本文接上篇《cups-pdf編譯安裝》，內(nèi)容都為本身根據(jù)項目經(jīng)驗總結(jié)，可以轉(zhuǎn)載但請注明出處。作者簡書id: weogkoii

開發(fā)環(huán)境：

Linux 4.4.0-31-generic #50~14.04.1-Ubuntu SMP Wed Jul 13 01:07:32 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

CUPS及周邊安裝請參考前篇：《CUPS-PDF編譯安裝》

http://www.itdecent.cn/p/4e9b15fe9386

1. lp和lpr命令簡介

這兩個命令都是CUPS系統(tǒng)自帶的打印命令，為了兼容老系統(tǒng)而保留下來的，也是使用起來最方便的。但是，在中文打印時經(jīng)常出現(xiàn)亂碼。命令參考：

https://www.cups.org/doc/man-lp.html

https://www.cups.org/doc/man-lpr.html

已安裝好的cups-pdf打印機：

#lpstat -a

cups-pdf 自從 2019年08月02日 星期五 09時13分34秒 開始接受請求

基本用法：

lpr [-P 打印機] [-#? 打印份數(shù)] -U [用戶名] file

lpr -P cups-pdf /tmp/3333.txt

lp [-d 打印機] [-n 打印份數(shù)] file

lp -d cups-pdf /tmp/3333.txt

2. lpr命令打印中文txt文檔

使用vim隨意編輯一個中文txt文檔，內(nèi)容如下：

#cat /tmp/ChinesePrintTest.txt

一須abc是口

調(diào)用lpr或lp使用cups-pdf進行打印，得到pdf文件卻是亂碼：

lpr -P cups-pdf /tmp/ChinesePrintTest.txt

期望的”一須abc是口“沒有出現(xiàn)，而是用空白方框代替了4個中文字符，只剩余中間的abc正常打印出來。

3. 解決亂碼調(diào)試分析過程

初步分析，生成的pdf文檔中只有位置中間的abc正常打印了，中文字符均為空白，有可能是不支持中文字符打印。于是上網(wǎng)google百度了很久，發(fā)現(xiàn)竟然都說lp/lpr命令不支持中文，要打印pdf的話，最好是用圖形化Linux的軟件。但是我有點不甘心，因為cups的文檔中并未說明不支持中文，而且現(xiàn)在utf8格式都這么多年了，這些命令也應該與時俱進了吧。反正是編譯安裝的，索性自己看日志看代碼嘗試解決。

3.1 首先分析cups日志

查看/var/log/cups/error_log，本次打印是把txt文檔轉(zhuǎn)換成pdf文檔，一共使用4個filters，分別是texttopdf、pdftopdf、pdftops、cups-pdf，4個filter的作用分別如日志所描述：

[Job 124] 4 filters for job:

[Job 124] texttopdf (text/plain to application/pdf, cost 32)

[Job 124] pdftopdf (application/pdf to application/vnd.cups-pdf, cost 66)

[Job 124] pdftops (application/vnd.cups-pdf to application/vnd.cups-postscript, cost 100)

[Job 124] - (application/vnd.cups-postscript to printer/cups-pdf, cost 0)

由于texttopdf是cups-filters項目編譯而來的，所以直接查看相應代碼。接下來模擬cups調(diào)用texttopdf（如果不熟悉這部分，可以去查看相關(guān)cups filters的原理文檔）。從error_log中獲取調(diào)用texttopdf的參數(shù)：

[Job 124] argv[0]="cups-pdf"

[Job 124] argv[1]="124"

[Job 124] argv[2]="root"

[Job 124] argv[3]="ChinesePrintTest.txt"

[Job 124] argv[4]="1"

[Job 124] argv[5]="finishings=3 number-up=1 job-uuid=urn:uuid:431814bd-dd50-3e6b-6fbc-ae490d3763a9 job-originating-host-name=localhost date-time-at-creati? ? on= date-time-at-processing= time-at-creation=1564970267 time-at-processing=1564970267 document-name-supplied=ChinesePrintTest.txt"

[Job 124] argv[6]="/var/spool/cups/d00124-001"

環(huán)境變量：

[Job 124] envp[0]="CUPS_CACHEDIR=/var/cache/cups"

[Job 124] envp[1]="CUPS_DATADIR=/usr/share/cups"

[Job 124] envp[2]="CUPS_DOCROOT=/usr/share/doc/cups"

[Job 124] envp[3]="CUPS_FONTPATH=/usr/share/cups/fonts"

[Job 124] envp[4]="CUPS_REQUESTROOT=/var/spool/cups"

[Job 124] envp[5]="CUPS_SERVERBIN=/usr/lib/cups"

[Job 124] envp[6]="CUPS_SERVERROOT=/etc/cups"

