Example usage for android.view VelocityTracker obtain

Introduction

In this page you can find the example usage for android.view VelocityTracker obtain.

Prototype

static public VelocityTracker obtain() 

Source Link

Document

Retrieve a new VelocityTracker object to watch the velocity of a motion.

Usage

From source file:com.viettel.image.zoom.ZoomViewPaper.java

@Override
public boolean onTouchEvent(MotionEvent ev) {

    if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) {
        // Don't handle edge touches immediately -- they may actually belong
        // to one of our
        // descendants.
        return false;
    }//  w w w . j a  v  a2 s  .co m

    if (mAdapter == null || mAdapter.getCount() == 0) {
        // Nothing to present or scroll; nothing to touch.
        return false;
    }

    if (mVelocityTracker == null) {
        mVelocityTracker = VelocityTracker.obtain();
    }
    mVelocityTracker.addMovement(ev);

    final int action = ev.getAction();

    switch (action & MotionEventCompat.ACTION_MASK) {
    case MotionEvent.ACTION_DOWN: {
        /*
         * If being flinged and user touches, stop the fling. isFinished
         * will be false if being flinged.
         */
        completeScroll();

        // Remember where the motion event started
        mLastMotionX = mInitialMotionX = ev.getX();
        mActivePointerId = MotionEventCompat.getPointerId(ev, 0);
        break;
    }
    case MotionEvent.ACTION_MOVE:
        if (!mIsBeingDragged) {
            final int pointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
            final float x = MotionEventCompat.getX(ev, pointerIndex);
            final float xDiff = Math.abs(x - mLastMotionX);
            final float y = MotionEventCompat.getY(ev, pointerIndex);
            final float yDiff = Math.abs(y - mLastMotionY);
            if (DEBUG)
                VTLog.v(TAG, "Moved x to " + x + "," + y + " diff=" + xDiff + "," + yDiff);
            if (xDiff > mTouchSlop && xDiff > yDiff) {
                if (DEBUG)
                    VTLog.v(TAG, "Starting drag!");
                mIsBeingDragged = true;
                mLastMotionX = x;
                setScrollState(SCROLL_STATE_DRAGGING);
                setScrollingCacheEnabled(true);
            }
        }
        if (mIsBeingDragged) {
            // Scroll to follow the motion event
            final int activePointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
            final float x = MotionEventCompat.getX(ev, activePointerIndex);
            final float deltaX = mLastMotionX - x;
            mLastMotionX = x;
            float scrollX = getScrollX() + deltaX;
            final int width = getWidth();

            final float leftBound = Math.max(0, (mCurItem - 1) * width);
            final float rightBound = Math.min(mCurItem + 1, mAdapter.getCount() - 1) * width;
            if (scrollX < leftBound) {
                scrollX = leftBound;
            } else if (scrollX > rightBound) {
                scrollX = rightBound;
            }
            // Don't lose the rounded component
            mLastMotionX += scrollX - (int) scrollX;
            scrollTo((int) scrollX, getScrollY());
            if (mOnPageChangeListener != null) {
                final int position = (int) scrollX / width;
                final int positionOffsetPixels = (int) scrollX % width;
                final float positionOffset = (float) positionOffsetPixels / width;
                mOnPageChangeListener.onPageScrolled(position, positionOffset, positionOffsetPixels);
            }
        }
        break;
    case MotionEvent.ACTION_UP:
        if (mIsBeingDragged) {
            final VelocityTracker velocityTracker = mVelocityTracker;
            velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
            int initialVelocity = (int) VelocityTrackerCompat.getYVelocity(velocityTracker, mActivePointerId);
            mPopulatePending = true;
            if ((Math.abs(initialVelocity) > mMinimumVelocity)
                    || Math.abs(mInitialMotionX - mLastMotionX) >= (getWidth() / 3)) {
                if (mLastMotionX > mInitialMotionX) {
                    setCurrentItemInternal(mCurItem - 1, true, true);
                } else {
                    setCurrentItemInternal(mCurItem + 1, true, true);
                }
            } else {
                setCurrentItemInternal(mCurItem, true, true);
            }

            mActivePointerId = INVALID_POINTER;
            endDrag();
        }
        break;
    case MotionEvent.ACTION_CANCEL:
        if (mIsBeingDragged) {
            setCurrentItemInternal(mCurItem, true, true);
            mActivePointerId = INVALID_POINTER;
            endDrag();
        }
        break;
    case MotionEventCompat.ACTION_POINTER_DOWN: {
        final int index = MotionEventCompat.getActionIndex(ev);
        final float x = MotionEventCompat.getX(ev, index);
        mLastMotionX = x;
        mActivePointerId = MotionEventCompat.getPointerId(ev, index);
        break;
    }
    case MotionEventCompat.ACTION_POINTER_UP:
        onSecondaryPointerUp(ev);
        mLastMotionX = MotionEventCompat.getX(ev, MotionEventCompat.findPointerIndex(ev, mActivePointerId));
        break;
    }
    return true;
}

---

From source file:atownsend.swipeopenhelper.SwipeOpenItemTouchHelper.java

private void obtainVelocityTracker() {
    if (velocityTracker != null) {
        velocityTracker.recycle();
    }
    velocityTracker = VelocityTracker.obtain();
}

---

From source file:com.coleman.demo.view.page.DirectionalViewPager.java

@Override
public boolean onTouchEvent(MotionEvent ev) {

    if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) {
        // Don't handle edge touches immediately -- they may actually belong
        // to one of our
        // descendants.
        return false;
    }//  w w w  .j ava 2  s .  c  o  m

    if (mAdapter == null || mAdapter.getCount() == 0) {
        // Nothing to present or scroll; nothing to touch.
        return false;
    }

    if (mVelocityTracker == null) {
        mVelocityTracker = VelocityTracker.obtain();
    }
    mVelocityTracker.addMovement(ev);

    final int action = ev.getAction();

    switch (action & MotionEventCompat.ACTION_MASK) {
    case MotionEvent.ACTION_DOWN: {
        /*
         * If being flinged and user touches, stop the fling. isFinished
         * will be false if being flinged.
         */
        completeScroll();

