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uniapp/Google Chrome/Form1.cs

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+using System.Text.Json;
+using System.Text.Json.Nodes;
+using Microsoft.Web.WebView2.Core;
+
+namespace WinFormsApp3
+{
+    /// <summary>
+    /// 当前正在播放的视频地址。
+    /// </summary>
+    /// <param name="Url">可直接 HTTP 访问的视频地址；PlaylistText 不为空时作为相对地址基准。</param>
+    /// <param name="PlaylistText">只在内存里拿到 m3u8 文本时使用（抖音这类 MSE 播放）。</param>
+    /// <param name="Referer">发出这个请求的文档地址；跨域 iframe 播放器必须用它，不然会被防盗链拒掉。</param>
+    public record VideoCandidate(string Url, string? PlaylistText = null, string? Referer = null);
+
+    public partial class Form1 : Form
+    {
+        private const string SnifferScript = @"Resources\media_sniffer.js";
+        private const string ButtonScript = @"Resources\video_button.js";
+        private const string GrabScript = @"Resources\video_grab.js";
+
+        private double currentZoomFactor = 1.3;
+        private readonly List<string> sniffedUrls = new();
+        private readonly List<string> sniffedPlaylists = new();
+
+        /// <summary>视频地址 → 发出请求的文档地址，用作下载时的 Referer。</summary>
+        private readonly Dictionary<string, string> urlReferers = new();
+        private readonly Dictionary<string, string> injectedScripts = new();
+        private CancellationTokenSource? downloadCts;
+        private bool hooksAttached;
+
+        public Form1()
+        {
+            InitializeComponent();
+
+            string css = @"
+                .pt-top-nav { display: none !important; }
+                .pt-head-bg { display: none !important; }
+                .pt-navbg { display: none !important; }
+                .erwm { display: none !important; }
+                .pt-right { display: none !important; }
+                .pt-copyright { display: none !important; }
+                .pt-crumb { display: none !important; }
+                .txtinfo { display: none !important; }
+                .mys-wrapper { display: none !important; }
+                .tools { display: none !important; }
+                .headbox  { display: none !important; }
+                .setbox  { display: none !important; }
+                .foot  { display: none !important; }
+            ";
+
+            if (File.Exists("css.txt"))
+            {
+                css = File.ReadAllText("css.txt");
+            }
+
+            webView21.NavigationCompleted += async (sender, e) =>
+            {
+                if (e.IsSuccess)
+                {
+                    await InjectCssAsync(css);
+                }
+            };
+
+            urlTxt.Text = "http://www.luoqiuzww.cc";
+        }
+
+        private async Task InjectCssAsync(string css)
+        {
+            if (File.Exists("css.txt"))
+            {
+                css = File.ReadAllText("css.txt");
+            }
+
+            string script = $@"
+        var style = document.createElement('style');
+        style.type = 'text/css';
+        style.innerHTML = `{css}`;
+        document.head.appendChild(style);
+    ";
+
+            await webView21.CoreWebView2.ExecuteScriptAsync(script);
+        }
+
+        private void OnNavigationCompleted(object sender, CoreWebView2NavigationCompletedEventArgs e)
+        {
+            if (e.IsSuccess)
+            {
+                urlTxt.Text = ((Microsoft.Web.WebView2.Core.CoreWebView2)sender).Source;
+                // 小延迟确保DOM完全加载
+                Task.Delay(100).ContinueWith(_ =>
+                {
+                    this.Invoke((MethodInvoker)delegate
+                    {
+                        if (Math.Abs(webView21.ZoomFactor - currentZoomFactor) > 0.01f)
+                        {
+                            webView21.ZoomFactor = currentZoomFactor;
+                        }
+                    });
+                });
+            }
+        }
+
+        /// <summary>
+        /// 顶层页面导航完成后重置嗅探结果：只保留当前页面里播过的地址，
+        /// 免得长时间浏览后下载地址越攒越多。
+        /// </summary>
+        private void OnMainNavigationCompleted(object? sender, CoreWebView2NavigationCompletedEventArgs e)
+        {
+            if (!e.IsSuccess)
+            {
+                return;
+            }
+
+            lock (sniffedUrls) sniffedUrls.Clear();
+            lock (urlReferers) urlReferers.Clear();
+            sniffedPlaylists.Clear();
+        }
+
+        private async Task EnsureCoreAsync()
+        {
