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QR-Code-generator
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QR-Code-generator/rust/src/lib.rs

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/*
* QR Code generator library (Rust)
*
* Copyright (c) Project Nayuki. (MIT License)
* https://www.nayuki.io/page/qr-code-generator-library
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
* - The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* - The Software is provided "as is", without warranty of any kind, express or
* implied, including but not limited to the warranties of merchantability,
* fitness for a particular purpose and noninfringement. In no event shall the
* authors or copyright holders be liable for any claim, damages or other
* liability, whether in an action of contract, tort or otherwise, arising from,
* out of or in connection with the Software or the use or other dealings in the
* Software.
*/
//! Generates QR Codes from text strings and byte arrays.
//!
//! This project aims to be the best, clearest QR Code generator library.
//! The primary goals are flexible options and absolute correctness.
//! Secondary goals are compact implementation size and good documentation comments.
//!
//! Home page with live JavaScript demo, extensive descriptions, and competitor comparisons:
//! [https://www.nayuki.io/page/qr-code-generator-library](https://www.nayuki.io/page/qr-code-generator-library)
//!
//! # Features
//!
//! Core features:
//!
//! - Available in 6 programming languages, all with nearly equal functionality: Java, TypeScript/JavaScript, Python, Rust, C++, C
//! - Significantly shorter code but more documentation comments compared to competing libraries
//! - Supports encoding all 40 versions (sizes) and all 4 error correction levels, as per the QR Code Model 2 standard
//! - Output formats: Raw modules/pixels of the QR symbol, SVG XML string
//! - Detects finder-like penalty patterns more accurately than other implementations
//! - Encodes numeric and special-alphanumeric text in less space than general text
//! - Open source code under the permissive MIT License
//!
//! Manual parameters:
//!
//! - User can specify minimum and maximum version numbers allowed, then library will automatically choose smallest version in the range that fits the data
//! - User can specify mask pattern manually, otherwise library will automatically evaluate all 8 masks and select the optimal one
//! - User can specify absolute error correction level, or allow the library to boost it if it doesn't increase the version number
//! - User can create a list of data segments manually and add ECI segments
//!
//! # Examples
//!
//! ```
//! extern crate qrcodegen;
//! use qrcodegen::QrCode;
//! use qrcodegen::QrCodeEcc;
//! use qrcodegen::QrSegment;
//! ```
//!
//! Simple operation:
//!
//! ```
//! let qr = QrCode::encode_text("Hello, world!",
//! QrCodeEcc::Medium).unwrap();
//! let svg = qr.to_svg_string(4);
//! ```
//!
//! Manual operation:
//!
//! ```
//! let chrs: Vec<char> = "3141592653589793238462643383".chars().collect();
//! let segs = QrSegment::make_segments(&chrs);
//! let qr = QrCode::encode_segments_advanced(
//! &segs, QrCodeEcc::High, 5, 5, Some(Mask::new(2)), false).unwrap();
//! for y in 0 .. qr.size() {
//! for x in 0 .. qr.size() {
//! (... paint qr.get_module(x, y) ...)
//! }
//! }
//! ```
/*---- QrCode functionality ----*/
/// A QR Code symbol, which is a type of two-dimension barcode.
///
/// Invented by Denso Wave and described in the ISO/IEC 18004 standard.
///
/// Instances of this struct represent an immutable square grid of black and light cells.
/// The impl provides static factory functions to create a QR Code from text or binary data.
/// The struct and impl cover the QR Code Model 2 specification, supporting all versions
/// (sizes) from 1 to 40, all 4 error correction levels, and 4 character encoding modes.
///
/// Ways to create a QR Code object:
///
/// - High level: Take the payload data and call `QrCode::encode_text()` or `QrCode::encode_binary()`.
/// - Mid level: Custom-make the list of segments and call
/// `QrCode::encode_segments()` or `QrCode::encode_segments_advanced()`.
/// - Low level: Custom-make the array of data codeword bytes (including segment
/// headers and final padding, excluding error correction codewords), supply the
/// appropriate version number, and call the `QrCode::encode_codewords()` constructor.
///
/// (Note that all ways require supplying the desired error correction level.)
#[derive(Clone, PartialEq, Eq)]
pub struct QrCode {
// Scalar parameters:
// The version number of this QR Code, which is between 1 and 40 (inclusive).
// This determines the size of this barcode.
version: Version,
// The width and height of this QR Code, measured in modules, between
// 21 and 177 (inclusive). This is equal to version * 4 + 17.
size: i32,
// The error correction level used in this QR Code.
errorcorrectionlevel: QrCodeEcc,
// The index of the mask pattern used in this QR Code, which is between 0 and 7 (inclusive).
// Even if a QR Code is created with automatic masking requested (mask = None),
// the resulting object still has a mask value between 0 and 7.
mask: Mask,
// Grids of modules/pixels, with dimensions of size*size:
// The modules of this QR Code (false = light, true = black).
// Immutable after constructor finishes. Accessed through get_module().
modules: Vec<bool>,
// Indicates function modules that are not subjected to masking. Discarded when constructor finishes.
isfunction: Vec<bool>,
}
impl QrCode {
/*---- Static factory functions (high level) ----*/
/// Returns a QR Code representing the given Unicode text string at the given error correction level.
///
/// As a conservative upper bound, this function is guaranteed to succeed for strings that have 738 or fewer Unicode
/// code points (not UTF-8 code units) if the low error correction level is used. The smallest possible
/// QR Code version is automatically chosen for the output. The ECC level of the result may be higher than
/// the ecl argument if it can be done without increasing the version.
///
/// Returns a wrapped `QrCode` if successful, or `Err` if the
/// data is too long to fit in any version at the given ECC level.
pub fn encode_text(text: &str, ecl: QrCodeEcc) -> Result<Self,DataTooLong> {
let chrs: Vec<char> = text.chars().collect();
let segs: Vec<QrSegment> = QrSegment::make_segments(&chrs);
QrCode::encode_segments(&segs, ecl)
}
/// Returns a QR Code representing the given binary data at the given error correction level.