        // Remember where the motion event started
        if (mOrientation == HORIZONTAL) {
            mLastMotionX = mInitialMotion = ev.getX();
        } else {
            mLastMotionY = mInitialMotion = ev.getY();
        }
        mActivePointerId = MotionEventCompat.getPointerId(ev, 0);
        break;
    }
    case MotionEvent.ACTION_MOVE:
        if (!mIsBeingDragged) {
            final int pointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
            final float x = MotionEventCompat.getX(ev, pointerIndex);
            final float y = MotionEventCompat.getY(ev, pointerIndex);
            final float xDiff = Math.abs(x - mLastMotionX);
            final float yDiff = Math.abs(y - mLastMotionY);
            float primaryDiff;
            float secondaryDiff;

            if (mOrientation == HORIZONTAL) {
                primaryDiff = xDiff;
                secondaryDiff = yDiff;
            } else {
                primaryDiff = yDiff;
                secondaryDiff = xDiff;
            }

            if (DEBUG)
                Log.v(TAG, "Moved x to " + x + "," + y + " diff=" + xDiff + "," + yDiff);
            if (primaryDiff > mTouchSlop && primaryDiff > secondaryDiff) {
                if (DEBUG)
                    Log.v(TAG, "Starting drag!");
                mIsBeingDragged = true;
                if (mOrientation == HORIZONTAL) {
                    mLastMotionX = x;
                } else {
                    mLastMotionY = y;
                }
                setScrollState(SCROLL_STATE_DRAGGING);
                setScrollingCacheEnabled(true);
            }
        }
        if (mIsBeingDragged) {
            // Scroll to follow the motion event
            final int activePointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
            final float x = MotionEventCompat.getX(ev, activePointerIndex);
            final float y = MotionEventCompat.getY(ev, activePointerIndex);

            int size;
            float scroll;

            if (mOrientation == HORIZONTAL) {
                size = getWidth();
                scroll = getScrollX() + (mLastMotionX - x);
                mLastMotionX = x;
            } else {
                size = getHeight();
                scroll = getScrollY() + (mLastMotionY - y);
                mLastMotionY = y;
            }

            final float lowerBound = Math.max(0, (mCurItem - 1) * size);
            final float upperBound = Math.min(mCurItem + 1, mAdapter.getCount() - 1) * size;
            if (scroll < lowerBound) {
                scroll = lowerBound;
            } else if (scroll > upperBound) {
                scroll = upperBound;
            }
            if (mOrientation == HORIZONTAL) {
                // Don't lose the rounded component
                mLastMotionX += scroll - (int) scroll;
                scrollTo((int) scroll, getScrollY());
            } else {
                // Don't lose the rounded component
                mLastMotionY += scroll - (int) scroll;
                scrollTo(getScrollX(), (int) scroll);
            }
            if (mOnPageChangeListener != null) {
                final int position = (int) scroll / size;
                final int positionOffsetPixels = (int) scroll % size;
                final float positionOffset = (float) positionOffsetPixels / size;
                mOnPageChangeListener.onPageScrolled(position, positionOffset, positionOffsetPixels);
            }
        }
        break;
    case MotionEvent.ACTION_UP:
        if (mIsBeingDragged) {
            final VelocityTracker velocityTracker = mVelocityTracker;
            velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
            int initialVelocity;
            float lastMotion;
            int sizeOverThree;

            if (mOrientation == HORIZONTAL) {
                initialVelocity = (int) VelocityTrackerCompat.getXVelocity(velocityTracker, mActivePointerId);
                lastMotion = mLastMotionX;
                sizeOverThree = getWidth() / 3;
            } else {
                initialVelocity = (int) VelocityTrackerCompat.getYVelocity(velocityTracker, mActivePointerId);
                lastMotion = mLastMotionY;
                sizeOverThree = getHeight() / 3;
            }

            mPopulatePending = true;
            if ((Math.abs(initialVelocity) > mMinimumVelocity)
                    || Math.abs(mInitialMotion - lastMotion) >= sizeOverThree) {
                if (lastMotion > mInitialMotion) {
                    setCurrentItemInternal(mCurItem - 1, true, true);
                } else {
                    setCurrentItemInternal(mCurItem + 1, true, true);
                }
            } else {
                setCurrentItemInternal(mCurItem, true, true);
            }

            mActivePointerId = INVALID_POINTER;
            endDrag();
        }
        break;
    case MotionEvent.ACTION_CANCEL:
        if (mIsBeingDragged) {
            setCurrentItemInternal(mCurItem, true, true);
            mActivePointerId = INVALID_POINTER;
            endDrag();
        }
        break;
    case MotionEventCompat.ACTION_POINTER_DOWN: {
        final int index = MotionEventCompat.getActionIndex(ev);
        if (mOrientation == HORIZONTAL) {
            mLastMotionX = MotionEventCompat.getX(ev, index);
        } else {
            mLastMotionY = MotionEventCompat.getY(ev, index);
        }
        mActivePointerId = MotionEventCompat.getPointerId(ev, index);
        break;
    }
    case MotionEventCompat.ACTION_POINTER_UP:
        onSecondaryPointerUp(ev);
        final int index = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
        if (mOrientation == HORIZONTAL) {
            mLastMotionX = MotionEventCompat.getX(ev, index);
        } else {
            mLastMotionY = MotionEventCompat.getY(ev, index);
        }
        break;
    }
    return true;
}

---

From source file:cn.com.zzwfang.view.directionalviewpager.DirectionalViewPager.java

@Override
public boolean onTouchEvent(MotionEvent ev) {

    if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) {
        // Don't handle edge touches immediately -- they may actually belong to one of our
        // descendants.
        return false;
    }/*from  www.j av a2 s  . c  o m*/

    if (mAdapter == null || mAdapter.getCount() == 0) {
        // Nothing to present or scroll; nothing to touch.
        return false;
    }

    if (mVelocityTracker == null) {
        mVelocityTracker = VelocityTracker.obtain();
    }
    mVelocityTracker.addMovement(ev);

    final int action = ev.getAction();

    switch (action & MotionEventCompat.ACTION_MASK) {
    case MotionEvent.ACTION_DOWN: {
        /*
         * If being flinged and user touches, stop the fling. isFinished
         * will be false if being flinged.
         */
        completeScroll();