[Job 124] envp[7]="CUPS_STATEDIR=/var/run/cups"

[Job 124] envp[8]="HOME=/var/spool/cups/tmp"

[Job 124] envp[9]="PATH=/usr/lib/cups/filter:/usr/bin:/usr/sbin:/bin:/usr/bin"

[Job 124] envp[10]="SERVER_ADMIN=root@ximi"

[Job 124] envp[11]="SOFTWARE=CUPS/2.2.9"

[Job 124] envp[12]="TMPDIR=/var/spool/cups/tmp"

[Job 124] envp[13]="USER=root"

[Job 124] envp[14]="CUPS_MAX_MESSAGE=2047"

[Job 124] envp[15]="CUPS_SERVER=/var/run/cups/cups.sock"

[Job 124] envp[16]="CUPS_ENCRYPTION=IfRequested"

[Job 124] envp[17]="IPP_PORT=631"

[Job 124] envp[18]="CHARSET=utf-8"

[Job 124] envp[19]="LANG=zh_CN.UTF-8"

[Job 124] envp[20]="PPD=/etc/cups/ppd/cups-pdf.ppd"

[Job 124] envp[21]="RIP_MAX_CACHE=128m"

[Job 124] envp[22]="CONTENT_TYPE=text/plain"

[Job 124] envp[23]="DEVICE_URI=cups-pdf:/"

[Job 124] envp[24]="PRINTER_INFO=cups-pdf"

[Job 124] envp[25]="PRINTER_LOCATION="

[Job 124] envp[26]="PRINTER=cups-pdf"

[Job 124] envp[27]="PRINTER_STATE_REASONS=none"

[Job 124] envp[28]="CUPS_FILETYPE=document"

[Job 124] envp[29]="FINAL_CONTENT_TYPE=application/vnd.cups-postscript"

[Job 124] envp[30]="AUTH_I****"

3.2 使用shell腳本模擬cups調(diào)用texttopdf，將stdout重寫向到文件中，這個文件中就包括轉(zhuǎn)換的pdf格式文件。查看其中內(nèi)容：

? 6 stream

? 7 q

? 8 0 g

? 9 BT

10? 18 745.884 Td

11? 105.522 Tz

12? /FN02 11.333 Tf <00000000> Tj

13 ET

14 0 g

15 BT

16? 46.800 745.884 Td

17? 105.522 Tz

18? /FN00 11.333 Tf <004400450046> Tj

19 ET

20 0 g

21 BT

22? 68.400 745.884 Td

23? 105.522 Tz

24? /FN02 11.333 Tf <00000000> Tj

25 ET

26 Q

27 endstream

可以看到在stream中，原本的中文字符變成了<00000000>，只剩余<004400450046>（abc，ASCII碼16進制）。從這里可以判斷，應該是這一步轉(zhuǎn)換出了問題，原來txt文件中的中文，在生成的pdf格式文件中已經(jīng)被0000所代替了。找到了問題點，再繼續(xù)分析出問題的原因。

3.3 查看txt文件格式和編碼

:set ff

fileformat=unix

:set fileencoding

fileencoding=utf-8

經(jīng)過查看，文件格式和編碼都沒有問題

3.4 查看texttopdf源碼

為什么會把中文弄成空格呢？經(jīng)過查看代碼終于是有所發(fā)現(xiàn)，texttopdf沒有找到中文字體？！為什么呢，vim都已經(jīng)可以顯示中文字符了，那為什么texttopdf卻又找不到字體呢？

查看cups-filters的README發(fā)現(xiàn)一點線索：

TEXTTOPDF

=========

This implements a texttopdf filter, and is derived from cups' texttops.

To configure:

-------------

- texttopdf uses CUPS_DATADIR/charset/pdf.utf-8 for font configuration

? (when utf-8 was requested as charset). The font names given there are

? used as fontconfig selectors; the best matching font, that is both

? monospaced and in a supported format (TTC, TTF or OTF) will then be used.

- As a special exception, all fontnames that start with a '.' or '/' are

? considered filenames, and fontconfig is skipped; the name is used directly

? for loading the font file.

- Implementation note: TrueType Collections (.TTC) are internally handled

? by appending '/' and the index of the font inside the collection to

? the filename (e.g. to use the second font of uming.ttc, the filename

? uming.ttc/1 must be given to the fontembed-library).

? By appending the index-field returned from fontconfig, this is completely

? transparent to the user (but currently not widely tested).

- You may look at the two examples: pdf.utf-8.simple and pdf.utf-8.heavy.

To use:

-------

The filter is called just like any other cups filter. Have a

look at test.sh for example.

Known Issues

------------

- Text extraction does not work (at least for pdftotext from xpdf)

? for the resulting pdfs.