///
/// This function always encodes using the binary segment mode, not any text mode. The maximum number of
/// bytes allowed is 2953. The smallest possible QR Code version is automatically chosen for the output.
/// The ECC level of the result may be higher than the ecl argument if it can be done without increasing the version.
///
/// Returns a wrapped `QrCode` if successful, or `Err` if the
/// data is too long to fit in any version at the given ECC level.
pub fn encode_binary(data: &[u8], ecl: QrCodeEcc) -> Result<Self,DataTooLong> {
let segs: [QrSegment; 1] = [QrSegment::make_bytes(data)];
QrCode::encode_segments(&segs, ecl)
}
/*---- Static factory functions (mid level) ----*/
/// Returns a QR Code representing the given segments at the given error correction level.
///
/// The smallest possible QR Code version is automatically chosen for the output. The ECC level
/// of the result may be higher than the ecl argument if it can be done without increasing the version.
///
/// This function allows the user to create a custom sequence of segments that switches
/// between modes (such as alphanumeric and byte) to encode text in less space.
/// This is a mid-level API; the high-level API is `encode_text()` and `encode_binary()`.
///
/// Returns a wrapped `QrCode` if successful, or `Err` if the
/// data is too long to fit in any version at the given ECC level.
pub fn encode_segments(segs: &[QrSegment], ecl: QrCodeEcc) -> Result<Self,DataTooLong> {
QrCode::encode_segments_advanced(segs, ecl, Version::MIN, Version::MAX, None, true)
}
/// Returns a QR Code representing the given segments with the given encoding parameters.
///
/// The smallest possible QR Code version within the given range is automatically
/// chosen for the output. Iff boostecl is `true`, then the ECC level of the result
/// may be higher than the ecl argument if it can be done without increasing the
/// version. The mask number is either between 0 to 7 (inclusive) to force that
/// mask, or `None` to automatically choose an appropriate mask (which may be slow).
///
/// This function allows the user to create a custom sequence of segments that switches
/// between modes (such as alphanumeric and byte) to encode text in less space.
/// This is a mid-level API; the high-level API is `encode_text()` and `encode_binary()`.
///
/// Returns a wrapped `QrCode` if successful, or `Err` if the data is too
/// long to fit in any version in the given range at the given ECC level.
pub fn encode_segments_advanced(segs: &[QrSegment], mut ecl: QrCodeEcc,
minversion: Version, maxversion: Version, mask: Option<Mask>, boostecl: bool) -> Result<Self,DataTooLong> {
assert!(minversion.value() <= maxversion.value(), "Invalid value");
// Find the minimal version number to use
let mut version: Version = minversion;
let datausedbits: usize = loop {
// Number of data bits available
let datacapacitybits: usize = QrCode::get_num_data_codewords(version, ecl) * 8;
let dataused: Option<usize> = QrSegment::get_total_bits(segs, version);
if dataused.map_or(false, |n| n <= datacapacitybits) {
break dataused.unwrap(); // This version number is found to be suitable
} else if version.value() >= maxversion.value() { // All versions in the range could not fit the given data
let msg: String = match dataused {
None => String::from("Segment too long"),
Some(n) => format!("Data length = {} bits, Max capacity = {} bits",
n, datacapacitybits),
};
return Err(DataTooLong(msg));
} else {
version = Version::new(version.value() + 1);
}
};
// Increase the error correction level while the data still fits in the current version number
for &newecl in &[QrCodeEcc::Medium, QrCodeEcc::Quartile, QrCodeEcc::High] { // From low to high
if boostecl && datausedbits <= QrCode::get_num_data_codewords(version, newecl) * 8 {
ecl = newecl;
}
}
// Concatenate all segments to create the data bit string
let mut bb = BitBuffer(Vec::new());
for seg in segs {
bb.append_bits(seg.mode.mode_bits(), 4);
bb.append_bits(seg.numchars as u32, seg.mode.num_char_count_bits(version));
bb.0.extend_from_slice(&seg.data);
}
assert_eq!(bb.0.len(), datausedbits);
// Add terminator and pad up to a byte if applicable
let datacapacitybits: usize = QrCode::get_num_data_codewords(version, ecl) * 8;
assert!(bb.0.len() <= datacapacitybits);
let numzerobits: usize = std::cmp::min(4, datacapacitybits - bb.0.len());
bb.append_bits(0, numzerobits as u8);
let numzerobits: usize = bb.0.len().wrapping_neg() & 7;
bb.append_bits(0, numzerobits as u8);
assert_eq!(bb.0.len() % 8, 0, "Assertion error");
// Pad with alternating bytes until data capacity is reached
for &padbyte in [0xEC, 0x11].iter().cycle() {
if bb.0.len() >= datacapacitybits {
break;
}
bb.append_bits(padbyte, 8);
}
// Pack bits into bytes in big endian
let mut datacodewords = vec![0u8; bb.0.len() / 8];
for (i, &bit) in bb.0.iter().enumerate() {
datacodewords[i >> 3] |= u8::from(bit) << (7 - (i & 7));
}
// Create the QR Code object
Ok(QrCode::encode_codewords(version, ecl, &datacodewords, mask))
}
/*---- Constructor (low level) ----*/
/// Creates a new QR Code with the given version number,
/// error correction level, data codeword bytes, and mask number.
///
/// This is a low-level API that most users should not use directly.