        // Remember where the motion event started
        if (mOrientation == HORIZONTAL) {
            mLastMotionX = mInitialMotion = ev.getX();
        } else {
            mLastMotionY = mInitialMotion = ev.getY();
        }
        mActivePointerId = MotionEventCompat.getPointerId(ev, 0);
        break;
    }
    case MotionEvent.ACTION_MOVE:
        if (!mIsBeingDragged) {
            final int pointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
            final float x = MotionEventCompat.getX(ev, pointerIndex);
            final float y = MotionEventCompat.getY(ev, pointerIndex);
            final float xDiff = Math.abs(x - mLastMotionX);
            final float yDiff = Math.abs(y - mLastMotionY);
            float primaryDiff;
            float secondaryDiff;

            if (mOrientation == HORIZONTAL) {
                primaryDiff = xDiff;
                secondaryDiff = yDiff;
            } else {
                primaryDiff = yDiff;
                secondaryDiff = xDiff;
            }

            if (DEBUG)
                Log.v(TAG, "Moved x to " + x + "," + y + " diff=" + xDiff + "," + yDiff);
            if (primaryDiff > mTouchSlop && primaryDiff > secondaryDiff) {
                if (DEBUG)
                    Log.v(TAG, "Starting drag!");
                mIsBeingDragged = true;
                if (mOrientation == HORIZONTAL) {
                    mLastMotionX = x;
                } else {
                    mLastMotionY = y;
                }
                setScrollState(SCROLL_STATE_DRAGGING);
                setScrollingCacheEnabled(true);
            }
        }
        if (mIsBeingDragged) {
            // Scroll to follow the motion event
            final int activePointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
            final float x = MotionEventCompat.getX(ev, activePointerIndex);
            final float y = MotionEventCompat.getY(ev, activePointerIndex);

            int size;
            float scroll;

            if (mOrientation == HORIZONTAL) {
                size = getWidth();
                scroll = getScrollX() + (mLastMotionX - x);
                mLastMotionX = x;
            } else {
                size = getHeight();
                scroll = getScrollY() + (mLastMotionY - y);
                mLastMotionY = y;
            }

            final float lowerBound = Math.max(0, (mCurItem - 1) * size);
            final float upperBound = Math.min(mCurItem + 1, mAdapter.getCount() - 1) * size;
            if (scroll < lowerBound) {
                scroll = lowerBound;
            } else if (scroll > upperBound) {
                scroll = upperBound;
            }
            if (mOrientation == HORIZONTAL) {
                // Don't lose the rounded component
                mLastMotionX += scroll - (int) scroll;
                scrollTo((int) scroll, getScrollY());
            } else {
                // Don't lose the rounded component
                mLastMotionY += scroll - (int) scroll;
                scrollTo(getScrollX(), (int) scroll);
            }
            if (mOnPageChangeListener != null) {
                final int position = (int) scroll / size;
                final int positionOffsetPixels = (int) scroll % size;
                final float positionOffset = (float) positionOffsetPixels / size;
                mOnPageChangeListener.onPageScrolled(position, positionOffset, positionOffsetPixels);
            }
        }
        break;
    case MotionEvent.ACTION_UP:
        if (mIsBeingDragged) {
            final VelocityTracker velocityTracker = mVelocityTracker;
            velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
            int initialVelocity;
            float lastMotion;
            int sizeOverThree;

            if (mOrientation == HORIZONTAL) {
                initialVelocity = (int) VelocityTrackerCompat.getXVelocity(velocityTracker, mActivePointerId);
                lastMotion = mLastMotionX;
                sizeOverThree = getWidth() / 3;
            } else {
                initialVelocity = (int) VelocityTrackerCompat.getYVelocity(velocityTracker, mActivePointerId);
                lastMotion = mLastMotionY;
                sizeOverThree = getHeight() / 3;
            }

            mPopulatePending = true;
            if ((Math.abs(initialVelocity) > mMinimumVelocity)
                    || Math.abs(mInitialMotion - lastMotion) >= sizeOverThree) {
                if (lastMotion > mInitialMotion) {
                    setCurrentItemInternal(mCurItem - 1, true, true);
                } else {
                    setCurrentItemInternal(mCurItem + 1, true, true);
                }
            } else {
                setCurrentItemInternal(mCurItem, true, true);
            }

            mActivePointerId = INVALID_POINTER;
            endDrag();
        }
        break;
    case MotionEvent.ACTION_CANCEL:
        if (mIsBeingDragged) {
            setCurrentItemInternal(mCurItem, true, true);
            mActivePointerId = INVALID_POINTER;
            endDrag();
        }
        break;
    case MotionEventCompat.ACTION_POINTER_DOWN: {
        final int index = MotionEventCompat.getActionIndex(ev);
        if (mOrientation == HORIZONTAL) {
            mLastMotionX = MotionEventCompat.getX(ev, index);
        } else {
            mLastMotionY = MotionEventCompat.getY(ev, index);
        }
        mActivePointerId = MotionEventCompat.getPointerId(ev, index);
        break;
    }
    case MotionEventCompat.ACTION_POINTER_UP:
        onSecondaryPointerUp(ev);
        final int index = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
        if (mOrientation == HORIZONTAL) {
            mLastMotionX = MotionEventCompat.getX(ev, index);
        } else {
            mLastMotionY = MotionEventCompat.getY(ev, index);
        }
        break;
    }
    return true;
}

---

From source file:jackson.com.slidingmenulib.MyViewDragHelper.java

/**
 * Check if this event as provided to the parent view's onInterceptTouchEvent should
 * cause the parent to intercept the touch event stream.
 *
 * @param ev MotionEvent provided to onInterceptTouchEvent
 * @return true if the parent view should return true from onInterceptTouchEvent
 *///from  ww  w . j  a v a2s .  c om
public boolean shouldInterceptTouchEvent(MotionEvent ev) {
    final int action = ev.getActionMasked();
    final int actionIndex = ev.getActionIndex();

    if (action == MotionEvent.ACTION_DOWN) {
        // Reset things for a new event stream, just in case we didn't get
        // the whole previous stream.
        cancel();
    }

    if (mVelocityTracker == null) {
        mVelocityTracker = VelocityTracker.obtain();
    }
    mVelocityTracker.addMovement(ev);

    switch (action) {
    case MotionEvent.ACTION_DOWN: {
        final float x = ev.getX();
        final float y = ev.getY();
        final int pointerId = ev.getPointerId(0);
        saveInitialMotion(x, y, pointerId);

        final View toCapture = findTopChildUnder((int) x, (int) y);

        // Catch a settling view if possible.
        if (toCapture == mCapturedView && mDragState == STATE_SETTLING) {
            tryCaptureViewForDrag(toCapture, pointerId);
        }

        final int edgesTouched = mInitialEdgesTouched[pointerId];
        if ((edgesTouched & mTrackingEdges) != 0) {
            mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId);
        }
        break;
    }

    case MotionEvent.ACTION_POINTER_DOWN: {
        final int pointerId = ev.getPointerId(actionIndex);
        final float x = ev.getX(actionIndex);
        final float y = ev.getY(actionIndex);

        saveInitialMotion(x, y, pointerId);

