/**
* Helper method for Overscrolling that encapsulates all of the necessary function. This is the
* advanced version of the call.
*
* @param view - PullToRefreshView that is calling this.
* @param deltaX - Change in X in pixels, passed through from from overScrollBy call
* @param scrollX - Current X scroll value in pixels before applying deltaY, passed through from
* from overScrollBy call
* @param deltaY - Change in Y in pixels, passed through from from overScrollBy call
* @param scrollY - Current Y scroll value in pixels before applying deltaY, passed through from
* from overScrollBy call
* @param scrollRange - Scroll Range of the View, specifically needed for ScrollView
* @param fuzzyThreshold - Threshold for which the values how fuzzy we should treat the other
* values. Needed for WebView as it doesn't always scroll back to it's edge. 0 = no fuzziness.
* @param scaleFactor - Scale Factor for overscroll amount
* @param isTouchEvent - true if this scroll operation is the result of a touch event, passed
* through from from overScrollBy call
*/
public static void overScrollBy(
final PullToRefreshBase<?> view,
final int deltaX,
final int scrollX,
final int deltaY,
final int scrollY,
final int scrollRange,
final int fuzzyThreshold,
final float scaleFactor,
final boolean isTouchEvent) {
final int deltaValue, currentScrollValue, scrollValue;
switch (view.getPullToRefreshScrollDirection()) {
case HORIZONTAL:
deltaValue = deltaX;
scrollValue = scrollX;
currentScrollValue = view.getScrollX();
break;
case VERTICAL:
default:
deltaValue = deltaY;
scrollValue = scrollY;
currentScrollValue = view.getScrollY();
break;
}
// Check that OverScroll is enabled and that we're not currently
// refreshing.
if (view.isPullToRefreshOverScrollEnabled() && !view.isRefreshing()) {
final PullToRefreshBase.Mode mode = view.getMode();
// Check that Pull-to-Refresh is enabled, and the event isn't from
// touch
if (mode.permitsPullToRefresh() && !isTouchEvent && deltaValue != 0) {
final int newScrollValue = (deltaValue + scrollValue);
if (PullToRefreshBase.DEBUG) {
Log.d(
LOG_TAG,
"OverScroll. DeltaX: "
+ deltaX
+ ", ScrollX: "
+ scrollX
+ ", DeltaY: "
+ deltaY
+ ", ScrollY: "
+ scrollY
+ ", NewY: "
+ newScrollValue
+ ", ScrollRange: "
+ scrollRange
+ ", CurrentScroll: "
+ currentScrollValue);
}
if (newScrollValue < (0 - fuzzyThreshold)) {
// Check the mode supports the overscroll direction, and
// then move scroll
if (mode.showHeaderLoadingLayout()) {
// If we're currently at zero, we're about to start
// overscrolling, so change the state
if (currentScrollValue == 0) {
view.setState(PullToRefreshBase.State.OVERSCROLLING);
}
view.setHeaderScroll((int) (scaleFactor * (currentScrollValue + newScrollValue)));
}
} else if (newScrollValue > (scrollRange + fuzzyThreshold)) {
// Check the mode supports the overscroll direction, and
// then move scroll
if (mode.showFooterLoadingLayout()) {
// If we're currently at zero, we're about to start
// overscrolling, so change the state
if (currentScrollValue == 0) {
view.setState(PullToRefreshBase.State.OVERSCROLLING);
}
view.setHeaderScroll(
(int) (scaleFactor * (currentScrollValue + newScrollValue - scrollRange)));
}
} else if (Math.abs(newScrollValue) <= fuzzyThreshold
|| Math.abs(newScrollValue - scrollRange) <= fuzzyThreshold) {
// Means we've stopped overscrolling, so scroll back to 0
view.setState(PullToRefreshBase.State.RESET);
}
} else if (isTouchEvent && PullToRefreshBase.State.OVERSCROLLING == view.getState()) {
// This condition means that we were overscrolling from a fling,
// but the user has touched the View and is now overscrolling
// from touch instead. We need to just reset.
view.setState(PullToRefreshBase.State.RESET);
}
}
}
