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use crate::plugins::Plugin;
use crate::tree::{Document, Node};
use std::f64::consts::PI;
pub struct ConvertTransform {
pub float_precision: usize,
pub deg_precision: usize,
}
impl Default for ConvertTransform {
fn default() -> Self {
Self {
float_precision: 3,
deg_precision: 3,
}
}
}
impl Plugin for ConvertTransform {
fn apply(&self, doc: &mut Document) {
process_transforms(&mut doc.root, self);
}
}
fn process_transforms(nodes: &mut Vec<Node>, opts: &ConvertTransform) {
for node in nodes {
if let Node::Element(elem) = node {
if let Some(t) = elem.attributes.get_mut("transform") {
let new_t = optimize_transform(t, opts);
if new_t.is_empty() {
elem.attributes.shift_remove("transform"); // Remove if identity/empty
} else {
*t = new_t;
}
}
process_transforms(&mut elem.children, opts);
}
}
}
// 2D Affine Matrix
// [ a c e ]
// [ b d f ]
// [ 0 0 1 ]
#[derive(Debug, Clone, Copy, PartialEq)]
struct Matrix {
a: f64,
b: f64,
c: f64,
d: f64,
e: f64,
f: f64,
}
impl Matrix {
fn identity() -> Self {
Self {
a: 1.0,
b: 0.0,
c: 0.0,
d: 1.0,
e: 0.0,
f: 0.0,
}
}
fn multiply(&self, other: &Matrix) -> Matrix {
// Self * Other (Order depends on pre/post mult convention. SVG is post-mult: P' = M * P)
Matrix {
a: self.a * other.a + self.c * other.b,
b: self.b * other.a + self.d * other.b,
c: self.a * other.c + self.c * other.d,
d: self.b * other.c + self.d * other.d,
e: self.a * other.e + self.c * other.f + self.e,
f: self.b * other.e + self.d * other.f + self.f,
}
}
}
fn optimize_transform(transform_str: &str, opts: &ConvertTransform) -> String {
// 1. Parse into list of matrices
let matrices = parse_transform(transform_str);
if matrices.is_empty() {
return String::new();
}
// 2. Multiply all into one
let mut combined = Matrix::identity();
for m in matrices {
combined = combined.multiply(&m);
}
// 3. Decompose / Stringify
// Check if identity
if is_identity(&combined) {
return String::new();
}
// Check for simple cases to stringify compactly
// 1. Translate only (a=1, d=1, b=0, c=0)
if is_approx(combined.a, 1.0)
&& is_approx(combined.d, 1.0)
&& is_approx(combined.b, 0.0)
&& is_approx(combined.c, 0.0)
{
return format!(
"translate({} {})",
format_num(combined.e, opts.float_precision),
format_num(combined.f, opts.float_precision)
);
}
// 2. Scale only (b=0, c=0, e=0, f=0)
if is_approx(combined.b, 0.0)
&& is_approx(combined.c, 0.0)
&& is_approx(combined.e, 0.0)
&& is_approx(combined.f, 0.0)
{
if (combined.a - combined.d).abs() < f64::EPSILON {
return format!("scale({})", format_num(combined.a, opts.float_precision));
}
return format!(
"scale({} {})",
format_num(combined.a, opts.float_precision),
format_num(combined.d, opts.float_precision)
);
}
// Default to matrix(...)
format!(
"matrix({} {} {} {} {} {})",
format_num(combined.a, opts.float_precision),
format_num(combined.b, opts.float_precision),
format_num(combined.c, opts.float_precision),
format_num(combined.d, opts.float_precision),
format_num(combined.e, opts.float_precision),
format_num(combined.f, opts.float_precision)
)
}
fn is_approx(a: f64, b: f64) -> bool {
(a - b).abs() < 1e-10
}
fn is_identity(m: &Matrix) -> bool {
is_approx(m.a, 1.0)
&& is_approx(m.b, 0.0)
&& is_approx(m.c, 0.0)
&& is_approx(m.d, 1.0)
&& is_approx(m.e, 0.0)
&& is_approx(m.f, 0.0)
}
fn format_num(n: f64, p: usize) -> String {
let factor = 10u32.pow(p as u32) as f64;
let rounded = (n * factor).round() / factor;
let s = rounded.to_string();
if s.starts_with("0.") {
s[1..].to_string()
} else if s.starts_with("-0.") {
format!("-{}", &s[2..])
