/**
* Like {@link View#scrollBy}, but scroll smoothly instead of immediately.
*
* @param x the number of pixels to scroll by on the X axis
* @param y the number of pixels to scroll by on the Y axis
* @param velocity the velocity associated with a fling, if applicable. (0 otherwise)
*/
void smoothScrollTo(int x, int y, int velocity) {
if (getChildCount() == 0) {
// Nothing to do.
setScrollingCacheEnabled(false);
return;
}
int sx = getScrollX();
int sy = getScrollY();
int dx = x - sx;
int dy = y - sy;
if (dx == 0 && dy == 0) {
completeScroll();
if (isMenuOpen()) {
if (mOpenedListener != null) mOpenedListener.onOpened();
} else {
if (mClosedListener != null) mClosedListener.onClosed();
}
return;
}
setScrollingCacheEnabled(true);
mScrolling = true;
final int width = getBehindWidth();
final int halfWidth = width / 2;
final float distanceRatio = Math.min(1f, 1.0f * Math.abs(dx) / width);
final float distance = halfWidth + halfWidth * distanceInfluenceForSnapDuration(distanceRatio);
int duration = 0;
velocity = Math.abs(velocity);
if (velocity > 0) {
duration = 4 * Math.round(1000 * Math.abs(distance / velocity));
} else {
final float pageDelta = (float) Math.abs(dx) / width;
duration = (int) ((pageDelta + 1) * 100);
duration = MAX_SETTLE_DURATION;
}
duration = Math.min(duration, MAX_SETTLE_DURATION);
mScroller.startScroll(sx, sy, dx, dy, duration);
invalidate();
}
private void completeScroll() {
boolean needPopulate = mScrolling;
if (needPopulate) {
// Done with scroll, no longer want to cache view drawing.
setScrollingCacheEnabled(false);
mScroller.abortAnimation();
int oldX = getScrollX();
int oldY = getScrollY();
int x = mScroller.getCurrX();
int y = mScroller.getCurrY();
if (oldX != x || oldY != y) {
scrollTo(x, y);
}
if (isMenuOpen()) {
if (mOpenedListener != null) mOpenedListener.onOpened();
} else {
if (mClosedListener != null) mClosedListener.onClosed();
}
}
mScrolling = false;
}
private void determineDrag(MotionEvent ev) {
final int activePointerId = mActivePointerId;
final int pointerIndex = getPointerIndex(ev, activePointerId);
if (activePointerId == INVALID_POINTER || pointerIndex == INVALID_POINTER) return;
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 dy = y - mLastMotionY;
final float yDiff = Math.abs(dy);
if (xDiff > (isMenuOpen() ? mTouchSlop / 2 : mTouchSlop)
&& xDiff > yDiff
&& thisSlideAllowed(dx)) {
startDrag();
mLastMotionX = x;
mLastMotionY = y;
setScrollingCacheEnabled(true);
// TODO add back in touch slop check
} else if (xDiff > mTouchSlop) {
mIsUnableToDrag = true;
}
}
void setCurrentItemInternal(int item, boolean smoothScroll, boolean always, int velocity) {
if (!always && mCurItem == item) {
setScrollingCacheEnabled(false);
return;
}
item = mViewBehind.getMenuPage(item);
final boolean dispatchSelected = mCurItem != item;
mCurItem = item;
final int destX = getDestScrollX(mCurItem);
if (dispatchSelected && mOnPageChangeListener != null) {
mOnPageChangeListener.onPageSelected(item);
}
if (dispatchSelected && mInternalPageChangeListener != null) {
mInternalPageChangeListener.onPageSelected(item);
}
if (smoothScroll) {
smoothScrollTo(destX, 0, velocity);
} else {
completeScroll();
scrollTo(destX, 0);
}
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
if (!mEnabled) return false;
if (!mIsBeingDragged && !thisTouchAllowed(ev)) return false;
// if (!mIsBeingDragged && !mQuickReturn)
// return false;
final int action = ev.getAction();
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(ev);
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) {
if (mActivePointerId == INVALID_POINTER) break;
final int pointerIndex = getPointerIndex(ev, mActivePointerId);
if (pointerIndex < 0 || pointerIndex >= ev.getPointerCount()) break;
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 - mLastMotionY);
if (DEBUG)
Log.v(
TAG,
"onTouch moved to:("
+ x
+ ", "
+ y
+ "), diff:("
+ xDiff
+ ", "
+ yDiff
+ ")\nmIsBeingDragged:"
+ mIsBeingDragged
+ ", mLastMotionX:"
+ mLastMotionX);
if ((xDiff > mTouchSlop || (mQuickReturn && xDiff > mTouchSlop / 4))
&& xDiff > yDiff