+            if (webView21.CoreWebView2 != null)
+            {
+                return;
+            }
+
+            try
+            {
+                // 初始化 CoreWebView2
+                await webView21.EnsureCoreWebView2Async(null);
+
+                if (!hooksAttached && webView21.CoreWebView2 is { } core)
+                {
+                    hooksAttached = true;
+
+                    core.FrameNavigationCompleted += OnNavigationCompleted;
+                    core.NavigationCompleted += OnNavigationCompleted;
+                    // 换了页面就把上一页嗅探到的地址清空，下载时只会拿到当前这页在播的视频
+                    core.NavigationCompleted += OnMainNavigationCompleted;
+                    core.DOMContentLoaded += (sender, e) => webView21.ZoomFactor = currentZoomFactor;
+                    webView21.ZoomFactorChanged += (sender, e) => currentZoomFactor = webView21.ZoomFactor;
+
+                    // 页面里的嗅探脚本靠这两个事件把视频地址回传
+                    core.WebMessageReceived += OnWebMessageReceived;
+                    // 站点自带的"下载"按钮（如抖音）也统一走另存为，避免存到看不见的默认目录
+                    core.DownloadStarting += OnDownloadStarting;
+                    // 新窗口就地导航，保证嗅探脚本仍然在跑
+                    core.NewWindowRequested += OnNewWindowRequested;
+                }
+
+                await InjectScriptsAsync();
+            }
+            catch (Exception ex)
+            {
+                MessageBox.Show($"初始化 WebView2 失败: {ex.Message}");
+            }
+        }
+
+        /// <summary>
+        /// 在文档创建阶段注入嗅探与悬浮按钮脚本，保证早于播放器脚本运行（抖音视频是翻页加载的，尤其需要早注入）。
+        /// </summary>
+        private async Task InjectScriptsAsync()
+        {
+            var core = webView21.CoreWebView2;
+            if (core == null)
+            {
+                return;
+            }
+
+            foreach (var file in new[] { SnifferScript, ButtonScript })
+            {
+                if (injectedScripts.ContainsKey(file))
+                {
+                    continue;
+                }
+
+                string code = ReadScript(file);
+                if (string.IsNullOrEmpty(code))
+                {
+                    continue;
+                }
+
+                string id = await core.AddScriptToExecuteOnDocumentCreatedAsync(code);
+                if (!string.IsNullOrEmpty(id))
+                {
+                    injectedScripts[file] = id;
+                }
+            }
+        }
+
+        private async void InitializeWebView()
+        {
+            await EnsureCoreAsync();
+
+            if (webView21.CoreWebView2 == null)
+            {
+                return;
+            }
+
+            try
+            {
+                // 加载网页
+                webView21.CoreWebView2.Navigate(urlTxt.Text);
+            }
+            catch (Exception ex)
+            {
+                MessageBox.Show($"加载页面失败: {ex.Message}");
+            }
+        }
+
+        private void Form1_Load(object sender, EventArgs e)
+        {
+            if (File.Exists("currentLink.txt"))
+            {
+                urlTxt.Text = File.ReadAllText("currentLink.txt");
+            }
+
+            // 打开就直接加载页面，不用先点一次“转到”才能看视频
+            InitializeWebView();
+        }
+
+        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
+        {
+            File.WriteAllText("currentLink.txt", urlTxt.Text);
+        }
+
+        private void cssBut_Click(object sender, EventArgs e)
+        {
+            ShowDialog("css.txt");
+        }
+
+        private void addLinkBut_Click(object sender, EventArgs e)
+        {
+            File.AppendAllText("link.txt", "\r\n" + urlTxt.Text);
+        }
+
+        private void linkBut_Click(object sender, EventArgs e)
+        {
+            ShowDialog("link.txt");
+        }
+
+        private void ShowDialog(string path)
+        {
+            Form2 form2 = new Form2();
+            form2.Path = path;
+            form2.ShowDialog();
+        }
+
+        private void displayBut_Click(object sender, EventArgs e)
+        {
+            urlTxt.Visible = !urlTxt.Visible;
+        }
+
+        private void goBut_Click(object sender, EventArgs e)
+        {
+            InitializeWebView();
+        }
+
+        #region 视频下载
+
+        private static string ReadScript(string file)
+        {
+            try
+            {
+                string path = Path.IsPathRooted(file) ? file : Path.Combine(Application.StartupPath, file);
