I need to navigate to a web site that ultimately contains a .pdf file and I want to save that file locally. I am using CEFSharp to do this. The nature of this site is such that once the .pdf appears in the browser, it cannot be accessed again. For this reason, I was wondering if once you have a .pdf displayed in the browser, is there a way to access the source for that file in the cache?
I have tried implementing IDownloadHandler and that works, but you have to click the save button on the embedded .pdf. I am trying to get around that.
OK, here is how I got it to work. There is a function in CEFSharp that allows you to filter an incoming web response. Consequently, this gives you complete access to the incoming stream. My solution is a little on the dirty side and not particularly efficient, but it works for my situation. If anyone sees a better way, I am open for suggestions. There are two things I have to assume in order for my code to work.
GetResourceResponseFilter is called every time a new page is downloaded.
The PDF is that last thing to be downloaded during the navigation process.
Start with the CEF Minimal Example found here : https://github.com/cefsharp/CefSharp.MinimalExample
I used the WinForms version. Implement the IRequestHandler and IResponseFilter in the form definition as follows:
public partial class BrowserForm : Form, IRequestHandler, IResponseFilter
{
public readonly ChromiumWebBrowser browser;
public BrowserForm(string url)
{
InitializeComponent();
browser = new ChromiumWebBrowser(url)
{
Dock = DockStyle.Fill,
};
toolStripContainer.ContentPanel.Controls.Add(browser);
browser.BrowserSettings.FileAccessFromFileUrls = CefState.Enabled;
browser.BrowserSettings.UniversalAccessFromFileUrls = CefState.Enabled;
browser.BrowserSettings.WebSecurity = CefState.Disabled;
browser.BrowserSettings.Javascript = CefState.Enabled;
browser.LoadingStateChanged += OnLoadingStateChanged;
browser.ConsoleMessage += OnBrowserConsoleMessage;
browser.StatusMessage += OnBrowserStatusMessage;
browser.TitleChanged += OnBrowserTitleChanged;
browser.AddressChanged += OnBrowserAddressChanged;
browser.FrameLoadEnd += browser_FrameLoadEnd;
browser.LifeSpanHandler = this;
browser.RequestHandler = this;
The declaration and the last two lines are the most important for this explanation. I implemented the IRequestHandler using the template found here:
https://github.com/cefsharp/CefSharp/blob/master/CefSharp.Example/RequestHandler.cs
I changed everything to what it recommends as default except for GetResourceResponseFilter which I implemented as follows:
IResponseFilter IRequestHandler.GetResourceResponseFilter(IWebBrowser browserControl, IBrowser browser, IFrame frame, IRequest request, IResponse response)
{
if (request.Url.EndsWith(".pdf"))
return this;
return null;
}
I then implemented IResponseFilter as follows:
FilterStatus IResponseFilter.Filter(Stream dataIn, out long dataInRead, Stream dataOut, out long dataOutWritten)
{
BinaryWriter sw;
if (dataIn == null)
{
dataInRead = 0;
dataOutWritten = 0;
return FilterStatus.Done;
}
dataInRead = dataIn.Length;
dataOutWritten = Math.Min(dataInRead, dataOut.Length);
byte[] buffer = new byte[dataOutWritten];
int bytesRead = dataIn.Read(buffer, 0, (int)dataOutWritten);
string s = System.Text.Encoding.UTF8.GetString(buffer);
if (s.StartsWith("%PDF"))
File.Delete(pdfFileName);
sw = new BinaryWriter(File.Open(pdfFileName, FileMode.Append));
sw.Write(buffer);
sw.Close();
dataOut.Write(buffer, 0, bytesRead);
return FilterStatus.Done;
}
bool IResponseFilter.InitFilter()
{
return true;
}
What I found is that the PDF is actually downloaded twice when it is loaded. In any case, there might be header information and what not at the beginning of the page. When I get a stream segment that begins with %PDF, I know it is the beginning of a PDF so I delete the file to discard any previous contents that might be there. Otherwise, I just keep appending each segment to the end of the file. Theoretically, the PDF file will be safe until you navigate to another PDF, but my recommendation is to do something with the file as soon as the page is loaded just to be safe.
Related
I want to open an existing PDF document and add different annotations to it. Namely bookmarks and some text
I am using the Telerik Document Processing Library (dpl) v2019.3.1021.40
I am new to dpl , but I believe the RadFlowDocument is the way to go.
I am having troubles creating the RadFlowDocument
FlowProvider.PdfFormatProvider provider = new FlowProvider.PdfFormatProvider();
using (Stream stream = File.OpenRead(sourceFile))
{
--> RadFlowDocument flowDoc = provider.Import(stream);
}
The line indicated w/ the arrow give the error "Import Not Supported"
There is a telerik blog post here
https://www.telerik.com/forums/radflowdocument-to-pdf-error
It seems relevant, but not 100% sure.
