C＃iTextPdf以正确的格式读取PDF格式的阿拉伯语文本
我正在开发一个应用程序，用于将PDF中的阿拉伯语文本提取为字符串变量，每个单词的顺序相反（وسيم而不是ميسو），有时会以正确的顺序排列但是字符（ميسو）相似英文字符，但在阿拉伯语中，字符连接在一起。 任何解决方案？： 我在Windows 10本地使用visual studio 2017 C＃MVC Application，使用iTextSharp从PDF读取文本。
在PDF查看器中它看起来不错，
但是在运行以下代码时：
private string GetTextFromPDF(string Path)
{
StringBuilder text = new StringBuilder();
using (PdfReader reader = new PdfReader(Path))
{
for (int i = 1; i <= reader.NumberOfPages; i++)
{
text.Append(PdfTextExtractor.GetTextFromPage(reader, i));
}
}
return text.ToString();
}
注意：问题不仅是逆序，如果我手动颠倒了字符顺序（反向数组顺序）它会显示分隔文本
1 个答案:
答案 0 :(得分：0)
您需要MirrorGlyphs，这就是大多数PDF编写者创建阿拉伯语PDF的方式。我已将bidi.js移植到C＃以解决此问题：
public class BidiResult
{
public string Text { set; get; }
public bool IsRtl { set; get; }
public BidiResult(string text, bool isRtl)
{
this.Text = text;
this.IsRtl = isRtl;
}
}
/// <summary>
/// Ported from https://github.com/mozilla/pdf.js/blob/master/src/core/bidi.js
/// </summary>
public static class Bidi
{
/// <summary>
/// Character types for symbols from 0000 to 00FF.
/// </summary>
public static string[] BaseTypes = new[] {
"BN", "BN", "BN", "BN", "BN", "BN", "BN", "BN", "BN", "S", "B", "S", "WS",
"B", "BN", "BN", "BN", "BN", "BN", "BN", "BN", "BN", "BN", "BN", "BN", "BN",
"BN", "BN", "B", "B", "B", "S", "WS", "ON", "ON", "ET", "ET", "ET", "ON",
"ON", "ON", "ON", "ON", "ON", "CS", "ON", "CS", "ON", "EN", "EN", "EN",
"EN", "EN", "EN", "EN", "EN", "EN", "EN", "ON", "ON", "ON", "ON", "ON",
"ON", "ON", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L",
"L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "ON", "ON",
"ON", "ON", "ON", "ON", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L",
"L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L",
"L", "ON", "ON", "ON", "ON", "BN", "BN", "BN", "BN", "BN", "BN", "B", "BN",
"BN", "BN", "BN", "BN", "BN", "BN", "BN", "BN", "BN", "BN", "BN", "BN",
"BN", "BN", "BN", "BN", "BN", "BN", "BN", "BN", "BN", "BN", "BN", "BN",
"BN", "CS", "ON", "ET", "ET", "ET", "ET", "ON", "ON", "ON", "ON", "L", "ON",
"ON", "ON", "ON", "ON", "ET", "ET", "EN", "EN", "ON", "L", "ON", "ON", "ON",
"EN", "L", "ON", "ON", "ON", "ON", "ON", "L", "L", "L", "L", "L", "L", "L",
"L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L",
"L", "ON", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L",
"L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L", "L",
"L", "L", "L", "ON", "L", "L", "L", "L", "L", "L", "L", "L"
};
/// <summary>
/// Character types for symbols from 0600 to 06FF
/// </summary>
public static string[] ArabicTypes = new[] {
"AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL",
"CS", "AL", "ON", "ON", "NSM", "NSM", "NSM", "NSM", "NSM", "NSM", "AL",
"AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL",
"AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL",
"AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL",
"AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL",
"AL", "AL", "AL", "AL", "NSM", "NSM", "NSM", "NSM", "NSM", "NSM", "NSM",
"NSM", "NSM", "NSM", "NSM", "NSM", "NSM", "NSM", "AL", "AL", "AL", "AL",
"AL", "AL", "AL", "AN", "AN", "AN", "AN", "AN", "AN", "AN", "AN", "AN",
"AN", "ET", "AN", "AN", "AL", "AL", "AL", "NSM", "AL", "AL", "AL", "AL",
"AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL",
"AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL",
"AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL",
"AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL",
"AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL",
"AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL",
"AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL",
"AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL",
"AL", "NSM", "NSM", "NSM", "NSM", "NSM", "NSM", "NSM", "NSM", "NSM", "NSM",
"NSM", "NSM", "NSM", "NSM", "NSM", "NSM", "NSM", "NSM", "NSM", "ON", "NSM",
"NSM", "NSM", "NSM", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL",
"AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL"
};
public static bool IsOdd(int i)
{
return (i & 1) != 0;
}
public static bool IsEven(int i)
{
return (i & 1) == 0;
}
public static int FindUnequal(string[] arr, int start, string value)
{
int j;
var jj = arr.Length;
for (j = start; j < jj; ++j)
{
if (arr[j] != value)
return j;
}
return j;
}
public static void SetValues(string[] arr, int start, int end, string value)
{
for (var j = start; j < end; ++j)
{
arr[j] = value;
}
}
