Skip to content

Commit

Permalink
Improve Color::hex performance (bevyengine#6940)
Browse files Browse the repository at this point in the history 
# Objective

Improve `Color::hex` performance

#### Bench

```bash
running 2 tests
test bench_color_hex_after  ... bench:           4 ns/iter (+/- 0)
test bench_color_hex_before ... bench:          14 ns/iter (+/- 0)
```

## Solution

Use `const fn` decode hex value.

---

## Changelog

Rename

```rust
HexColorError::Hex(FromHexError) -> HexColorError::Char(char)
```
  • Loading branch information
@wyhaya @alradish
wyhaya authored and alradish committed Jan 22, 2023
1 parent 2c0fade commit 637df33
Show file tree
Hide file tree
Showing 2 changed files with 70 additions and 76 deletions.
1 change: 0 additions & 1 deletion crates/bevy_render/Cargo.toml
View file
Expand Up @@ -62,7 +62,6 @@ thread_local = "1.1"
thiserror = "1.0"
futures-lite = "1.4.0"
anyhow = "1.0"
hex = "0.4.2"
hexasphere = "8.0"
parking_lot = "0.12.1"
regex = "1.5"
Expand Down
145 changes: 70 additions & 75 deletions crates/bevy_render/src/color/mod.rs
View file
Expand Up @@ -260,37 +260,29 @@ impl Color {
let hex = hex.as_ref();
let hex = hex.strip_prefix('#').unwrap_or(hex);

// RGB
if hex.len() == 3 {
let mut data = [0; 6];
for (i, ch) in hex.chars().enumerate() {
data[i * 2] = ch as u8;
data[i * 2 + 1] = ch as u8;
match *hex.as_bytes() {
// RGB
[r, g, b] => {
let [r, g, b, ..] = decode_hex([r, r, g, g, b, b])?;
Ok(Color::rgb_u8(r, g, b))
}
return decode_rgb(&data);
}

// RGBA
if hex.len() == 4 {
let mut data = [0; 8];
for (i, ch) in hex.chars().enumerate() {
data[i * 2] = ch as u8;
data[i * 2 + 1] = ch as u8;
// RGBA
[r, g, b, a] => {
let [r, g, b, a, ..] = decode_hex([r, r, g, g, b, b, a, a])?;
Ok(Color::rgba_u8(r, g, b, a))
}
return decode_rgba(&data);
}

// RRGGBB
if hex.len() == 6 {
return decode_rgb(hex.as_bytes());
}

// RRGGBBAA
if hex.len() == 8 {
return decode_rgba(hex.as_bytes());
// RRGGBB
[r1, r2, g1, g2, b1, b2] => {
let [r, g, b, ..] = decode_hex([r1, r2, g1, g2, b1, b2])?;
Ok(Color::rgb_u8(r, g, b))
}
// RRGGBBAA
[r1, r2, g1, g2, b1, b2, a1, a2] => {
let [r, g, b, a, ..] = decode_hex([r1, r2, g1, g2, b1, b2, a1, a2])?;
Ok(Color::rgba_u8(r, g, b, a))
}
_ => Err(HexColorError::Length),
}

Err(HexColorError::Length)
}

/// New `Color` from sRGB colorspace.
Expand Down Expand Up @@ -1337,38 +1329,49 @@ impl encase::private::CreateFrom for Color {

impl encase::ShaderSize for Color {}

#[derive(Debug, Error)]
#[derive(Debug, Error, PartialEq, Eq)]
pub enum HexColorError {
#[error("Unexpected length of hex string")]
Length,
#[error("Error parsing hex value")]
Hex(#[from] hex::FromHexError),
#[error("Invalid hex char")]
Char(char),
}