/// A mid-level API is the `encode_segments()` function.
pub fn encode_codewords(ver: Version, ecl: QrCodeEcc, datacodewords: &[u8], mut mask: Option<Mask>) -> Self {
// Initialize fields
let size = usize::from(ver.value()) * 4 + 17;
let mut result = Self {
version: ver,
size: size as i32,
mask: Mask::new(0), // Dummy value
errorcorrectionlevel: ecl,
modules : vec![false; size * size], // Initially all light
isfunction: vec![false; size * size],
};
// Compute ECC, draw modules
result.draw_function_patterns();
let allcodewords: Vec<u8> = result.add_ecc_and_interleave(datacodewords);
result.draw_codewords(&allcodewords);
// Do masking
if mask.is_none() { // Automatically choose best mask
let mut minpenalty = std::i32::MAX;
for i in 0u8 .. 8 {
let newmask = Mask::new(i);
result.apply_mask(newmask);
result.draw_format_bits(newmask);
let penalty: i32 = result.get_penalty_score();
if penalty < minpenalty {
mask = Some(newmask);
minpenalty = penalty;
}
result.apply_mask(newmask); // Undoes the mask due to XOR
}
}
let mask: Mask = mask.unwrap();
result.mask = mask;
result.apply_mask(mask); // Apply the final choice of mask
result.draw_format_bits(mask); // Overwrite old format bits
result.isfunction.clear();
result.isfunction.shrink_to_fit();
result
}
/*---- Public methods ----*/
/// Returns this QR Code's version, in the range [1, 40].
pub fn version(&self) -> Version {
self.version
}
/// Returns this QR Code's size, in the range [21, 177].
pub fn size(&self) -> i32 {
self.size
}
/// Returns this QR Code's error correction level.
pub fn error_correction_level(&self) -> QrCodeEcc {
self.errorcorrectionlevel
}
/// Returns this QR Code's mask, in the range [0, 7].
pub fn mask(&self) -> Mask {
self.mask
}
/// Returns the color of the module (pixel) at the given coordinates,
/// which is `false` for light or `true` for black.
///
/// The top left corner has the coordinates (x=0, y=0). If the given
/// coordinates are out of bounds, then `false` (light) is returned.
pub fn get_module(&self, x: i32, y: i32) -> bool {
0 <= x && x < self.size && 0 <= y && y < self.size && self.module(x, y)
}
// Returns the color of the module at the given coordinates, which must be in bounds.
fn module(&self, x: i32, y: i32) -> bool {
self.modules[(y * self.size + x) as usize]
}
// Returns a mutable reference to the module's color at the given coordinates, which must be in bounds.
fn module_mut(&mut self, x: i32, y: i32) -> &mut bool {
&mut self.modules[(y * self.size + x) as usize]
}
/// Returns a string of SVG code for an image depicting
/// this QR Code, with the given number of border modules.
///
/// The string always uses Unix newlines (\n), regardless of the platform.
pub fn to_svg_string(&self, border: i32) -> String {
assert!(border >= 0, "Border must be non-negative");
let mut result = String::new();
result += "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n";
result += "<!DOCTYPE svg PUBLIC \"-//W3C//DTD SVG 1.1//EN\" \"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd\">\n";
let dimension = self.size.checked_add(border.checked_mul(2).unwrap()).unwrap();
result += &format!(
"<svg xmlns=\"http://www.w3.org/2000/svg\" version=\"1.1\" viewBox=\"0 0 {0} {0}\" stroke=\"none\">\n", dimension);
result += "\t<rect width=\"100%\" height=\"100%\" fill=\"#FFFFFF\"/>\n";
result += "\t<path d=\"";
for y in 0 .. self.size {
for x in 0 .. self.size {
if self.get_module(x, y) {
if x != 0 || y != 0 {
result += " ";
}
result += &format!("M{},{}h1v1h-1z", x + border, y + border);
}
}
}
result += "\" fill=\"#000000\"/>\n";
result += "</svg>\n";
result
}
/*---- Private helper methods for constructor: Drawing function modules ----*/
// Reads this object's version field, and draws and marks all function modules.
fn draw_function_patterns(&mut self) {
// Draw horizontal and vertical timing patterns
let size: i32 = self.size;
for i in 0 .. size {
self.set_function_module(6, i, i % 2 == 0);
self.set_function_module(i, 6, i % 2 == 0);
}
// Draw 3 finder patterns (all corners except bottom right; overwrites some timing modules)
self.draw_finder_pattern(3, 3);
self.draw_finder_pattern(size - 4, 3);
self.draw_finder_pattern(3, size - 4);
// Draw numerous alignment patterns
let alignpatpos: Vec<i32> = self.get_alignment_pattern_positions();
let numalign: usize = alignpatpos.len();
for i in 0 .. numalign {
for j in 0 .. numalign {
// Don't draw on the three finder corners
if !(i == 0 && j == 0 || i == 0 && j == numalign - 1 || i == numalign - 1 && j == 0) {
self.draw_alignment_pattern(alignpatpos[i], alignpatpos[j]);
}
}
}
// Draw configuration data
self.draw_format_bits(Mask::new(0)); // Dummy mask value; overwritten later in the constructor
self.draw_version();
}
// Draws two copies of the format bits (with its own error correction code)
// based on the given mask and this object's error correction level field.
fn draw_format_bits(&mut self, mask: Mask) {
// Calculate error correction code and pack bits
let bits: u32 = {
// errcorrlvl is uint2, mask is uint3
let data: u32 = u32::from(self.errorcorrectionlevel.format_bits() << 3 | mask.value());
let mut rem: u32 = data;
for _ in 0 .. 10 {
rem = (rem << 1) ^ ((rem >> 9) * 0x537);
}
(data << 10 | rem) ^ 0x5412 // uint15
};
assert_eq!(bits >> 15, 0, "Assertion error");
// Draw first copy
for i in 0 .. 6 {
self.set_function_module(8, i, get_bit(bits, i));
}
self.set_function_module(8, 7, get_bit(bits, 6));
self.set_function_module(8, 8, get_bit(bits, 7));
self.set_function_module(7, 8, get_bit(bits, 8));
for i in 9 .. 15 {
self.set_function_module(14 - i, 8, get_bit(bits, i));
}
// Draw second copy
let size: i32 = self.size;
for i in 0 .. 8 {
self.set_function_module(size - 1 - i, 8, get_bit(bits, i));
}
for i in 8 .. 15 {
self.set_function_module(8, size - 15 + i, get_bit(bits, i));
}
self.set_function_module(8, size - 8, true); // Always black
}
// Draws two copies of the version bits (with its own error correction code),
// based on this object's version field, iff 7 <= version <= 40.
