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I got a problem with NavManager.NavigateTo(); for Blazor webassembly application The scenario is the following:
I have a drop-down menu with possible website language translations and when the user wants to change the website language he should access a Web API controller action which will set the culture into the website cookies via the drop-down menu.
Let me share some code.
Here is the UI part from the Razor component
<div class="languageChanger">
<select class="form-select" #bind="this.Culture">
#foreach (var culture in cultures)
{
<option value="#culture">#this.Localizer[culture.Name]</option>
}
</select>
</div>
And here is the C# code part ot the Razor Component
CultureInfo[] cultures = new[]
{
new CultureInfo("en-US"),
new CultureInfo("bg-BG")
};
public CultureInfo Culture
{
get => CultureInfo.CurrentCulture;
set
{
if (CultureInfo.CurrentCulture != value)
{
var js = (IJSInProcessRuntime)this.JsRuntime;
js.InvokeVoid("SimeonValevPortfolioCulture.set", value.Name);
var uri = new Uri(this.NavManager.Uri).GetComponents(UriComponents.PathAndQuery, UriFormat.Unescaped);
var query = $"?cultureName={Uri.EscapeDataString(value.Name)}&" + $"redirectUri={Uri.EscapeDataString(uri)}";
this.NavManager.NavigateTo($"api/Culture/SetCulture" + query, forceLoad: true);
}
}
}
And here is the API Controller action
[HttpGet]
public IActionResult SetCulture(string cultureName, string redirectUri)
{
if (cultureName != null)
{
this.HttpContext.Response.Cookies.Append(
CookieRequestCultureProvider.DefaultCookieName,
CookieRequestCultureProvider.MakeCookieValue(
new RequestCulture(cultureName)), new CookieOptions()
{
Expires = DateTimeOffset.UtcNow.AddMonths(1),
});
}
return this.LocalRedirect(redirectUri);
}
When I run the application locally, the controller action is accessed correctly and also when I deployed the application, the api action is correctly accessed from Google Chrome under Windows 10 OS. But via phone, under Android(Chrome web browser) and iOS(Safari web browser) the user is not able to access the API action. When he try to change the website culture the only thing which he can get from that operation is 404 status code. I noticed that when he try to update the drop-down value, he receive the following URL into the browser:
https://MySiteName.com/api/Culture/SetCulture?cultureName=bg-BG&redirectUri=%2F
And after that the application returns 404 status code
The conclusion which I get is somehow the api action could not be accessed only from phones. The issue is not faced under laptop usage.
Please let me know is there something which I missed.
Regards,
Simeon Valev
P.S. If it will be much better for you, I can share the website URL, it is hosted. Let me know
I fix the issue by creating a standard GET request. I apply the code changes.
Now it work properly.
#code {
private string currentCulture;
CultureInfo[] cultures = new[]
{
new CultureInfo("en-US"),
new CultureInfo("bg-BG")
};
protected override async Task OnInitializedAsync()
{
this.currentCulture = CultureInfo.CurrentCulture.Name;
await base.OnInitializedAsync();
}
public async Task OnCultureChanged(ChangeEventArgs e)
{
var cultureName = e.Value.ToString();
var js = (IJSInProcessRuntime)this.JsRuntime;
js.InvokeVoid("SimeonValevPortfolioCulture.set", cultureName);
var response = await this.HttpClient.GetFromJsonAsync<CompletedOperationViewModel>($"api/Culture/SetCulture/{cultureName}");
this.NavManager.NavigateTo(this.NavManager.Uri, forceLoad: true);
await response.DisplayMessage(this.JsRuntime);
}
}
I'm making a small web application which is built on ASP.NET Core. My application is for streaming video from clients to clients through service.
I've followed this post :
http://www.strathweb.com/2013/01/asynchronously-streaming-video-with-asp-net-web-api/
I've implemented the application of tutorial successfully, but, that was for streaming Video from server to clients.
What I wanna do now is :
Clients register to service for streaming. (using video or audio tag)
Service receives client submitted data (submit through POSTMAN)
Service broadcast the data to its every registered clients.
