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// SPDX-FileCopyrightText: 2014 kennytm
// SPDX-FileCopyrightText: 2018 Ignas Anikevicius
// SPDX-FileCopyrightText: 2023 Nakanishi
// SPDX-FileCopyrightText: 2024 Shun Sakai
//
// SPDX-License-Identifier: Apache-2.0 OR MIT
//! Implementation of features related to the penalty score.
use alloc::boxed::Box;
use core::{cmp, iter};
use super::{Canvas, Module};
use crate::{
cast::As,
types::{Color, Version},
};
impl Canvas {
/// Computes the penalty score for having too many adjacent modules with the
/// same color.
///
/// Every 5+N adjacent modules in the same column/row having the same color
/// will contribute 3+N points.
fn compute_adjacent_penalty_score(&self, is_horizontal: bool) -> u16 {
let mut total_score = 0;
for i in 0..self.width {
let map_fn = |j| {
if is_horizontal {
self.get(j, i)
} else {
self.get(i, j)
}
};
let colors = (0..self.width).map(map_fn).chain(iter::once(Module::Empty));
let mut last_color = Module::Empty;
let mut consecutive_len = 1_u16;
for color in colors {
if color == last_color {
consecutive_len += 1;
} else {
last_color = color;
if consecutive_len >= 5 {
total_score += consecutive_len - 2;
}
consecutive_len = 1;
}
}
}
total_score
}
/// Computes the penalty score for having too many rectangles with the same
/// color.
///
/// Every 2×2 blocks (with overlapping counted) having the same color will
/// contribute 3 points.
fn compute_block_penalty_score(&self) -> u16 {
let mut total_score = 0;
for i in 0..self.width - 1 {
for j in 0..self.width - 1 {
let this = self.get(i, j);
let right = self.get(i + 1, j);
let bottom = self.get(i, j + 1);
let bottom_right = self.get(i + 1, j + 1);
if this == right && right == bottom && bottom == bottom_right {
total_score += 3;
}
}
}
total_score
}
/// Computes the penalty score for having a pattern similar to the finder
/// pattern in the wrong place.
///
/// Every pattern that looks like `#.###.#....` in any orientation will add
/// 40 points.
fn compute_finder_penalty_score(&self, is_horizontal: bool) -> u16 {
static PATTERN: [Color; 7] = [
Color::Dark,
Color::Light,
Color::Dark,
Color::Dark,
Color::Dark,
Color::Light,
Color::Dark,
];
let mut total_score = 0;
for i in 0..self.width {
for j in 0..self.width - 6 {
// TODO a ref to a closure should be enough?
let get: Box<dyn Fn(i16) -> Color> = if is_horizontal {
Box::new(|k| self.get(k, i).into())
} else {
Box::new(|k| self.get(i, k).into())
};
if (j..(j + 7)).map(&get).ne(PATTERN.iter().copied()) {
continue;
}
let check = |k| 0 <= k && k < self.width && get(k) != Color::Light;
if !((j - 4)..j).any(&check) || !((j + 7)..(j + 11)).any(&check) {
total_score += 40;
}
}
}
total_score - 360
}
/// Computes the penalty score for having an unbalanced dark/light ratio.
///
/// The score is given linearly by the deviation from a 50% ratio of dark
/// modules. The highest possible score is 100.
///
/// <div class="warning">
///
/// Note that this algorithm differs slightly from the standard we do not
/// round the result every 5%, but the difference should be negligible and
/// should not affect which mask is chosen.
///
/// </div>
fn compute_balance_penalty_score(&self) -> u16 {
let dark_modules = self.modules.iter().filter(|m| m.is_dark()).count();
let total_modules = self.modules.len();
let ratio = dark_modules * 200 / total_modules;
ratio.abs_diff(100).as_u16()
}
/// Computes the penalty score for having too many light modules on the
/// sides.
///
/// This penalty score is exclusive to Micro QR code.
///
/// <div class="warning">
///
/// Note that the standard gives the formula for *efficiency* score, which
/// has the inverse meaning of this method, but it is very easy to convert
/// between the two (this score is (16×width − standard-score)).