        // A ViewDragHelper can only manipulate one view at a time.
        if (mDragState == STATE_IDLE) {
            final int edgesTouched = mInitialEdgesTouched[pointerId];
            if ((edgesTouched & mTrackingEdges) != 0) {
                mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId);
            }
        } else if (mDragState == STATE_SETTLING) {
            // Catch a settling view if possible.
            final View toCapture = findTopChildUnder((int) x, (int) y);
            if (toCapture == mCapturedView) {
                tryCaptureViewForDrag(toCapture, pointerId);
            }
        }
        break;
    }

    case MotionEvent.ACTION_MOVE: {
        if (mInitialMotionX == null || mInitialMotionY == null)
            break;

        // First to cross a touch slop over a draggable view wins. Also report edge drags.
        final int pointerCount = ev.getPointerCount();
        for (int i = 0; i < pointerCount; i++) {
            final int pointerId = ev.getPointerId(i);

            // If pointer is invalid then skip the ACTION_MOVE.
            if (!isValidPointerForActionMove(pointerId))
                continue;

            final float x = ev.getX(i);
            final float y = ev.getY(i);
            final float dx = x - mInitialMotionX[pointerId];
            final float dy = y - mInitialMotionY[pointerId];

            final View toCapture = findTopChildUnder((int) x, (int) y);
            final boolean pastSlop = toCapture != null && checkTouchSlop(toCapture, dx, dy);
            if (pastSlop) {
                // check the callback's
                // getView[Horizontal|Vertical]DragRange methods to know
                // if you can move at all along an axis, then see if it
                // would clamp to the same value. If you can't move at
                // all in every dimension with a nonzero range, bail.
                final int oldLeft = toCapture.getLeft();
                final int targetLeft = oldLeft + (int) dx;
                final int newLeft = mCallback.clampViewPositionHorizontal(toCapture, targetLeft, (int) dx);
                final int oldTop = toCapture.getTop();
                final int targetTop = oldTop + (int) dy;
                final int newTop = mCallback.clampViewPositionVertical(toCapture, targetTop, (int) dy);
                final int horizontalDragRange = mCallback.getViewHorizontalDragRange(toCapture);
                final int verticalDragRange = mCallback.getViewVerticalDragRange(toCapture);
                if ((horizontalDragRange == 0 || horizontalDragRange > 0 && newLeft == oldLeft)
                        && (verticalDragRange == 0 || verticalDragRange > 0 && newTop == oldTop)) {
                    break;
                }
            }
            reportNewEdgeDrags(dx, dy, pointerId);
            if (mDragState == STATE_DRAGGING) {
                // Callback might have started an edge drag
                break;
            }

            if (pastSlop && tryCaptureViewForDrag(toCapture, pointerId)) {
                break;
            }
        }
        saveLastMotion(ev);
        break;
    }

    case MotionEvent.ACTION_POINTER_UP: {
        final int pointerId = ev.getPointerId(actionIndex);
        clearMotionHistory(pointerId);
        break;
    }

    case MotionEvent.ACTION_UP:
    case MotionEvent.ACTION_CANCEL: {
        cancel();
        break;
    }
    }

    return mDragState == STATE_DRAGGING;
}

---

From source file:com.icloud.listenbook.base.view.DraggableGridViewPager.java

@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
    /*/*from   w  w  w .jav  a  2  s . c o  m*/
     * This method JUST determines whether we want to intercept the motion.
     * If we return true, onMotionEvent will be called and we do the actual
     * scrolling there.
     */

    final int action = ev.getAction() & MotionEventCompat.ACTION_MASK;

    // Always take care of the touch gesture being complete.
    // ? ??
    if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP) {
        // Release the drag.
        DEBUG_LOG("Intercept done!");
        mIsBeingDragged = false;
        mIsUnableToDrag = false;
        mActivePointerId = INVALID_POINTER;
        if (mVelocityTracker != null) {
            mVelocityTracker.recycle();
            mVelocityTracker = null;
        }
        return false;
    }

    // Nothing more to do here if we have decided whether or not we
    // are dragging.
    /*
     * ??,? 
     */
    if (action != MotionEvent.ACTION_DOWN) {
        if (mIsBeingDragged || mLastDragged >= 0) {
            DEBUG_LOG("Intercept returning true!");
            return true;
        }
        if (mIsUnableToDrag) {
            DEBUG_LOG("Intercept returning false!");
            return false;
        }
    }

    switch (action) {
    case MotionEvent.ACTION_MOVE: {
        /*
         * mIsBeingDragged == false, otherwise the shortcut would have
         * caught it. Check whether the user has moved far enough from his
         * original down touch.
         */

        /*
         * Locally do absolute value. mLastMotionY is set to the y value of
         * the down event.
         */
        final int activePointerId = mActivePointerId;
        if (activePointerId == INVALID_POINTER) {
            // If we don't have a valid id, the touch down wasn't on
            // content.
            break;
        }

        final int pointerIndex = MotionEventCompat.findPointerIndex(ev, activePointerId);
        final float x = MotionEventCompat.getX(ev, pointerIndex);
        final float dx = x - mLastMotionX;
        final float xDiff = Math.abs(dx);
        final float y = MotionEventCompat.getY(ev, pointerIndex);
        final float yDiff = Math.abs(y - mInitialMotionY);
        DEBUG_LOG("***Moved to " + x + "," + y + " diff=" + xDiff + "," + yDiff);

        if (xDiff > mTouchSlop && xDiff * 0.5f > yDiff) {
            DEBUG_LOG("***Starting drag!");
            mIsBeingDragged = true;
            requestParentDisallowInterceptTouchEvent(true);
            setScrollState(SCROLL_STATE_DRAGGING);
            mLastMotionX = dx > 0 ? mInitialMotionX + mTouchSlop : mInitialMotionX - mTouchSlop;
            mLastMotionY = y;
            setScrollingCacheEnabled(true);
        } else if (yDiff > mTouchSlop) {
            // The finger has moved enough in the vertical
            // direction to be counted as a drag... abort
            // any attempt to drag horizontally, to work correctly
            // with children that have scrolling containers.
            DEBUG_LOG("***Unable to drag!");
            mIsUnableToDrag = true;
        }
        if (mIsBeingDragged) {
            // Scroll to follow the motion event
            if (performDrag(x)) {
                ViewCompat.postInvalidateOnAnimation(this);
            }
        }
        break;
    }