Here is what I've implemented:
(Index.cshtml)
<div>
<video width="480"
height="320"
controls="controls"
autoplay="autoplay">
<source src="/api/video/initiate"
type="video/mp4">
</source>
</video>
</div>
StreamingService
public class StreamingService: IStreamingService
{
public IList<Stream> Connections {get;set;}
public StreamingService()
{
Connections = new List<Stream>();
}
public byte[] AnalyzeStream(Stream stream)
{
long originalPosititon = 0;
if (stream.CanSeek)
{
originalPosititon = stream.Position;
stream.Position = 0;
}
try
{
var readBuffer = new byte[4096];
int bytesReader;
while ((byteRead = stream.Read(readBuffer, totalBytesRead, readBuffer.Length - totalBytesRead)) > 0)
{
totalBytesRead += byteRead;
if (totalBytesRead == readBuffer.Length)
{
var nextByte = stream.ReadByte();
if (nextByte != -1)
{
var temp = new byte[readBuffer * 2];
Buffer.BlockCopy(readBuffer, 0, temp, 0, readBuffer.Length);
Buffer.SetByte(temp, totalBytesRead, (byte)nextByte);
readBuffer = temp;
totalBytesRead++;
}
}
}
var buffer = readBuffer;
if (readBuffer.Length != totalBytesRead)
{
buffer = new byte[totalBytesRead];
Buffer.BlockCopy(readBuffer, 0, buffer, 0, totalBytesRead);
}
return buffer;
}
finally
{
if (stream.CanSeek)
stream.Position = originalPosititon;
}
}
}
VideoController
public class VideoController: Controller
{
private readonly IStreamingService _streamingService;
private readonly IHostingEnvironment _hostingEnvironment;
public VideoController(IStreamingService streamingService, IHostingEnvironment hostingEnvironment)
{
_streamingService = streamingService;
_hostingEnvironment = hostingEnvironment;
}
[HttpGet("initiate")]
public IActionResult Initiate()
{
_streamingService.Connections.Add(Response.Body);
}
[HttpPost("broadcast")]
public async Task<IActionResult> Broadcast()
{
// Retrieve data submitted from POSTMAN.
var data = _streamingService.AnalyzeStream(Request.Body);
foreach (var stream in _streamingService.Connections)
{
try
{
await stream.WriteAsync(data, 0, data.Length);
}
catch (Exception exception)
{
stream.Dispose();
_streamingService.Connections.Remove(stream);
}
}
}
}
When I send data from POSTMAN through api/video/broadcast . For loop ran and I got an exception said the stream has been disposed.
My question is:
How can I keep the stream alive for streaming ?
(Stream created in api/video/initiate is kept alive and when a client calls api/video/broadcast , all initiated stream will update its date without having disposed)
Thank you,
Is it an option to keep the stream in cache?
You can read more about it here. The simplest way it to add the cache services to the dependency injection container and the request the concrete implementation of IMemoryCache through constructor injection in your VideoController (as you've done with IStreamingService and IHostingEnvironment).
Just add the stream to the cache and use the cached stream the next time api/video/broadcast is hit.
Be aware though that if you are on a webfarm or hosted in the cloud it is recommended to use Distributed Cache like Redis Cache, or else your cache could disapear unexpected. I use Azure Redis Cache for instance which works great!
I want to export a piece of html to a pdf file but i do not any compatible nuget package.
When I try to install anyone: "X not compatible with netcoreapp1.0 (.NETCoreApp,Version=v1.0)."
Does anyone know any way to export to a pdf using asp.net core??
You can use jsreport .net sdk if you are in .net core 2.0 also without more complex node services. This includes among other features filters to convert your existing razor views into pdf. From the docs:
1.
Install nugets jsreport.Binary, jsreport.Local and jsreport.AspNetCore
2.
In you Startup.cs configure it as the following
public void ConfigureServices(IServiceCollection services)
{
services.AddMvc();
services.AddJsReport(new LocalReporting()
.UseBinary(JsReportBinary.GetBinary())
.AsUtility()
.Create());
}
3.
Then you need to add MiddlewareFilter attribute to the particular action and specify which conversion you want to use. In this case html to pdf conversion.
[MiddlewareFilter(typeof(JsReportPipeline))]
public IActionResult Invoice()
{
HttpContext.JsReportFeature().Recipe(Recipe.ChromePdf);
return View();
}
You can reach bunch of other options for headers, footers or page layout on JsReportFeature(). Note that the same way you can also produce excel files from html. See more information in the documentation.
PS: I'm the author of jsreport.
Copied from my original answer here Export to pdf using ASP.NET 5:
One way to generate pdf from html in .NET Core (without any .NET framework dependencies) is using Node.js from within the .NET Core application.
The following example shows how to implement an HTML to PDF converter in a clean ASP.NET Core Web Application project (Web API template).
Install the NuGet package Microsoft.AspNetCore.NodeServices
In Startup.cs add the line services.AddNodeServices() like this
public void ConfigureServices(IServiceCollection services)
{
// ... all your existing configuration is here ...
