I'm trying to draw QR barcodes in a PDF file using iTextSharp. If I'm using English text the barcodes are fine, they are decoded properly, but if I'm using Chinese text, the barcode is decoded as question marks. For example this character '测' (\u6D4B) is decoded as '?'. I tried all supported character sets, but none of them helped.
What combination of parameters should I use for the QR barcode in iTextSharp in order to encode correctly Chinese text?
iText and iTextSharp apparently don't natively support this but you can write some code to handle this on your own. The trick is to get the QR code parser to work with just an arbitrary byte array instead of a string. What's really nice is that the iTextSharp code is almost ready for this but doesn't expose the functionality. Unfortunately many of the required classes are sealed so you can't just subclass them, you'll have to recreate them. You can either download the entire source and add these changes or just create separate classes with the same names. (Please check over the license to make sure you are allowed to do this.) My changes below don't have any error correction so make sure you do that, too.
The first class that you'll need to recreate is iTextSharp.text.pdf.qrcode.BlockPair and the only change you'll need to make is to make the constructor public instead of internal. (You only need to do this if you are creating your own code and not modifying the existing code.)
The second class is iTextSharp.text.pdf.qrcode.Encoder. This is where we'll make the most changes. Add an overload to Append8BitBytes that looks like this:
static void Append8BitBytes(byte[] bytes, BitVector bits) {
for (int i = 0; i < bytes.Length; ++i) {
bits.AppendBits(bytes[i], 8);
}
}
The string version of this method converts text to a byte array and then uses the above so we're just cutting out the middle man. Next, add a new overload to the constructor that takes in a byte array instead of a string. We'll then just cut out the string detection part and force the system to byte-mode, otherwise the code below is pretty much the same.
public static void Encode(byte[] bytes, ErrorCorrectionLevel ecLevel, IDictionary<EncodeHintType, Object> hints, QRCode qrCode) {
String encoding = DEFAULT_BYTE_MODE_ENCODING;
// Step 1: Choose the mode (encoding).
Mode mode = Mode.BYTE;
// Step 2: Append "bytes" into "dataBits" in appropriate encoding.
BitVector dataBits = new BitVector();
Append8BitBytes(bytes, dataBits);
// Step 3: Initialize QR code that can contain "dataBits".
int numInputBytes = dataBits.SizeInBytes();
InitQRCode(numInputBytes, ecLevel, mode, qrCode);
// Step 4: Build another bit vector that contains header and data.
BitVector headerAndDataBits = new BitVector();
// Step 4.5: Append ECI message if applicable
if (mode == Mode.BYTE && !DEFAULT_BYTE_MODE_ENCODING.Equals(encoding)) {
CharacterSetECI eci = CharacterSetECI.GetCharacterSetECIByName(encoding);
if (eci != null) {
AppendECI(eci, headerAndDataBits);
}
}
AppendModeInfo(mode, headerAndDataBits);
int numLetters = dataBits.SizeInBytes();
AppendLengthInfo(numLetters, qrCode.GetVersion(), mode, headerAndDataBits);
headerAndDataBits.AppendBitVector(dataBits);
// Step 5: Terminate the bits properly.
TerminateBits(qrCode.GetNumDataBytes(), headerAndDataBits);
// Step 6: Interleave data bits with error correction code.
BitVector finalBits = new BitVector();
InterleaveWithECBytes(headerAndDataBits, qrCode.GetNumTotalBytes(), qrCode.GetNumDataBytes(),
qrCode.GetNumRSBlocks(), finalBits);
// Step 7: Choose the mask pattern and set to "qrCode".
ByteMatrix matrix = new ByteMatrix(qrCode.GetMatrixWidth(), qrCode.GetMatrixWidth());
qrCode.SetMaskPattern(ChooseMaskPattern(finalBits, qrCode.GetECLevel(), qrCode.GetVersion(),
matrix));
// Step 8. Build the matrix and set it to "qrCode".
MatrixUtil.BuildMatrix(finalBits, qrCode.GetECLevel(), qrCode.GetVersion(),
qrCode.GetMaskPattern(), matrix);
qrCode.SetMatrix(matrix);
// Step 9. Make sure we have a valid QR Code.