    case MotionEvent.ACTION_DOWN: {
        /*
         * Remember location of down touch. ACTION_DOWN always refers to
         * pointer index 0.
         */
        // ?
        mLastMotionX = mInitialMotionX = ev.getX();
        mLastMotionY = mInitialMotionY = ev.getY();
        mActivePointerId = MotionEventCompat.getPointerId(ev, 0);
        mIsUnableToDrag = false;

        mScroller.computeScrollOffset();
        /*
         *  mScroller   ?? ?
         */
        if (mScrollState == SCROLL_STATE_SETTLING
                && Math.abs(mScroller.getFinalX() - mScroller.getCurrX()) > mCloseEnough) {
            // Let the user 'catch' the pager as it animates.
            mScroller.abortAnimation();
            mIsBeingDragged = true;
            requestParentDisallowInterceptTouchEvent(true);
            setScrollState(SCROLL_STATE_DRAGGING);
        } else {
            completeScroll(false);
            mIsBeingDragged = false;
        }

        DEBUG_LOG("***Down at " + mLastMotionX + "," + mLastMotionY + " mIsBeingDragged=" + mIsBeingDragged
                + " mIsUnableToDrag=" + mIsUnableToDrag);
        mLastDragged = -1;
        break;
    }

    case MotionEventCompat.ACTION_POINTER_UP:
        onSecondaryPointerUp(ev);
        break;
    }

    if (mVelocityTracker == null) {
        mVelocityTracker = VelocityTracker.obtain();
    }
    // 
    mVelocityTracker.addMovement(ev);
    /*
     * ???
     */
    /*
     * The only time we want to intercept motion events is if we are in the
     * drag mode.
     */
    return mIsBeingDragged;
}

---

From source file:com.samsistemas.calendarview.widget.CalendarView.java

@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
    /*//from  ww w . ja  v a2s.co m
     * This method JUST determines whether we want to intercept the motion.
     * If we return true, onMotionEvent will be called and we do the actual
     * scrolling there.
     */

    final int action = ev.getAction() & MotionEventCompat.ACTION_MASK;

    // Always take care of the touch gesture being complete.
    if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP) {
        // Release the drag.
        mIsBeingDragged = false;
        mIsUnableToDrag = false;
        mActivePointerId = INVALID_POINTER;
        if (mVelocityTracker != null) {
            mVelocityTracker.recycle();
            mVelocityTracker = null;
        }
        return false;
    }

    // Nothing more to do here if we have decided whether or not we
    // are dragging.
    if (action != MotionEvent.ACTION_DOWN) {
        if (mIsBeingDragged) {
            return true;
        }
        if (mIsUnableToDrag) {
            return false;
        }
    }

    switch (action) {
    case MotionEvent.ACTION_MOVE: {
        /*
         * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check
         * whether the user has moved far enough from his original down touch.
         */

        /*
        * Locally do absolute value. mLastMotionY is set to the y value
        * of the down event.
        */
        final int activePointerId = mActivePointerId;
        if (activePointerId == INVALID_POINTER) {
            // If we don't have a valid id, the touch down wasn't on content.
            break;
        }

        final int pointerIndex = MotionEventCompat.findPointerIndex(ev, activePointerId);
        final float x = MotionEventCompat.getX(ev, pointerIndex);
        final float dx = x - mLastMotionX;
        final float xDiff = Math.abs(dx);
        final float y = MotionEventCompat.getY(ev, pointerIndex);
        final float yDiff = Math.abs(y - mInitialMotionY);

        if (dx != 0 && !isGutterDrag(mLastMotionX, dx) && canScroll(this, false, (int) dx, (int) x, (int) y)) {
            // Nested view has scrollable area under this point. Let it be handled there.
            mLastMotionX = x;
            mLastMotionY = y;
            mIsUnableToDrag = true;
            return false;
        }
        if (xDiff > mTouchSlop && xDiff * 0.5f > yDiff) {
            mIsBeingDragged = true;
            requestParentDisallowInterceptTouchEvent(true);
            setScrollState(SCROLL_STATE_DRAGGING);
            mLastMotionX = dx > 0 ? mInitialMotionX + mTouchSlop : mInitialMotionX - mTouchSlop;
            mLastMotionY = y;
            setScrollingCacheEnabled(true);
        } else if (yDiff > mTouchSlop) {
            // The finger has moved enough in the vertical
            // direction to be counted as a drag...  abort
            // any attempt to drag horizontally, to work correctly
            // with children that have scrolling containers.
            mIsUnableToDrag = true;
        }
        break;
    }

    case MotionEvent.ACTION_DOWN: {
        /*
         * Remember location of down touch.
         * ACTION_DOWN always refers to pointer index 0.
         */
        mLastMotionX = mInitialMotionX = ev.getX();
        mLastMotionY = mInitialMotionY = ev.getY();
        mActivePointerId = MotionEventCompat.getPointerId(ev, 0);
        mIsUnableToDrag = false;

        mScroller.computeScrollOffset();
        if (mScrollState == SCROLL_STATE_SETTLING
                && Math.abs(mScroller.getFinalX() - mScroller.getCurrX()) > mCloseEnough) {
            mIsBeingDragged = true;
            requestParentDisallowInterceptTouchEvent(true);
            setScrollState(SCROLL_STATE_DRAGGING);
        } else {
            completeScroll(false);
            mIsBeingDragged = false;
        }
        break;
    }

    case MotionEventCompat.ACTION_POINTER_UP:
        onSecondaryPointerUp(ev);
        break;
    }

    if (mVelocityTracker == null) {
        mVelocityTracker = VelocityTracker.obtain();
    }

    mVelocityTracker.addMovement(ev);

    /*
     * The only time we want to intercept motion events is if we are in the
     * drag mode.
     */
    return mIsBeingDragged;
}

---

From source file:com.shine.demo.viewpager.DirectionalViewPager.java

@Override
public boolean onTouchEvent(MotionEvent ev) {

    if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) {
        // Don't handle edge touches immediately -- they may actually belong to one of our
        // descendants.
        return false;
    }//w  w w.ja  v a  2s  .co  m

    if (mAdapter == null || mAdapter.getCount() == 0) {
        // Nothing to present or scroll; nothing to touch.
        return false;
    }

    if (mVelocityTracker == null) {
        mVelocityTracker = VelocityTracker.obtain();
    }
    mVelocityTracker.addMovement(ev);

    final int action = ev.getAction();

    switch (action & MotionEventCompat.ACTION_MASK) {
    case MotionEvent.ACTION_DOWN: {
        /*
         * If being flinged and user touches, stop the fling. isFinished
         * will be false if being flinged.
         */
        completeScroll();