// Enable Node Services
services.AddNodeServices();
}
Now install the required Node.js packages:
From the command line change working directory to the root of the .NET Core project and run these commands.
npm init
and follow the instructions to create the package.json file
npm install jsreport-core --save
npm install jsreport-jsrender --save
npm install jsreport-phantom-pdf --save
Create a file pdf.js in the root of the project containing
module.exports = function (callback) {
var jsreport = require('jsreport-core')();
jsreport.init().then(function () {
return jsreport.render({
template: {
content: '<h1>Hello {{:foo}}</h1>',
engine: 'jsrender',
recipe: 'phantom-pdf'
},
data: {
foo: "world"
}
}).then(function (resp) {
callback(/* error */ null, resp.content.toJSON().data);
});
}).catch(function (e) {
callback(/* error */ e, null);
})
};
Have a look here for more explanation on jsreport-core.
Now create an action in an Mvc controller that calls this Node.js script
[HttpGet]
public async Task<IActionResult> MyAction([FromServices] INodeServices nodeServices)
{
var result = await nodeServices.InvokeAsync<byte[]>("./pdf");
HttpContext.Response.ContentType = "application/pdf";
string filename = #"report.pdf";
HttpContext.Response.Headers.Add("x-filename", filename);
HttpContext.Response.Headers.Add("Access-Control-Expose-Headers", "x-filename");
HttpContext.Response.Body.Write(result, 0, result.Length);
return new ContentResult();
}
Off course you can do whatever you want with the byte[] returned from nodeServices, in this example I'm just outputting it from a controller action so it can be viewed in the browser.
You could also exchange the data between Node.js and .NET Core by a base64 encoded string using resp.content.toString('base64') in pdf.js and use
var result = await nodeServices.InvokeAsync<byte[]>("./pdf"); in the action and then decode the base64 encoded string.
Alternatives
Most pdf generator solutions still depend on .NET 4.5/4.6 framework. But there seems to be some paid alternatives available if you don't like to use Node.js:
NReco.PdfGenerator.LT
EVO HTML to PDF Converter Client for .NET Core
Winnovative HTML to PDF Converter Client for .NET Core
I haven't tried any of these though.
I hope we will soon see some open source progress in this area.
You can check DinkToPdf library. It is a wrapper around wkhtmltopdf library for .NET Core.
Synchronized converter
Use this converter in multi threaded applications and web servers. Conversion tasks are saved to blocking collection and executed on a single thread.
var converter = new SynchronizedConverter(new PdfTools());
Define document to convert
var doc = new HtmlToPdfDocument()
{
GlobalSettings = {
ColorMode = ColorMode.Color,
Orientation = Orientation.Landscape,
PaperSize = PaperKind.A4Plus,
},
Objects = {
new ObjectSettings() {
PagesCount = true,
HtmlContent = #"Lorem ipsum dolor sit amet, consectetur adipiscing elit. In consectetur mauris eget ultrices iaculis. Ut odio viverra, molestie lectus nec, venenatis turpis.",
WebSettings = { DefaultEncoding = "utf-8" },
HeaderSettings = { FontSize = 9, Right = "Page [page] of [toPage]", Line = true, Spacing = 2.812 }
}
}
};
I was having the same issue! I wanted to generate PDF files from HTML strings. I then came across PhantomJs which is a command line utility for converting html files to pdf. I wrote a cross-platform wrapper over it in C# for .NET CORE and its working great on Linux! Though as of now its only for 64-bit Linux, because that is the only platform .NET Core Supports currently.
The project can be found here
PhantomJs.NetCore.PdfGenerator gen = new PhantomJs.NetCore.PdfGenerator("/path/to/pantomjsfolder");
string outputFilePath = gen.GeneratePdf("<h1>Hello</h1>","/folder/to/write/file/in");
This is a solution working for ASP.NET Core 2.0, which allows either to generate dynamic PDF files from cshtml, directly send them to users and/or save them before sending.