It cautions to be sure the providers are mated correctly, I believe they are in my example....
Again, ultimate goal is to open a PDF and add some stuff to it. I think the RadFlowDocument is the right direction. If there is a better solution, Im happy to hear that too.
I figured it out. The DPL is pretty good, but doc is still growing, hope this helps someone out...
This draws from a myriad of articles, I cant begin to cite them all.
There are 2 notions for working w/ PDFs in the DPL.
FixedDocument takes pages. I think this is meant for sewing docs together.
FlowDocument I believe lays things out like an HTML renderer would.
I am using Fixed, mainly b/c I can get that to work.
using System;
using System.IO;
using System.Windows; //nec for Size struct
using System.Diagnostics; //nec for launching the pdf at the end
using Telerik.Windows.Documents.Fixed.Model;
//if you have fixed and flow provider, you have to specify, so I make a shortcut
using FixedProvider = Telerik.Windows.Documents.Fixed.FormatProviders.Pdf;
using Telerik.Windows.Documents.Fixed.Model.Editing;
using Microsoft.VisualStudio.TestTools.UnitTesting;
namespace DocAggregator
{
[TestClass]
public class UnitTest2
{
[TestMethod]
public void EditNewFIle_SrcAsFixed_TrgAsFixed()
{
String dt = #"C:\USERS\greg\DESKTOP\DPL\";
String sourceFile = dt + "output.pdf";
//Open the sourceDoc so you can add stuff to it
RadFixedDocument sourceDoc;
//a provider parses the actual file into the model.
FixedProvider.PdfFormatProvider fixedProv = new FixedProvider.PdfFormatProvider();
using (Stream stream = File.OpenRead(sourceFile))
{
//'populate' the doc object from the file
//using the FLOW classes, I get "Import Not Supported".
sourceDoc = fixedProv.Import(stream);
}
int pages = sourceDoc.Pages.Count;
int pageCounter = 1;
int xoffset = 150;
int yoffset = 50;
//editor is the thing that lets you add elements into the source doc
//Like the provider, the Editor needs to match the document class (Fixed or Flow)
RadFixedDocumentEditor editor = new RadFixedDocumentEditor(sourceDoc);
foreach (RadFixedPage page in sourceDoc.Pages)
{
FixedContentEditor pEd = new FixedContentEditor(page);
Size ps = page.Size;
pEd.Position.Translate(ps.Width - xoffset, ps.Height - yoffset);
Block block = new Block();
block.HorizontalAlignment = Telerik.Windows.Documents.Fixed.Model.Editing.Flow.HorizontalAlignment.Center;
block.TextProperties.FontSize = 22;
block.InsertText(string.Format("Page {0} of {1} ", pageCounter, pages));
pEd.DrawBlock(block);
pageCounter++;
}
string exportFileName = "addedPageNums.pdf";
if (File.Exists(exportFileName))
{
File.Delete(exportFileName);
}
File.WriteAllBytes(exportFileName, fixedProv.Export(sourceDoc));
//launch the app
Process.Start(exportFileName);
}
}
}
I made a custom editor plugin, in a Seam 2.2.2 project, which makes file upload this way:
1) config the editor to load my specific xhtml upload page;
2) call the following method inside this page, and return a javascript callback;
public String sendImageToServer()
{
HttpServletRequest request = ServletContexts.instance().getRequest();
try
{
List<FileItem> items = new ServletFileUpload(new DiskFileItemFactory()).parseRequest(request);
processItems(items);//set the file data to specific att
saveOpenAttachment();//save the file to disk
}
//build callback
For this to work I have to put this inside components.xml:
<web:multipart-filter create-temp-files="false"
max-request-size="1024000" url-pattern="*"/>
The attribute create-temp-files do not seems to matter whatever its value.
But url-pattern has to be "" or "/myUploadPage.seam", any other value makes the item list returns empty. Does Anyone know why?
This turns into a problem because when I use a url-pattern that work to this case, every form with enctype="multipart/form-data" in my application stops to submit data. So I end up with other parts of the system crashing.
Could someone help me?
To solve my problem, I changed the solution to be like Seam multipart filter handle requests:
ServletRequest request = (ServletRequest) FacesContext.getCurrentInstance().getExternalContext().getRequest();
try
{
if (!(request instanceof MultipartRequest))
{
request = unwrapMultipartRequest(request);
}
if (request instanceof MultipartRequest)
{
MultipartRequest multipartRequest = (MultipartRequest) request;
String clientId = "upload";
setFileData(multipartRequest.getFileBytes(clientId));
setFileContentType(multipartRequest.getFileContentType(clientId));
setFileName(multipartRequest.getFileName(clientId));
saveOpenAttachment();
}
}
Now I handle the request like Seam do, and do not need the web:multipart-filter config that was breaking other types of request.