+                return File.Exists(path) ? File.ReadAllText(path) : string.Empty;
+            }
+            catch
+            {
+                return string.Empty;
+            }
+        }
+
+        private void SetStatus(string text)
+        {
+            if (IsHandleCreated && InvokeRequired)
+            {
+                BeginInvoke(new Action(() => statusLbl.Text = text));
+            }
+            else
+            {
+                statusLbl.Text = text;
+            }
+        }
+
+        /// <summary>
+        /// 嗅探到的地址可能来自不同 iframe，列表要加锁并限制长度，
+        /// 只留最近若干个，供“当前播放地址取不到时”兜底用。
+        /// </summary>
+        private void AddSniffedUrl(string url, string? referer)
+        {
+            lock (sniffedUrls)
+            {
+                if (!sniffedUrls.Contains(url))
+                {
+                    sniffedUrls.Add(url);
+                }
+
+                while (sniffedUrls.Count > 50) sniffedUrls.RemoveAt(0);
+            }
+
+            if (!string.IsNullOrWhiteSpace(referer))
+            {
+                lock (urlReferers) urlReferers[url] = referer;
+            }
+        }
+
+        private string? RefererFor(string url, string? fallback)
+        {
+            lock (urlReferers)
+            {
+                if (urlReferers.TryGetValue(url, out var referer)) return referer;
+            }
+
+            return string.IsNullOrWhiteSpace(fallback) ? null : fallback;
+        }
+
+        private List<string> SnapshotSniffedUrls()
+        {
+            lock (sniffedUrls) return sniffedUrls.ToList();
+        }
+
+        /// <summary>
+        /// 接收页面嗅探脚本回传的视频地址与播放列表文本。
+        /// </summary>
+        private void OnWebMessageReceived(object? sender, CoreWebView2WebMessageReceivedEventArgs e)
+        {
+            try
+            {
+                string json = e.TryGetWebMessageAsString();
+                JsonNode? node = JsonNode.Parse(json);
+                string? type = node?["type"]?.GetValue<string>();
+
+                switch (type)
+                {
+                    case "media":
+                        {
+                            string? url = node?["url"]?.GetValue<string>();
+                            string? referer = node?["base"]?.GetValue<string>();
+                            if (!string.IsNullOrEmpty(url) && VideoDownloader.LooksLikeMedia(url))
+                            {
+                                AddSniffedUrl(url, referer);
+                                if (VideoDownloader.IsHlsUrl(url))
+                                {
+                                    SetStatus("已嗅探到 m3u8，可点击下载");
+                                }
+                            }
+                            break;
+                        }
+                    case "hlsText":
+                        {
+                            string? text = node?["text"]?.GetValue<string>();
+                            if (!string.IsNullOrEmpty(text) && text.Contains("#EXTM3U") && !sniffedPlaylists.Contains(text))
+                            {
+                                sniffedPlaylists.Add(text);
+                                // 只留最近几份播放列表，够用又不会越积越多
+                                while (sniffedPlaylists.Count > 10) sniffedPlaylists.RemoveAt(0);
+                                SetStatus("已抓到播放列表，可点击下载");
+                            }
+                            break;
+                        }
+                    case "downloadClick":
+                        // 播放器右下角的悬浮按钮
+                        _ = DownloadCurrentVideoAsync();
+                        break;
+                }
+            }
+            catch
+            {
+                // 非本程序约定的消息直接忽略
+            }
+        }
+
+        /// <summary>
+        /// 站点自己发起的下载（例如抖音自带的下载入口）改为用户选择保存位置。
+        /// </summary>
+        private void OnDownloadStarting(object? sender, CoreWebView2DownloadStartingEventArgs e)
+        {
+            string suggested = Path.GetFileName(e.DownloadOperation.ResultFilePath);
+            if (string.IsNullOrWhiteSpace(suggested))
+            {
+                suggested = "video.mp4";
+            }
+
+            using SaveFileDialog dlg = new SaveFileDialog
+            {
+                Title = "保存视频",
+                FileName = suggested,
+                Filter = "视频文件|*.mp4;*.ts;*.mkv;*.flv;*.mov|所有文件|*.*"
+            };
+
+            if (dlg.ShowDialog(this) != DialogResult.OK)