fn draw_version(&mut self) {
if self.version.value() < 7 {
return;
}
// Calculate error correction code and pack bits
let bits: u32 = {
let data = u32::from(self.version.value()); // uint6, in the range [7, 40]
let mut rem: u32 = data;
for _ in 0 .. 12 {
rem = (rem << 1) ^ ((rem >> 11) * 0x1F25);
}
data << 12 | rem // uint18
};
assert!(bits >> 18 == 0, "Assertion error");
// Draw two copies
for i in 0 .. 18 {
let bit: bool = get_bit(bits, i);
let a: i32 = self.size - 11 + i % 3;
let b: i32 = i / 3;
self.set_function_module(a, b, bit);
self.set_function_module(b, a, bit);
}
}
// Draws a 9*9 finder pattern including the border separator,
// with the center module at (x, y). Modules can be out of bounds.
fn draw_finder_pattern(&mut self, x: i32, y: i32) {
for dy in -4 ..= 4 {
for dx in -4 ..= 4 {
let xx: i32 = x + dx;
let yy: i32 = y + dy;
if 0 <= xx && xx < self.size && 0 <= yy && yy < self.size {
let dist: i32 = std::cmp::max(dx.abs(), dy.abs()); // Chebyshev/infinity norm
self.set_function_module(xx, yy, dist != 2 && dist != 4);
}
}
}
}
// Draws a 5*5 alignment pattern, with the center module
// at (x, y). All modules must be in bounds.
fn draw_alignment_pattern(&mut self, x: i32, y: i32) {
for dy in -2 ..= 2 {
for dx in -2 ..= 2 {
self.set_function_module(x + dx, y + dy, std::cmp::max(dx.abs(), dy.abs()) != 1);
}
}
}
// Sets the color of a module and marks it as a function module.
// Only used by the constructor. Coordinates must be in bounds.
fn set_function_module(&mut self, x: i32, y: i32, isblack: bool) {
*self.module_mut(x, y) = isblack;
self.isfunction[(y * self.size + x) as usize] = true;
}
/*---- Private helper methods for constructor: Codewords and masking ----*/
// Returns a new byte string representing the given data with the appropriate error correction
// codewords appended to it, based on this object's version and error correction level.
fn add_ecc_and_interleave(&self, data: &[u8]) -> Vec<u8> {
let ver: Version = self.version;
let ecl: QrCodeEcc = self.errorcorrectionlevel;
assert_eq!(data.len(), QrCode::get_num_data_codewords(ver, ecl), "Illegal argument");
// Calculate parameter numbers
let numblocks: usize = QrCode::table_get(&NUM_ERROR_CORRECTION_BLOCKS, ver, ecl);
let blockecclen: usize = QrCode::table_get(&ECC_CODEWORDS_PER_BLOCK , ver, ecl);
let rawcodewords: usize = QrCode::get_num_raw_data_modules(ver) / 8;
let numshortblocks: usize = numblocks - rawcodewords % numblocks;
let shortblocklen: usize = rawcodewords / numblocks;
// Split data into blocks and append ECC to each block
let mut blocks = Vec::<Vec<u8>>::with_capacity(numblocks);
let rsdiv: Vec<u8> = QrCode::reed_solomon_compute_divisor(blockecclen);
let mut k: usize = 0;
for i in 0 .. numblocks {
let datlen: usize = shortblocklen - blockecclen + usize::from(i >= numshortblocks);
let mut dat = data[k .. k + datlen].to_vec();
k += datlen;
let ecc: Vec<u8> = QrCode::reed_solomon_compute_remainder(&dat, &rsdiv);
if i < numshortblocks {
dat.push(0);
}
dat.extend_from_slice(&ecc);
blocks.push(dat);
}
// Interleave (not concatenate) the bytes from every block into a single sequence
let mut result = Vec::<u8>::with_capacity(rawcodewords);
for i in 0 ..= shortblocklen {
for (j, block) in blocks.iter().enumerate() {
// Skip the padding byte in short blocks
if i != shortblocklen - blockecclen || j >= numshortblocks {
result.push(block[i]);
}
}
}
result
}
// Draws the given sequence of 8-bit codewords (data and error correction) onto the entire
// data area of this QR Code. Function modules need to be marked off before this is called.
fn draw_codewords(&mut self, data: &[u8]) {
assert_eq!(data.len(), QrCode::get_num_raw_data_modules(self.version) / 8, "Illegal argument");
let mut i: usize = 0; // Bit index into the data
// Do the funny zigzag scan
let mut right: i32 = self.size - 1;
while right >= 1 { // Index of right column in each column pair
if right == 6 {
right = 5;
}
for vert in 0 .. self.size { // Vertical counter
for j in 0 .. 2 {
let x: i32 = right - j; // Actual x coordinate
let upward: bool = (right + 1) & 2 == 0;
let y: i32 = if upward { self.size - 1 - vert } else { vert }; // Actual y coordinate
if !self.isfunction[(y * self.size + x) as usize] && i < data.len() * 8 {
*self.module_mut(x, y) = get_bit(u32::from(data[i >> 3]), 7 - ((i & 7) as i32));
i += 1;
}
// If this QR Code has any remainder bits (0 to 7), they were assigned as
// 0/false/light by the constructor and are left unchanged by this method
}
}
right -= 2;
}
assert_eq!(i, data.len() * 8, "Assertion error");
}
// XORs the codeword modules in this QR Code with the given mask pattern.
