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浅谈PDFlib中文输出（四）

PDFlib的textformat参数用以设定文本输入形式，其有效值如下:

    bytes: 在字符串中每个字节对应于一个字符。主要应用于8位编码。
    utf8：字符串是 UTF-8编码。
    ebcdicutf8：字符串是EBCDIC的UTF-8编码，只应用于IBM iSeries和zSeries。
    utf16：字符串是 UTF-16编码。如果字符串是以Unicode的标记字节顺序号(BOM)开始，PDFlib会接收BOM信息后将其从字符串首移去。如果字符串不带BOM，字符串的字节顺序将取决于主机的字节顺序。Intel x86系统是小尾（little-endian，0xFFFE ）, 而Sparc和PowerPC系统是大尾（big-endian, 0xFEFF)。
    utf16be：字符串是大尾字节顺序的UTF-16编码。对BOM没有特殊处理。
    utf16le：字符串是小尾字节顺序的UTF-16编码。对BOM没有特殊处理。
    auto:对于8位编码，它相当于“bytes”, 对于宽字符字符串(Unicode, glyphid, UCS2 或UTF16 CMap)，它相当于“utf16”。

    在编程语言里，我们将可以自动处理Unicode字符串的语言称为支持Unicode语言（Unicode-capable），它们是COM, .NET, Java, REALbasic及Tcl等。对于需对Unicode字符串进行特殊处理的语言称为不支持Unicode语言（non-Unicode-capable），它们是C, C++, Cobol, Perl, PHP, Python 及RPG等。
    在non-Unicode-capable语言里，“auto”设置将会正确处理大部分文本字符串。
    对于Unicode-capable语言，textformat参数的缺省值是“utf16”；而non-Unicode-capable语言的缺省值是“auto”。
    除此之外，PDFlib还支持在SGML和HTML经常使用的字符引用方法（Character Reference）。前提是将参数charref设成真, textformat设成“bytes”:

PDF_set_parameter(p, "charref", "true");
PDF_set_parameter(p, "textformat", "bytes");

    下面给出一些有效的Character Reference:
     soft hyphen
     soft hyphen
     soft hyphen
    € Euro glyph (hexadecimal)
    € Euro glyph (decimal)
    € Euro glyph (entity name)
    < less than sign
    > greater than sign
    & ampersand sign
    Α Greek Alpha
    下面是一个相关的例子--C 源程序(附上生成的pdf文件 –PDFlib_cs4.pdf)。