///
/// </div>
fn compute_light_side_penalty_score(&self) -> u16 {
let h = (1..self.width)
.filter(|j| !self.get(*j, -1).is_dark())
.count();
let v = (1..self.width)
.filter(|j| !self.get(-1, *j).is_dark())
.count();
(h + v + 15 * cmp::max(h, v)).as_u16()
}
/// Computes the total penalty scores. A QR code having higher points is
/// less desirable.
pub(super) fn compute_total_penalty_scores(&self) -> u16 {
match self.version {
Version::Normal(_) => {
let s1_a = self.compute_adjacent_penalty_score(true);
let s1_b = self.compute_adjacent_penalty_score(false);
let s2 = self.compute_block_penalty_score();
let s3_a = self.compute_finder_penalty_score(true);
let s3_b = self.compute_finder_penalty_score(false);
let s4 = self.compute_balance_penalty_score();
s1_a + s1_b + s2 + s3_a + s3_b + s4
}
Version::Micro(_) => self.compute_light_side_penalty_score(),
Version::RectMicro(..) => 0,
}
}
}
#[cfg(test)]
mod tests {
use super::{super::MaskPattern, *};
use crate::types::EcLevel;
fn create_test_canvas() -> Canvas {
let mut c = Canvas::new(Version::Normal(1), EcLevel::Q);
c.draw_all_functional_patterns();
c.draw_data(
b"\x20\x5B\x0B\x78\xD1\x72\xDC\x4D\x43\x40\xEC\x11\x00",
b"\xA8\x48\x16\x52\xD9\x36\x9C\x00\x2E\x0F\xB4\x7A\x10",
);
c.apply_mask(MaskPattern::Checkerboard);
c
}
#[test]
fn check_penalty_canvas() {
let c = create_test_canvas();
assert_eq!(
c.to_debug_str(),
concat!(
"\n",
"#######.##....#######\n",
"#.....#.#..#..#.....#\n",
"#.###.#.#..##.#.###.#\n",
"#.###.#.#.....#.###.#\n",
"#.###.#.#.#...#.###.#\n",
"#.....#...#...#.....#\n",
"#######.#.#.#.#######\n",
"........#............\n",
".##.#.##....#.#.#####\n",
".#......####....#...#\n",
"..##.###.##...#.##...\n",
".##.##.#..##.#.#.###.\n",
"#...#.#.#.###.###.#.#\n",
"........##.#..#...#.#\n",
"#######.#.#....#.##..\n",
"#.....#..#.##.##.#...\n",
"#.###.#.#.#...#######\n",
"#.###.#..#.#.#.#...#.\n",
"#.###.#.#...####.#..#\n",
"#.....#.#.##.#...#.##\n",
"#######.....####....#"
)
);
}
#[test]
fn test_penalty_score_adjacent() {
let c = create_test_canvas();
assert_eq!(c.compute_adjacent_penalty_score(true), 88);
assert_eq!(c.compute_adjacent_penalty_score(false), 92);
}
#[test]
fn test_penalty_score_block() {
let c = create_test_canvas();
assert_eq!(c.compute_block_penalty_score(), 90);
}
#[test]
fn test_penalty_score_finder() {
let c = create_test_canvas();
assert_eq!(c.compute_finder_penalty_score(true), 0);
assert_eq!(c.compute_finder_penalty_score(false), 40);
}
#[test]
fn test_penalty_score_balance() {
let c = create_test_canvas();
assert_eq!(c.compute_balance_penalty_score(), 2);
}
#[test]
fn test_penalty_score_light_sides() {
static HORIZONTAL_SIDE: [Color; 17] = [
Color::Dark,
Color::Light,
Color::Light,
Color::Dark,
Color::Dark,
Color::Dark,
Color::Light,
Color::Light,
Color::Dark,
Color::Light,
Color::Dark,
Color::Light,
Color::Light,
Color::Dark,
Color::Light,
Color::Light,
Color::Light,
];
static VERTICAL_SIDE: [Color; 17] = [
Color::Dark,
Color::Dark,
Color::Dark,
Color::Light,
Color::Light,
Color::Dark,
Color::Dark,
Color::Light,
Color::Dark,
Color::Light,
Color::Dark,
Color::Light,
Color::Dark,
Color::Light,
Color::Light,
Color::Dark,
Color::Light,
];
let mut c = Canvas::new(Version::Micro(4), EcLevel::Q);
for i in 0_i16..17 {
c.put(i, -1, HORIZONTAL_SIDE[i.as_usize()]);
c.put(-1, i, VERTICAL_SIDE[i.as_usize()]);
}
assert_eq!(c.compute_light_side_penalty_score(), 168);
}
}