// The function modules must be marked and the codeword bits must be drawn
// before masking. Due to the arithmetic of XOR, calling apply_mask() with
// the same mask value a second time will undo the mask. A final well-formed
// QR Code needs exactly one (not zero, two, etc.) mask applied.
fn apply_mask(&mut self, mask: Mask) {
for y in 0 .. self.size {
for x in 0 .. self.size {
let invert: bool = match mask.value() {
0 => (x + y) % 2 == 0,
1 => y % 2 == 0,
2 => x % 3 == 0,
3 => (x + y) % 3 == 0,
4 => (x / 3 + y / 2) % 2 == 0,
5 => x * y % 2 + x * y % 3 == 0,
6 => (x * y % 2 + x * y % 3) % 2 == 0,
7 => ((x + y) % 2 + x * y % 3) % 2 == 0,
_ => unreachable!(),
};
*self.module_mut(x, y) ^= invert & !self.isfunction[(y * self.size + x) as usize];
}
}
}
// Calculates and returns the penalty score based on state of this QR Code's current modules.
// This is used by the automatic mask choice algorithm to find the mask pattern that yields the lowest score.
fn get_penalty_score(&self) -> i32 {
let mut result: i32 = 0;
let size: i32 = self.size;
// Adjacent modules in row having same color, and finder-like patterns
for y in 0 .. size {
let mut runcolor = false;
let mut runx: i32 = 0;
let mut runhistory = FinderPenalty::new(size);
for x in 0 .. size {
if self.module(x, y) == runcolor {
runx += 1;
if runx == 5 {
result += PENALTY_N1;
} else if runx > 5 {
result += 1;
}
} else {
runhistory.add_history(runx);
if !runcolor {
result += runhistory.count_patterns() * PENALTY_N3;
}
runcolor = self.module(x, y);
runx = 1;
}
}
result += runhistory.terminate_and_count(runcolor, runx) * PENALTY_N3;
}
// Adjacent modules in column having same color, and finder-like patterns
for x in 0 .. size {
let mut runcolor = false;
let mut runy: i32 = 0;
let mut runhistory = FinderPenalty::new(size);
for y in 0 .. size {
if self.module(x, y) == runcolor {
runy += 1;
if runy == 5 {
result += PENALTY_N1;
} else if runy > 5 {
result += 1;
}
} else {
runhistory.add_history(runy);
if !runcolor {
result += runhistory.count_patterns() * PENALTY_N3;
}
runcolor = self.module(x, y);
runy = 1;
}
}
result += runhistory.terminate_and_count(runcolor, runy) * PENALTY_N3;
}
// 2*2 blocks of modules having same color
for y in 0 .. size - 1 {
for x in 0 .. size - 1 {
let color: bool = self.module(x, y);
if color == self.module(x + 1, y) &&
color == self.module(x, y + 1) &&
color == self.module(x + 1, y + 1) {
result += PENALTY_N2;
}
}
}
// Balance of black and light modules
let black: i32 = self.modules.iter().copied().map(i32::from).sum();
let total: i32 = size * size; // Note that size is odd, so black/total != 1/2
// Compute the smallest integer k >= 0 such that (45-5k)% <= black/total <= (55+5k)%
let k: i32 = ((black * 20 - total * 10).abs() + total - 1) / total - 1;
result += k * PENALTY_N4;
result
}
/*---- Private helper functions ----*/
// Returns an ascending list of positions of alignment patterns for this version number.
// Each position is in the range [0,177), and are used on both the x and y axes.
// This could be implemented as lookup table of 40 variable-length lists of unsigned bytes.
fn get_alignment_pattern_positions(&self) -> Vec<i32> {
let ver: u8 = self.version.value();
if ver == 1 {
vec![]
} else {
let numalign = i32::from(ver) / 7 + 2;
let step: i32 = if ver == 32 { 26 } else
{(i32::from(ver)*4 + numalign*2 + 1) / (numalign*2 - 2) * 2};
let mut result: Vec<i32> = (0 .. numalign - 1).map(
|i| self.size - 7 - i * step).collect();
result.push(6);
result.reverse();
result
}
}
// Returns the number of data bits that can be stored in a QR Code of the given version number, after
// all function modules are excluded. This includes remainder bits, so it might not be a multiple of 8.
// The result is in the range [208, 29648]. This could be implemented as a 40-entry lookup table.
fn get_num_raw_data_modules(ver: Version) -> usize {
let ver = usize::from(ver.value());
let mut result: usize = (16 * ver + 128) * ver + 64;
if ver >= 2 {
let numalign: usize = ver / 7 + 2;
result -= (25 * numalign - 10) * numalign - 55;
if ver >= 7 {
result -= 36;
}
}
assert!(208 <= result && result <= 29648);
result
}
// Returns the number of 8-bit data (i.e. not error correction) codewords contained in any
// QR Code of the given version number and error correction level, with remainder bits discarded.
// This stateless pure function could be implemented as a (40*4)-cell lookup table.
fn get_num_data_codewords(ver: Version, ecl: QrCodeEcc) -> usize {
QrCode::get_num_raw_data_modules(ver) / 8
- QrCode::table_get(&ECC_CODEWORDS_PER_BLOCK , ver, ecl)
* QrCode::table_get(&NUM_ERROR_CORRECTION_BLOCKS, ver, ecl)
}
// Returns an entry from the given table based on the given values.
fn table_get(table: &'static [[i8; 41]; 4], ver: Version, ecl: QrCodeEcc) -> usize {
table[ecl.ordinal()][usize::from(ver.value())] as usize
}
// Returns a Reed-Solomon ECC generator polynomial for the given degree. This could be
// implemented as a lookup table over all possible parameter values, instead of as an algorithm.
fn reed_solomon_compute_divisor(degree: usize) -> Vec<u8> {
assert!(1 <= degree && degree <= 255, "Degree out of range");
// Polynomial coefficients are stored from highest to lowest power, excluding the leading term which is always 1.
// For example the polynomial x^3 + 255x^2 + 8x + 93 is stored as the uint8 array [255, 8, 93].
let mut result = vec![0u8; degree - 1];
result.push(1); // Start off with the monomial x^0
// Compute the product polynomial (x - r^0) * (x - r^1) * (x - r^2) * ... * (x - r^{degree-1}),
// and drop the highest monomial term which is always 1x^degree.
