打印功能探求之路四

其步骤如下：

创建一个PrintDialog的实例。如下：
System.Windows.Forms.PrintDialog PrintDialog1=new PrintDialog ();
创建一个PrintDocument的实例.如下：
System.Drawing.Printing.PrintDocument docToPrint =
new System.Drawing.Printing.PrintDocument();
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)
将事件处理函数添加到PrintDocument的PrintPage事件中。
docToPrint.PrintPage+=new PrintPageEventHandler(docToPrint_PrintPage);
设置PrintDocument的相关属性，如：
PrintDialog1.AllowSomePages = true;PrintDialog1.ShowHelp = true;
把PrintDialog的Document属性设为上面配置好的PrintDocument的实例：
PrintDialog1.Document = docToPrint;
调用PrintDialog的ShowDialog函数显示打印对话框：
DialogResult result = PrintDialog1.ShowDialog();
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）；




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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;
}

}

}
}