    /*******************************************************************/
    /* This example demostrates output Chinese Simplified text with different
    /* 'textformat' option under Chinese Simplifed Windows.
    /*******************************************************************/
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include "pdflib.h"
    int main(void)
    {
    PDF             *p = NULL;
    int                 Font_E = 0, Font_H = 0, Font_CS = 0, Left = 50, y = 800, i = 0;
    const int       INCRY = 25;
    char              text[128], buf[128];
    /* 1 byte text (English: "Simplified Chinese") */
    static const char byte_text[] =
    "\123\151\155\160\154\151\146\151\145\144\040\103\150\151\156\145\163\145";
    static const int byte_len = 18;
    static const char byte2_text[] = {0x53,0x69,0x6D,0x70,0x6C,0x69,0x66,0x69,0x65,
    0x64,0x20,0x43,0x68,0x69,0x6E,0x65,0x73,0x65};
    static const int byte2_len = 18;
    /* 2 byte text (Simplified Chinese) */
    static const unsigned short utf16_text[] = {0x7B80,0x4F53,0x4E2D,0x6587};
    static const int utf16_len = 8;
    static const unsigned char utf16be_text[] ="\173\200\117\123\116\055\145\207";
    static const int utf16be_len = 8;
    static const unsigned char utf16be_bom_text[] = "\376\377\173\200\117\123\116\055\145\207";
    static const int utf16be_bom_len = 10;
    static const unsigned char utf16le_text[] ="\200\173\123\117\055\116\207\145";
    static const int utf16le_len = 8;
    static const unsigned char utf16le_bom_text[] = "\377\376\200\173\123\117\055\116\207\145";
    static const int utf16le_bom_len = 10;
    static const unsigned char utf8_text[] = "\347\256\200\344\275\223\344\270\255\346\226\207";
    static const int utf8_len = 12;
    static const unsigned char utf8_bom_text[] = "\xEF\xBB\xBF\xE7\xAE\x80\xE4\xBD\x93\xE4\xB8\xAD\xE6\x96\x87";
    static const int utf8_bom_len = 15;
    static const char htmlutf16_text[] = "简体中文";
    static const int htmlutf16_len = sizeof(htmlutf16_text) - 1;
    typedef struct
    {
    char *textformat;
    char *encname;
    const char *textstring;
    const int *textlength;
    const char *bomkind;
    } TestCase;
    static const TestCase table_8[] = {
    { "bytes",      "winansi", (const char *)byte_text,         &byte_len,      ""},
    { "auto",        "winansi", (const char *)byte_text,         &byte_len,      ""},
    { "bytes",      "winansi", (const char *)byte2_text,       &byte2_len,     ""}, };
    static const TestCase table_16[] = {
    { "auto", "unicode", (const char *)utf16_text,       &utf16_len,      ""},
    { "utf16", "unicode", (const char *)utf16_text,       &utf16_len,      ""},
    { "auto", "unicode", (const char *)utf16be_bom_text, &utf16be_bom_len, ", UTF-16+BE-BOM"},
    { "auto",     "unicode",     (const char *)utf16le_bom_text, &utf16le_bom_len, ", UTF-16+LE-BOM"},
    { "utf16be", "unicode",    (const char *)utf16be_text,         &utf16be_len,    ""},
    { "utf16le",   "unicode",   (const char *)utf16le_text,           &utf16le_len,    ""},
    { "utf8",       "unicode",    (const char *)utf8_text,               &utf8_len,       ""},
    { "auto",       "unicode",   (const char *)utf8_bom_text,      &utf8_bom_len, ", UTF-8+BOM"},
    { "bytes", "unicode",   (const char *)htmlutf16_text, &htmlutf16_len, ", HTML unicode character"}, };
    const int   tsize_8 = sizeof table_8 / sizeof (TestCase);
    const int   tsize_16 = sizeof table_16 / sizeof (TestCase);
    /* create a new PDFlib object */
    if ((p = PDF_new()) == (PDF *) 0)
    {
    printf("Couldn't create PDFlib object (out of memory)!\n");
    return(2);
    }
    PDF_TRY(p) {
    if (PDF_begin_document(p, "pdflib_cs4.pdf", 0, "") == -1)
    {
    printf("Error: %s\n", PDF_get_errmsg(p));
    return(2);
    }
    PDF_set_info(p, "Creator", "pdflib_cs4.c");
    PDF_set_info(p, "Author", "[email protected]");
    PDF_set_info(p, "Title", "Output Chinese Simplify with Different textformat");
    /* Start a new page. */
    PDF_begin_page_ext(p, a4_width, a4_height, "");
    Font_H = PDF_load_font(p, "Helvetica-Bold", 0, "winansi", "");
    /* 8-bit encoding */
    Font_E = PDF_load_font(p, "Times", 0, "winansi", "");
    PDF_setfont(p, Font_H, 24);
    PDF_show_xy(p, "8-bit encoding", Left+40, y);
    y -= 2*INCRY;
    for (i = 0; i < tsize_8; ++i)
    {
    PDF_setfont(p, Font_H, 14);
    sprintf(text, "%s encoding, %s textformat %s: ", table_8[i].encname,
    table_8[i].textformat, table_8[i].bomkind);
    PDF_show_xy(p, text, Left, y);
    y -= INCRY;
    PDF_set_parameter(p, "textformat", table_8[i].textformat);
    PDF_setfont(p, Font_E, 14);
    PDF_show_xy(p, table_8[i].textstring, Left, y);
    y -= INCRY;
    } /* for */
    /* 16-bit encoding */
    PDF_setfont(p, Font_H, 24);
    y -= 2*INCRY;
    PDF_show_xy(p, "16-bit encoding", Left+40, y);
    y -= 2*INCRY;
    PDF_set_parameter(p, "charref", "true");
    Font_CS = PDF_load_font(p, "STSong-Light", 0, "UniGB-UCS2-H", "");
    for (i = 0; i < tsize_16; i++)
    {
    PDF_setfont(p, Font_H, 14);
    sprintf(text, "%s encoding, %s textformat %s: ", table_16[i].encname,
    table_16[i].textformat, table_16[i].bomkind);
    PDF_show_xy(p, text, Left, y);
    y -= INCRY;
    PDF_setfont(p, Font_CS, 14);
    sprintf(buf, "textformat %s",table_16[i].textformat);
    PDF_fit_textline(p, table_16[i].textstring, *table_16[i].textlength,
    Left, y, buf);
    y -= INCRY;
    } /* for */
    /* End of page. */
    PDF_end_page_ext(p, "");
    PDF_end_document(p, "");
    }
    PDF_CATCH(p) {
    printf("PDFlib exception occurred in pdflib_cs4 sample:\n");
    printf("[%d] %s: %s\n",
    PDF_get_errnum(p), PDF_get_apiname(p), PDF_get_errmsg(p));
    PDF_delete(p);
    return(2);
    }
    PDF_delete(p);
    return 0;
    }