如何提取本地打印机打印的文字？

操作系统为Windows XP
需要在本地打印机打印文字的时候提取它打印的文字。目前想到的方案有：
1）使用虚拟打印机，让虚拟打印机打印txt文件，完成后再将打印任务转移(Redirect)到本地打印机。
使用这个方案，不知道有没有免费的SDK可供使用？
2）监控打印机端口
据我监控的结果看起来像是乱码，应该是并口发送给打印机的指令集，不知道如何从这些指令集中提取打印文字？

另外其它简单可行的方法也希望大家提供。

如果往打印机送的是字符的像素或图片，你能保证正确识别出对应啥文字吗？

首先可以肯定打印的是文字，不是图片，因为使用虚拟打印机后输出的是文字

不知道可不可以从打印缓冲池中提取文字？

没有人帮忙解决吗？

Windows下Hook打印文字相关API？
Printer: Printing Sample

Click to open or copy the files for the Printer sample.

The Printer sample shows how to print using both the CreateDC and the PrinterDlg methods for acquiring a printer HDC. The user is allowed to print different graphical objects, as well as a complete device font set. An "Abort" dialog box is also implemented. 

The Printer sample also does the following: 

Provides complete device capabilities for all printers and the display.


Provides information (levels 1 and 2) returned by a call to EnumPrinters.


Shows how to enumerate fonts for a particular DC.


Illustrates differences among the various mapping modes.


Demonstrates GDI features. 
Building SDK Samples 

This sample uses the following keywords:

createdc; deletedc; errmsgbox; getlasterror; getstringres; getstringres2; isdbcsleadbyte; mainwndproc; makeintresource; my_mbslen; outnum; outstr; outstr2; outstr3; printdlg; printthread; registerclass; strcat; winmain; wsprintf