Using C++ how do I add RTL and LTR mixed text?

Technical Support Apryse SDK
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1

Question:
How do I add LTR/RTL (bidi) text to a PDF using C++?

Answer:
The easiest is to use our FlowDocument class which will handle this nicely for you. The below code adds the text

عندمانُشرالكتابفیعام 2019 قوبلبالتصفیق

Which according to google translates to

When the book was published in 2019, it was applauded.

The below C++ code accomplishes this (See the UnicodeWriteTest sample more examples of other languages).

FlowDocument flowdoc;
Paragraph para = flowdoc.AddParagraph();
TextStyledElement st_para = para.GetTextStyledElement();
st_para.SetFontSize(24);
st_para.SetTextColor(255, 0, 0);
Unicode arabic[]{
	0x0639, 0x0646, 0x062F, 0x0645, 0x0627 , 0x0646, 0x064F, 0x0634, 0x0631 , 0x0627, 0x0644, 0x0643, 0x062A, 0x0627, 0x0628 , 0x0641, 0x064A , 0x0639, 0x0627, 0x0645 , 0x0032, 0x0030, 0x0031, 0x0039 , 0x0642, 0x0648, 0x0628, 0x0644 , 0x0628, 0x0627, 0x0644, 0x062A, 0x0635, 0x0641, 0x06CC, 0x0642
};
UString ustring(arabic, sizeof(arabic) / sizeof(Unicode));
para.AddText(ustring);
PDFDoc my_pdf = flowdoc.PaginateToPDF();
my_pdf.Save("created_doc.pdf", SDFDoc::e_linearized, 0);

If you wanted to use the lower level ElementBuilder API, then you would have to reverse the numbers “2019” to “9102” but then it will work as expected, see below.

PDFDoc doc;
ElementBuilder eb;
ElementWriter writer;
Page page = doc.PageCreate(Rect(0, 0, 612, 794));
writer.Begin(page);	// begin writing to this page
// note, the bytes for the text "2019" is reversed below, because I need to reverse the arabic text
Unicode arabic[]{
	0x0639, 0x0646, 0x062F, 0x0645, 0x0627 , 0x0646, 0x064F, 0x0634, 0x0631 , 0x0627, 0x0644, 0x0643, 0x062A, 0x0627, 0x0628 , 0x0641, 0x064A , 0x0639, 0x0627, 0x0645 , 0x0039, 0x0031, 0x0030, 0x0032 , 0x0642, 0x0648, 0x0628, 0x0644 , 0x0628, 0x0627, 0x0644, 0x062A, 0x0635, 0x0641, 0x06CC, 0x0642
};
int n = sizeof(arabic) / sizeof(arabic[0]);
std::reverse(arabic, arabic + n);
UString ustring(arabic, sizeof(arabic) / sizeof(Unicode));
Font fnt = Font::Create(doc, "arial", ustring);
Element element = eb.CreateTextBegin(fnt, 24);
element.SetTextMatrix(10, 0, 0, 10, 50, 600);
writer.WriteElement(eb.CreateUnicodeTextRun(arabic, sizeof(arabic)/sizeof(Unicode)));
writer.WriteElement(eb.CreateTextNewLine());
writer.WriteElement(eb.CreateTextEnd());
writer.End();
doc.PagePushBack(page);
doc.Save("unicodewrite.pdf", SDFDoc::e_remove_unused | SDFDoc::e_hex_strings, NULL);
3

Hello, I’m AiRon, an automated tech support bot :robot:
While you wait for one of our customer support representatives, I can help you with your question.


To add mixed RTL (Right-to-Left) and LTR (Left-to-Right) text in a PDF using C++, you have two main approaches with Apryse’s PDF SDK: using the high-level FlowDocument class or the lower-level ElementBuilder API.

Some things you can try:

  • Using the FlowDocument class, you can easily manage complex text layouts including mixed RTL and LTR text. You create a FlowDocument, add paragraphs, and then text elements with specific styles like font size and color.

  • For more control, use the ElementBuilder API. This requires manually reversing the order of LTR numbers within RTL text. You create a PDFDoc, initialize ElementBuilder and ElementWriter, and write your text elements to a page.



Here are some resources that might help you:


Hopefully, this helps you solve your problem while you wait for a human to get back to you.