Programmatically Export Multi-page report to PNG format

[Ring Lee]

Hi,

I would like to programmatically do an export of my multi-paged report to PNG format, i.e. the end result should be 3 PNG files for a 3 paged report and so on. Is it possible to do this? And can I specify the filenames for each file programmatically or is it auto-generated? The whole process should be transparent to the end-user, i.e. I do not want the end user to click on the Export button and type in the file name in the File Dialog that pops up. Instead the program should do an auto-export to the required format and use names such as "Report1_pg1.png", "Report1_pg2.png" etc... Hope you can help me on this. Thanks.

[IvanY]

Hello Ring,

You can export each page of the report to a separate png file. The Render Report method has an overload with CreateStream callback method. Here is a simple code snippet which illustrates the approach:

List<Stream> streams = new List<Stream>();

       void RenderReport()
       {
           var reportProcessor = new ReportProcessor();
           var documentName = "";
           var deviceInfo = new Hashtable();
           deviceInfo["OutputFormat"] = "JPEG";
           reportProcessor.RenderReport("IMAGE", new ReportCatalog(), deviceInfo, this.CreateStream, out documentName);
           this.CloseStreams();
       }

       void CloseStreams()
       {
           foreach (var stream in this.streams)
           {
               stream.Close();
           }
           this.streams.Clear();
       }

       public Stream CreateStream(string name, string extension, Encoding encoding, string mimeType)
       {
           const string path = @"C:\Reports\";

           var filePath = Path.Combine(path, name + "." + extension);
           var fs = new FileStream(filePath, FileMode.Create);
           this.streams.Add(fs);
           return fs;
       }

       private void button1_Click(object sender, System.EventArgs e)
       {
           RenderReport();
       }

Greetings,
IvanY
the Telerik team

[Karl]

Could you provide an example of how to use the code in your example to return the image from a html page response? The code below returns an image file but it is corrupt.

System.Collections.Hashtable deviceInfo =
            new System.Collections.Hashtable();

        deviceInfo["OutputFormat"] = "JPEG";

        string documentName = "";

        InstanceReportSource reportToExport = new InstanceReportSource();
        reportToExport.ReportDocument = new RecruitmentBulletinPDF.RecruitmentBulletin(Convert.ToInt32(yearSelector.SelectedItem.Text), Convert.ToInt32(weekSelector.SelectedValue), rtbIssueNo.Text);

        ReportProcessor reportProcessor = new ReportProcessor();

        bool result = reportProcessor.RenderReport("IMAGE", reportToExport, deviceInfo, this.CreateStream, out documentName);

byte[] filebytes = new byte[streams[0].Length];
        streams[0].Read(filebytes, 0, Convert.ToInt32(streams[0].Length));


        Response.Clear();
        Response.ContentType = "image/jpeg";
        Response.Cache.SetCacheability(HttpCacheability.Private);
        Response.Expires = -1;
        Response.Buffer = true;

        Response.AddHeader("Content-Disposition",
                           string.Format("{0};FileName=\"{1}\"",
                                         "attachment",
                                         "imagefile"));

        Response.BinaryWrite(filebytes);
        Response.End();

        this.CloseStreams();

[Nasko]

Hello Karl,

Please follow the examples in the Exporting Report Programmatically help article.
I have tested with the following sample code and it is working correctly:

Telerik.Reporting.Report report = new ReportLibrary.Report1();

Telerik.Reporting.Processing.ReportProcessor reportProcessor = new Telerik.Reporting.Processing.ReportProcessor();

//set any deviceInfo settings if necessary
System.Collections.Hashtable deviceInfo = new System.Collections.Hashtable();

Telerik.Reporting.InstanceReportSource instanceReportSource = new Telerik.Reporting.InstanceReportSource();

instanceReportSource.ReportDocument = report;

Telerik.Reporting.Processing.RenderingResult result = reportProcessor.RenderReport("IMAGE", instanceReportSource, deviceInfo);

string fileName = result.DocumentName + "." + result.Extension;

Response.Clear();
Response.ContentType = "image/jpeg";
Response.Cache.SetCacheability(HttpCacheability.Private);
Response.Expires = -1;
Response.Buffer = true;

Response.AddHeader("Content-Disposition",
                   string.Format("{0};FileName=\"{1}\"",
                                 "attachment",
                                 fileName));

Response.BinaryWrite(result.DocumentBytes);
Response.End();

If you still experience any difficulties we will appreciate if you open a support thread and send us a runnable sample to debug on our end.

Regards,
Nasko
Telerik