+            {
+                e.Cancel = true;
+                SetStatus("已取消下载");
+                return;
+            }
+
+            string target = dlg.FileName;
+            e.Handled = true;
+            e.ResultFilePath = target;
+            SetStatus($"正在下载 {Path.GetFileName(target)}");
+
+            CoreWebView2DownloadOperation operation = e.DownloadOperation;
+            operation.BytesReceivedChanged += (s, ev) =>
+            {
+                ulong? total = operation.TotalBytesToReceive;
+                string totalText = total > 0 ? $" / {VideoDownloader.FormatSize((long)total!.Value)}" : string.Empty;
+                SetStatus($"下载中 {VideoDownloader.FormatSize(operation.BytesReceived)}{totalText}");
+            };
+            operation.StateChanged += (s, ev) =>
+            {
+                switch (operation.State)
+                {
+                    case CoreWebView2DownloadState.Completed:
+                        SetStatus($"已保存 {target}");
+                        break;
+                    case CoreWebView2DownloadState.Interrupted:
+                        SetStatus($"下载中断：{operation.InterruptReason}");
+                        break;
+                }
+            };
+        }
+
+        private void OnNewWindowRequested(object? sender, CoreWebView2NewWindowRequestedEventArgs e)
+        {
+            // 抖音等站点的 window.open 在这里就地导航，避免新窗口没有嗅探脚本
+            e.Handled = true;
+            webView21.CoreWebView2?.Navigate(e.Uri);
+        }
+
+        private async void dlBut_Click(object sender, EventArgs e)
+        {
+            await DownloadCurrentVideoAsync();
+        }
+
+        /// <summary>
+        /// 只下载当前正在播放的那一个视频地址，不再列出一堆候选让用户挑。
+        /// </summary>
+        private async Task DownloadCurrentVideoAsync()
+        {
+            if (webView21.CoreWebView2 == null)
+            {
+                SetStatus("页面还没加载好，请稍候");
+                return;
+            }
+
+            if (downloadCts != null)
+            {
+                SetStatus("已有下载在进行中，可先点“取消下载”");
+                return;
+            }
+
+            dlBut.Enabled = false;
+            try
+            {
+                SetStatus("正在识别当前视频…");
+                string raw = await webView21.CoreWebView2.ExecuteScriptAsync(BuildGrabScript());
+                VideoCandidate? candidate = CollectCurrentCandidate(raw);
+
+                if (candidate == null)
+                {
+                    SetStatus("没识别到视频地址");
+                    MessageBox.Show(this,
+                        "没有抓到当前正在播放的视频地址。\n\n" +
+                        "常见原因：\r\n1. 视频还没真正开始播放，请先点播放再点本按钮；\r\n" +
+                        "2. 站点用了加密流（DRM），无法直接下载；\r\n" +
+                        "3. 视频在 iframe 里且尚未加载完，稍等一两秒重试。",
+                        "下载视频", MessageBoxButtons.OK, MessageBoxIcon.Information);
+                    return;
+                }
+
+                await DownloadVideoAsync(candidate);
+            }
+            catch (OperationCanceledException)
+            {
+                SetStatus("已取消");
+            }
+            catch (Exception ex)
+            {
+                SetStatus($"识别失败：{ex.Message}");
+                MessageBox.Show(this, ex.Message, "下载视频", MessageBoxButtons.OK, MessageBoxIcon.Warning);
+            }
+            finally
+            {
+                dlBut.Enabled = true;
+            }
+        }
+
+        /// <summary>
+        /// 抓取脚本兜底版本：资源文件丢失时仍能取到当前 video 标签的播放地址。
+        /// </summary>
+        private static string BuildGrabScript()
+        {
+            string code = ReadScript(GrabScript);
+            if (!string.IsNullOrEmpty(code))
+            {
+                return code;
+            }
+
+            return "(function(){var v=document.querySelector('video');"
+                + "return JSON.stringify({current:v?(v.currentSrc||v.src):'',title:document.title,pageUrl:location.href,"
+                + "sniffed:(window.__mediaUrls||[]).slice(-60),m3u8Blobs:(window.__m3u8Blobs||[]).slice(-1)});})()";
+        }
+
+        /// <summary>
+        /// 只取当前正在播放的那一个视频地址，按三层递降：
+        /// 1. video 标签自己的播放源（最准确，就是正在播的这个）；
+        /// 2. 抖音这类 blob+MSE 播放、或播放器在 iframe 里取不到源时，
+        ///    退回用本页最近嗅探到的那一个整片地址（m3u8 或直链，分片不算）；
+        /// 3. 只在内存里拿到播放列表文本时，用页面地址做分片相对地址的基准。
+        /// </summary>
+        private VideoCandidate? CollectCurrentCandidate(string grabResultJson)
+        {
