在C#中实现打印功能(C#中PrintDialog,PrintDocument的使用）

 在C#中使用PrintDialog可以很方便的实现程序的打印功能。

其步骤如下：

1. 创建一个PrintDialog的实例。如下：
   System.Windows.Forms.PrintDialog PrintDialog1=new PrintDialog ();
2. 创建一个PrintDocument的实例.如下：
   System.Drawing.Printing.PrintDocument docToPrint =
      new System.Drawing.Printing.PrintDocument();
3. 设置打印机开始打印的事件处理函数.函数原形如下：
   void docToPrint_PrintPage(object sender,
      System.Drawing.Printing.PrintPageEventArgs e)
4. 将事件处理函数添加到PrintDocument的PrintPage事件中。
   docToPrint.PrintPage+=new PrintPageEventHandler(docToPrint_PrintPage);
5. 设置PrintDocument的相关属性，如：
   PrintDialog1.AllowSomePages = true;PrintDialog1.ShowHelp = true;
6. 把PrintDialog的Document属性设为上面配置好的PrintDocument的实例：
   PrintDialog1.Document = docToPrint;
7. 调用PrintDialog的ShowDialog函数显示打印对话框：
   DialogResult result = PrintDialog1.ShowDialog();
8. 根据用户的选择，开始打印：
   if (result==DialogResult.OK)
      {
       docToPrint.Print();
      }

例子如下：

使用时先创建PrintService类的实例，然后调用void StartPrint(Stream streamToPrint,string streamType)函数开始打印。其中streamToPrint是要打印的内容（字节流），streamType是流的类型（txt表示普通文本，image表示图像）；

using System;
using System.Drawing.Printing;
using System.Windows.Forms;
using System.IO;

namespace EDImageSystem
{
 /// <summary>
 /// PrintService 的摘要说明。
 /// </summary>
 public class PrintService
 {
  public PrintService()
  {
   //
   // TODO: 在此处添加构造函数逻辑
   //
   this.docToPrint.PrintPage+=new PrintPageEventHandler(docToPrint_PrintPage);
  }//将事件处理函数添加到PrintDocument的PrintPage中

  // Declare the PrintDocument object.
  private System.Drawing.Printing.PrintDocument docToPrint =
   new System.Drawing.Printing.PrintDocument();//创建一个PrintDocument的实例

  private System.IO.Stream streamToPrint;
  string streamType;

  // This method will set properties on the PrintDialog object and
  // then display the dialog.
  public void StartPrint(Stream streamToPrint,string streamType)
  {

   this.streamToPrint=streamToPrint;
   this.streamType=streamType;
   // Allow the user to choose the page range he or she would
   // like to print.
   System.Windows.Forms.PrintDialog PrintDialog1=new PrintDialog ();//创建一个PrintDialog的实例。
   PrintDialog1.AllowSomePages = true;

   // Show the help button.
   PrintDialog1.ShowHelp = true;

   // Set the Document property to the PrintDocument for
   // which the PrintPage Event has been handled. To display the
   // dialog, either this property or the PrinterSettings property
   // must be set
   PrintDialog1.Document = docToPrint;//把PrintDialog的Document属性设为上面配置好的PrintDocument的实例

   DialogResult result = PrintDialog1.ShowDialog();//调用PrintDialog的ShowDialog函数显示打印对话框

   // If the result is OK then print the document.
   if (result==DialogResult.OK)
   {
    docToPrint.Print();//开始打印
   }

  }

// The PrintDialog will print the document
  // by handling the document's PrintPage event.
  private void docToPrint_PrintPage(object sender,
   System.Drawing.Printing.PrintPageEventArgs e)//设置打印机开始打印的事件处理函数
  {

   // Insert code to render the page here.
   // This code will be called when the control is drawn.

   // The following code will render a simple
   // message on the printed document
   switch(this.streamType)
   {
    case "txt":
     string text = null;
     System.Drawing.Font printFont = new System.Drawing.Font
      ("Arial", 35, System.Drawing.FontStyle.Regular);

     // Draw the content.
     System.IO.StreamReader streamReader=new StreamReader(this.streamToPrint);
     text=streamReader.ReadToEnd();
     e.Graphics.DrawString(text,printFont,System.Drawing.Brushes.Black,e.MarginBounds.X,e.MarginBounds.Y);
     break;
    case "image":
     System.Drawing.Image image=System.Drawing.Image.FromStream(this.streamToPrint);
     int x=e.MarginBounds.X;
     int y=e.MarginBounds.Y;
     int width=image.Width;
     int height=image.Height;
     if((width/e.MarginBounds.Width)>(height/e.MarginBounds.Height))
     {
      width=e.MarginBounds.Width;
      height=image.Height*e.MarginBounds.Width/image.Width;
     }
     else
     {
      height=e.MarginBounds.Height;
      width=image.Width*e.MarginBounds.Height/image.Height;
     }
     System.Drawing.Rectangle destRect=new System.Drawing.Rectangle(x,y,width,height);
     e.Graphics.DrawImage(image,destRect,0,0,image.Width,image.Height,System.Drawing.GraphicsUnit.Pixel);
     break;
    default:
     break;
   }
   
  }

 }
}