69 lines
3.3 KiB
Swift
69 lines
3.3 KiB
Swift
import UIKit
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extension RDPDFReaderView: UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
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public func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
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pageCount()
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}
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public func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
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let view = dataSource?.pageContentView(readerView: self, pageNum: indexPath.item) ?? UIView()
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view.tag = indexPath.item
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configureSpreadAlignment(for: view, page: indexPath.item)
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configureInteraction(for: view)
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if let cell = view.superview?.superview as? RDPDFReaderContentCell { return cell }
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let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "fallback", for: indexPath) as! RDPDFReaderContentCell
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cell.hostedView = view
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return cell
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}
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public func collectionView(
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_ collectionView: UICollectionView,
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layout collectionViewLayout: UICollectionViewLayout,
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sizeForItemAt indexPath: IndexPath
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) -> CGSize {
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// 手机横屏竖滑：cell 高度=宽度适配后的纸张高度，超出一屏的内容由
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// collectionView 自身的连续滚动承接；页面未加载时先按一屏高占位。
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if usesWidthFitVerticalScroll,
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let height = verticalScrollWidthFitPageHeightProvider?(indexPath.item, bounds.width),
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height > 0 {
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return CGSize(width: bounds.width, height: height)
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}
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return usesLandscapeSpread
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? CGSize(width: bounds.width / 2, height: bounds.height)
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: bounds.size
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}
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public func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
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updateCurrentPageAfterScroll(scrollView)
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}
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public func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
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// 竖滑是连续滚动（isPagingEnabled = false），轻推后直接停下不会触发
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// 减速回调；此处兜底，否则页码停留在旧值。
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if !decelerate { updateCurrentPageAfterScroll(scrollView) }
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}
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private func updateCurrentPageAfterScroll(_ scrollView: UIScrollView) {
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guard currentDisplayType != .pageCurl else { return }
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// 用户主动滚动后保留其页内阅读位置；不再应用先前跳页等待异步布局的顶部锚点。
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pendingWidthFitJumpPage = nil
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if currentDisplayType == .verticalScroll {
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// 宽度适配下各 cell 高度不同，页码取视口中心命中的 cell。
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// 顶部/底部回弹时中心点会越出内容范围，钳制回内容内再取 cell。
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let centerY = scrollView.contentOffset.y + scrollView.bounds.height / 2
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let center = CGPoint(
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x: scrollView.bounds.width / 2,
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y: min(max(0, centerY), max(0, collectionView.contentSize.height - 1))
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)
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if let indexPath = collectionView.indexPathForItem(at: center) {
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currentPage = indexPath.item
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} else if let first = collectionView.indexPathsForVisibleItems.min(by: { $0.item < $1.item }) {
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currentPage = first.item
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}
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return
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}
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let value = scrollView.contentOffset.x / max(bounds.width, 1)
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currentPage = Int(value.rounded()) * (usesLandscapeSpread ? 2 : 1)
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}
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}
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