fn decode_rgb(data: &[u8]) -> Result<Color, HexColorError> {
let mut buf = [0; 3];
match hex::decode_to_slice(data, &mut buf) {
Ok(_) => {
let r = buf[0] as f32 / 255.0;
let g = buf[1] as f32 / 255.0;
let b = buf[2] as f32 / 255.0;
Ok(Color::rgb(r, g, b))
}
Err(err) => Err(HexColorError::Hex(err)),
/// Converts hex bytes to an array of RGB\[A\] components
///
/// # Example
/// For RGB: *b"ffffff" -> [255, 255, 255, ..]
/// For RGBA: *b"E2E2E2FF" -> [226, 226, 226, 255, ..]
const fn decode_hex<const N: usize>(mut bytes: [u8; N]) -> Result<[u8; N], HexColorError> {
let mut i = 0;
while i < bytes.len() {
// Convert single hex digit to u8
let val = match hex_value(bytes[i]) {
Ok(val) => val,
Err(byte) => return Err(HexColorError::Char(byte as char)),
};
bytes[i] = val;
i += 1;
}
// Modify the original bytes to give an `N / 2` length result
i = 0;
while i < bytes.len() / 2 {
// Convert pairs of u8 to R/G/B/A
// e.g `ff` -> [102, 102] -> [15, 15] = 255
bytes[i] = bytes[i * 2] * 16 + bytes[i * 2 + 1];
i += 1;
}
Ok(bytes)
}

fn decode_rgba(data: &[u8]) -> Result<Color, HexColorError> {
let mut buf = [0; 4];
match hex::decode_to_slice(data, &mut buf) {
Ok(_) => {
let r = buf[0] as f32 / 255.0;
let g = buf[1] as f32 / 255.0;
let b = buf[2] as f32 / 255.0;
let a = buf[3] as f32 / 255.0;
Ok(Color::rgba(r, g, b, a))
}
Err(err) => Err(HexColorError::Hex(err)),
/// Parse a single hex digit (a-f/A-F/0-9) as a `u8`
const fn hex_value(b: u8) -> Result<u8, u8> {
match b {
b'0'..=b'9' => Ok(b - b'0'),
b'A'..=b'F' => Ok(b - b'A' + 10),
b'a'..=b'f' => Ok(b - b'a' + 10),
// Wrong hex digit
_ => Err(b),
}
}

Expand All @@ -1378,29 +1381,21 @@ mod tests {

#[test]
fn hex_color() {
assert_eq!(Color::hex("FFF").unwrap(), Color::rgb(1.0, 1.0, 1.0));
assert_eq!(Color::hex("000").unwrap(), Color::rgb(0.0, 0.0, 0.0));
assert!(Color::hex("---").is_err());

assert_eq!(Color::hex("FFFF").unwrap(), Color::rgba(1.0, 1.0, 1.0, 1.0));
assert_eq!(Color::hex("0000").unwrap(), Color::rgba(0.0, 0.0, 0.0, 0.0));
assert!(Color::hex("----").is_err());

assert_eq!(Color::hex("FFFFFF").unwrap(), Color::rgb(1.0, 1.0, 1.0));
assert_eq!(Color::hex("000000").unwrap(), Color::rgb(0.0, 0.0, 0.0));
assert!(Color::hex("------").is_err());

assert_eq!(
Color::hex("FFFFFFFF").unwrap(),
Color::rgba(1.0, 1.0, 1.0, 1.0)
);
assert_eq!(
Color::hex("00000000").unwrap(),
Color::rgba(0.0, 0.0, 0.0, 0.0)
);
assert!(Color::hex("--------").is_err());

assert!(Color::hex("1234567890").is_err());
assert_eq!(Color::hex("FFF"), Ok(Color::WHITE));
assert_eq!(Color::hex("FFFF"), Ok(Color::WHITE));
assert_eq!(Color::hex("FFFFFF"), Ok(Color::WHITE));
assert_eq!(Color::hex("FFFFFFFF"), Ok(Color::WHITE));
assert_eq!(Color::hex("000"), Ok(Color::BLACK));
assert_eq!(Color::hex("000F"), Ok(Color::BLACK));
assert_eq!(Color::hex("000000"), Ok(Color::BLACK));
assert_eq!(Color::hex("000000FF"), Ok(Color::BLACK));
assert_eq!(Color::hex("03a9f4"), Ok(Color::rgb_u8(3, 169, 244)));
assert_eq!(Color::hex("yy"), Err(HexColorError::Length));
assert_eq!(Color::hex("yyy"), Err(HexColorError::Char('y')));
assert_eq!(Color::hex("#f2a"), Ok(Color::rgb_u8(255, 34, 170)));
assert_eq!(Color::hex("#e23030"), Ok(Color::rgb_u8(226, 48, 48)));
assert_eq!(Color::hex("#ff"), Err(HexColorError::Length));
assert_eq!(Color::hex("##fff"), Err(HexColorError::Char('#')));
}

#[test]
Expand Down

0 comments on commit 637df33

Please sign in to comment.