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fix: prevent single-page reader startup crash #51

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Merged
zyk1172 merged 1 commit into from
Sep 12, 2026
Merged

fix: prevent single-page reader startup crash #51

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31 changes: 14 additions & 17 deletions mreader/ReaderView.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -171,6 +171,18 @@ nonisolated private struct InitialReadingPreset {
)
}

nonisolated enum ReadingPresetSamplePagePolicy {
static func pageIndices(totalPages: Int) -> [Int] {
guard totalPages > 0 else { return [] }

let preferredEnd = min(totalPages, 5)
guard 2 < preferredEnd else {
return Array(0..<totalPages)
}
return Array(2..<preferredEnd)
}
}

/// 阅读预设检测器：在 Reader 第一次创建之前完成“这本漫画是不是长条”的判断，
/// 避免先按普通模式预载再切到 8192 重解码（审查 #17）。
nonisolated private enum InitialReadingPresetDetector {
Expand All @@ -186,7 +198,7 @@ nonisolated private enum InitialReadingPresetDetector {
if isDocument(comic, "pdf") {
return InitialReadingPreset.longStrip
}
let sampleIndices = samplePageIndices(totalPages: pages.count)
let sampleIndices = ReadingPresetSamplePagePolicy.pageIndices(totalPages: pages.count)
guard !sampleIndices.isEmpty else { return .normalPage }
var ratios: [CGFloat] = []
for index in sampleIndices {
Expand Down Expand Up @@ -253,12 +265,6 @@ nonisolated private enum InitialReadingPresetDetector {
return comic.chapterTypeRaw?.lowercased() == expectedExtension
}

private static func samplePageIndices(totalPages: Int) -> [Int] {
guard totalPages > 0 else { return [] }
let preferred = (2..<min(totalPages, 5)).map { $0 }
return preferred.isEmpty ? Array(0..<totalPages) : preferred
}

private static func medianRatio(_ ratios: [CGFloat]) -> CGFloat? {
guard !ratios.isEmpty else { return nil }
let sortedRatios = ratios.sorted()
Expand Down Expand Up @@ -1594,7 +1600,7 @@ struct ReaderView: View {
reason: "pdf"
)
}
let sampleIndices = readingPresetSamplePageIndices(totalPages: manager.pages.count)
let sampleIndices = ReadingPresetSamplePagePolicy.pageIndices(totalPages: manager.pages.count)
guard !sampleIndices.isEmpty else {
print("MReader initial preset fallback: no sample pages for comic=\(comic.id)")
return InitialReadingPreset.normalPage
Expand Down Expand Up @@ -1628,15 +1634,6 @@ struct ReaderView: View {
)
}

private func readingPresetSamplePageIndices(totalPages: Int) -> [Int] {
guard totalPages > 0 else { return [] }
let preferred = (2..<min(totalPages, 5)).map { $0 }
if !preferred.isEmpty {
return preferred
}
return Array(0..<totalPages)
}

private func medianRatio(_ ratios: [CGFloat]) -> CGFloat? {
guard !ratios.isEmpty else { return nil }
let sortedRatios = ratios.sorted()
Expand Down
14 changes: 14 additions & 0 deletions mreaderTests/ReaderReadingPresetTests.swift
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Original file line number Diff line number Diff line change
@@ -0,0 +1,14 @@
import Testing
@testable import mreader

struct ReaderReadingPresetTests {
@Test
func samplePageIndicesHandleShortBooksWithoutCreatingAnInvalidRange() {
#expect(ReadingPresetSamplePagePolicy.pageIndices(totalPages: 0) == [])
#expect(ReadingPresetSamplePagePolicy.pageIndices(totalPages: 1) == [0])
#expect(ReadingPresetSamplePagePolicy.pageIndices(totalPages: 2) == [0, 1])
#expect(ReadingPresetSamplePagePolicy.pageIndices(totalPages: 3) == [2])
#expect(ReadingPresetSamplePagePolicy.pageIndices(totalPages: 5) == [2, 3, 4])
#expect(ReadingPresetSamplePagePolicy.pageIndices(totalPages: 8) == [2, 3, 4])
}
}