add iOS PagedBookView with UIPageViewController and curl transition

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-03-14 06:16:12 +01:00
parent d2c2586009
commit 46f7d255eb
1 changed files with 186 additions and 0 deletions
--- a/Vorleser-iOS/PagedBookView.swift
+++ b/Vorleser-iOS/PagedBookView.swift
@@ -0,0 +1,186 @@
+import SwiftUI
+import UIKit
+import VorleserKit
+
+struct PagedBookView: UIViewControllerRepresentable {
+	let attributedText: NSAttributedString
+	let highlightRange: Range<Int>?
+	let onTapCharacter: (CharacterOffset) -> Void
+	var scrollToOffset: CharacterOffset?
+
+	func makeUIViewController(context: Context) -> UIPageViewController {
+		let pageVC = UIPageViewController(
+			transitionStyle: .pageCurl,
+			navigationOrientation: .horizontal
+		)
+		pageVC.dataSource = context.coordinator
+		pageVC.delegate = context.coordinator
+
+		context.coordinator.parent = self
+		context.coordinator.recomputePages(for: pageVC.view.bounds.size)
+
+		if let firstPage = context.coordinator.pageViewController(for: 0) {
+			pageVC.setViewControllers([firstPage], direction: .forward, animated: false)
+		}
+
+		return pageVC
+	}
+
+	func updateUIViewController(_ pageVC: UIPageViewController, context: Context) {
+		context.coordinator.parent = self
+		context.coordinator.recomputePages(for: pageVC.view.bounds.size)
+
+		// Navigate to page containing scrollToOffset
+		if let offset = scrollToOffset {
+			let pageIndex = context.coordinator.pageIndex(containing: offset)
+			if let vc = context.coordinator.pageViewController(for: pageIndex) {
+				pageVC.setViewControllers([vc], direction: .forward, animated: false)
+			}
+		}
+		// Auto-follow highlight
+		else if let range = highlightRange {
+			let pageIndex = context.coordinator.pageIndex(containing: range.lowerBound)
+			if pageIndex != context.coordinator.currentPageIndex,
+			   let vc = context.coordinator.pageViewController(for: pageIndex) {
+				let direction: UIPageViewController.NavigationDirection = pageIndex > context.coordinator.currentPageIndex ? .forward : .reverse
+				pageVC.setViewControllers([vc], direction: direction, animated: true)
+				context.coordinator.currentPageIndex = pageIndex
+			}
+		}
+	}
+
+	func makeCoordinator() -> Coordinator {
+		Coordinator(parent: self)
+	}
+
+	class Coordinator: NSObject, UIPageViewControllerDataSource, UIPageViewControllerDelegate {
+		var parent: PagedBookView
+		var currentPageIndex = 0
+		/// Each page boundary is a character offset where the page starts.
+		var pageBreaks: [Int] = [0]
+
+		init(parent: PagedBookView) {
+			self.parent = parent
+		}
+
+		func recomputePages(for size: CGSize) {
+			guard parent.attributedText.length > 0 else {
+				pageBreaks = [0]
+				return
+			}
+
+			let insets = UIEdgeInsets(top: 16, left: 16, bottom: 16, right: 16)
+			let pageWidth = size.width - insets.left - insets.right
+			let pageHeight = size.height - insets.top - insets.bottom
+			guard pageWidth > 0, pageHeight > 0 else {
+				pageBreaks = [0]
+				return
+			}
+
+			let textStorage = NSTextStorage(attributedString: parent.attributedText)
+			let layoutManager = NSLayoutManager()
+			textStorage.addLayoutManager(layoutManager)
+
+			var breaks: [Int] = [0]
+			var offset = 0
+
+			while offset < parent.attributedText.length {
+				let container = NSTextContainer(size: CGSize(width: pageWidth, height: pageHeight))
+				container.lineFragmentPadding = 0
+				layoutManager.addTextContainer(container)
+
+				let glyphRange = layoutManager.glyphRange(for: container)
+				let charRange = layoutManager.characterRange(forGlyphRange: glyphRange, actualGlyphRange: nil)
+
+				if charRange.length == 0 { break }
+
+				offset = charRange.location + charRange.length
+				if offset < parent.attributedText.length {
+					breaks.append(offset)
+				}
+			}
+
+			pageBreaks = breaks
+		}
+
+		func pageIndex(containing characterOffset: Int) -> Int {
+			for (i, breakOffset) in pageBreaks.enumerated().reversed() {
+				if characterOffset >= breakOffset {
+					return i
+				}
+			}
+			return 0
+		}
+
+		func pageViewController(for index: Int) -> UIViewController? {
+			guard index >= 0, index < pageBreaks.count else { return nil }
+			let start = pageBreaks[index]
+			let end = index + 1 < pageBreaks.count ? pageBreaks[index + 1] : parent.attributedText.length
+			let range = NSRange(location: start, length: end - start)
+
+			let pageText = NSMutableAttributedString(attributedString: parent.attributedText.attributedSubstring(from: range))
+
+			// Apply highlight if it falls within this page
+			if let highlightRange = parent.highlightRange {
+				let hlStart = max(highlightRange.lowerBound - start, 0)
+				let hlEnd = min(highlightRange.upperBound - start, pageText.length)
+				if hlStart < hlEnd {
+					let nsRange = NSRange(location: hlStart, length: hlEnd - hlStart)
+					pageText.addAttribute(.backgroundColor, value: UIColor.systemYellow.withAlphaComponent(0.3), range: nsRange)
+				}
+			}
+
+			let vc = UIViewController()
+			let textView = UITextView()
+			textView.isEditable = false
+			textView.isSelectable = false
+			textView.isScrollEnabled = false
+			textView.textContainerInset = UIEdgeInsets(top: 16, left: 16, bottom: 16, right: 16)
+			textView.attributedText = pageText
+			textView.tag = index
+
+			let tap = UITapGestureRecognizer(target: self, action: #selector(handleTap(_:)))
+			textView.addGestureRecognizer(tap)
+
+			vc.view = textView
+			return vc
+		}
+
+		@objc func handleTap(_ gesture: UITapGestureRecognizer) {
+			guard let textView = gesture.view as? UITextView else { return }
+			let pageIndex = textView.tag
+			let pageStart = pageBreaks[pageIndex]
+			let point = gesture.location(in: textView)
+			let localIndex = textView.offset(
+				from: textView.beginningOfDocument,
+				to: textView.closestPosition(to: point) ?? textView.beginningOfDocument
+			)
+			let globalIndex = pageStart + localIndex
+			if globalIndex < parent.attributedText.length {
+				parent.onTapCharacter(globalIndex)
+			}
+		}
+
+		// MARK: - UIPageViewControllerDataSource
+
+		func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {
+			guard let textView = viewController.view as? UITextView else { return nil }
+			let index = textView.tag
+			return self.pageViewController(for: index - 1)
+		}
+
+		func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
+			guard let textView = viewController.view as? UITextView else { return nil }
+			let index = textView.tag
+			return self.pageViewController(for: index + 1)
+		}
+
+		// MARK: - UIPageViewControllerDelegate
+
+		func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
+			guard completed,
+			      let textView = pageViewController.viewControllers?.first?.view as? UITextView else { return }
+			currentPageIndex = textView.tag
+		}
+	}
+}