        // Remember where the motion event started
        if (mOrientation == HORIZONTAL) {
            mLastMotionX = mInitialMotion = ev.getX();
        } else {
            mLastMotionY = mInitialMotion = ev.getY();
        }
        mActivePointerId = MotionEventCompat.getPointerId(ev, 0);
        break;
    }
    case MotionEvent.ACTION_MOVE:
        if (!mIsBeingDragged) {
            final int pointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
            final float x = MotionEventCompat.getX(ev, pointerIndex);
            final float y = MotionEventCompat.getY(ev, pointerIndex);
            final float xDiff = Math.abs(x - mLastMotionX);
            final float yDiff = Math.abs(y - mLastMotionY);
            float primaryDiff;
            float secondaryDiff;

            if (mOrientation == HORIZONTAL) {
                primaryDiff = xDiff;
                secondaryDiff = yDiff;
            } else {
                primaryDiff = yDiff;
                secondaryDiff = xDiff;
            }

            if (DEBUG)
                Log.v(TAG, "Moved x to " + x + "," + y + " diff=" + xDiff + "," + yDiff);
            if (primaryDiff > mTouchSlop && primaryDiff > secondaryDiff) {
                if (DEBUG)
                    Log.v(TAG, "Starting drag!");
                mIsBeingDragged = true;
                if (mOrientation == HORIZONTAL) {
                    mLastMotionX = x;
                } else {
                    mLastMotionY = y;
                }
                setScrollState(SCROLL_STATE_DRAGGING);
                setScrollingCacheEnabled(true);
            }
        }
        if (mIsBeingDragged) {
            // Scroll to follow the motion event
            final int activePointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
            final float x = MotionEventCompat.getX(ev, activePointerIndex);
            final float y = MotionEventCompat.getY(ev, activePointerIndex);

            int size;
            float scroll;

            if (mOrientation == HORIZONTAL) {
                size = getWidth();
                scroll = getScrollX() + (mLastMotionX - x);
                mLastMotionX = x;
            } else {
                size = getHeight();
                scroll = getScrollY() + (mLastMotionY - y);
                mLastMotionY = y;
            }

            final float lowerBound = Math.max(0, (mCurItem - 1) * size);
            final float upperBound = Math.min(mCurItem + 1, mAdapter.getCount() - 1) * size;
            if (scroll < lowerBound) {
                scroll = lowerBound;
            } else if (scroll > upperBound) {
                scroll = upperBound;
            }
            if (mOrientation == HORIZONTAL) {
                // Don't lose the rounded component
                mLastMotionX += scroll - (int) scroll;
                scrollTo((int) scroll, getScrollY());
            } else {
                // Don't lose the rounded component
                mLastMotionY += scroll - (int) scroll;
                scrollTo(getScrollX(), (int) scroll);
            }
            if (mOnPageChangeListener != null
                    || (mOnPageChangeListeners != null && mOnPageChangeListeners.size() > 0)) {
                final int position = (int) scroll / size;
                final int positionOffsetPixels = (int) scroll % size;
                final float positionOffset = (float) positionOffsetPixels / size;

                if (mOnPageChangeListener != null) {
                    mOnPageChangeListener.onPageScrolled(position, positionOffset, positionOffsetPixels);
                }

                if (mOnPageChangeListeners != null) {
                    for (int i = 0, z = mOnPageChangeListeners.size(); i < z; i++) {
                        OnPageChangeListener listener = mOnPageChangeListeners.get(i);
                        if (listener != null) {
                            listener.onPageScrolled(position, positionOffset, positionOffsetPixels);
                        }
                    }
                }
            }
        }
        break;
    case MotionEvent.ACTION_UP:
        if (mIsBeingDragged) {
            final VelocityTracker velocityTracker = mVelocityTracker;
            velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
            int initialVelocity;
            float lastMotion;
            int sizeOverThree;

            if (mOrientation == HORIZONTAL) {
                initialVelocity = (int) VelocityTrackerCompat.getXVelocity(velocityTracker, mActivePointerId);
                lastMotion = mLastMotionX;
                sizeOverThree = getWidth() / 3;
            } else {
                initialVelocity = (int) VelocityTrackerCompat.getYVelocity(velocityTracker, mActivePointerId);
                lastMotion = mLastMotionY;
                sizeOverThree = getHeight() / 3;
            }

            mPopulatePending = true;
            if ((Math.abs(initialVelocity) > mMinimumVelocity)
                    || Math.abs(mInitialMotion - lastMotion) >= sizeOverThree) {
                if (lastMotion > mInitialMotion) {
                    setCurrentItemInternal(mCurItem - 1, true, true);
                } else {
                    setCurrentItemInternal(mCurItem + 1, true, true);
                }
            } else {
                setCurrentItemInternal(mCurItem, true, true);
            }

            mActivePointerId = INVALID_POINTER;
            endDrag();
        }
        break;
    case MotionEvent.ACTION_CANCEL:
        if (mIsBeingDragged) {
            setCurrentItemInternal(mCurItem, true, true);
            mActivePointerId = INVALID_POINTER;
            endDrag();
        }
        break;
    case MotionEventCompat.ACTION_POINTER_DOWN: {
        final int index = MotionEventCompat.getActionIndex(ev);
        if (mOrientation == HORIZONTAL) {
            mLastMotionX = MotionEventCompat.getX(ev, index);
        } else {
            mLastMotionY = MotionEventCompat.getY(ev, index);
        }
        mActivePointerId = MotionEventCompat.getPointerId(ev, index);
        break;
    }
    case MotionEventCompat.ACTION_POINTER_UP:
        onSecondaryPointerUp(ev);
        final int index = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
        if (mOrientation == HORIZONTAL) {
            mLastMotionX = MotionEventCompat.getX(ev, index);
        } else {
            mLastMotionY = MotionEventCompat.getY(ev, index);
        }
        break;
    }
    return true;
}