// Note that r = 0x02, which is a generator element of this field GF(2^8/0x11D).
let mut root: u8 = 1;
for _ in 0 .. degree { // Unused variable i
// Multiply the current product by (x - r^i)
for j in 0 .. degree {
result[j] = QrCode::reed_solomon_multiply(result[j], root);
if j + 1 < result.len() {
result[j] ^= result[j + 1];
}
}
root = QrCode::reed_solomon_multiply(root, 0x02);
}
result
}
// Returns the Reed-Solomon error correction codeword for the given data and divisor polynomials.
fn reed_solomon_compute_remainder(data: &[u8], divisor: &[u8]) -> Vec<u8> {
let mut result = vec![0u8; divisor.len()];
for b in data { // Polynomial division
let factor: u8 = b ^ result.remove(0);
result.push(0);
for (x, &y) in result.iter_mut().zip(divisor.iter()) {
*x ^= QrCode::reed_solomon_multiply(y, factor);
}
}
result
}
// Returns the product of the two given field elements modulo GF(2^8/0x11D).
// All inputs are valid. This could be implemented as a 256*256 lookup table.
fn reed_solomon_multiply(x: u8, y: u8) -> u8 {
// Russian peasant multiplication
let mut z: u8 = 0;
for i in (0 .. 8).rev() {
z = (z << 1) ^ ((z >> 7) * 0x1D);
z ^= ((y >> i) & 1) * x;
}
z
}
}
/*---- Helper struct for get_penalty_score() ----*/
struct FinderPenalty {
qr_size: i32,
run_history: [i32; 7],
}
impl FinderPenalty {
pub fn new(size: i32) -> Self {
Self {
qr_size: size,
run_history: [0i32; 7],
}
}
// Pushes the given value to the front and drops the last value.
pub fn add_history(&mut self, mut currentrunlength: i32) {
if self.run_history[0] == 0 {
currentrunlength += self.qr_size; // Add light border to initial run
}
let rh = &mut self.run_history;
for i in (0 .. rh.len()-1).rev() {
rh[i + 1] = rh[i];
}
rh[0] = currentrunlength;
}
// Can only be called immediately after a light run is added, and returns either 0, 1, or 2.
pub fn count_patterns(&self) -> i32 {
let rh = &self.run_history;
let n = rh[1];
assert!(n <= self.qr_size * 3);
let core = n > 0 && rh[2] == n && rh[3] == n * 3 && rh[4] == n && rh[5] == n;
( i32::from(core && rh[0] >= n * 4 && rh[6] >= n)
+ i32::from(core && rh[6] >= n * 4 && rh[0] >= n))
}
// Must be called at the end of a line (row or column) of modules.
pub fn terminate_and_count(mut self, currentruncolor: bool, mut currentrunlength: i32) -> i32 {
if currentruncolor { // Terminate black run
self.add_history(currentrunlength);
currentrunlength = 0;
}
currentrunlength += self.qr_size; // Add light border to final run
self.add_history(currentrunlength);
self.count_patterns()
}
}
/*---- Constants and tables ----*/
// For use in get_penalty_score(), when evaluating which mask is best.
const PENALTY_N1: i32 = 3;
const PENALTY_N2: i32 = 3;
const PENALTY_N3: i32 = 40;
const PENALTY_N4: i32 = 10;
static ECC_CODEWORDS_PER_BLOCK: [[i8; 41]; 4] = [
// Version: (note that index 0 is for padding, and is set to an illegal value)
//0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 Error correction level
[-1, 7, 10, 15, 20, 26, 18, 20, 24, 30, 18, 20, 24, 26, 30, 22, 24, 28, 30, 28, 28, 28, 28, 30, 30, 26, 28, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30], // Low
[-1, 10, 16, 26, 18, 24, 16, 18, 22, 22, 26, 30, 22, 22, 24, 24, 28, 28, 26, 26, 26, 26, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28], // Medium
[-1, 13, 22, 18, 26, 18, 24, 18, 22, 20, 24, 28, 26, 24, 20, 30, 24, 28, 28, 26, 30, 28, 30, 30, 30, 30, 28, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30], // Quartile
[-1, 17, 28, 22, 16, 22, 28, 26, 26, 24, 28, 24, 28, 22, 24, 24, 30, 28, 28, 26, 28, 30, 24, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30], // High
];
static NUM_ERROR_CORRECTION_BLOCKS: [[i8; 41]; 4] = [
// Version: (note that index 0 is for padding, and is set to an illegal value)
//0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 Error correction level
[-1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 4, 4, 4, 4, 4, 6, 6, 6, 6, 7, 8, 8, 9, 9, 10, 12, 12, 12, 13, 14, 15, 16, 17, 18, 19, 19, 20, 21, 22, 24, 25], // Low
[-1, 1, 1, 1, 2, 2, 4, 4, 4, 5, 5, 5, 8, 9, 9, 10, 10, 11, 13, 14, 16, 17, 17, 18, 20, 21, 23, 25, 26, 28, 29, 31, 33, 35, 37, 38, 40, 43, 45, 47, 49], // Medium
[-1, 1, 1, 2, 2, 4, 4, 6, 6, 8, 8, 8, 10, 12, 16, 12, 17, 16, 18, 21, 20, 23, 23, 25, 27, 29, 34, 34, 35, 38, 40, 43, 45, 48, 51, 53, 56, 59, 62, 65, 68], // Quartile
[-1, 1, 1, 2, 4, 4, 4, 5, 6, 8, 8, 11, 11, 16, 16, 18, 16, 19, 21, 25, 25, 25, 34, 30, 32, 35, 37, 40, 42, 45, 48, 51, 54, 57, 60, 63, 66, 70, 74, 77, 81], // High
];
/*---- QrCodeEcc functionality ----*/
/// The error correction level in a QR Code symbol.
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug)]
pub enum QrCodeEcc {
/// The QR Code can tolerate about 7% erroneous codewords.
Low ,
/// The QR Code can tolerate about 15% erroneous codewords.
Medium ,
/// The QR Code can tolerate about 25% erroneous codewords.