- OTF(CFF) embedding currently does not subset the fonts.

- Text wrapping in pretty-printing mode does not respect double-wide

? characters (CJK), and thus produce wrong results (wrap too late)

? for lines where they occur.? The fix is not trivial, since all the

? pretty-printing processing is done without knowledge of / prior to

? the font configuration (which is where single or double width

? code-ranges are specified).

- The hebrew example in test5.pdf shows one of our limitations:

? Compose glyphs are not composed with the primary glyph but printed

? as separate glyphs.

原來texttopdf使用CUPS_DATADIR/charset/pdf.utf-8文件配置自身的字體和字符集，看樣子是這個文件配置不對。

3.5 研究pdf.utf-8配置格式

這個配置文件是一段注釋，但是說得不是特別清楚，還是根據(jù)代碼反推才搞明白。原來texttopdf是讀取fontconfig字體配置。需要texttopdf中使用的字體都需要在這個配置文件中添加，相應字體才能被加載到texttopdf中正常使用。打開文件一看，果然沒有中文字體：

charset utf8

#

# This file defines the font mappings used for Unicode/UTF-8 text printing

# through PDF.

#

# Each line consists of:

#

#? first last direction width normal bold italic bold-italic

#

# First and last are the first and last glyphs in the font mapping

# that correspond to that font; contrary to PostScript printing

# they only select the font. To find the glyph the complete unicode

# character will be looked up in the (3,1) resp. (3,0) cmap of the

# TrueType font. The glyph values are hexadecimal.

#

# Direction is the string "ltor" or "rtol", indicating left-to-right or

# right-to-left text.

#

# Width is the string "single" or "double"; double means that the glyphs

# are twice as wide as ASCII characters in the Courier typeface.

#

# "Normal", "bold", "italic", and "bold-italic" are the typefaces to use

# for each presentation.? If characters are only available in a single

# style then only one typeface should be listed (e.g. "Symbol")

#

# Each font that is listed will be used (and downloaded if needed) when

# printing.

#

0000 04FF ltor single monospace monospace:bold monospace:oblique monospace:bold:oblique

0500 05FF rtol single monospace

“#”號開頭的都是注釋可以直接跳過。重點在最后面兩排，表示utf8編碼范圍使用的對應字體。

3.5 fontconfig配置字體

用fc-list查看當前已經(jīng)配置字體

/usr/share/fonts/truetype/dejavu/DejaVuSerif-Bold.ttf: DejaVu Serif:style=Bold

/usr/share/fonts/truetype/arphic/uming.ttc: AR PL UMing TW MBE:style=Light

/usr/share/fonts/truetype/dejavu/DejaVuSansMono.ttf: DejaVu Sans Mono:style=Book

/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf: DejaVu Sans:style=Book

/usr/share/fonts/truetype/wqy/wqy-microhei.ttc: 文泉驛微米黑,文泉驛微米黑,WenQuanYi Micro Hei:style=Regular

/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf: DejaVu Sans:style=Bold

/usr/share/fonts/truetype/dejavu/DejaVuSansMono-Bold.ttf: DejaVu Sans Mono:style=Bold

/usr/share/fonts/truetype/arphic/uming.ttc: AR PL UMing TW:style=Light

/usr/share/fonts/truetype/arphic/uming.ttc: AR PL UMing CN:style=Light

/usr/share/fonts/truetype/arphic/uming.ttc: AR PL UMing HK:style=Light

/usr/share/fonts/truetype/wqy/wqy-microhei.ttc: 文泉驛等寬微米黑,文泉驛等寬微米黑,WenQuanYi Micro Hei Mono:style=Regular

/usr/share/fonts/truetype/dejavu/DejaVuSerif.ttf: DejaVu Serif:style=Book

3.6 修改pdf.utf-8配置文件

參考pdf.utf-8.heavy文件，配置中文字體，添加下面一行在配置文件中

3000 9FFF ltor double /usr/share/fonts/truetype/arphic/uming.ttc/0

7. 成功打印中文

再次執(zhí)行打印，查看pdf格式文件：

? 6 stream

? 7 q

? 8 0 g

? 9 BT

10? 18 745.884 Td

11? 127.059 Tz

12? /FN02 11.333 Tf <086149ba> Tj

13 ET

14 0 g

15 BT

16? 46.800 745.884 Td

17? 105.522 Tz

18? /FN00 11.333 Tf <004400450046> Tj

19 ET

20 0 g

21 BT

22? 68.400 745.884 Td

23? 127.059 Tz

24? /FN02 11.333 Tf <1dad0e10> Tj

25 ET

26 Q

27 endstream

這一次，相應的中文編碼不再是0000了，變成實際對應的utf-8編碼。再查看打印出來的文件：

終于使用lp/lpr命令成功打印中文了！