How do I open an existing file on the server when a user clicks an actionlink? The following code works for downloading a file but I want to open a new browser window, or tab, and display the file contents.
public ActionResult Download()
{
return File(#"~\Files\output.txt", "application/text", "blahblahblah.txt");
}
You must add "inline" for a new tab.
byte[] fileBytes = System.IO.File.ReadAllBytes(contentDetailInfo.ContentFilePath);
Response.AppendHeader("Content-Disposition", "inline; filename=" + contentDetailInfo.ContentFileName);
return File(fileBytes, contentDetailInfo.ContentFileMimeType);
The way you're using the File() method is to specify a file name in the third argument, which results in a content-disposition header being sent to the client. This header is what tells a web browser that the response is a file to be saved (and suggests a name to save it). A browser can override this behavior, but that's not controllable from the server.
One thing you can try is to not specify a file name:
return File(#"~\Files\output.txt", "application/text");
The response is still a file, and ultimately it's still up to the browser what to do with it. (Again, not controllable from the server.) Technically there's no such thing as a "file" in HTTP, it's just headers and content in the response. By omitting a suggested file name, the framework in this case may omit the content-disposition header, which is your desired outcome. It's worth testing the result in your browser to see if the header is actually omitted.
Use a target of blank on your link to open it in a new window or tab:
Download File
However, forcing the browser to display the contents is out of your control, as it entirely depends on how the user has configured their browser to deal with files that are application/text.
If you are dealing with text, you can create a view and populate the text on that view, which is then returned to the user as a regular HTML page.
please try this and replace your controller name and action name in html action link
public ActionResult ShowFileInNewTab()
{
using (var client = new WebClient()) //this is to open new webclient with specifice file
{
var buffer = client.DownloadData("~\Files\output.txt");
return File(buffer, "application/text");
}
}
OR
public ActionResult ShowFileInNewTab()
{
var buffer = "~\Files\output.txt"; //bytes form this
return File(buffer, "application/text");
}
this is action link which show in new blank tab
<%=Html.ActionLink("Open File in New Tab", "ShowFileInNewTab","ControllerName", new { target = "_blank" })%>
I canĀ“t vote your answered as is useful, follow dow. Thanks very much !
public FileResult Downloads(string file)
{
string diretorio = Server.MapPath("~/Docs");
var ext = ".pdf";
file = file + extensao;
var arquivo = Path.Combine(diretorio, file);
var contentType = "application/pdf";
using (var client = new WebClient())
{
var buffer = client.DownloadData(arquivo);
return File(buffer, contentType);
}
}
I'm new to JavaCV and I have difficult time finding good tutorials about different issues on the topics that I'm interested in. I've succeed to implement some sort of real time video streaming from my webcam but the problem is that I use this code snippet which I found on the net :
#Override
public void run() {
FrameGrabber grabber = new VideoInputFrameGrabber(0); // 1 for next
// camera
int i = 0;
try {
grabber.start();
IplImage img;
while (true) {
img = grabber.grab();
if (img != null) {
cvFlip(img, img, 1);// l-r = 90_degrees_steps_anti_clockwise
cvSaveImage((i++) + "-aa.jpg", img);
// show image on window
canvas.showImage(img);
}
that results in multiple jpg files.
What I really want to do is capture my webcam input and along with showing it I want to save it in a proper video file. I find out about FFmpegFrameRecorder but don't know how to implement it. Also I've been wondering what are the different options for the format of the video file, because flv maybe would be more useful for me.
