private int determineTargetPage(float pageOffset, int velocity, int deltaX) {
int targetPage = mCurItem;
if (Math.abs(deltaX) > mFlingDistance && Math.abs(velocity) > mMinimumVelocity) {
if (velocity > 0 && deltaX > 0) {
targetPage -= 1;
} else if (velocity < 0 && deltaX < 0) {
targetPage += 1;
}
} else {
targetPage = (int) Math.round(mCurItem + pageOffset);
}
return targetPage;
}
@Override
public void onNestedScroll(
View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed) {
if (dyUnconsumed < 0) {
dyUnconsumed = Math.abs(dyUnconsumed);
mTotalUnconsumed += dyUnconsumed;
moveSpinner(mTotalUnconsumed);
}
// Dispatch up to the nested parent
dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dxConsumed, null);
}
private void moveSpinner(float overscrollTop) {
mProgress.showArrow(true);
float originalDragPercent = overscrollTop / mTotalDragDistance;
float dragPercent = Math.min(1f, Math.abs(originalDragPercent));
float adjustedPercent = (float) Math.max(dragPercent - .4, 0) * 5 / 3;
float extraOS = Math.abs(overscrollTop) - mTotalDragDistance;
float slingshotDist =
mUsingCustomStart ? mSpinnerFinalOffset - mOriginalOffsetTop : mSpinnerFinalOffset;
float tensionSlingshotPercent =
Math.max(0, Math.min(extraOS, slingshotDist * 2) / slingshotDist);
float tensionPercent =
(float) ((tensionSlingshotPercent / 4) - Math.pow((tensionSlingshotPercent / 4), 2)) * 2f;
float extraMove = (slingshotDist) * tensionPercent * 2;
int targetY = mOriginalOffsetTop + (int) ((slingshotDist * dragPercent) + extraMove);
// where 1.0f is a full circle
if (mCircleView.getVisibility() != View.VISIBLE) {
mCircleView.setVisibility(View.VISIBLE);
}
if (!mScale) {
ViewCompat.setScaleX(mCircleView, 1f);
ViewCompat.setScaleY(mCircleView, 1f);
}
if (overscrollTop < mTotalDragDistance) {
if (mScale) {
setAnimationProgress(overscrollTop / mTotalDragDistance);
}
if (mProgress.getAlpha() > STARTING_PROGRESS_ALPHA
&& !isAnimationRunning(mAlphaStartAnimation)) {
// Animate the alpha
startProgressAlphaStartAnimation();
}
float strokeStart = adjustedPercent * .8f;
mProgress.setStartEndTrim(0f, Math.min(MAX_PROGRESS_ANGLE, strokeStart));
mProgress.setArrowScale(Math.min(1f, adjustedPercent));
} else {
if (mProgress.getAlpha() < MAX_ALPHA && !isAnimationRunning(mAlphaMaxAnimation)) {
// Animate the alpha
startProgressAlphaMaxAnimation();
}
}
float rotation = (-0.25f + .4f * adjustedPercent + tensionPercent * 2) * .5f;
mProgress.setProgressRotation(rotation);
setTargetOffsetTopAndBottom(targetY - mCurrentTargetOffsetTop, true /* requires update */);
}
@Override
public void applyTransformation(float interpolatedTime, Transformation t) {
int targetTop = 0;
int endTarget = 0;
if (!mUsingCustomStart) {
endTarget = (int) (mSpinnerFinalOffset - Math.abs(mOriginalOffsetTop));
} else {
endTarget = (int) mSpinnerFinalOffset; // mSpinnerFinalOffset;
}
targetTop = (mFrom + (int) ((endTarget - mFrom) * interpolatedTime));
int offset = targetTop - mCircleView.getTop();
setTargetOffsetTopAndBottom(offset, false /* requires update */);
mProgress.setArrowScale(1 - interpolatedTime);
}
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 (mViewBehind.getbMode()) {
if (yDiff > (isMenuOpen() ? mTouchSlop / 2 : mTouchSlop)
&& yDiff > xDiff
&& thisSlideAllowed(dy)) {
startDrag();
mLastMotionX = x;
mLastMotionY = y;
setScrollingCacheEnabled(true);
// TODO add back in touch slop check
} else if (yDiff > mTouchSlop) {
mIsUnableToDrag = true;
}
} else {
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;
}
}
}
/**
* 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();
}
protected float getPercentOpen() {
return Math.abs(mScrollX - mContent.getLeft()) / getBehindWidth();
}
// We want the duration of the page snap animation to be influenced by the distance that
// the screen has to travel, however, we don't want this duration to be effected in a
// purely linear fashion. Instead, we use this method to moderate the effect that the distance
// of travel has on the overall snap duration.
float distanceInfluenceForSnapDuration(float f) {
f -= 0.5f; // center the values about 0.
f *= 0.3f * Math.PI / 2.0f;
return (float) Math.sin(f);
}
