文本文件打印类库(C#)

我写了一个打印文本文件的类库，功能包括：打印预览、打印。打印时可以选择打印机，可以指定页码范围。调用方法非常简单：
TextFilePrinter p = new TextFilePrinter(tbxFileName.Text);
p.View(); // 打印预览
p.Print(); // 打印文件
使用 TextFilePrinter 类的以下构造函数可以指定打印时使用的字体：
TextFilePrinter(string fileName, Encoding theEncode, Font theFont)
下面测试程序运行时的截图:

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

namespace Skyiv.Util
{
sealed class TextFilePrinter
{
string fileName;
Encoding theEncode;
Font theFont;
StreamReader srToPrint;
int currPage;

public TextFilePrinter(string fileName)
: this(fileName, Encoding.GetEncoding("GB18030"), new Font("新宋体", 10))
{
}

public TextFilePrinter(string fileName, Encoding theEncode, Font theFont)
{
this.fileName = fileName;
this.theEncode = theEncode;
this.theFont = theFont;
}

public void Print()
{
using (srToPrint = new StreamReader(fileName, theEncode))
{
PrintDialog dlg = new PrintDialog();
dlg.Document = GetPrintDocument();
dlg.AllowSomePages = true;
dlg.AllowPrintToFile = false;
if (dlg.ShowDialog() == DialogResult.OK) dlg.Document.Print();
}
}

public void View()
{
using (srToPrint = new StreamReader(fileName, theEncode))
{
PrintPreviewDialog dlg = new PrintPreviewDialog();
dlg.Document = GetPrintDocument();
dlg.ShowDialog();
}
}

PrintDocument GetPrintDocument()
{
currPage = 1;
PrintDocument doc = new PrintDocument();
doc.DocumentName = fileName;
doc.PrintPage += new PrintPageEventHandler(PrintPageEvent);
return doc;
}

void PrintPageEvent(object sender, PrintPageEventArgs ev)
{
string line = null;
float linesPerPage = ev.MarginBounds.Height / theFont.GetHeight(ev.Graphics);
bool isSomePages = ev.PageSettings.PrinterSettings.PrintRange == PrintRange.SomePages;
if (isSomePages)
{
while (currPage < ev.PageSettings.PrinterSettings.FromPage)
{
for (int count = 0; count < linesPerPage; count++)
{
line = srToPrint.ReadLine();
if (line == null) break;
}
if (line == null) return;
currPage++;
}
if (currPage > ev.PageSettings.PrinterSettings.ToPage) return;
}
for (int count = 0; count < linesPerPage; count++)
{
line = srToPrint.ReadLine();
if (line == null) break;
ev.Graphics.DrawString(line, theFont, Brushes.Black, ev.MarginBounds.Left,
ev.MarginBounds.Top + (count * theFont.GetHeight(ev.Graphics)), new StringFormat());
}
currPage++;
if (isSomePages && currPage > ev.PageSettings.PrinterSettings.ToPage) return;
if (line != null) ev.HasMorePages = true;
}
}
}

View Code
这些程序都相当简当明了，这里就不再解释了。
这个类库有个缺点：当文本文件中的一行不能在打印纸的一行中打印完时，该行的后半部就丢失了。