---

From source file:com.icloud.listenbook.base.view.DraggableGridViewPager.java

@Override
public boolean onTouchEvent(MotionEvent ev) {
    if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) {
        // Don't handle edge touches immediately -- they may actually belong
        // to one of our
        // descendants.
        return false;
    }/*  w  w  w . jav a 2 s.  c o  m*/

    if (mPageCount <= 0) {
        // Nothing to present or scroll; nothing to touch.
        return false;
    }
    //  
    if (mVelocityTracker == null) {
        mVelocityTracker = VelocityTracker.obtain();
    }
    mVelocityTracker.addMovement(ev);

    final int action = ev.getAction();
    boolean needsInvalidate = false;

    switch (action & MotionEventCompat.ACTION_MASK) {
    case MotionEvent.ACTION_DOWN: {
        // ?
        mScroller.abortAnimation();
        // Remember where the motion event started
        // ??
        mLastMotionX = mInitialMotionX = ev.getX();
        mLastMotionY = mInitialMotionY = ev.getY();
        mActivePointerId = MotionEventCompat.getPointerId(ev, 0);

        DEBUG_LOG("Down at " + mLastMotionX + "," + mLastMotionY + " mIsBeingDragged=" + mIsBeingDragged
                + " mIsUnableToDrag=" + mIsUnableToDrag);
        //  ? 
        if (!mIsBeingDragged && mScrollState == SCROLL_STATE_IDLE) {
            mLastPosition = getPositionByXY((int) mLastMotionX, (int) mLastMotionY);
        } else {
            mLastPosition = -1;
        }

        // 
        if (mLastPosition >= 0) {
            mLastDownTime = System.currentTimeMillis();
        } else {
            mLastDownTime = Long.MAX_VALUE;
        }
        DEBUG_LOG("Down at mLastPosition=" + mLastPosition);
        mLastDragged = -1;
        break;
    }
    case MotionEvent.ACTION_MOVE: {
        final int pointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
        final float x = MotionEventCompat.getX(ev, pointerIndex);
        final float y = MotionEventCompat.getY(ev, pointerIndex);
        // ?
        if (mLastDragged >= 0) {
            // change draw location of dragged visual
            // ? ?
            final View v = getChildAt(mLastDragged);
            final int l = getScrollX() + (int) x - v.getWidth() / 2;
            final int t = getScrollY() + (int) y - v.getHeight() / 2;
            v.layout(l, t, l + v.getWidth(), t + v.getHeight());

            // check for new target hover
            // 
            if (mScrollState == SCROLL_STATE_IDLE) {
                final int target = getTargetByXY((int) x, (int) y);
                // ?? ??
                if (target != -1 && mLastTarget != target) {
                    animateGap(target);
                    mLastTarget = target;
                    DEBUG_LOG("Moved to mLastTarget=" + mLastTarget);
                }
                // edge holding
                /**
                 * ? 
                 * */
                final int edge = getEdgeByXY((int) x, (int) y);
                if (mLastEdge == -1) {
                    if (edge != mLastEdge) {
                        mLastEdge = edge;
                        mLastEdgeTime = System.currentTimeMillis();
                    }
                } else {
                    // ?? 1.2 ?
                    if (edge != mLastEdge) {
                        mLastEdge = -1;
                    } else {
                        if ((System.currentTimeMillis() - mLastEdgeTime) >= EDGE_HOLD_DURATION) {
                            // ???
                            performHapticFeedback(HapticFeedbackConstants.LONG_PRESS);
                            triggerSwipe(edge);
                            mLastEdge = -1;
                        }
                    }
                }
            }
        }
        // ?
        else if (!mIsBeingDragged) {
            final float xDiff = Math.abs(x - mLastMotionX);
            final float yDiff = Math.abs(y - mLastMotionY);
            DEBUG_LOG("Moved to " + x + "," + y + " diff=" + xDiff + "," + yDiff);
            // ?? ???
            if (xDiff > mTouchSlop && xDiff > yDiff) {
                DEBUG_LOG("Starting drag!");
                mIsBeingDragged = true;
                requestParentDisallowInterceptTouchEvent(true);
                mLastMotionX = x - mInitialMotionX > 0 ? mInitialMotionX + mTouchSlop
                        : mInitialMotionX - mTouchSlop;
                mLastMotionY = y;
                setScrollState(SCROLL_STATE_DRAGGING);
                setScrollingCacheEnabled(true);
            }
        }
        // Not else! Note that mIsBeingDragged can be set above.

        if (mIsBeingDragged) {
            // Scroll to follow the motion event
            // ?
            needsInvalidate |= performDrag(x);
        }
        // ??? ?
        else if (mLastPosition >= 0) {
            final int currentPosition = getPositionByXY((int) x, (int) y);
            DEBUG_LOG("Moved to currentPosition=" + currentPosition);
            // ?
            if (currentPosition == mLastPosition) {

                // 1S?
                if ((System.currentTimeMillis() - mLastDownTime) >= LONG_CLICK_DURATION) {
                    if (onItemLongClick(currentPosition)) {
                        performHapticFeedback(HapticFeedbackConstants.LONG_PRESS);
                        mLastDragged = mLastPosition;
                        requestParentDisallowInterceptTouchEvent(true);
                        mLastTarget = -1;
                        animateDragged();
                        mLastPosition = -1;
                    }
                    mLastDownTime = Long.MAX_VALUE;
                }
            } else {
                mLastPosition = -1;
            }
        }
        break;
    }
    case MotionEvent.ACTION_UP: {
        DEBUG_LOG("Touch up!!!");
        final int pointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
        final float x = MotionEventCompat.getX(ev, pointerIndex);
        final float y = MotionEventCompat.getY(ev, pointerIndex);
        //  ?
        if (mLastDragged >= 0) {
            rearrange();
        } else if
        //  ??
        (mIsBeingDragged) {
            final VelocityTracker velocityTracker = mVelocityTracker;
            velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
            int initialVelocity = (int) VelocityTrackerCompat.getXVelocity(velocityTracker, mActivePointerId);
            final int width = getWidth();
            final int scrollX = getScrollX();
            final int currentPage = scrollX / width;
            final int offsetPixels = scrollX - currentPage * width;
            final float pageOffset = (float) offsetPixels / (float) width;
            final int totalDelta = (int) (x - mInitialMotionX);
            int nextPage = determineTargetPage(currentPage, pageOffset, initialVelocity, totalDelta);
            setCurrentItemInternal(nextPage, true, true, initialVelocity);