if (!qrCode.IsValid()) {
throw new WriterException("Invalid QR code: " + qrCode.ToString());
}
}
The third class is iTextSharp.text.pdf.qrcode.QRCodeWriter and once again we just need to add an overloaded Encode method supports a byte array and that calls are new constructor created above:
public ByteMatrix Encode(byte[] bytes, int width, int height, IDictionary<EncodeHintType, Object> hints) {
ErrorCorrectionLevel errorCorrectionLevel = ErrorCorrectionLevel.L;
if (hints != null && hints.ContainsKey(EncodeHintType.ERROR_CORRECTION))
errorCorrectionLevel = (ErrorCorrectionLevel)hints[EncodeHintType.ERROR_CORRECTION];
QRCode code = new QRCode();
Encoder.Encode(bytes, errorCorrectionLevel, hints, code);
return RenderResult(code, width, height);
}
The last class is iTextSharp.text.pdf.BarcodeQRCode which we once again add our new constructor overload:
public BarcodeQRCode(byte[] bytes, int width, int height, IDictionary<EncodeHintType, Object> hints) {
newCode.QRCodeWriter qc = new newCode.QRCodeWriter();
bm = qc.Encode(bytes, width, height, hints);
}
The last trick is to make sure when calling this that you include the byte order mark (BOM) so that decoders know to decode this properly, in this case UTF-8.
//Create an encoder that supports outputting a BOM
System.Text.Encoding enc = new System.Text.UTF8Encoding(true, true);
//Get the BOM
byte[] bom = enc.GetPreamble();
//Get the raw bytes for the string
byte[] bytes = enc.GetBytes("测");
//Combine the byte arrays
byte[] final = new byte[bom.Length + bytes.Length];
System.Buffer.BlockCopy(bom, 0, final, 0, bom.Length);
System.Buffer.BlockCopy(bytes, 0, final, bom.Length, bytes.Length);
//Create are barcode using our new constructor
var q = new BarcodeQRCode(final, 100, 100, null);
//Add it to the document
doc.Add(q.GetImage());
Looks like you may be out of luck. I tried too and got the same results as you did. Then looked at the Java API:
"*CHARACTER_SET the values are strings and can be Cp437, Shift_JIS and
ISO-8859-1 to ISO-8859-16. The default value is ISO-8859-1.*"
Lastly, looked at the iTextSharp BarcodeQRCode class source code to confirm that only those characters sets are supported. I'm by no means an authority on Unicode or encoding, but according to ISO/IEC 8859, the character sets above won't work for Chinese.
Essentially the same trick that Chris has done in his answer could be implemented by specifying UTF-8 charset in barcode hints.
var hints = new Dictionary<EncodeHintType, Object>() {{EncodeHintType.CHARACTER_SET, "UTF-8"}};
var q = new BarcodeQRCode("\u6D4B", 100, 100, hints);
If you want to be more safe, you can start your string with BOM character '\uFEFF', like Chris suggested, so it would be "\uFEFF\u6D4B".
UTF-8 is unfortunately not supported by QR codes specification, and there are a lot of discussions on this subject, but the fact is that most QR code readers will correctly read the code created by this method.
Related
I am using FontAwesome to display glyphs in my Xamarin Android application. If I hardcode the glyph like this, where everything works fine:
string iconKey = "\uf0a3";
var drawable = new IconDrawable(this.Context, iconKey, "Font Awesome 5 Pro-Regular-400.otf").Color(Xamarin.Forms.Color.White.ToAndroid()).SizeDp(fontSize);
However, if what I have is the four letter code "f0a3" from FontAwesome's cheatsheet, stored in a string variable, I don't know how to set my iconKey variable to a value that works. Just concatenating a "\u" onto the beginning doesn't work, which makes sense since that's a Unicode escape indicator, not part of a standard string, but I don't know what to do instead. I also tried converting to and from Unicode in various random ways - e.g.
iconKey = unicode.GetChars(unicode.GetBytes("/u" + myFourChar.ToString())).ToString();
but unsurprisingly that didn't work either.
The IconDrawable is from here. The value I send becomes an input there to the Paint.GetTextBounds method and the Canvas.DrawText method.
Thanks for any assistance!
Found the answer here. Here is the code I am using, based on that post but simplified since I have only one hexadecimal character to handle:
string myString = "f0a3";
var chars = new char[] { (char)Convert.ToInt32(myString, 16) };
string iconKey = new string(chars);
var drawable = new IconDrawable(this.Context, iconKey, "Font Awesome 5 Pro-Regular-400.otf").Color(Xamarin.Forms.Color.White.ToAndroid()).SizeDp(fontSize);
When trying to read a PDF417 barcode that contains embedded NULL characters:
// load image and convert to bitmap
Bitmap bmp = new Bitmap(Image.FromFile(#"C:\Sample.png"));
IBarcodeReader reader = new BarcodeReader();
ZXing.Result result = reader.Decode(bmp);
// do something with the result
String decodedString = result.Text;
The returned text is cut off when it encounters an embedded null character:
IDUS3*1GORRELL, LIDIA 9991001041 0060150RDBR1992OCT31NNYYUNONE NONE 2RRT 2011NOV042052OCT308 5RESRETUSAF AMN E1 I UNKÿØÿà
What i need is the RawBytes of the PDF417 barcode.
