C#，连接打印机
C#实现打印功能具体的操作步骤如下：
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();
}
C#实现打印功能的实例如下：
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 ();//实现C#打印之创建一个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();//实现C#打印之开始打印
}
}
// 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;
}
}
}
}
