97 lines
3.2 KiB
C#
97 lines
3.2 KiB
C#
using System.IO;
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using System.Text;
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using System.Windows;
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using Microsoft.Web.WebView2.Core;
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using Microsoft.Web.WebView2.Wpf;
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using YY.Admin.Core.Util;
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namespace YY.Admin.Infrastructure.Print;
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/// <summary>
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/// 使用隐藏 WebView2 窗口将 HTML 字符串渲染为 PDF base64。
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/// 所有调用必须最终在 WPF UI 线程执行，由内部 Dispatcher 保证。
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/// </summary>
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public static class HtmlToPdfRenderer
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{
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public static Task<string> RenderAsync(string html, double widthMm = 210, double heightMm = 297)
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{
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var tcs = new TaskCompletionSource<string>(TaskCreationOptions.RunContinuationsAsynchronously);
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Application.Current.Dispatcher.InvokeAsync(async () =>
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{
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try
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{
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var result = await RenderOnUiThreadAsync(html, widthMm, heightMm);
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tcs.SetResult(result);
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}
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catch (Exception ex)
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{
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tcs.SetException(ex);
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}
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});
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return tcs.Task;
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}
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private static async Task<string> RenderOnUiThreadAsync(string html, double widthMm, double heightMm)
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{
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var tempHtml = Path.ChangeExtension(Path.GetTempFileName(), ".html");
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var tempPdf = Path.ChangeExtension(Path.GetTempFileName(), ".pdf");
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Window? win = null;
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try
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{
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File.WriteAllText(tempHtml, html, Encoding.UTF8);
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var userData = AppWritablePaths.EnsureDirectoryExists(
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Path.Combine(AppWritablePaths.LocalApplicationRoot, "WebView2", "HtmlToPdf"));
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var env = await CoreWebView2Environment.CreateAsync(browserExecutableFolder: null, userDataFolder: userData);
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var wv = new WebView2();
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win = new Window
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{
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Width = 1,
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Height = 1,
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Left = -99999,
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Top = -99999,
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ShowInTaskbar = false,
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WindowStyle = WindowStyle.None,
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Visibility = Visibility.Visible
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};
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win.Content = wv;
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win.Show();
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await wv.EnsureCoreWebView2Async(env);
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var navTcs = new TaskCompletionSource();
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wv.CoreWebView2.NavigationCompleted += (_, _) => navTcs.TrySetResult();
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wv.CoreWebView2.Navigate(new Uri(tempHtml).AbsoluteUri);
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await navTcs.Task;
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// 短暂等待 JS/CSS 完成渲染
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await Task.Delay(200);
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var settings = env.CreatePrintSettings();
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settings.PageWidth = widthMm / 25.4;
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settings.PageHeight = heightMm / 25.4;
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settings.MarginTop = 0;
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settings.MarginBottom = 0;
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settings.MarginLeft = 0;
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settings.MarginRight = 0;
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settings.ShouldPrintHeaderAndFooter = false;
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settings.ShouldPrintBackgrounds = true;
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await wv.CoreWebView2.PrintToPdfAsync(tempPdf, settings);
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var pdfBytes = File.ReadAllBytes(tempPdf);
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return Convert.ToBase64String(pdfBytes);
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}
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finally
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{
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win?.Close();
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try { File.Delete(tempHtml); } catch { }
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try { File.Delete(tempPdf); } catch { }
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}
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}
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}
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