To complement Jan Blaha answer there, for more flexibility, you may want to use the following code:
/// Generate a PDF from a html string
async Task<(string ContentType, MemoryStream GeneratedFileStream)> GeneratePDFAsync(string htmlContent)
{
IJsReportFeature feature = new JsReportFeature(HttpContext);
feature.Recipe(Recipe.PhantomPdf);
if (!feature.Enabled) return (null, null);
feature.RenderRequest.Template.Content = htmlContent;
var report = await _RenderService.RenderAsync(feature.RenderRequest);
var contentType = report.Meta.ContentType;
MemoryStream ms = new MemoryStream();
report.Content.CopyTo(ms);
return (contentType, ms);
}
Using a class to render cshtml files as string, you may use the following service (which can be injected as a scoped service):
public class ViewToStringRendererService: ViewExecutor
{
private ITempDataProvider _tempDataProvider;
private IServiceProvider _serviceProvider;
public ViewToStringRendererService(
IOptions<MvcViewOptions> viewOptions,
IHttpResponseStreamWriterFactory writerFactory,
ICompositeViewEngine viewEngine,
ITempDataDictionaryFactory tempDataFactory,
DiagnosticSource diagnosticSource,
IModelMetadataProvider modelMetadataProvider,
ITempDataProvider tempDataProvider,
IServiceProvider serviceProvider)
: base(viewOptions, writerFactory, viewEngine, tempDataFactory, diagnosticSource, modelMetadataProvider)
{
_tempDataProvider = tempDataProvider;
_serviceProvider = serviceProvider;
}
public async Task<string> RenderViewToStringAsync<TModel>(string viewName, TModel model)
{
var context = GetActionContext();
if (context == null) throw new ArgumentNullException(nameof(context));
var result = new ViewResult()
{
ViewData = new ViewDataDictionary<TModel>(
metadataProvider: new EmptyModelMetadataProvider(),
modelState: new ModelStateDictionary())
{
Model = model
},
TempData = new TempDataDictionary(
context.HttpContext,
_tempDataProvider),
ViewName = viewName,
};
var viewEngineResult = FindView(context, result);
viewEngineResult.EnsureSuccessful(originalLocations: null);
var view = viewEngineResult.View;
using (var output = new StringWriter())
{
var viewContext = new ViewContext(
context,
view,
new ViewDataDictionary<TModel>(
metadataProvider: new EmptyModelMetadataProvider(),
modelState: new ModelStateDictionary())
{
Model = model
},
new TempDataDictionary(
context.HttpContext,
_tempDataProvider),
output,
new HtmlHelperOptions());
await view.RenderAsync(viewContext);
return output.ToString();
}
}
private ActionContext GetActionContext()
{
var httpContext = new DefaultHttpContext();
httpContext.RequestServices = _serviceProvider;
return new ActionContext(httpContext, new RouteData(), new ActionDescriptor());
}
/// <summary>
/// Attempts to find the <see cref="IView"/> associated with <paramref name="viewResult"/>.
/// </summary>
/// <param name="actionContext">The <see cref="ActionContext"/> associated with the current request.</param>
/// <param name="viewResult">The <see cref="ViewResult"/>.</param>
/// <returns>A <see cref="ViewEngineResult"/>.</returns>
ViewEngineResult FindView(ActionContext actionContext, ViewResult viewResult)
{
if (actionContext == null)
{
throw new ArgumentNullException(nameof(actionContext));
}
if (viewResult == null)
{
throw new ArgumentNullException(nameof(viewResult));
}
var viewEngine = viewResult.ViewEngine ?? ViewEngine;
var viewName = viewResult.ViewName ?? GetActionName(actionContext);
var result = viewEngine.GetView(executingFilePath: null, viewPath: viewName, isMainPage: true);
var originalResult = result;
if (!result.Success)
{
result = viewEngine.FindView(actionContext, viewName, isMainPage: true);
}
if (!result.Success)
{
if (originalResult.SearchedLocations.Any())
{
if (result.SearchedLocations.Any())
{
// Return a new ViewEngineResult listing all searched locations.
var locations = new List<string>(originalResult.SearchedLocations);
locations.AddRange(result.SearchedLocations);
result = ViewEngineResult.NotFound(viewName, locations);
}
else
{
// GetView() searched locations but FindView() did not. Use first ViewEngineResult.
result = originalResult;
}
}
}
if(!result.Success)
throw new InvalidOperationException(string.Format("Couldn't find view '{0}'", viewName));
return result;
}
private const string ActionNameKey = "action";
private static string GetActionName(ActionContext context)
{
if (context == null)
{
throw new ArgumentNullException(nameof(context));
}
if (!context.RouteData.Values.TryGetValue(ActionNameKey, out var routeValue))
{
return null;
}
var actionDescriptor = context.ActionDescriptor;
string normalizedValue = null;
if (actionDescriptor.RouteValues.TryGetValue(ActionNameKey, out var value) &&
!string.IsNullOrEmpty(value))
{
normalizedValue = value;
}
var stringRouteValue = routeValue?.ToString();
if (string.Equals(normalizedValue, stringRouteValue, StringComparison.OrdinalIgnoreCase))
{
return normalizedValue;
}
return stringRouteValue;
}
}
Then to conclude, in your controller, supposing the razor cshtml view template to be /Views/Home/PDFTemplate.cshtml you may use the following.