Quartile,
/// The QR Code can tolerate about 30% erroneous codewords.
High ,
}
impl QrCodeEcc {
// Returns an unsigned 2-bit integer (in the range 0 to 3).
fn ordinal(self) -> usize {
use QrCodeEcc::*;
match self {
Low => 0,
Medium => 1,
Quartile => 2,
High => 3,
}
}
// Returns an unsigned 2-bit integer (in the range 0 to 3).
fn format_bits(self) -> u8 {
use QrCodeEcc::*;
match self {
Low => 1,
Medium => 0,
Quartile => 3,
High => 2,
}
}
}
/*---- QrSegment functionality ----*/
/// A segment of character/binary/control data in a QR Code symbol.
///
/// Instances of this struct are immutable.
///
/// The mid-level way to create a segment is to take the payload data
/// and call a static factory function such as `QrSegment::make_numeric()`.
/// The low-level way to create a segment is to custom-make the bit buffer
/// and call the `QrSegment::new()` constructor with appropriate values.
///
/// This segment struct imposes no length restrictions, but QR Codes have restrictions.
/// Even in the most favorable conditions, a QR Code can only hold 7089 characters of data.
/// Any segment longer than this is meaningless for the purpose of generating QR Codes.
#[derive(Clone, PartialEq, Eq)]
pub struct QrSegment {
// The mode indicator of this segment. Accessed through mode().
mode: QrSegmentMode,
// The length of this segment's unencoded data. Measured in characters for
// numeric/alphanumeric/kanji mode, bytes for byte mode, and 0 for ECI mode.
// Not the same as the data's bit length. Accessed through num_chars().
numchars: usize,
// The data bits of this segment. Accessed through data().
data: Vec<bool>,
}
impl QrSegment {
/*---- Static factory functions (mid level) ----*/
/// Returns a segment representing the given binary data encoded in byte mode.
///
/// All input byte slices are acceptable.
///
/// Any text string can be converted to UTF-8 bytes and encoded as a byte mode segment.
pub fn make_bytes(data: &[u8]) -> Self {
let mut bb = BitBuffer(Vec::with_capacity(data.len() * 8));
for &b in data {
bb.append_bits(u32::from(b), 8);
}
QrSegment::new(QrSegmentMode::Byte, data.len(), bb.0)
}
/// Returns a segment representing the given string of decimal digits encoded in numeric mode.
///
/// Panics if the string contains non-digit characters.
pub fn make_numeric(text: &[char]) -> Self {
let mut bb = BitBuffer(Vec::with_capacity(text.len() * 3 + (text.len() + 2) / 3));
let mut accumdata: u32 = 0;
let mut accumcount: u8 = 0;
for &c in text {
assert!('0' <= c && c <= '9', "String contains non-numeric characters");
accumdata = accumdata * 10 + (u32::from(c) - u32::from('0'));
accumcount += 1;
if accumcount == 3 {
bb.append_bits(accumdata, 10);
accumdata = 0;
accumcount = 0;
}
}
if accumcount > 0 { // 1 or 2 digits remaining
bb.append_bits(accumdata, accumcount * 3 + 1);
}
QrSegment::new(QrSegmentMode::Numeric, text.len(), bb.0)
}
/// Returns a segment representing the given text string encoded in alphanumeric mode.
///
/// The characters allowed are: 0 to 9, A to Z (uppercase only), space,
/// dollar, percent, asterisk, plus, hyphen, period, slash, colon.
///
/// Panics if the string contains non-encodable characters.
pub fn make_alphanumeric(text: &[char]) -> Self {
let mut bb = BitBuffer(Vec::with_capacity(text.len() * 5 + (text.len() + 1) / 2));
let mut accumdata: u32 = 0;
let mut accumcount: u32 = 0;
for &c in text {
let i: usize = ALPHANUMERIC_CHARSET.iter().position(|&x| x == c)
.expect("String contains unencodable characters in alphanumeric mode");
accumdata = accumdata * 45 + (i as u32);
accumcount += 1;
if accumcount == 2 {
bb.append_bits(accumdata, 11);
accumdata = 0;
accumcount = 0;
}
}
if accumcount > 0 { // 1 character remaining
bb.append_bits(accumdata, 6);
}
QrSegment::new(QrSegmentMode::Alphanumeric, text.len(), bb.0)
}
/// Returns a list of zero or more segments to represent the given Unicode text string.
///
/// The result may use various segment modes and switch
/// modes to optimize the length of the bit stream.
pub fn make_segments(text: &[char]) -> Vec<Self> {
if text.is_empty() {
vec![]
} else if QrSegment::is_numeric(text) {
vec![QrSegment::make_numeric(text)]
} else if QrSegment::is_alphanumeric(text) {
vec![QrSegment::make_alphanumeric(text)]
} else {
let s: String = text.iter().cloned().collect();
vec![QrSegment::make_bytes(s.as_bytes())]
}
}
/// Returns a segment representing an Extended Channel Interpretation
/// (ECI) designator with the given assignment value.
pub fn make_eci(assignval: u32) -> Self {
let mut bb = BitBuffer(Vec::with_capacity(24));
if assignval < (1 << 7) {
bb.append_bits(assignval, 8);
} else if assignval < (1 << 14) {
bb.append_bits(2, 2);
bb.append_bits(assignval, 14);
} else if assignval < 1_000_000 {
bb.append_bits(6, 3);
bb.append_bits(assignval, 21);
} else {
panic!("ECI assignment value out of range");
}
QrSegment::new(QrSegmentMode::Eci, 0, bb.0)
}
/*---- Constructor (low level) ----*/
/// Creates a new QR Code segment with the given attributes and data.