public static char[] ReverseValues(char[] arr, int start, int end)
{
var j = end - 1;
for (var i = start; i < j; ++i, --j)
{
var temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
return arr;
}
public static char MirrorGlyphs(char c)
{
/*
# BidiMirroring-1.txt
0028; 0029 # LEFT PARENTHESIS
0029; 0028 # RIGHT PARENTHESIS
003C; 003E # LESS-THAN SIGN
003E; 003C # GREATER-THAN SIGN
005B; 005D # LEFT SQUARE BRACKET
005D; 005B # RIGHT SQUARE BRACKET
007B; 007D # LEFT CURLY BRACKET
007D; 007B # RIGHT CURLY BRACKET
00AB; 00BB # LEFT-POINTING DOUBLE ANGLE QUOTATION MARK
00BB; 00AB # RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK
*/
switch (c)
{
case '(':
return ')';
case ')':
return '(';
case '<':
return '>';
case '>':
return '<';
case ']':
return '[';
case '[':
return ']';
case '}':
return '{';
case '{':
return '}';
case '\u00AB':
return '\u00BB';
case '\u00BB':
return '\u00AB';
default:
return c;
}
}
public static BidiResult BidiText(string str, int startLevel)
{
var isLtr = true;
var strLength = str.Length;
if (strLength == 0)
return new BidiResult(str, false);
// get types, fill arrays
var chars = new char[strLength];
var types = new string[strLength];
var oldtypes = new string[strLength];
var numBidi = 0;
for (var i = 0; i < strLength; ++i)
{
chars[i] = str[i];
var charCode = str[i];
string charType = "L";
if (charCode <= 0x00ff)
charType = BaseTypes[charCode];
else if (0x0590 <= charCode && charCode <= 0x05f4)
charType = "R";
else if (0x0600 <= charCode && charCode <= 0x06ff)
charType = ArabicTypes[charCode & 0xff];
else if (0x0700 <= charCode && charCode <= 0x08AC)
charType = "AL";
if (charType == "R" || charType == "AL" || charType == "AN")
numBidi++;
oldtypes[i] = types[i] = charType;
}
// detect the bidi method
// if there are no rtl characters then no bidi needed
// if less than 30% chars are rtl then string is primarily ltr
// if more than 30% chars are rtl then string is primarily rtl
if (numBidi == 0)
{
return new BidiResult(str, true);
}
if (startLevel == -1)
{
if ((strLength / numBidi) < 0.3)
{
startLevel = 0;
}
else
{
isLtr = false;
startLevel = 1;
}
}
var levels = new int[strLength];
for (var i = 0; i < strLength; ++i)
{
levels[i] = startLevel;
}
/*
X1-X10: skip most of this, since we are NOT doing the embeddings.
*/
var e = IsOdd(startLevel) ? "R" : "L";
var sor = e;
var eor = sor;
/*
W1. Examine each non-spacing mark (NSM) in the level run, and change the
type of the NSM to the type of the previous character. If the NSM is at the
start of the level run, it will get the type of sor.
*/
var lastType = sor;
for (var i = 0; i < strLength; ++i)
{
if (types[i] == "NSM")
types[i] = lastType;
else
lastType = types[i];
}
/*
W2. Search backwards from each instance of a European number until the
first strong type (R, L, AL, or sor) is found. If an AL is found, change
the type of the European number to Arabic number.
*/
lastType = sor;
for (var i = 0; i < strLength; ++i)
{
var t = types[i];
if (t == "EN")
types[i] = (lastType == "AL") ? "AN" : "EN";
else if (t == "R" || t == "L" || t == "AL")
lastType = t;
}
/*
W3. Change all ALs to R.
*/
for (var i = 0; i < strLength; ++i)
{
var t = types[i];
if (t == "AL")
types[i] = "R";
}
/*
W4. A single European separator between two European numbers changes to a
European number. A single common separator between two numbers of the same
type changes to that type:
*/
for (var i = 1; i < strLength - 1; ++i)
{
if (types[i] == "ES" && types[i - 1] == "EN" && types[i + 1] == "EN")
types[i] = "EN";
if (types[i] == "CS" && (types[i - 1] == "EN" || types[i - 1] == "AN") &&
types[i + 1] == types[i - 1])
types[i] = types[i - 1];
}
/*
W5. A sequence of European terminators adjacent to European numbers changes
to all European numbers:
*/
for (var i = 0; i < strLength; ++i)
{
if (types[i] == "EN")
{
// do before
for (var j = i - 1; j >= 0; --j)
{
if (types[j] != "ET")
break;
types[j] = "EN";
}
// do after
for (var j = i + 1; j < strLength; --j)
{
if (types[j] != "ET")
break;
types[j] = "EN";
}
}
}
/*
W6. Otherwise, separators and terminators change to Other Neutral:
*/
for (var i = 0; i < strLength; ++i)
{
var t = types[i];
if (t == "WS" || t == "ES" || t == "ET" || t == "CS")
types[i] = "ON";
}
/*
W7. Search backwards from each instance of a European number until the
first strong type (R, L, or sor) is found. If an L is found, then change
the type of the European number to L.