Note: The cshtml file may need to be copied when published (even if views are compiled).
var htmlContent = await _ViewToStringRendererService.RenderViewToStringAsync("Home/PDFTemplate", viewModel);
(var contentType, var generatedFile) = await GeneratePDFAsync(htmlContent);
Response.Headers["Content-Disposition"] = $"attachment; filename=\"{System.Net.WebUtility.UrlEncode(fileName)}\"";
// You may save your file here
using (var fileStream = new FileStream(Path.Combine(folder, fileName), FileMode.Create))
{
await generatedFile.CopyToAsync(fileStream);
}
// You may need this for re-use of the stream
generatedFile.Seek(0, SeekOrigin.Begin);
return File(generatedFile.ToArray(), "application/pdf", fileName);
On the server-side, you can output pdf of a html and use library that generate PDF from HTML string .NET Core after you got pdf, you need to pass it to the library see this link to convert HTML to PDF in .NET.
install nuget package : Select.HtmlToPdf.NetCore
HtmlToPdf htmlToPdf = new HtmlToPdf();
htmlToPdf.Options.PdfPageOrientation = PdfPageOrientation.Portrait;
// put css in pdf
htmlToPdf.Options.MarginLeft = 15;
htmlToPdf.Options.MarginRight = 15;
---------------------------
string url = "<html><head></head><body>Hello World</body></html>"
PdfDocument pdfDocument = htmlToPdf.ConvertHtmlString(url);
byte[] pdf = pdfDocument.Save();
//convert to memory stream
Stream stream = new MemoryStream(pdf);
pdfDocument.Close();
//if want to transfer stream to file
File(stream, "application/pdf", Guid.NewGuid().ToString() + ".pdf");
For exporting html to pdf you can use itextsharp library and even you can place html inside a partial view and export that view as pdf. Recently , i have tried that in a project where i needed to export pdf and i got refer How to export view as pdf in Asp.Net core . So you can give this a try.
I'm trying to convert HTML to PDF using iTextSharp in an ASP.NET web application that uses both MVC, and web forms. The <img> and <a> elements have absolute and relative URLs, and some of the <img> elements are base64. Typical answers here at SO and Google search results use generic HTML to PDF code with XMLWorkerHelper that looks something like this:
using (var stringReader = new StringReader(xHtml))
{
using (Document document = new Document())
{
PdfWriter writer = PdfWriter.GetInstance(document, stream);
document.Open();
XMLWorkerHelper.GetInstance().ParseXHtml(
writer, document, stringReader
);
}
}
So with sample HTML like this:
<div>
<h3>HTML Works, but Broken in Converted PDF</h3>
<div>Relative local <img>: <img src='./../content/images/kuujinbo_320-30.gif' /></div>
<div>
Base64 <img>:
<img src='data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg==' />
</div>
<div><a href='/somePage.html'>Relative local hyperlink, broken in PDF</a></div>
<div>
The resulting PDF: (1) is missing all images, and (2) all hyperlink(s) with relative URLs are broken and use a file URI scheme (file///XXX...) instead of pointing to the correct web site.
Some answers here at SO and others from Google search recommend replacing relative URLs with absolute URLs, which is perfectly acceptable for one-off cases. However, globally replacing all <img src> and <a href> attributes with a hard-coded string is unacceptable for this question, so please do not post an answer like that, because it will accordingly be downvoted.
Am looking for a solution that works for many different web applications residing in test, development, and production environments.
Out of the box XMLWorker only understands absolute URIs, so the described issues are expected behavior. The parser can't automagically deduce URI schemes or paths without some additional information.
Implementing an ILinkProvider fixes the broken hyperlink problem, and implementing an IImageProvider fixes the broken image problem. Since both implementations must perform URI resolution, that's the first step. The following helper class does that, and also tries to make web (ASP.NET) context calls (examples follow) as simple as possible:
// resolve URIs for LinkProvider & ImageProvider
public class UriHelper
{
/* IsLocal; when running in web context:
* [1] give LinkProvider http[s] scheme; see CreateBase(string baseUri)
* [2] give ImageProvider relative path starting with '/' - see:
* Join(string relativeUri)
*/
public bool IsLocal { get; set; }
public HttpContext HttpContext { get; private set; }
public Uri BaseUri { get; private set; }
public UriHelper(string baseUri) : this(baseUri, true) {}
public UriHelper(string baseUri, bool isLocal)
{
IsLocal = isLocal;
HttpContext = HttpContext.Current;
BaseUri = CreateBase(baseUri);
}
/* get URI for IImageProvider to instantiate iTextSharp.text.Image for
* each <img> element in the HTML.
