaximumMinorVelocity) {
xVelocity = mMaximumMinorVelocity;
}
} else {
negative = xVelocity < 0;
if (yVelocity < 0) {
yVelocity = -yVelocity;
}
if (yVelocity > mMaximumMinorVelocity) {
yVelocity = mMaximumMinorVelocity;
}
}
float velocity = (float) Math.hypot(xVelocity, yVelocity);
if (negative) {
velocity = -velocity;
}
final int top = mHandle.getTop();
final int left = mHandle.getLeft();
if (Math.abs(velocity) < mMaximumTapVelocity) {
if (inThreshold(top, left)) {
if (mAllowSingleTap) {
playSoundEffect(SoundEffectConstants.CLICK);
if (mExpanded) {
//animateClose(vertical ? top : left);
animateClose(getSide());
} else {
animateOpen(getSide());
//animateOpen(vertical ? top : left);
}
} else {
performFling(vertical ? top : left, velocity, false);
}
} else {
performFling(vertical ? top : left, velocity, false);
}
} else {
performFling(vertical ? top : left, velocity, false);
}
}
break;
}
}
return mTracking || mAnimating || super.onTouchEvent(event);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if (mLocked) {
return true;
}
if (mTracking) {
mVelocityTracker.addMovement(event);
final int action = event.getAction();
switch (action) {
case MotionEvent.ACTION_MOVE:
moveHandle((int) (event.getY()));
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL: {
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(mVelocityUnits);
float yVelocity = velocityTracker.getYVelocity();
float xVelocity = velocityTracker.getXVelocity();
boolean negative;
negative = yVelocity < 0;
if (xVelocity < 0) {
xVelocity = -xVelocity;
}
if (xVelocity > mMaximumMinorVelocity) {
xVelocity = mMaximumMinorVelocity;
}
float velocity = (float) Math.hypot(xVelocity, yVelocity);
if (negative) {
velocity = -velocity;
}
final int top = mHandle.getTop();
if (Math.abs(velocity) < mMaximumTapVelocity) {
if ((mExpanded && top < mTapThreshold + mTopOffset) || (!mExpanded && top > mBottomOffset + getBottom() - getTop() - mHandleHeight - mTapThreshold)) {
if (mAllowSingleTap) {
playSoundEffect(SoundEffectConstants.CLICK);
if (mExpanded) {
animateClose(top);
} else {
animateOpen(top);
}
} else {
performFling(top, velocity, false);
}
} else {
performFling(top, velocity, false);
}
} else {
performFling(top, velocity, false);
}
}
break;
}
}
return mTracking || mAnimating || super.onTouchEvent(event);
}
public static float getYVelocity(VelocityTracker tracker, int pointerId) {
return tracker.getYVelocity(pointerId);
}