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CreateStreamCallback Delegate

Visual Studio 2005

Provides a stream to the ReportViewer control for rendering.

Namespace: Microsoft.Reporting.WebForms
Assembly: Microsoft.ReportViewer.WebForms (in microsoft.reportviewer.webforms.dll)

Syntax

C++

public delegate Stream CreateStreamCallback (
	string name,
	string extension,
	Encoding encoding,
	string mimeType,
	bool willSeek
)

/** @delegate */
public delegate Stream CreateStreamCallback (
	String name, 
	String extension, 
	Encoding encoding, 
	String mimeType, 
	boolean willSeek
)

JScript

JScript supports the use of delegates, but not the declaration of new ones.

Parameters

name: The name of the stream.

extension: The file name extension to use if a file stream is being created.

encoding: An Encoding enumerator value specifying the character encoding of the stream. This may be null if the stream does not contain characters.

mimeType: A string containing the MIME type of the stream.

willSeek: A Boolean value indicated whether the stream needs to support seeking. If the value is false, the stream will be forward-only and will be sent to the client in chunks as it is created. If the value is true, the stream may be written in any order.

Return Value

A Stream object to which the ReportViewer control can write data.

Remarks

This delegate function may be passed into the Render method of the LocalReport object to support custom handling of secondary streams. The main body of the report is the first stream that is created.

Example

The following code snippet shows a CreateStreamCallback callback function being passed to the Render method.

using System;
using System.IO;
using System.Data;
using System.Text;
using System.Drawing.Imaging;
using System.Drawing.Printing;
using System.Collections.Generic;
using Microsoft.Reporting.WebForms;

public class Demo : IDisposable
{
    private int m_currentPageIndex;
    private IList<Stream> m_streams;

    private DataTable LoadSalesData()
    {
        DataSet dataSet = new DataSet();
        dataSet.ReadXml("data.xml");
        return dataSet.Tables[0];
    }

    private Stream CreateStream(string name, string fileNameExtension,
        Encoding encoding,
            string mimeType, bool willSeek)
    {
        Stream stream = new FileStream(name + "." + fileNameExtension, 
            FileMode.Create);
        m_streams.Add(stream);
        return stream;
    }

    private void Export(LocalReport report)
    {
        string deviceInfo =
          "<DeviceInfo>" +
          "  <OutputFormat>EMF</OutputFormat>" + 
          "  <PageWidth>8.5in</PageWidth>" +
          "  <PageHeight>11in</PageHeight>" +
          "  <MarginTop>0.25in</MarginTop>" +
          "  <MarginLeft>0.25in</MarginLeft>" +
          "  <MarginRight>0.25in</MarginRight>" +
          "  <MarginBottom>0.25in</MarginBottom>" +
          "</DeviceInfo>";
        Warning[] warnings;
        m_streams = new List<Stream>();
        report.Render("Image", deviceInfo, CreateStream, out warnings);

        foreach (Stream stream in m_streams)
            stream.Position = 0;
    }

    private void PrintPage(object sender, PrintPageEventArgs ev)
    {
        Metafile pageImage = new Metafile(m_streams[m_currentPageIndex]);
        ev.Graphics.DrawImage(pageImage, 0, 0);

        m_currentPageIndex++;
        ev.HasMorePages = (m_currentPageIndex < m_streams.Count);
    }

    private void Print()
    {
        const string printerName = "Microsoft Office Document Image 
            Writer";

        if (m_streams == null || m_streams.Count == 0)
            return;

        PrintDocument printDoc = new PrintDocument(); 
        printDoc.PrinterSettings.PrinterName = printerName;
        if (!printDoc.PrinterSettings.IsValid)
        {
            string msg = String.Format("Can't find printer \"{0}\".", 
                printerName);
            Console.WriteLine(msg);
            return;
        }
        printDoc.PrintPage += new PrintPageEventHandler(PrintPage);
        printDoc.Print();
    }

    private void Run()
    {
        LocalReport report = new LocalReport();
        report.ReportPath = "Report.rdlc";
        report.DataSources.Add(new ReportDataSource("Sales", 
            LoadSalesData()));

        Export(report);

        m_currentPageIndex = 0;
        Print();
    }

    public void Dispose()
    {
        if (m_streams != null)
        {
            foreach (Stream stream in m_streams)
                stream.Close();
            m_streams = null;
        }
    }

    public static int Main(string[] args) 
    {
        using (Demo demo = new Demo())
        {
            demo.Run();
        }
        return 0;
    }
}

Reference

Microsoft.Reporting.WebForms Namespace

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