} else {
s
}
}
fn parse_transform(s: &str) -> Vec<Matrix> {
parse_transform_manual(s)
}
fn parse_transform_manual(s: &str) -> Vec<Matrix> {
let mut matrices = Vec::new();
let mut chars = s.char_indices().peekable();
while let Some((_, c)) = chars.next() {
if c.is_ascii_alphabetic() {
// Read name
let mut name = String::new();
name.push(c);
while let Some((_, nc)) = chars.peek() {
if nc.is_ascii_alphabetic() {
name.push(*nc);
chars.next();
} else {
break;
}
}
// Skip to (
while let Some((_, nc)) = chars.peek() {
if *nc == '(' {
chars.next();
break;
}
chars.next();
}
// Read args
let mut args = Vec::new();
let mut cur_num = String::new();
while let Some((_, nc)) = chars.peek() {
if *nc == ')' {
chars.next();
break;
}
let cc = *nc;
if cc.is_numeric() || cc == '.' || cc == '-' || cc == 'e' || cc == 'E' {
cur_num.push(cc);
chars.next();
} else {
if !cur_num.is_empty() {
if let Ok(n) = cur_num.parse::<f64>() {
args.push(n);
}
cur_num.clear();
}
chars.next(); // Skip separator
}
}
if !cur_num.is_empty() {
if let Ok(n) = cur_num.parse::<f64>() {
args.push(n);
}
}
match name.as_str() {
"translate" => {
let tx = *args.get(0).unwrap_or(&0.0);
let ty = *args.get(1).unwrap_or(&0.0);
matrices.push(Matrix {
a: 1.0,
b: 0.0,
c: 0.0,
d: 1.0,
e: tx,
f: ty,
});
}
"scale" => {
let sx = *args.get(0).unwrap_or(&1.0);
let sy = *args.get(1).unwrap_or(&sx); // if 1 arg, scale(s, s)
matrices.push(Matrix {
a: sx,
b: 0.0,
c: 0.0,
d: sy,
e: 0.0,
f: 0.0,
});
}
"rotate" => {
let angle = *args.get(0).unwrap_or(&0.0);
// cx, cy optional
let cx = *args.get(1).unwrap_or(&0.0);
let cy = *args.get(2).unwrap_or(&0.0);
let rad = angle * PI / 180.0;
let c = rad.cos();
let s = rad.sin();
// define rotate(a, cx, cy) as translate(cx, cy) rotate(a) translate(-cx, -cy)
let mut m = Matrix::identity();
if cx != 0.0 || cy != 0.0 {
m = m.multiply(&Matrix {
a: 1.0,
b: 0.0,
c: 0.0,
d: 1.0,
e: cx,
f: cy,
});
}
m = m.multiply(&Matrix {
a: c,
b: s,
c: -s,
d: c,
e: 0.0,
f: 0.0,
});
if cx != 0.0 || cy != 0.0 {
m = m.multiply(&Matrix {
a: 1.0,
b: 0.0,
c: 0.0,
d: 1.0,
e: -cx,
f: -cy,
});
}
matrices.push(m);
}
"skewX" => {
let a = *args.get(0).unwrap_or(&0.0);
let rad = a * PI / 180.0;
matrices.push(Matrix {
a: 1.0,
b: 0.0,
c: rad.tan(),
d: 1.0,
e: 0.0,
f: 0.0,
});
}
"skewY" => {
let a = *args.get(0).unwrap_or(&0.0);
let rad = a * PI / 180.0;
matrices.push(Matrix {
a: 1.0,
b: rad.tan(),
c: 0.0,
d: 1.0,
e: 0.0,
f: 0.0,
});
}
"matrix" => {
if args.len() == 6 {
matrices.push(Matrix {
a: args[0],
b: args[1],
c: args[2],
d: args[3],
e: args[4],
f: args[5],
});
}
}
_ => {}
}
}
}
matrices
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_translate_merge() {
// translate(10) translate(20) -> translate(30 0)
let input = "translate(10) translate(20)";
let opts = ConvertTransform::default();
let out = optimize_transform(input, &opts);
// translate(30 0) vs translate(30).
assert!(out.contains("translate(30 0)"));
}
#[test]
fn test_scale_merge() {
let input = "scale(2) scale(3)";
let opts = ConvertTransform::default();
let out = optimize_transform(input, &opts);
// 2*3 = 6
assert!(out.contains("scale(6)"));
}
#[test]
fn test_identity() {
let input = "translate(0) scale(1)";
let opts = ConvertTransform::default();
let out = optimize_transform(input, &opts);
assert_eq!(out, "");
}
}