It's been quite a journey. Still a few things that I'm not sure what's the meaning behind them, but here is a working example for capturing and recording video from a webcam using JavaCV:
import com.googlecode.javacv.CanvasFrame;
import com.googlecode.javacv.FFmpegFrameRecorder;
import com.googlecode.javacv.OpenCVFrameGrabber;
import com.googlecode.javacv.cpp.avutil;
import com.googlecode.javacv.cpp.opencv_core.IplImage;
public class CameraTest {
public static final String FILENAME = "output.mp4";
public static void main(String[] args) throws Exception {
OpenCVFrameGrabber grabber = new OpenCVFrameGrabber(0);
grabber.start();
IplImage grabbedImage = grabber.grab();
CanvasFrame canvasFrame = new CanvasFrame("Cam");
canvasFrame.setCanvasSize(grabbedImage.width(), grabbedImage.height());
System.out.println("framerate = " + grabber.getFrameRate());
grabber.setFrameRate(grabber.getFrameRate());
FFmpegFrameRecorder recorder = new FFmpegFrameRecorder(FILENAME, grabber.getImageWidth(),grabber.getImageHeight());
recorder.setVideoCodec(13);
recorder.setFormat("mp4");
recorder.setPixelFormat(avutil.PIX_FMT_YUV420P);
recorder.setFrameRate(30);
recorder.setVideoBitrate(10 * 1024 * 1024);
recorder.start();
while (canvasFrame.isVisible() && (grabbedImage = grabber.grab()) != null) {
canvasFrame.showImage(grabbedImage);
recorder.record(grabbedImage);
}
recorder.stop();
grabber.stop();
canvasFrame.dispose();
}
}
It was somewhat hard for me to make this work so in addition to those that may have the same issue, if you follow the official guide about how to setup JavaCV on Windows 7/64bit and want to capture video using the code above you should create a new directory in C:\ : C:\ffmpeg and extract the files from the ffmped release that you've been told to download in the official guide. Then you should add C:\ffmpeg\bin to your Enviorment variable PATH and that's all. About this step all credits go to karlphillip
and his post here
I'm simply trying to attach a file named Document.pdf in the DocumentsLibrary to an email using the Share Charm. My code below works perfectly on the Local Machine:
private async void OnDataRequestedFiles(DataTransferManager sender, DataRequestedEventArgs e)
{
List<IStorageItem> shares = new List<IStorageItem>();
StorageFile filetoShare = await Windows.Storage.KnownFolders.DocumentsLibrary.GetFileAsync("Document.pdf");
if (filetoShare != null)
{
shares.Add(filetoShare);
filetoShare = null;
}
if (shares != null)
{
DataPackage requestData = e.Request.Data;
requestData.Properties.Title = "Title";
requestData.Properties.Description = "Description"; // The description is optional.
requestData.SetStorageItems(shares);
shares = null;
}
else
{
e.Request.FailWithDisplayText("File not Found.");
}
}
But when I run the exact same code on a Windows Surface Tablet, I get the dreaded "There's nothing to share right now." on the right in the Charms flyout area.
Here's a little more background to help:
I'm not looking to use a File Picker...I know the exact file I'm looking for
I've enabled the Documents Library Capability in the manifest
I've added a File Type Association for pdf in the manifest
and yes, the file does exist and is in the Documents Library
an email account is properly setup in the Mail App on the surface
I can successfully send text emails from the Tablet...just not emails with attachments
Like I said, this works on my Win 8 Development Machine as expected...just not on the Surface. I'm wondering if the Surface has different file or folder permissions?
Thanks for the help...this is driving me CRAZY
I finally figured it out - the problem was that my Event Handler was async (so that I could use await to set the StorageFile variable).
I solved it by setting the StorageFile variable earlier in my code so that it was already available when the Event Handler was called.
I still have no idea why it worked on my development machine, but no on the WinRT surface...
The handler can be an async method. In this case, it is critical to use DataTransferManager. Please refer to the MSDN page specifically for this scenario. For your convenience, the code from the page is copied to here:
private void RegisterForShare()
{
DataTransferManager dataTransferManager = DataTransferManager.GetForCurrentView();
dataTransferManager.DataRequested += new TypedEventHandler<DataTransferManager,
DataRequestedEventArgs>(this.ShareStorageItemsHandler);
}
private async void ShareStorageItemsHandler(DataTransferManager sender,
DataRequestedEventArgs e)
{
DataRequest request = e.Request;
request.Data.Properties.Title = "Share StorageItems Example";
request.Data.Properties.Description = "Demonstrates how to share files.";
// Because we are making async calls in the DataRequested event handler,
// we need to get the deferral first.
DataRequestDeferral deferral = request.GetDeferral();
// Make sure we always call Complete on the deferral.
try
{
StorageFile logoFile =
await Package.Current.InstalledLocation.GetFileAsync("Assets\\Logo.png");
List<IStorageItem> storageItems = new List<IStorageItem>();
storageItems.Add(logoFile);
request.Data.SetStorageItems(storageItems);
}
finally
{
deferral.Complete();
}
}
It is critical to place the following statement before any async method is called:
DataTransferManager dataTransferManager = DataTransferManager.GetForCurrentView();
You only have half a second to get the whole job done (getting the file, attaching...etc.). If the half-second deadline occurs you'll get this "driving crazy" message. Consider implementing some resumable logic and replace the message with "the attachment is being prepared please try again in a few seconds" (or else).
Your WinRT device might be just slower than your development machine. The latter just does the job before the deadline...