Other, hardware, decoders do return the entire string (since it is perfectly valid for a string to contain embedded NULL characters).
There is a:
Byte[] rawResult = result.RawBytes;
But RawBytes is always null - it doesn't mean what you think it means. It is not the RawBytes of the read barcode; it is the raw bytes from a QR code.
How can i get the raw bytes encoded on a PDF417 card?
I want to know whether is it possible to reject numeric phrases or numeric values while indexing or searching in Lucene.net.
For example (this is one line),
Hi all my no is 4756396
Now, when I index or search it should reject the numeric value 4756396 to be indexed or searched. I tried making a custom stop word list with 1, 2, 3, 4, 5, 6, etc, but I guess it will only ignore if a single number will appears.
You can copy the StandardAnalyzer and customize the grammar (simple JFlex stuff) to reject number tokens. If you do that, you'll need to port back the analyzer to Java since JFlex will generate java code, tho you could give it a try with C# Flex.
You could also write a TokenFilter that scans tokens one by one and rejects them if they are numbers. If you wanna filter only whole numbers and still retain numbers that are for example separate by hyphens, the filter could simply attempt a double.TryParse() and if it fails you accept the Token. A more robust and customizable solution would still use a lexical parser.
Edit:
Heres a quick sample of what I mean, with a little main method that shows how to use it. In this I used a TryParse() to filter out tokens, if it were for a more complex production system I'd use a lexical parser system. (take a look at C# Flex for that)
public class NumericFilter : TokenFilter
{
private ITermAttribute termAtt ;
public NumericFilter(TokenStream tokStream)
: base(tokStream)
{
termAtt = AddAttribute<ITermAttribute>();
}
public override bool IncrementToken()
{
while (base.input.IncrementToken())
{
string term = termAtt.Term;
double res ;
if(double.TryParse(term, out res))
{
// skip this token
continue;
}
// accept this token
return true;
}
// no more token in the stream
return false;
}
}
static void Main(string[] args)
{
RAMDirectory dir = new RAMDirectory();
IndexWriter iw = new IndexWriter(dir, new KeywordAnalyzer(), IndexWriter.MaxFieldLength.UNLIMITED);
Document d = new Document();
Field f = new Field("text", "", Field.Store.YES, Field.Index.ANALYZED);
d.Add(f);
// use our Filter here
f.SetTokenStream(new NumericFilter(new LowerCaseFilter(new WhitespaceTokenizer(new StringReader("I have 300 dollars")))));
iw.AddDocument(d);
iw.Commit();
IndexReader reader = iw.GetReader();
// print all terms in the text field
TermEnum terms = reader.Terms(new Term("text", ""));
do
{
Console.WriteLine(terms.Term.Text);
}
while (terms.Next());
reader.Dispose();
iw.Dispose();
Console.ReadLine();
Environment.Exit(42);
}
How can one find where are lines located in a document with iText?
Suppose say I have a table in a PDF document, and want to read its contents; I would like to find where exactly the cells are located. In order to do that I thought I might find the intersections of lines.
I think your only option using iText will be to parse the PDF tokens manually. Before doing that I would have a copy of the PDF spec handy.
(I'm a .Net guy so I use iTextSharp but other than some capitalization differences and property declarations they're almost 100% the same.)
You can get the individual tokens using the PRTokeniser object which you feed bytes into from calling getPageContent(pageNum) on your PdfReader.
//Get bytes for page 1
byte[] pageBytes = reader.getPageContent(1);
//Get the tokens for page 1
PRTokeniser tokeniser = new PRTokeniser(pageBytes);
Then just loop through the PRTokeniser:
PRTokeniser.TokType tokenType;
string tokenValue;
while (tokeniser.nextToken()) {
tokenType = tokeniser.tokenType;
tokenValue = tokeniser.stringValue;
//...check tokenValue, do something with it
}
As far a tokenValue, you'd want to probably look for re and l values for rectangle and line. If you see an re then you want to look at the previous 4 values and if you see an l then previous 2 values. This also means that you need to store each tokenValue in an array so you can look back later.
Depending on what you used to create the PDF with you might get some interesting results. For instance, I created a 4 cell table with Microsoft Word and saved as a PDF. For some reason there are two sets of 10 rectangles with many duplicates, but the general idea still works.
Below is C# code targeting iTextSharp 5.1.1.0. You should be able to convert it to Java and iText very easily, I noted the one line that has .Net-specific code that needs to be adjusted from a Generic List (List<string>) to a Java equivalent, probably an ArrayList. You'll also need to adjust some casing, .Net uses Object.Method() whereas Java uses Object.method(). Lastly, .Net accesses properties without gets and sets, so Object.Property is both the getter and setter compared to Java's Object.getProperty and Object.setProperty.
