110 lines
3.3 KiB
Swift
110 lines
3.3 KiB
Swift
//
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// MediaPreviewItem.swift
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// suixinkan
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//
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import UIKit
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/// 媒体预览资源项，描述可全屏预览的图片或视频。
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public struct MediaPreviewItem: Hashable {
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/// 媒体类型。
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public enum MediaType: Equatable {
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case image
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case video
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}
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/// 预览资源来源。
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public enum Source {
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case remoteImage(URL)
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case localImageFile(URL)
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case image(UIImage)
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case remoteVideo(URL)
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case localVideoFile(URL)
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}
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/// 资源唯一标识，用于 Diffable Data Source。
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public let id: UUID
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/// 预览资源来源。
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public let source: Source
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/// 创建媒体预览资源项。
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public init(id: UUID = UUID(), source: Source) {
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self.id = id
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self.source = source
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}
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/// 媒体类型。
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public var mediaType: MediaType {
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switch source {
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case .remoteImage, .localImageFile, .image:
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return .image
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case .remoteVideo, .localVideoFile:
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return .video
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}
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}
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/// 是否为图片资源。
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public var isImage: Bool {
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mediaType == .image
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}
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/// 是否为视频资源。
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public var isVideo: Bool {
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mediaType == .video
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}
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/// 通过远程图片地址创建资源项，空字符串或非法地址返回 nil。
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public static func remoteImage(_ urlString: String) -> MediaPreviewItem? {
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makeRemoteURL(from: urlString).map { MediaPreviewItem(source: .remoteImage($0)) }
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}
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/// 通过远程视频地址创建资源项，空字符串或非法地址返回 nil。
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public static func remoteVideo(_ urlString: String) -> MediaPreviewItem? {
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makeRemoteURL(from: urlString).map { MediaPreviewItem(source: .remoteVideo($0)) }
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}
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/// 通过本地图片文件地址创建资源项。
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public static func localImage(url: URL) -> MediaPreviewItem {
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MediaPreviewItem(source: .localImageFile(url))
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}
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/// 通过本地图片对象创建资源项。
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public static func image(_ image: UIImage) -> MediaPreviewItem {
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MediaPreviewItem(source: .image(image))
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}
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/// 通过本地视频文件地址创建资源项。
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public static func localVideo(url: URL) -> MediaPreviewItem {
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MediaPreviewItem(source: .localVideoFile(url))
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}
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/// 将起始索引限制在可用范围内。
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public static func clampedStartIndex(_ startIndex: Int, itemCount: Int) -> Int {
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guard itemCount > 0 else { return 0 }
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return min(max(0, startIndex), itemCount - 1)
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}
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/// 从媒体数组中读取安全的起始资源项。
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public static func currentItem(in items: [MediaPreviewItem], startIndex: Int) -> MediaPreviewItem? {
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guard !items.isEmpty else { return nil }
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return items[clampedStartIndex(startIndex, itemCount: items.count)]
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}
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public static func == (lhs: MediaPreviewItem, rhs: MediaPreviewItem) -> Bool {
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lhs.id == rhs.id
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}
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public func hash(into hasher: inout Hasher) {
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hasher.combine(id)
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}
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private static func makeRemoteURL(from text: String) -> URL? {
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let trimmed = text.trimmingCharacters(in: .whitespacesAndNewlines)
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guard !trimmed.isEmpty, let url = URL(string: trimmed) else { return nil }
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guard let scheme = url.scheme?.lowercased(), ["http", "https"].contains(scheme) else { return nil }
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return url
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}
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}
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