+            string current = string.Empty;
+            string pageUrl = string.Empty;
+            List<string> sniffed = new List<string>();
+
+            try
+            {
+                // ExecuteScriptAsync 返回的是 JSON 编码后的字符串，需要先脱一层引号
+                string? inner = JsonSerializer.Deserialize<string>(grabResultJson);
+                if (!string.IsNullOrEmpty(inner))
+                {
+                    JsonNode? node = JsonNode.Parse(inner);
+                    current = node?["current"]?.GetValue<string>() ?? string.Empty;
+                    pageUrl = node?["pageUrl"]?.GetValue<string>() ?? string.Empty;
+
+                    if (node?["sniffed"] is JsonArray arr)
+                    {
+                        foreach (JsonNode? item in arr)
+                        {
+                            string? u = item?.GetValue<string>();
+                            if (!string.IsNullOrEmpty(u)) sniffed.Add(u);
+                        }
+                    }
+                }
+            }
+            catch
+            {
+                // 页面没有返回可解析结果时，只用宿主侧嗅探到的地址
+            }
+
+            if (VideoDownloader.LooksLikeMedia(current) && !VideoDownloader.IsSegmentUrl(current))
+            {
+                return new VideoCandidate(current, null, pageUrl);
+            }
+
+            // 嗅探结果里最后一个整片地址最接近“正在播的这个”，前面翻页留下的旧地址和单个分片都不取
+            List<string> pool = sniffed.Concat(SnapshotSniffedUrls())
+                .Where(VideoDownloader.LooksLikeMedia)
+                .Distinct()
+                .ToList();
+
+            int index = pool.FindLastIndex(u => !VideoDownloader.IsSegmentUrl(u));
+
+            if (index >= 0)
+            {
+                string url = pool[index];
+                return new VideoCandidate(url, null, RefererFor(url, pageUrl));
+            }
+
+            string? text = sniffedPlaylists.Concat(ReadBlobPlaylists(grabResultJson))
+                .Distinct()
+                .LastOrDefault(t => t.Contains("#EXTM3U"));
+
+            return text == null ? null : new VideoCandidate(pageUrl, text, pageUrl);
+        }
+
+        private static List<string> ReadBlobPlaylists(string grabResultJson)
+        {
+            List<string> result = new List<string>();
+            try
+            {
+                string? inner = JsonSerializer.Deserialize<string>(grabResultJson);
+                if (inner != null && JsonNode.Parse(inner)?["m3u8Blobs"] is JsonArray arr)
+                {
+                    foreach (JsonNode? item in arr)
+                    {
+                        string? text = item?.GetValue<string>();
+                        if (!string.IsNullOrWhiteSpace(text) && text.Contains("#EXTM3U")) result.Add(text);
+                    }
+                }
+            }
+            catch
+            {
+                // 忽略
+            }
+            return result;
+        }
+
+        /// <summary>
+        /// 下载当前播放的这个地址：先让用户选保存位置，再流式落盘。
+        /// 地址只有一个，失败就直接报错误信息，不再翻别的地址重试。
+        /// </summary>
+        private async Task DownloadVideoAsync(VideoCandidate candidate)
+        {
+            string url = candidate.Url;
+            VideoDownloader namer = new VideoDownloader(RefererFor(url, webView21.CoreWebView2?.Source));
+
+            using SaveFileDialog dlg = new SaveFileDialog
+            {
+                Title = "下载视频",
+                FileName = namer.SuggestedFileName(url, PageTitle),
+                Filter = "视频文件|*.mp4;*.ts;*.mkv;*.flv;*.mov|所有文件|*.*",
+                AddExtension = true
+            };
+
+            if (dlg.ShowDialog(this) != DialogResult.OK)
+            {
+                SetStatus("已取消");
+                return;
+            }
+
+            string? failure = await TryDownloadAsync(candidate, dlg.FileName);
+            if (failure == null) return;
+
+            SetStatus($"下载失败：{failure}");
+            MessageBox.Show(this, failure, "下载视频", MessageBoxButtons.OK, MessageBoxIcon.Warning);
+        }
+
+        /// <summary>
+        /// 执行一次下载。返回 null 表示成功或用户主动取消，否则返回错误信息给上层提示。
+        /// </summary>
+        private async Task<string?> TryDownloadAsync(VideoCandidate candidate, string filePath)
+        {
+            VideoDownloader downloader = await CreateDownloaderAsync(candidate);
+
+            downloadCts = new CancellationTokenSource();
+            Progress<DownloadProgress> progress = new Progress<DownloadProgress>(ReportProgress);