Hopefully this gets you started at least!
//Source file to read from
string sourceFile = "c:\\Hello.pdf";
//Bind a reader to our PDF
PdfReader reader = new PdfReader(sourceFile);
//Create our buffer for previous token values. For Java users, List<string> is a generic list, probably most similar to an ArrayList
List<string> buf = new List<string>();
//Get the raw bytes for the page
byte[] pageBytes = reader.GetPageContent(1);
//Get the raw tokens from the bytes
PRTokeniser tokeniser = new PRTokeniser(pageBytes);
//Create some variables to set later
PRTokeniser.TokType tokenType;
string tokenValue;
//Loop through each token
while (tokeniser.NextToken()) {
//Get the types and value
tokenType = tokeniser.TokenType;
tokenValue = tokeniser.StringValue;
//If the type is a numeric type
if (tokenType == PRTokeniser.TokType.NUMBER) {
//Store it in our buffer for later user
buf.Add(tokenValue);
//Otherwise we only care about raw commands which are categorized as "OTHER"
} else if (tokenType == PRTokeniser.TokType.OTHER) {
//Look for a rectangle token
if (tokenValue == "re") {
//Sanity check, make sure we have enough items in the buffer
if (buf.Count < 4) throw new Exception("Not enough elements in buffer for a rectangle");
//Read and convert the values
float x = float.Parse(buf[buf.Count - 4]);
float y = float.Parse(buf[buf.Count - 3]);
float w = float.Parse(buf[buf.Count - 2]);
float h = float.Parse(buf[buf.Count - 1]);
//..do something with them here
}
}
}
I have several characters that aren't recognized properly.
Characters like:
º
á
ó
(etc..)
This means that the characters encoding is not utf-8 right?
So, can you tell me what character encoding could it be please.
We don't have nearly enough information to really answer this, but the gist of it is: you shouldn't just guess. You need to work out where the data is coming from, and find out what the encoding is. You haven't told us anything about the data source, so we're completely in the dark. You might want to try Encoding.Default if these are files saved with something like Notepad.
If you know what the characters are meant to be and how they're represented in binary, that should suggest an encoding... but again, we'd need to know more information.
read this first http://www.joelonsoftware.com/articles/Unicode.html
There are two encodings: the one that was used to encode string and one that is used to decode string. They must be the same to get expected result. If they are different then some characters will be displayed incorrectly. we can try to guess if you post actual and expected results.
I wrote a couple of methods to narrow down the possibilities a while back for situations just like this.
static void Main(string[] args)
{
Encoding[] matches = FindEncodingTable('Ÿ');
Encoding[] enc2 = FindEncodingTable(159, 'Ÿ');
}
// Locates all Encodings with the specified Character and position
// "CharacterPosition": Decimal position of the character on the unknown encoding table. E.G. 159 on the extended ASCII table
//"character": The character to locate in the encoding table. E.G. 'Ÿ' on the extended ASCII table
static Encoding[] FindEncodingTable(int CharacterPosition, char character)
{
List matches = new List();
byte myByte = (byte)CharacterPosition;
byte[] bytes = { myByte };
foreach (EncodingInfo encInfo in Encoding.GetEncodings())
{
Encoding thisEnc = Encoding.GetEncoding(encInfo.CodePage);
char[] chars = thisEnc.GetChars(bytes);
if (chars[0] == character)
{
matches.Add(thisEnc);
break;
}
}
return matches.ToArray();
}
// Locates all Encodings that contain the specified character
static Encoding[] FindEncodingTable(char character)
{
List matches = new List();
foreach (EncodingInfo encInfo in Encoding.GetEncodings())
{
Encoding thisEnc = Encoding.GetEncoding(encInfo.CodePage);
char[] chars = { character };
byte[] temp = thisEnc.GetBytes(chars);
if (temp != null)
matches.Add(thisEnc);
}
return matches.ToArray();
}
Encoding is the form of modifying some existing content; thus allowing it to be parsed by the required destination protocols.
An example of encoding can be seen when browsing the internet:
The URL you visit: www.example.com, may have the search facility to run custom searches via the URL address:
www.example.com?search=...
The following variables on the URL require URL encoding. If you was to write:
www.example.com?search=cat food cheap
The browser wouldn't understand your request as you have used an invalid character of ' ' (a white space)
To correct this encoding error you should exchange the ' ' with '%20' to form this URL:
www.example.com?search=cat%20food%20cheap
Different systems use different forms of encoding, in this example I have used standard Hex encoding for a URL. In other applications and instances you may find the need to use other types of encoding.
Good Luck!