*/
public string Combine(string relativeUri)
{
/* when running in a web context, the HTML is coming from a MVC view
* or web form, so convert the incoming URI to a **local** path
*/
if (HttpContext != null && !BaseUri.IsAbsoluteUri && IsLocal)
{
return HttpContext.Server.MapPath(
// Combine() checks directory traversal exploits
VirtualPathUtility.Combine(BaseUri.ToString(), relativeUri)
);
}
return BaseUri.Scheme == Uri.UriSchemeFile
? Path.Combine(BaseUri.LocalPath, relativeUri)
// for this example we're assuming URI.Scheme is http[s]
: new Uri(BaseUri, relativeUri).AbsoluteUri;
}
private Uri CreateBase(string baseUri)
{
if (HttpContext != null)
{ // running on a web server; need to update original value
var req = HttpContext.Request;
baseUri = IsLocal
// IImageProvider; absolute virtual path (starts with '/')
// used to convert to local file system path. see:
// Combine(string relativeUri)
? req.ApplicationPath
// ILinkProvider; absolute http[s] URI scheme
: req.Url.GetLeftPart(UriPartial.Authority)
+ HttpContext.Request.ApplicationPath;
}
Uri uri;
if (Uri.TryCreate(baseUri, UriKind.RelativeOrAbsolute, out uri)) return uri;
throw new InvalidOperationException("cannot create a valid BaseUri");
}
}
Implementing ILinkProvider is pretty simple now that UriHelper gives the base URI. We just need the correct URI scheme (file or http[s]):
// make hyperlinks with relative URLs absolute
public class LinkProvider : ILinkProvider
{
// rfc1738 - file URI scheme section 3.10
public const char SEPARATOR = '/';
public string BaseUrl { get; private set; }
public LinkProvider(UriHelper uriHelper)
{
var uri = uriHelper.BaseUri;
/* simplified implementation that only takes into account:
* Uri.UriSchemeFile || Uri.UriSchemeHttp || Uri.UriSchemeHttps
*/
BaseUrl = uri.Scheme == Uri.UriSchemeFile
// need trailing separator or file paths break
? uri.AbsoluteUri.TrimEnd(SEPARATOR) + SEPARATOR
// assumes Uri.UriSchemeHttp || Uri.UriSchemeHttps
: BaseUrl = uri.AbsoluteUri;
}
public string GetLinkRoot()
{
return BaseUrl;
}
}
IImageProvider only requires implementing a single method, Retrieve(string src), but Store(string src, Image img) is easy - note inline comments there and for GetImageRootPath():
// handle <img> elements in HTML
public class ImageProvider : IImageProvider
{
private UriHelper _uriHelper;
// see Store(string src, Image img)
private Dictionary<string, Image> _imageCache =
new Dictionary<string, Image>();
public virtual float ScalePercent { get; set; }
public virtual Regex Base64 { get; set; }
public ImageProvider(UriHelper uriHelper) : this(uriHelper, 67f) { }
// hard-coded based on general past experience ^^^
// but call the overload to supply your own
public ImageProvider(UriHelper uriHelper, float scalePercent)
{
_uriHelper = uriHelper;
ScalePercent = scalePercent;
Base64 = new Regex( // rfc2045, section 6.8 (alphabet/padding)
#"^data:image/[^;]+;base64,(?<data>[a-z0-9+/]+={0,2})$",
RegexOptions.Compiled | RegexOptions.IgnoreCase
);
}
public virtual Image ScaleImage(Image img)
{
img.ScalePercent(ScalePercent);
return img;
}
public virtual Image Retrieve(string src)
{
if (_imageCache.ContainsKey(src)) return _imageCache[src];
try
{
if (Regex.IsMatch(src, "^https?://", RegexOptions.IgnoreCase))
{
return ScaleImage(Image.GetInstance(src));
}
Match match;
if ((match = Base64.Match(src)).Length > 0)
{
return ScaleImage(Image.GetInstance(
Convert.FromBase64String(match.Groups["data"].Value)
));
}
var imgPath = _uriHelper.Combine(src);
return ScaleImage(Image.GetInstance(imgPath));
}
// not implemented to keep the SO answer (relatively) short
catch (BadElementException ex) { return null; }
catch (IOException ex) { return null; }
catch (Exception ex) { return null; }
}
/*
* always called after Retrieve(string src):
* [1] cache any duplicate <img> in the HTML source so the image bytes
* are only written to the PDF **once**, which reduces the
* resulting file size.
* [2] the cache can also **potentially** save network IO if you're
* running the parser in a loop, since Image.GetInstance() creates
* a WebRequest when an image resides on a remote server. couldn't
* find a CachePolicy in the source code
*/
public virtual void Store(string src, Image img)
{
if (!_imageCache.ContainsKey(src)) _imageCache.Add(src, img);
}
/* XMLWorker documentation for ImageProvider recommends implementing
* GetImageRootPath():
*
* http://demo.itextsupport.com/xmlworker/itextdoc/flatsite.html#itextdoc-menu-10
*
* but a quick run through the debugger never hits the breakpoint, so
* not sure if I'm missing something, or something has changed internally
* with XMLWorker....
