qrkit/render/png

Pure Gleam PNG renderer for qrkit QR codes.

Types

PngOptions

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Rendering options for to_bit_array_with.

Mirrors the shape of qrkit/render/svg’s SvgOptions. The colour fields accept CSS-style hex strings (#rgb, #rrggbb, or #rrggbbaa); unparseable values fall back to the default colour rather than rejecting the call, so callers can keep the surface non-fallible.

pub opaque type PngOptions

Values

default_options

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pub fn default_options() -> PngOptions

Default PNG rendering options: 8×8 px modules, 4-module quiet zone, black on white, background on. Mirrors qrkit/render/svg’s defaults.

to_bit_array

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pub fn to_bit_array(
  qr: qrkit.QrCode,
  scale scale: Int,
  margin margin: Int,
) -> BitArray

Render a QR code as PNG bytes.

scale values less than 1 are normalised to 1, and negative margin values are normalised to 0. Thin wrapper around to_bit_array_with using the default black-on-white palette.

to_bit_array_with

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pub fn to_bit_array_with(
  qr: qrkit.QrCode,
  options: PngOptions,
) -> BitArray

Render a QR code as PNG bytes using the options builder.

Equivalent to to_bit_array when called with default_options overridden only by with_module_size and with_margin; the colour and background knobs add the surface not previously reachable through the positional entry point.

with_background

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pub fn with_background(
  options: PngOptions,
  draw: Bool,
) -> PngOptions

Toggle whether the light/background pixels are drawn opaquely.

When False, the light palette entry is marked transparent via a tRNS chunk so the QR code can be composited over an existing background.

with_dark_color

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pub fn with_dark_color(
  options: PngOptions,
  css_color: String,
) -> PngOptions

Set the dark module colour. Accepts #rgb, #rrggbb, or #rrggbbaa — same syntax as the SVG renderer. Unparseable strings keep the previous value rather than failing the call.

with_light_color

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pub fn with_light_color(
  options: PngOptions,
  css_color: String,
) -> PngOptions

Set the light / background colour. Accepts the same hex syntax as with_dark_color.

with_margin

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pub fn with_margin(
  options: PngOptions,
  modules: Int,
) -> PngOptions

Set the quiet-zone margin in modules.

Negative values are normalised to 0.

with_module_size

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pub fn with_module_size(
  options: PngOptions,
  px: Int,
) -> PngOptions

Set the PNG module size in pixels.

Values less than 1 are normalised to 1 to keep the rendered output usable.