///
/// The character count (numchars) must agree with the mode and
/// the bit buffer length, but the constraint isn't checked.
pub fn new(mode: QrSegmentMode, numchars: usize, data: Vec<bool>) -> Self {
Self { mode, numchars, data }
}
/*---- Instance field getters ----*/
/// Returns the mode indicator of this segment.
pub fn mode(&self) -> QrSegmentMode {
self.mode
}
/// Returns the character count field of this segment.
pub fn num_chars(&self) -> usize {
self.numchars
}
/// Returns the data bits of this segment.
pub fn data(&self) -> &Vec<bool> {
&self.data
}
/*---- Other static functions ----*/
// Calculates and returns the number of bits needed to encode the given
// segments at the given version. The result is None if a segment has too many
// characters to fit its length field, or the total bits exceeds usize::MAX.
fn get_total_bits(segs: &[Self], version: Version) -> Option<usize> {
let mut result: usize = 0;
for seg in segs {
let ccbits: u8 = seg.mode.num_char_count_bits(version);
// ccbits can be as large as 16, but usize can be as small as 16
if let Some(limit) = 1usize.checked_shl(u32::from(ccbits)) {
if seg.numchars >= limit {
return None; // The segment's length doesn't fit the field's bit width
}
}
result = result.checked_add(4 + usize::from(ccbits))?;
result = result.checked_add(seg.data.len())?;
}
Some(result)
}
// Tests whether the given string can be encoded as a segment in alphanumeric mode.
// A string is encodable iff each character is in the following set: 0 to 9, A to Z
// (uppercase only), space, dollar, percent, asterisk, plus, hyphen, period, slash, colon.
fn is_alphanumeric(text: &[char]) -> bool {
text.iter().all(|c| ALPHANUMERIC_CHARSET.contains(c))
}
// Tests whether the given string can be encoded as a segment in numeric mode.
// A string is encodable iff each character is in the range 0 to 9.
fn is_numeric(text: &[char]) -> bool {
text.iter().all(|&c| '0' <= c && c <= '9')
}
}
// The set of all legal characters in alphanumeric mode,
// where each character value maps to the index in the string.
static ALPHANUMERIC_CHARSET: [char; 45] = ['0','1','2','3','4','5','6','7','8','9',
'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z',
' ','$','%','*','+','-','.','/',':'];
/*---- QrSegmentMode functionality ----*/
/// Describes how a segment's data bits are interpreted.
#[derive(Clone, Copy, PartialEq, Eq, Debug)]
pub enum QrSegmentMode {
Numeric,
Alphanumeric,
Byte,
Kanji,
Eci,
}
impl QrSegmentMode {
// Returns an unsigned 4-bit integer value (range 0 to 15)
// representing the mode indicator bits for this mode object.
fn mode_bits(self) -> u32 {
use QrSegmentMode::*;
match self {
Numeric => 0x1,
Alphanumeric => 0x2,
Byte => 0x4,
Kanji => 0x8,
Eci => 0x7,
}
}
// Returns the bit width of the character count field for a segment in this mode
// in a QR Code at the given version number. The result is in the range [0, 16].
fn num_char_count_bits(self, ver: Version) -> u8 {
use QrSegmentMode::*;
(match self {
Numeric => [10, 12, 14],
Alphanumeric => [ 9, 11, 13],
Byte => [ 8, 16, 16],
Kanji => [ 8, 10, 12],
Eci => [ 0, 0, 0],
})[usize::from((ver.value() + 7) / 17)]
}
}
/*---- Bit buffer functionality ----*/
/// An appendable sequence of bits (0s and 1s).
///
/// Mainly used by QrSegment.
pub struct BitBuffer(pub Vec<bool>);
impl BitBuffer {
/// Appends the given number of low-order bits of the given value to this buffer.
///
/// Requires len &#x2264; 31 and val &lt; 2<sup>len</sup>.
pub fn append_bits(&mut self, val: u32, len: u8) {
assert!(len <= 31 && (val >> len) == 0, "Value out of range");
self.0.extend((0 .. i32::from(len)).rev().map(|i| get_bit(val, i))); // Append bit by bit
}
}
/*---- Miscellaneous values ----*/
/// The error type when the supplied data does not fit any QR Code version.
///
/// Ways to handle this exception include:
///
/// - Decrease the error correction level if it was greater than `QrCodeEcc::Low`.
/// - If the `encode_segments_advanced()` function was called, then increase the maxversion
/// argument if it was less than `Version::MAX`. (This advice does not apply to the
/// other factory functions because they search all versions up to `Version::MAX`.)
/// - Split the text data into better or optimal segments in order to reduce the number of bits required.
/// - Change the text or binary data to be shorter.
/// - Change the text to fit the character set of a particular segment mode (e.g. alphanumeric).
/// - Propagate the error upward to the caller/user.
#[derive(Debug, Clone)]
pub struct DataTooLong(String);
impl std::error::Error for DataTooLong {
fn description(&self) -> &str {
&self.0
}
}
impl std::fmt::Display for DataTooLong {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
f.write_str(&self.0)
}
}
/// A number between 1 and 40 (inclusive).
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug)]
pub struct Version(u8);
impl Version {
/// The minimum version number supported in the QR Code Model 2 standard.
pub const MIN: Version = Version( 1);
/// The maximum version number supported in the QR Code Model 2 standard.
pub const MAX: Version = Version(40);
/// Creates a version object from the given number.
///
/// Panics if the number is outside the range [1, 40].
pub fn new(ver: u8) -> Self {
assert!(Version::MIN.value() <= ver && ver <= Version::MAX.value(), "Version number out of range");
Self(ver)
}
/// Returns the value, which is in the range [1, 40].
pub fn value(self) -> u8 {
self.0
}
}
/// A number between 0 and 7 (inclusive).
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug)]
pub struct Mask(u8);
impl Mask {
/// Creates a mask object from the given number.
///
/// Panics if the number is outside the range [0, 7].
pub fn new(mask: u8) -> Self {
assert!(mask <= 7, "Mask value out of range");
Self(mask)
}
/// Returns the value, which is in the range [0, 7].
pub fn value(self) -> u8 {
self.0
}
}
// Returns true iff the i'th bit of x is set to 1.
fn get_bit(x: u32, i: i32) -> bool {
(x >> i) & 1 != 0
}
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