CreateStreamCallback 委托

项目
08/31/2012

为 ReportViewer 控件提供流以进行呈现。

命名空间： Microsoft.Reporting.WebForms
程序集： Microsoft.ReportViewer.WebForms（在 Microsoft.ReportViewer.WebForms.dll 中）

语法

声明
Public Delegate Function CreateStreamCallback ( _
    name As String, _
    extension As String, _
    encoding As Encoding, _
    mimeType As String, _
    willSeek As Boolean _
) As Stream
用法
Dim instance As New CreateStreamCallback(AddressOf HandlerMethod)

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

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

type CreateStreamCallback = 
    delegate of 
        name:string * 
        extension:string * 
        encoding:Encoding * 
        mimeType:string * 
        willSeek:bool -> Stream

参数

name
类型：System.String
流的名称。

extension
类型：System.String
创建文件流时要使用的文件扩展名。

encoding
类型：System.Text.Encoding
指定流的字符编码的 Encoding 枚举器值。如果流不包含字符，则此值可能为 nullnull 引用（在 Visual Basic 中为 Nothing）。

mimeType
类型：System.String
一个包含流的 MIME 类型的字符串。

willSeek
类型：System.Boolean
指示流是否需要支持查找的 Boolean 值。如果值为 false，则流将为只前推，并将按其创建顺序发送到块区中的客户端。如果值为 true，则流可以任何顺序写入。

返回值

类型：System.IO.Stream
ReportViewer 控件可以写入数据的 Stream 对象。

注释

此委托函数可以传递到 LocalReport() 对象的 Render(IRenderingExtension, String, String, CreateAndRegisterStream, array<Warning[]%) 方法中，以支持对辅助流进行自定义处理。报表的主体是创建的第一个流。

示例

下面的代码段展示了要传递给 Render(IRenderingExtension, String, String, CreateAndRegisterStream, array<Warning[]%) 方法的 CreateStreamCallback 回调函数。

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

Public Class Demo
    Implements IDisposable

    private m_currentPageIndex As Integer
    private m_streams As IList(Of Stream)

    Private Function LoadSalesData() As DataTable
        Dim dataSet As New DataSet()
        dataSet.ReadXml("data.xml")
        Return dataSet.Tables(0)
    End Function

    Private Function CreateStream(name As String, _
         fileNameExtension As String, _
              encoding As Encoding, mimeType As String, _
                  willSeek As Boolean) As Stream
        Dim stream As Stream = New FileStream(name + "." +  fileNameExtension, FileMode.Create)
        m_streams.Add(stream)
        Return stream
    End Function

    Private Sub Export(report As LocalReport)
        Dim deviceInfo As string = _
          "<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>"
        Dim warnings() As Warning = Nothing
        m_streams = New List(Of Stream)()
        report.Render("Image", deviceInfo, _
              AddressOf CreateStream, warnings)

        Dim stream As Stream
        For Each stream In m_streams
            stream.Position = 0
        Next
    End Sub

    Private Sub PrintPage(sender As Object, ev As PrintPageEventArgs)
        Dim pageImage As New Metafile(m_streams(m_currentPageIndex))
        ev.Graphics.DrawImage(pageImage, ev.PageBounds)
      
        m_currentPageIndex += 1
        ev.HasMorePages = (m_currentPageIndex < m_streams.Count)
    End Sub

    Private Sub Print()
        Const printerName As String = "Microsoft Office Document Image Writer"

        If m_streams Is Nothing Or m_streams.Count = 0 Then
            Return
        End If 

        Dim printDoc As New PrintDocument()
        printDoc.PrinterSettings.PrinterName = printerName
        If Not printDoc.PrinterSettings.IsValid Then
            Dim msg As String = String.Format(_
                 "Can't find printer ""{0}"".", printerName)
            Console.WriteLine(msg)
            Return
        End If
        AddHandler printDoc.PrintPage, AddressOf PrintPage
        printDoc.Print()
    End Sub

    Private Sub Run()
        Dim report As LocalReport = new LocalReport()
        report.ReportPath = "Report.rdlc"
        report.DataSources.Add(new ReportDataSource("Sales", LoadSalesData()))

        Export(report)

        m_currentPageIndex = 0
        Print()
    End Sub

    Public Overloads Sub Dispose() Implements IDisposable.Dispose
        If Not (m_streams Is Nothing) Then
            Dim stream As Stream
            For Each stream In m_streams
               stream.Close()
            Next
            m_streams = Nothing
        End If
    End Sub

    Public Shared Sub Main(args as string())
        Using demo As Demo = new Demo()
            demo.Run()
        End Using
    End Sub
End Class

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;
    }
}

请参阅

参考

Microsoft.Reporting.WebForms 命名空间

通过

CreateStreamCallback 委托

语法

参数

返回值

注释

示例

请参阅

参考

其他资源