*/
lastType = sor;
for (var i = 0; i < strLength; ++i)
{
var t = types[i];
if (t == "EN")
types[i] = (lastType == "L") ? "L" : "EN";
else if (t == "R" || t == "L")
lastType = t;
}
/*
N1. A sequence of neutrals takes the direction of the surrounding strong
text if the text on both sides has the same direction. European and Arabic
numbers are treated as though they were R. Start-of-level-run (sor) and
end-of-level-run (eor) are used at level run boundaries.
*/
for (var i = 0; i < strLength; ++i)
{
if (types[i] == "ON")
{
var end = FindUnequal(types, i + 1, "ON");
var before = sor;
if (i > 0)
before = types[i - 1];
var after = eor;
if (end + 1 < strLength)
after = types[end + 1];
if (before != "L")
before = "R";
if (after != "L")
after = "R";
if (before == after)
SetValues(types, i, end, before);
i = end - 1; // reset to end (-1 so next iteration is ok)
}
}
/*
N2. Any remaining neutrals take the embedding direction.
*/
for (var i = 0; i < strLength; ++i)
{
if (types[i] == "ON")
types[i] = e;
}
/*
I1. For all characters with an even (left-to-right) embedding direction,
those of type R go up one level and those of type AN or EN go up two
levels.
I2. For all characters with an odd (right-to-left) embedding direction,
those of type L, EN or AN go up one level.
*/
for (var i = 0; i < strLength; ++i)
{
var t = types[i];
if (IsEven(levels[i]))
{
if (t == "R")
{
levels[i] += 1;
}
else if (t == "AN" || t == "EN")
{
levels[i] += 2;
}
}
else
{ // isOdd, so
if (t == "L" || t == "AN" || t == "EN")
{
levels[i] += 1;
}
}
}
/*
L1. On each line, reset the embedding level of the following characters to
the paragraph embedding level:
segment separators,
paragraph separators,
any sequence of whitespace characters preceding a segment separator or
paragraph separator, and any sequence of white space characters at the end
of the line.
*/
// don't bother as text is only single line
/*
L2. From the highest level found in the text to the lowest odd level on
each line, reverse any contiguous sequence of characters that are at that
level or higher.
*/
// find highest level & lowest odd level
var highestLevel = -1;
var lowestOddLevel = 99;
var ii = levels.Length;
for (var i = 0; i < ii; ++i)
{
var level = levels[i];
if (highestLevel < level)
highestLevel = level;
if (lowestOddLevel > level && IsOdd(level))
lowestOddLevel = level;
}
// now reverse between those limits
for (var level = highestLevel; level >= lowestOddLevel; --level)
{
// find segments to reverse
var start = -1;
ii = levels.Length;
for (var i = 0; i < ii; ++i)
{
if (levels[i] < level)
{
if (start >= 0)
{
chars = ReverseValues(chars, start, i);
start = -1;
}
}
else if (start < 0)
{
start = i;
}
}
if (start >= 0)
{
chars = ReverseValues(chars, start, levels.Length);
}
}
/*
L3. Combining marks applied to a right-to-left base character will at this
point precede their base character. If the rendering engine expects them to
follow the base characters in the final display process, then the ordering
of the marks and the base character must be reversed.
*/
// don't bother for now
/*
L4. A character that possesses the mirrored property as specified by
Section 4.7, Mirrored, must be depicted by a mirrored glyph if the resolved
directionality of that character is R.
*/
// don't mirror as characters are already mirrored in the pdf
// Finally, return string
var result = string.Empty;
ii = chars.Length;
for (var i = 0; i < ii; ++i)
{
var ch = chars[i];
if (ch != '<' && ch != '>')
result += ch;
}
return new BidiResult(result, isLtr);
}
}
如何使用它：
public static string GetTextFromPDF(string path)
{
var reader = new PdfReader(path);
var text = new StringBuilder();
for (var i = 1; i <= reader.NumberOfPages; i++)
{
var data = PdfTextExtractor.GetTextFromPage(reader, i, new SimpleTextExtractionStrategy());
text.Append(Bidi.BidiText(data, 1).Text);
}
return text.ToString();
}
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