*/
public virtual string GetImageRootPath() { return null; }
public virtual void Reset() { }
}
Based on the XML Worker documentation it's pretty straightforward to hook the implementations of ILinkProvider and IImageProvider above into a simple parser class:
/* a simple parser that uses XMLWorker and XMLParser to handle converting
* (most) images and hyperlinks internally
*/
public class SimpleParser
{
public virtual ILinkProvider LinkProvider { get; set; }
public virtual IImageProvider ImageProvider { get; set; }
public virtual HtmlPipelineContext HtmlPipelineContext { get; set; }
public virtual ITagProcessorFactory TagProcessorFactory { get; set; }
public virtual ICSSResolver CssResolver { get; set; }
/* overloads simplfied to keep SO answer (relatively) short. if needed
* set LinkProvider/ImageProvider after instantiating SimpleParser()
* to override the defaults (e.g. ImageProvider.ScalePercent)
*/
public SimpleParser() : this(null) { }
public SimpleParser(string baseUri)
{
LinkProvider = new LinkProvider(new UriHelper(baseUri, false));
ImageProvider = new ImageProvider(new UriHelper(baseUri, true));
HtmlPipelineContext = new HtmlPipelineContext(null);
// another story altogether, and not implemented for simplicity
TagProcessorFactory = Tags.GetHtmlTagProcessorFactory();
CssResolver = XMLWorkerHelper.GetInstance().GetDefaultCssResolver(true);
}
/*
* when sending XHR via any of the popular JavaScript frameworks,
* <img> tags are **NOT** always closed, which results in the
* infamous iTextSharp.tool.xml.exceptions.RuntimeWorkerException:
* 'Invalid nested tag a found, expected closing tag img.' a simple
* workaround.
*/
public virtual string SimpleAjaxImgFix(string xHtml)
{
return Regex.Replace(
xHtml,
"(?<image><img[^>]+)(?<=[^/])>",
new MatchEvaluator(match => match.Groups["image"].Value + " />"),
RegexOptions.IgnoreCase | RegexOptions.Multiline
);
}
public virtual void Parse(Stream stream, string xHtml)
{
xHtml = SimpleAjaxImgFix(xHtml);
using (var stringReader = new StringReader(xHtml))
{
using (Document document = new Document())
{
PdfWriter writer = PdfWriter.GetInstance(document, stream);
document.Open();
HtmlPipelineContext
.SetTagFactory(Tags.GetHtmlTagProcessorFactory())
.SetLinkProvider(LinkProvider)
.SetImageProvider(ImageProvider)
;
var pdfWriterPipeline = new PdfWriterPipeline(document, writer);
var htmlPipeline = new HtmlPipeline(HtmlPipelineContext, pdfWriterPipeline);
var cssResolverPipeline = new CssResolverPipeline(CssResolver, htmlPipeline);
XMLWorker worker = new XMLWorker(cssResolverPipeline, true);
XMLParser parser = new XMLParser(worker);
parser.Parse(stringReader);
}
}
}
}
As commented inline, SimpleAjaxImgFix(string xHtml) specifically handles XHR that may send unclosed <img> tags, which is valid HTML, but invalid XML that will break XMLWorker . A simple explanation & implementation of how to receive a PDF or other binary data with XHR and iTextSharp can be found here.
A Regex was used in SimpleAjaxImgFix(string xHtml) so that anyone using (copy/paste?) the code doesn't need to add another nuget package, but a HTML parser like HtmlAgilityPack should be used, since it's turns this:
<div><img src='a.gif'><br><hr></div>
into this:
<div><img src='a.gif' /><br /><hr /></div>
with only a few lines of code:
var hDocument = new HtmlDocument()
{
OptionWriteEmptyNodes = true,
OptionAutoCloseOnEnd = true
};
hDocument.LoadHtml("<div><img src='a.gif'><br><hr></div>");
var closedTags = hDocument.DocumentNode.WriteTo();
Also of note - use SimpleParser.Parse() above as a general blueprint to additionally implement a custom ICSSResolver or ITagProcessorFactory, which is explained in the documentation.