&& thisSlideAllowed(dx)) {
if (DEBUG) Log.v(TAG, "Starting drag! from onTouch");
startDrag();
mLastMotionX = x;
setScrollingCacheEnabled(true);
} else {
if (DEBUG) Log.v(TAG, "onTouch returning false");
return false;
}
}
if (mIsBeingDragged) {
// Scroll to follow the motion event
final int activePointerIndex = getPointerIndex(ev, mActivePointerId);
if (mActivePointerId == INVALID_POINTER) {
break;
}
final float x = MotionEventCompat.getX(ev, activePointerIndex);
final float deltaX = mLastMotionX - x;
mLastMotionX = x;
float oldScrollX = getScrollX();
float scrollX = oldScrollX + deltaX;
final float leftBound = getLeftBound();
final float rightBound = getRightBound();
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());
pageScrolled((int) scrollX);
}
break;
case MotionEvent.ACTION_UP:
if (mIsBeingDragged) {
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
int initialVelocity =
(int) VelocityTrackerCompat.getXVelocity(velocityTracker, mActivePointerId);
final int scrollX = getScrollX();
// final int widthWithMargin = getWidth();
// final float pageOffset = (float) (scrollX % widthWithMargin) / widthWithMargin;
// TODO test this. should get better flinging behavior
final float pageOffset = (float) (scrollX - getDestScrollX(mCurItem)) / getBehindWidth();
final int activePointerIndex = getPointerIndex(ev, mActivePointerId);
if (mActivePointerId != INVALID_POINTER) {
final float x = MotionEventCompat.getX(ev, activePointerIndex);
final int totalDelta = (int) (x - mInitialMotionX);
int nextPage = determineTargetPage(pageOffset, initialVelocity, totalDelta);
setCurrentItemInternal(nextPage, true, true, initialVelocity);
} else {
setCurrentItemInternal(mCurItem, true, true, initialVelocity);
}
mActivePointerId = INVALID_POINTER;
endDrag();
} else if (mQuickReturn
&& mViewBehind.menuTouchInQuickReturn(mContent, mCurItem, ev.getX() + mScrollX)) {
// close the menu
setCurrentItem(1);
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);
int pointerIndex = this.getPointerIndex(ev, mActivePointerId);
if (mActivePointerId == INVALID_POINTER) break;
mLastMotionX = MotionEventCompat.getX(ev, pointerIndex);
break;
}
return true;
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
if (!mEnabled) return false;
final int action = ev.getAction() & MotionEventCompat.ACTION_MASK;
if (DEBUG) if (action == MotionEvent.ACTION_DOWN) Log.v(TAG, "Received ACTION_DOWN");
if (action == MotionEvent.ACTION_CANCEL
|| action == MotionEvent.ACTION_UP
|| (action != MotionEvent.ACTION_DOWN && mIsUnableToDrag)) {
endDrag();
return false;
}
switch (action) {
case MotionEvent.ACTION_MOVE:
final int activePointerId = mActivePointerId;
if (activePointerId == INVALID_POINTER) break;
final int pointerIndex = this.getPointerIndex(ev, activePointerId);
if (pointerIndex < 0 || pointerIndex >= ev.getPointerCount()) break;
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 - mLastMotionY);
if (DEBUG)
Log.v(
TAG,
"onInterceptTouch moved to:("
+ x
+ ", "
+ y
+ "), diff:("
+ xDiff
+ ", "
+ yDiff
+ "), mLastMotionX:"
+ mLastMotionX);
if (xDiff > mTouchSlop && xDiff > yDiff && thisSlideAllowed(dx)) {
if (DEBUG) Log.v(TAG, "Starting drag! from onInterceptTouch");
startDrag();
mLastMotionX = x;
setScrollingCacheEnabled(true);
} else if (yDiff > mTouchSlop) {
mIsUnableToDrag = true;
}
break;
case MotionEvent.ACTION_DOWN:
mActivePointerId =
ev.getAction()
& ((Build.VERSION.SDK_INT >= 8)
? MotionEvent.ACTION_POINTER_INDEX_MASK
: MotionEvent.ACTION_POINTER_INDEX_MASK);
mLastMotionX = mInitialMotionX = MotionEventCompat.getX(ev, mActivePointerId);
mLastMotionY = MotionEventCompat.getY(ev, mActivePointerId);
if (thisTouchAllowed(ev)) {
mIsBeingDragged = false;
mIsUnableToDrag = false;
if (isMenuOpen()
&& mViewBehind.menuTouchInQuickReturn(mContent, mCurItem, ev.getX() + mScrollX)) {
mQuickReturn = true;
}
} else {
mIsUnableToDrag = true;
}
break;
case MotionEventCompat.ACTION_POINTER_UP:
onSecondaryPointerUp(ev);
break;
}
if (!mIsBeingDragged) {
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(ev);
}
return mIsBeingDragged || mQuickReturn;
}