+            progressBar.Visible = true;
+            progressBar.Value = 0;
+            cancelBut.Enabled = true;
+            SetStatus($"准备下载 {Path.GetFileName(filePath)}");
+
+            try
+            {
+                DownloadResult result = candidate.PlaylistText != null
+                    ? await downloader.DownloadFromPlaylistTextAsync(candidate.PlaylistText, candidate.Url, filePath, progress, downloadCts.Token)
+                    : await downloader.DownloadAsync(candidate.Url, filePath, progress, downloadCts.Token);
+
+                SetStatus($"已下载 {Path.GetFileName(result.FilePath)}（{VideoDownloader.FormatSize(result.Bytes)}）");
+
+                if (MessageBox.Show(this, $"视频已保存到：\n{result.FilePath}\n\n要打开所在文件夹吗？",
+                        "下载完成", MessageBoxButtons.YesNo, MessageBoxIcon.Information) == DialogResult.Yes)
+                {
+                    OpenFolder(result.FilePath);
+                }
+
+                return null;
+            }
+            catch (OperationCanceledException)
+            {
+                // 用户主动取消就别再换地址重试了
+                SetStatus("已取消下载");
+                return null;
+            }
+            catch (Exception ex)
+            {
+                DeletePartFiles(filePath);
+                return ex.Message;
+            }
+            finally
+            {
+                downloadCts?.Dispose();
+                downloadCts = null;
+                progressBar.Visible = false;
+                cancelBut.Enabled = false;
+            }
+        }
+
+        /// <summary>
+        /// 用候选地址自己的 Referer 和浏览器里的 Cookie 建下载器：
+        /// 播放器在跨域 iframe 里时，拿顶层页面地址当 Referer 会被防盗链拒掉。
+        /// </summary>
+        private async Task<VideoDownloader> CreateDownloaderAsync(VideoCandidate candidate)
+        {
+            string? referer = candidate.Referer ?? RefererFor(candidate.Url, webView21.CoreWebView2?.Source);
+            string? cookie = await GetCookieHeaderAsync(candidate.Url);
+            return new VideoDownloader(referer, cookie);
+        }
+
+        private async Task<string?> GetCookieHeaderAsync(string url)
+        {
+            CoreWebView2? core = webView21.CoreWebView2;
+            if (core == null || !Uri.TryCreate(url, UriKind.Absolute, out Uri? uri)) return null;
+
+            try
+            {
+                var cookies = await core.CookieManager.GetCookiesAsync(uri.ToString());
+                string header = string.Join("; ", cookies
+                    .Where(c => !string.IsNullOrEmpty(c.Name))
+                    .Select(c => $"{c.Name}={c.Value}"));
+                return header.Length == 0 ? null : header;
+            }
+            catch
+            {
+                // 拿不到 Cookie 就按匿名请求下载
+                return null;
+            }
+        }
+
+        private void ReportProgress(DownloadProgress value)
+        {
+            SetStatus(value.Message);
+
+            if (value.Ratio != null)
+            {
+                progressBar.Value = (int)Math.Clamp(value.Ratio.Value * 100, 0, 100);
+            }
+        }
+
+        private void cancelBut_Click(object sender, EventArgs e)
+        {
+            try
+            {
+                downloadCts?.Cancel();
+                SetStatus("正在取消…");
+            }
+            catch (Exception ex)
+            {
+                SetStatus($"取消失败：{ex.Message}");
+            }
+        }
+
+        private static void DeletePartFiles(string target)
+        {
+            try
+            {
+                string part = target + ".part";
+                if (File.Exists(part)) File.Delete(part);
+            }
+            catch
+            {
+                // 残留的 .part 交给下次覆盖
+            }
+        }
+
+        private static void OpenFolder(string filePath)
+        {
+            try
+            {
+                System.Diagnostics.Process.Start("explorer.exe", $"/select,\"{filePath}\"");
+            }
+            catch
+            {
+                // 打不开文件夹不影响下载结果
+            }
+        }
+
+        private string PageTitle
+        {
+            get
+            {
+                try
+                {
+                    return webView21.CoreWebView2?.DocumentTitle ?? string.Empty;
+                }
+                catch
+                {
+                    return string.Empty;
+                }
+            }
+        }
+
+        #endregion
+    }
+}