            mActivePointerId = INVALID_POINTER;
            endDrag();
        } else if (mLastPosition >= 0) {
            final int currentPosition = getPositionByXY((int) x, (int) y);
            DEBUG_LOG("Touch up!!! currentPosition=" + currentPosition);
            if (currentPosition == mLastPosition) {
                onItemClick(currentPosition);
            }
        }
        break;
    }
    case MotionEvent.ACTION_CANCEL:
        DEBUG_LOG("Touch cancel!!!");
        //  ? 
        if (mLastDragged >= 0) {
            rearrange();
        } else
        // ???
        if (mIsBeingDragged) {
            scrollToItem(mCurItem, true, 0, false);
            mActivePointerId = INVALID_POINTER;
            endDrag();
        }
        break;
    case MotionEventCompat.ACTION_POINTER_DOWN: {
        //  ???
        final int index = MotionEventCompat.getActionIndex(ev);
        final float x = MotionEventCompat.getX(ev, index);
        mLastMotionX = x;
        mActivePointerId = MotionEventCompat.getPointerId(ev, index);
        break;
    }
    case MotionEventCompat.ACTION_POINTER_UP:
        //  ?
        onSecondaryPointerUp(ev);
        mLastMotionX = MotionEventCompat.getX(ev, MotionEventCompat.findPointerIndex(ev, mActivePointerId));
        break;
    }
    if (needsInvalidate) {
        ViewCompat.postInvalidateOnAnimation(this);
    }
    return true;
}

---

From source file:com.open.ui.viewpager.view.TabViewPager.java

@Override
public boolean onTouchEvent(MotionEvent ev) {
    //Log.d(TAG,"onTouchEvent getAction: "+ ev.getAction());
    if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) {
        // Don't handle edge touches immediately -- they may actually belong to one of our
        // descendants.
        return false;
    }/*from w  ww  .j  a  va2s .c  o m*/

    if (mAdapter == null || mAdapter.getCount() == 0) {
        // Nothing to present or scroll; nothing to touch.
        return false;
    }

    if (mVelocityTracker == null) {
        mVelocityTracker = VelocityTracker.obtain();
    }
    mVelocityTracker.addMovement(ev);

    final int action = ev.getAction();

    switch (action & MotionEventCompat.ACTION_MASK) {
    case MotionEvent.ACTION_DOWN: {
        /*
         * If being flinged and user touches, stop the fling. isFinished
         * will be false if being flinged.
         */
        completeScroll();

        // Remember where the motion event started
        mLastMotionX = mInitialMotionX = ev.getX();
        mActivePointerId = MotionEventCompat.getPointerId(ev, 0);
        break;
    }
    case MotionEvent.ACTION_MOVE:
        if (!mIsBeingDragged) {
            final int pointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
            final float x = MotionEventCompat.getX(ev, pointerIndex);
            final float xDiff = Math.abs(x - mLastMotionX);
            final float y = MotionEventCompat.getY(ev, pointerIndex);
            final float yDiff = Math.abs(y - mLastMotionY);
            //if (DEBUG) Log.v(TAG, "Moved x to " + x + "," + y + " diff=" + xDiff + "," + yDiff);
            if (xDiff > mTouchSlop && xDiff > yDiff) {
                //if (DEBUG) Log.v(TAG, "Starting drag!");
                mIsBeingDragged = true;
                mLastMotionX = x;
                setScrollState(SCROLL_STATE_DRAGGING);
                setScrollingCacheEnabled(true);
            }
        }
        if (mIsBeingDragged) {
            // Scroll to follow the motion event
            final int activePointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
            final float x = MotionEventCompat.getX(ev, activePointerIndex);
            final float deltaX = mLastMotionX - x;
            mLastMotionX = x;
            float scrollX = getScrollX() + deltaX;
            final int width = getWidth();

            final float leftBound = Math.max(0, (mCurItem - 1) * width);
            final float rightBound = Math.min(mCurItem + 1, mAdapter.getCount() - 1) * width;
            if (scrollX < leftBound) {
                scrollX = leftBound;
            } else if (scrollX > rightBound) {
                scrollX = rightBound;
            }
            // Don't lose the rounded component
            mLastMotionX += scrollX - (int) scrollX;

            if (!mHasTrulyChangeX && getScrollX() != (int) scrollX) {
                mHasTrulyChangeX = true;
                getParent().requestDisallowInterceptTouchEvent(true);
            }
            scrollTo((int) scrollX, getScrollY());
            if (mOnPageChangeListener != null) {
                final int position = (int) scrollX / width;
                final int positionOffsetPixels = (int) scrollX % width;
                final float positionOffset = (float) positionOffsetPixels / width;

                mOnPageChangeListener.onPageScrollDeltaX(deltaX);
                mOnPageChangeListener.onPageScrolled(position, positionOffset, positionOffsetPixels);

            }
            //if (DEBUG) Log.v(TAG, "Moved mIsBeingDragged " +  "deltaX  " + deltaX+" scrollX  " + scrollX+ "width  " + width );
        }
        break;
    case MotionEvent.ACTION_UP:
        if (mIsBeingDragged) {
            final VelocityTracker velocityTracker = mVelocityTracker;
            velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
            int initialVelocity = (int) VelocityTrackerCompat.getYVelocity(velocityTracker, mActivePointerId);
            mPopulatePending = true;
            if ((Math.abs(initialVelocity) > mMinimumVelocity)
                    || Math.abs(mInitialMotionX - mLastMotionX) >= (getWidth() / 3)) {
                if (mLastMotionX > mInitialMotionX) {
                    setCurrentItemInternal(mCurItem - 1, true, true);
                } else {
                    setCurrentItemInternal(mCurItem + 1, true, true);
                }
            } else {
                setCurrentItemInternal(mCurItem, true, true);
            }

            mActivePointerId = INVALID_POINTER;
            endDrag();
        }
        break;
    case MotionEvent.ACTION_CANCEL:
        if (mIsBeingDragged) {
            setCurrentItemInternal(mCurItem, true, true);
            mActivePointerId = INVALID_POINTER;
            endDrag();
        }
        break;
    case MotionEventCompat.ACTION_POINTER_DOWN: {
        final int index = MotionEventCompat.getActionIndex(ev);
        final float x = MotionEventCompat.getX(ev, index);
        mLastMotionX = x;
        mActivePointerId = MotionEventCompat.getPointerId(ev, index);
        break;
    }
    case MotionEventCompat.ACTION_POINTER_UP:
        onSecondaryPointerUp(ev);
        mLastMotionX = MotionEventCompat.getX(ev, MotionEventCompat.findPointerIndex(ev, mActivePointerId));
        break;
    }
    return true;
}

---

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