UIScrollViewDelegates.swift
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//
// UIScrollViewDelegates.swift
//
// Copyright (c) 2016-2017 JTAppleCalendar (https://github.com/patchthecode/JTAppleCalendar)
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//
extension JTAppleCalendarView: UIScrollViewDelegate {
/// Inform the scrollViewDidEndDecelerating
/// function that scrolling just occurred
public func scrollViewDidScrollToTop(_ scrollView: UIScrollView) {
scrollViewDidEndDecelerating(self)
}
public func saveLastContentOffset(_ offset: CGPoint) {
lastSavedContentOffset = scrollDirection == .horizontal ? offset.x : offset.y
}
/// Tells the delegate when the user finishes scrolling the content.
open func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
guard let theCurrentSection = currentSection() else { return }
let contentSizeEndOffset: CGFloat
var contentOffset: CGFloat = 0,
theTargetContentOffset: CGFloat = 0,
directionVelocity: CGFloat = 0
let calendarLayout = calendarViewLayout
if scrollDirection == .horizontal {
contentOffset = scrollView.contentOffset.x
theTargetContentOffset = targetContentOffset.pointee.x
directionVelocity = velocity.x
contentSizeEndOffset = scrollView.contentSize.width - scrollView.frame.width
} else {
contentOffset = scrollView.contentOffset.y
theTargetContentOffset = targetContentOffset.pointee.y
directionVelocity = velocity.y
contentSizeEndOffset = scrollView.contentSize.height - scrollView.frame.height
}
// If no scrolling is occuring
if contentOffset == lastSavedContentOffset {
return
}
let setTargetContentOffset = {(finalOffset: CGFloat) -> Void in
if self.scrollDirection == .horizontal {
targetContentOffset.pointee.x = finalOffset
} else {
targetContentOffset.pointee.y = finalOffset
}
self.endScrollTargetLocation = finalOffset
}
if didEndScollCount > 0, directionVelocity == 0, scrollingMode != .none {
setTargetContentOffset(endScrollTargetLocation)
return
}
didEndScollCount += 1
if directionVelocity == 0.0 {
decelerationRate = .fast
}
let isScrollingForward = {
return directionVelocity > 0 || contentOffset > self.lastSavedContentOffset
}
let calculatedCurrentFixedContentOffsetFrom = {(interval: CGFloat) -> CGFloat in
if isScrollingForward() {
return ceil(contentOffset / interval) * interval
} else {
return floor(contentOffset / interval) * interval
}
}
let recalculateOffset = {(diff: CGFloat, interval: CGFloat) -> CGFloat in
if isScrollingForward() {
let recalcOffsetAfterResistanceApplied = theTargetContentOffset - diff
return ceil(recalcOffsetAfterResistanceApplied / interval) * interval
} else {
let recalcOffsetAfterResistanceApplied = theTargetContentOffset + diff
return floor(recalcOffsetAfterResistanceApplied / interval) * interval
}
}
let scrollViewShouldStopAtBeginning = {() -> Bool in
return contentOffset < 0 && theTargetContentOffset == 0 ?
true : false
}
let scrollViewShouldStopAtEnd = {
(calculatedOffSet: CGFloat) -> Bool in
return calculatedOffSet > contentSizeEndOffset
}
switch scrollingMode {
case let .stopAtEach(customInterval: interval):
let calculatedOffset = calculatedCurrentFixedContentOffsetFrom(interval)
setTargetContentOffset(calculatedOffset)
case .stopAtEachCalendarFrame:
#if os(tvOS)
let interval = scrollDirection == .horizontal ? scrollView.frame.width : scrollView.frame.height
let calculatedOffset = calculatedCurrentFixedContentOffsetFrom(interval)
setTargetContentOffset(calculatedOffset)
#else
setTargetContentOffset(scrollDirection == .horizontal ? targetContentOffset.pointee.x : targetContentOffset.pointee.y)
#endif
break
case .stopAtEachSection:
var calculatedOffSet: CGFloat = 0
if scrollDirection == .horizontal ||
(scrollDirection == .vertical && !calendarViewLayout.thereAreHeaders && _cachedConfiguration.generateOutDates == .tillEndOfGrid) {
// Horizontal has a fixed width.
// Vertical with no header has fixed height
let interval = calendarLayout.sizeOfContentForSection(theCurrentSection)
calculatedOffSet = calculatedCurrentFixedContentOffsetFrom(interval)
} else {
// Vertical with headers have variable heights.
