Code 39¶

Code 39 is a 1D symbology widely used for industrial labelling. The default character set is uppercase letters, digits, space and -.$/+%; pass full_ascii=True to encode any 7-bit character as a pair of symbols.

Code39Encoder("17 E North 32 St", full_ascii=True).save("code39-address.png")

Example¶

from pystrich.code39 import Code39Encoder

encoder = Code39Encoder("64755")
encoder.save_svg("code39-example.svg")

Sizing, label, font and layout¶

The bar_width argument to save() and get_imagedata() sets the pixel width of the narrowest bar (default 3).

The options dict passed to Code39Encoder controls the human-readable label and the surrounding layout. All keys are optional.

show_label: Whether to render the human-readable label underneath the bars. Defaults to True; set to False to suppress it.
ttf_font: Absolute path to a TrueType font file used for the label. Defaults to a bundled bitmap font if unset.
ttf_fontsize: Font size in points.
height: Total image height in pixels. Defaults to 120.
label_border: Pixels of vertical space between the bars and the label.
bottom_border: Pixels of vertical space between the label and the bottom edge.

Output formats¶

SVG output¶

For embedding in web pages or any workflow that benefits from resolution-independent output, use save_svg() (or get_svg() to receive the SVG as a string).

Code39Encoder("64755").save_svg("code39.svg")

The SVG’s viewBox is in module units (one narrow bar = one unit), while width and height scale by bar_width. The 10-module quiet zones mandated by the standard are applied automatically on each side.

Added in version 0.12.

PNG output¶

For raster output, use save() to write a PNG file or get_imagedata() to receive the raw PNG bytes.

Code39Encoder("64755").save("code39.png")

EPS output¶

For embedding in LaTeX (\includegraphics) or other vector print workflows, use save_eps() (or get_eps() to receive the EPS as a string).

Code39Encoder("64755").save_eps("code39.eps")

The bar_width argument is the width of the narrowest bar in PostScript points (1 point = 1/72 inch). The 10-module quiet zones are applied automatically.

Added in version 0.12.

API¶

class Code39Encoder(text: str, full_ascii: bool = False, options: BarcodeRenderOptions | None = None)[source]¶

Bases: Bar1DEncoder

Encode a string as a Code 39 1D barcode.

By default only the standard Code 39 character set is accepted (0-9, A-Z, space, and -.$/+%). Pass full_ascii=True to use the Full ASCII extension, which encodes any 7-bit character via paired symbols.

Typical use:

encoder = Code39Encoder("ABC-123")
encoder.save("barcode.png")

Variables:

text – The original input text.
encoded_text – List of code values produced by the text encoder.
bars – The bar/space pattern as a string of "1" and "0".
options – Render-time options dict (empty if none were supplied).
width – Pixel width of the most recently rendered image.
height – Pixel height of the most recently rendered image.

get_eps(bar_width: int = 3) → str¶

Render the barcode and return EPS markup.

Parameters:: bar_width – Width in PostScript points of the narrowest bar.
Return type:: str

Added in version 0.12.

get_imagedata(bar_width: int = 3) → bytes¶

Render the barcode and return PNG bytes.

Parameters:: bar_width – Width in pixels of the narrowest bar.
Returns:: PNG-encoded image data.
Return type:: bytes

get_pilimage(bar_width: int = 3) → PIL.Image.Image¶

Render the barcode and return a Pillow image.

Parameters:: bar_width – Width in pixels of the narrowest bar.
Returns:: The rendered barcode.
Return type:: PIL.Image.Image

Added in version 0.11.

get_svg(bar_width: int = 3) → str¶

Render the barcode and return SVG markup.

Parameters:: bar_width – Width in user units of the narrowest bar.
Return type:: str

Added in version 0.12.

save(filename: str | PathLike[str], bar_width: int = 3) → None¶

Render the barcode to a PNG file.

Parameters:

filename – Path to write the PNG to.
bar_width – Width in pixels of the narrowest bar.

save_eps(filename: str | PathLike[str], bar_width: int = 3) → None¶

Save the barcode as an EPS file. Pass an .eps filename.

Parameters:

filename – EPS output path.
bar_width – Width in PostScript points of the narrowest bar.

Added in version 0.12.

save_svg(filename: str | PathLike[str], bar_width: int = 3) → None¶

Save the barcode as an SVG file. Pass a .svg filename.

Parameters:

filename – SVG output path.
bar_width – Width in user units of the narrowest bar.

Added in version 0.12.

init_renderer() → Code39Renderer[source]¶

Construct a Code39Renderer for the encoded bars.

Return type:: Code39Renderer