Now the issues described in the question should be taken care of. Called from a MVC Action Method:
[HttpPost] // some browsers have URL length limits
[ValidateInput(false)] // or throws HttpRequestValidationException
public ActionResult Index(string xHtml)
{
Response.ContentType = "application/pdf";
Response.AppendHeader(
"Content-Disposition", "attachment; filename=test.pdf"
);
var simpleParser = new SimpleParser();
simpleParser.Parse(Response.OutputStream, xHtml);
return new EmptyResult();
}
or from a Web Form that gets HTML from a server control:
Response.ContentType = "application/pdf";
Response.AppendHeader("Content-Disposition", "attachment; filename=test.pdf");
using (var stringWriter = new StringWriter())
{
using (var htmlWriter = new HtmlTextWriter(stringWriter))
{
ConvertControlToPdf.RenderControl(htmlWriter);
}
var simpleParser = new SimpleParser();
simpleParser.Parse(Response.OutputStream, stringWriter.ToString());
}
Response.End();
or a simple HTML file with hyperlinks and images on the file system:
<h1>HTML Page 00 on Local File System</h1>
<div>
<div>
Relative <img>: <img src='Images/alt-gravatar.png' />
</div>
<div>
Hyperlink to file system HTML page:
<a href='file-system-html-01.html'>Page 01</a>
</div>
</div>
or HTML from a remote web site:
<div>
<div>
<img width="200" alt="Wikipedia Logo"
src="portal/wikipedia.org/assets/img/Wikipedia-logo-v2.png">
</div>
<div lang="en">
English
</div>
<div lang="en">
iText
</div>
</div>
Above two HTML snippets run from a console app:
var filePaths = Path.Combine(basePath, "file-system-html-00.html");
var htmlFile = File.ReadAllText(filePaths);
var remoteUrl = Path.Combine(basePath, "wikipedia.html");
var htmlRemote = File.ReadAllText(remoteUrl);
var outputFile = Path.Combine(basePath, "filePaths.pdf");
var outputRemote = Path.Combine(basePath, "remoteUrl.pdf");
using (var stream = new FileStream(outputFile, FileMode.Create))
{
var simpleParser = new SimpleParser(basePath);
simpleParser.Parse(stream, htmlFile);
}
using (var stream = new FileStream(outputRemote, FileMode.Create))
{
var simpleParser = new SimpleParser("https://wikipedia.org");
simpleParser.Parse(stream, htmlRemote);
}
Quite a long answer, but taking a look at questions here at SO tagged html, pdf, and itextsharp, as of this writing (2016-02-23) there are 776 results against 4,063 total tagged itextsharp - that's 19%.
Very helpful post,
I was problem to render images in my report html to pdf. with your post I could do it.
I'm working with asp.mvc 5.
I only have to change this method of the ImageProviderClass
public virtual string GetImageRootPath() { return null; }
to
public virtual string GetImageRootPath() { HostingEnvironment.MapPath("~/Content/Images/") }
thanks!
I'm making an app in Unity3D for release on the windows store.
It seems you cant write files using the .net streamwriter.
I'd like to save a csv file to a certain location and then later send it to a server using the WWW class.
I found a project which reads a file from the assets folder.
Heres the code for that...
using UnityEngine;
using System;
using System.Collections;
using System.IO;
#if NETFX_CORE
using System.Text;
using System.Threading.Tasks;
using Windows.Storage;
using Windows.Storage.Streams;
#endif
namespace IOS
{
public class File
{
public static object result;
#if NETFX_CORE
public static async Task<byte[]> _ReadAllBytes(string path)
{
StorageFile file = await StorageFile.GetFileFromPathAsync(path.Replace("/", "\\"));
byte[] fileBytes = null;
using (IRandomAccessStreamWithContentType stream = await file.OpenReadAsync())
{
fileBytes = new byte[stream.Size];
using (DataReader reader = new DataReader(stream))
{
await reader.LoadAsync((uint)stream.Size);
reader.ReadBytes(fileBytes);
}
}
return fileBytes;
}
#endif
public static IEnumerator ReadAllText(string path)
{
#if NETFX_CORE
Task<byte[]> task = _ReadAllBytes(path);
while (!task.IsCompleted)
{
yield return null;
}
UTF8Encoding enc = new UTF8Encoding();
result = enc.GetString(task.Result, 0, task.Result.Length);
#else
yield return null;
result = System.IO.File.ReadAllText(path);
#endif
}
}
}
public class Example : MonoBehaviour
{
private string data;
IEnumerator ReadFile(string path)
{
yield return StartCoroutine(IOS.File.ReadAllText(path));
data = IOS.File.result as string;
}
public void OnGUI()
{
string path = Path.Combine(Application.dataPath, "StreamingAssets/Data.txt");
if (GUILayout.Button("Read file '" + path + "'"))
{
StartCoroutine(ReadFile(path));
}
GUILayout.Label(data == null ? "<NoData>" : data);
}
}
Heres the MSDN docs for serializing with Windows Store apps
https://msdn.microsoft.com/en-us/library/windows/apps/xaml/hh758325.aspx
I'm wondering how to adapt this to suit my purposes. ie. Write a file to a specific location that I can reference later when I am sending the file via WWW.
The main issue is the location. The Application.dataPath is read only data within the app's package. To write data use Application.persistentDataPath to get a writable location in the application data folder.
Unity provides alternatives to System.IO.File with its UnityEngine.Windows.File object. You can just switch the using between System.IO and UnityEngine.Windows then call File.ReadAllBytes or File.WriteAllBytes regardless of platform.
This is essentially what your code snippit is doing, except that Unity already provides it.