///|
/// 将一段明/暗模块序列渲染为 SVG。
///
/// 静区（quiet zone）按模块数计，左右各留 `quiet_zone` 个模块；
/// 相邻的暗模块会被合并为一个矩形以减小 SVG 体积。
pub fn render_svg(barcode : Barcode, options : BarcodeOptions) -> String {
  let mw = max_int(options.module_width, 1)
  let qz = max_int(options.quiet_zone, 0)
  let modules = barcode.modules
  let content_width = modules.length() * mw
  let total_width = content_width + 2 * qz * mw
  let bar_height = max_int(options.height, 1)
  let text_height = if options.show_text {
    max_int(options.text_margin, 0) + 14
  } else {
    0
  }
  let total_height = bar_height + text_height
  let out = Buffer()
  out.write_string_utf8(
    "")
  @utf8.decode_lossy(out.to_bytes())
}

///|
/// 渲染为单行 ASCII 预览（暗模块为 `#`，明模块为空格）。
/// 每个模块按 `module_width` 重复，便于肉眼检查。
pub fn render_ascii(barcode : Barcode, options : BarcodeOptions) -> String {
  let mw = max_int(options.module_width, 1)
  let qz = max_int(options.quiet_zone, 0)
  let out = Buffer()
  for _ in 0..<(qz * mw) {
    out.write_string_utf8(" ")
  }
  for m in barcode.modules {
    let ch = if m { "#" } else { " " }
    for _ in 0.. String {
  let mw = max_int(options.module_width, 1)
  let qz = max_int(options.quiet_zone, 0)
  let out = Buffer()
  for _ in 0..<(qz * mw) {
    out.write_string_utf8(" ")
  }
  for m in barcode.modules {
    for _ in 0.. String {
  let b = @utf8.encode(s)
  let out = Buffer()
  for i = 0; i < b.length(); i = i + 1 {
    let c = b[i]
    if c == b'&' {
      out.write_string_utf8("&")
    } else if c == b'<' {
      out.write_string_utf8("<")
    } else if c == b'>' {
      out.write_string_utf8(">")
    } else {
      out.write_byte(c)
    }
  }
  @utf8.decode_lossy(out.to_bytes())
}

///|
/// 返回两个整数中的较大者。
fn max_int(a : Int, b : Int) -> Int {
  if a > b {
    a
  } else {
    b
  }
}