Thai DOCX — Word documents with proper Thai line breaking

Problem

Thai has no spaces between words. Word doesn't know where to break lines, so it breaks too early → short lines, wasted space on the right margin. English text is unaffected since Word breaks at spaces.

Solution

Insert Zero-Width Space (U+200B) between Thai words before writing to docx. ZWS is invisible and zero-width but tells Word "you can break here." More break points → smarter wrapping → text fills lines fully.

Setup

pip install pythainlp python-docx --break-system-packages

Usage

The script at scripts/thai_docx.py provides two functions:

insert_zwsp(text) — add ZWS between Thai words

Only processes Thai character runs. English, numbers, URLs stay untouched.

from thai_docx import insert_zwsp
processed = insert_zwsp("สวัสดีครับผมชื่อสมชาย")
# → "สวัสดี\u200bครับ\u200bผม\u200bชื่อ\u200bสมชาย"

create_docx(paragraphs, output_path, ...) — build the Word file

from thai_docx import create_docx

paragraphs = [
    {"text": "Main heading", "type": "heading1"},
    {"text": "Body paragraph with Thai text...", "type": "body"},
    {"text": "Subheading", "type": "heading2"},
    {"text": "Another paragraph...", "type": "body"},
]

create_docx(
    paragraphs,
    "output.docx",
    font_name="TH Sarabun New",  # default
    font_size=14,                 # pt, default 14
    page_size="A4",               # "A4" or "Letter"
    line_spacing=1.5,             # default 1.5
    margins={"top": 2.54, "bottom": 2.54, "left": 2.54, "right": 2.54},  # cm
)

Paragraph types: body, heading1, heading2, heading3.

Critical rules

• Always use python-docx (Python), never docx-js (JavaScript) for Thai documents
• Always use LEFT alignment — JUSTIFIED stretches spaces grotesquely, THAI_DISTRIBUTE stretches characters
• insert_zwsp() is called automatically inside create_docx() — no need to call it separately
• ZWS is invisible, zero-width, doesn't change text appearance — just enables line breaking

CLI

python scripts/thai_docx.py input.txt -o output.docx --font "TH Sarabun New" --size 14

Blank lines in input.txt separate paragraphs. Lines starting with numbers (e.g. "15.5.2 ...") become headings automatically.