// It needs to be calculated
let currentScrollOffset = scrollView.contentOffset.y
let currentScrollSection = calendarLayout.sectionFromOffset(currentScrollOffset)
var sectionSize: CGFloat = 0
if isScrollingForward() {
sectionSize = calendarLayout.sectionSize[currentScrollSection]
calculatedOffSet = sectionSize
} else {
if currentScrollSection - 1 >= 0 {
calculatedOffSet = calendarLayout.sectionSize[currentScrollSection - 1]
}
}
}
setTargetContentOffset(calculatedOffSet)
case .nonStopToSection, .nonStopToCell, .nonStopTo:
let diff = abs(theTargetContentOffset - contentOffset)
let targetSection = calendarLayout.sectionFromOffset(theTargetContentOffset)
var calculatedOffSet = contentOffset
switch scrollingMode {
case let .nonStopToSection(resistance):
let interval = calendarLayout.sizeOfContentForSection(targetSection)
let diffResistance = diff * resistance
if scrollDirection == .horizontal {
calculatedOffSet = recalculateOffset(diffResistance, interval)
} else {
if isScrollingForward() {
calculatedOffSet = theTargetContentOffset - diffResistance
} else {
calculatedOffSet = theTargetContentOffset + diffResistance
}
let stopSection = isScrollingForward() ?
calendarLayout.sectionFromOffset(calculatedOffSet) :
calendarLayout.sectionFromOffset(calculatedOffSet) - 1
calculatedOffSet = stopSection < 0 ?
0 : calendarLayout.sectionSize[stopSection]
}
setTargetContentOffset(calculatedOffSet)
case let .nonStopToCell(resistance):
let interval = calendarLayout.cellCache[targetSection]![0].4
let diffResistance = diff * resistance
if scrollDirection == .horizontal {
if scrollViewShouldStopAtBeginning() {
calculatedOffSet = 0
} else if scrollViewShouldStopAtEnd(calculatedOffSet) {
calculatedOffSet = theTargetContentOffset
} else {
calculatedOffSet = recalculateOffset(diffResistance, interval)
}
} else {
var stopSection: Int
if isScrollingForward() {
calculatedOffSet = scrollViewShouldStopAtEnd(calculatedOffSet) ? theTargetContentOffset : theTargetContentOffset - diffResistance
stopSection = calendarLayout.sectionFromOffset(calculatedOffSet)
} else {
calculatedOffSet = scrollViewShouldStopAtBeginning() ? 0 : theTargetContentOffset + diffResistance
stopSection = calendarLayout.sectionFromOffset(calculatedOffSet)
}
let pathPoint = CGPoint( x: targetContentOffset.pointee.x, y: calculatedOffSet)
let attribPath = IndexPath(item: 0, section: stopSection)
if contentOffset > 0, let path = indexPathForItem(at: pathPoint) {
guard let attrib = calendarViewLayout.layoutAttributesForItem(at: path) else { return }
if isScrollingForward() {
calculatedOffSet = attrib.frame.origin.y + attrib.frame.size.height
} else {
calculatedOffSet = attrib.frame.origin.y
}
} else if calendarViewLayout.thereAreHeaders,
let attrib = calendarLayout.layoutAttributesForSupplementaryView(ofKind: UICollectionView.elementKindSectionHeader, at: attribPath) { // JT101 this was changed
// change the final value to the end of the header
if isScrollingForward() {
calculatedOffSet = attrib.frame.origin.y + attrib.frame.size.height
} else {
calculatedOffSet = stopSection - 1 < 0 ? 0 : calendarLayout.sectionSize[stopSection - 1]
}
}
}
setTargetContentOffset(calculatedOffSet)
case let .nonStopTo(interval, resistance):
// Both horizontal and vertical are fixed
let diffResistance = diff * resistance
calculatedOffSet =
recalculateOffset(diffResistance, interval)
setTargetContentOffset(calculatedOffSet)
default:
break
}
case .none: break
}
let futureScrollPoint = CGPoint(x: targetContentOffset.pointee.x, y: targetContentOffset.pointee.y)
saveLastContentOffset(futureScrollPoint)
let dateSegmentInfo = datesAtCurrentOffset(futureScrollPoint)
calendarDelegate?.calendar(self, willScrollToDateSegmentWith: dateSegmentInfo)
DispatchQueue.main.asyncAfter(deadline: .now() + 0.7) {
self.decelerationRate = UIScrollView.DecelerationRate(rawValue: self.decelerationRateMatchingScrollingMode)
}
DispatchQueue.main.async {
self.calendarDelegate?.scrollDidEndDecelerating(for: self)
}
}
/// Tells the delegate when a scrolling
/// animation in the scroll view concludes.
public func scrollViewDidEndScrollingAnimation(_ scrollView: UIScrollView) {
isScrollInProgress = false
if
let shouldTrigger = triggerScrollToDateDelegate,
shouldTrigger == true {
scrollViewDidEndDecelerating(scrollView)
triggerScrollToDateDelegate = nil
}
DispatchQueue.main.async { // https://github.com/patchthecode/JTAppleCalendar/issues/778
self.executeDelayedTasks(.scroll)
self.saveLastContentOffset(scrollView.contentOffset)
}
}
/// Tells the delegate that the scroll view has
/// ended decelerating the scrolling movement.
public func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
didEndScollCount = 0
visibleDates {[unowned self] dates in
self.calendarDelegate?.calendar(self, didScrollToDateSegmentWith: dates)
}
}
/// Tells the delegate that a scroll occured
public func scrollViewDidScroll(_ scrollView: UIScrollView) {
calendarDelegate?.calendarDidScroll(self)
}
}