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speed up rgb conversion from u8 -> linear f32

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This commit is contained in:
Wez Furlong 2019-09-29 20:52:47 -07:00
parent c6fd88d8c5
commit 1e25003cb6
1 changed files with 59 additions and 13 deletions
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72
window/src/color.rs
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@ -1,5 +1,27 @@
use crate::Operator;
use palette::{Blend, Srgb, Srgba};
use palette::{Blend, LinSrgb, LinSrgba, Srgb, Srgba};
lazy_static::lazy_static! {
static ref SRGB_TO_F32_TABLE: [f32;256] = generate_srgb8_to_linear_f32_table();
}
fn generate_srgb8_to_linear_f32_table() -> [f32; 256] {
let mut table = [0.; 256];
for val in 0..256 {
let c = (val as f32) / 255.0;
let f = if c < 0.04045 {
c / 12.92
} else {
((c + 0.055) / 1.055).powf(2.4)
};
table[val] = f;
}
table
}
fn srgb8_to_linear_f32(val: u8) -> f32 {
unsafe { *SRGB_TO_F32_TABLE.get_unchecked(val as usize) }
}
/// A color stored as big endian bgra32
#[derive(Copy, Clone, Debug)]
@ -23,6 +45,31 @@ impl From<Srgba> for Color {
}
}
impl From<Color> for LinSrgb {
#[inline]
fn from(c: Color) -> LinSrgb {
let c = c.as_rgba();
LinSrgb::new(
srgb8_to_linear_f32(c.0),
srgb8_to_linear_f32(c.1),
srgb8_to_linear_f32(c.2),
)
}
}
impl From<Color> for LinSrgba {
#[inline]
fn from(c: Color) -> LinSrgba {
let c = c.as_rgba();
LinSrgba::new(
srgb8_to_linear_f32(c.0),
srgb8_to_linear_f32(c.1),
srgb8_to_linear_f32(c.2),
srgb8_to_linear_f32(c.3),
)
}
}
impl From<Color> for Srgb {
#[inline]
fn from(c: Color) -> Srgb {
@ -70,30 +117,29 @@ impl Color {
pub fn composite(&self, dest: Color, operator: &Operator) -> Color {
match operator {
&Operator::Over => {
let src: Srgba = (*self).into();
let dest: Srgba = dest.into();
Srgba::from_linear(src.into_linear().over(dest.into_linear())).into()
let src: LinSrgba = (*self).into();
let dest: LinSrgba = dest.into();
Srgba::from_linear(src.over(dest)).into()
}
&Operator::Source => *self,
&Operator::Multiply => {
let src: Srgba = (*self).into();
let dest: Srgba = dest.into();
let result: Color =
Srgba::from_linear(src.into_linear().multiply(dest.into_linear())).into();
let src: LinSrgba = (*self).into();
let dest: LinSrgba = dest.into();
let result: Color = Srgba::from_linear(src.multiply(dest)).into();
result.into()
}
&Operator::MultiplyThenOver(ref tint) => {
// First multiply by the tint color. This colorizes the glyph.
let src: Srgba = (*self).into();
let tint: Srgba = (*tint).into();
let mut tinted = src.into_linear().multiply(tint.into_linear());
let src: LinSrgba = (*self).into();
let tint: LinSrgba = (*tint).into();
let mut tinted = src.multiply(tint);
// We take the alpha from the source. This is important because
// we're using Multiply to tint the glyph and if we don't reset the
// alpha we tend to end up with a background square of the tint color.
tinted.alpha = src.alpha;
// Then blend the tinted glyph over the destination background
let dest: Srgba = dest.into();
Srgba::from_linear(tinted.over(dest.into_linear())).into()
let dest: LinSrgba = dest.into();
Srgba::from_linear(tinted.over(dest)).into()
}
}
}