From 68b3ce274a1f02b8cc19020d4e6d7e9725e5a452 Mon Sep 17 00:00:00 2001
From: Bruce Mitchener <bruce.mitchener@gmail.com>
Date: Mon, 2 Dec 2024 08:17:30 +0700
Subject: [PATCH] Remove `ColorF64` (#759)

This is a step towards using `color` for the gradients, first moving to
use the `lerp` function in `AlphaColor` and getting rid of `ColorF64`
since our colors are now `f32`-based.
---
 vello_encoding/src/ramp_cache.rs          | 47 ++++-------------------
 vello_tests/snapshots/big_colr.png        |  4 +-
 vello_tests/snapshots/gradient_extend.png |  4 +-
 vello_tests/snapshots/little_colr.png     |  4 +-
 4 files changed, 14 insertions(+), 45 deletions(-)

diff --git a/vello_encoding/src/ramp_cache.rs b/vello_encoding/src/ramp_cache.rs
index 84ad5677d..4ddd423fa 100644
--- a/vello_encoding/src/ramp_cache.rs
+++ b/vello_encoding/src/ramp_cache.rs
@@ -3,8 +3,8 @@
 
 use std::collections::HashMap;
 
-use peniko::color::Srgb;
-use peniko::{Color, ColorStop, ColorStops};
+use peniko::color::{HueDirection, Srgb};
+use peniko::{ColorStop, ColorStops};
 
 const N_SAMPLES: usize = 512;
 const RETAINED_COUNT: usize = 64;
@@ -82,18 +82,18 @@ impl RampCache {
 
 fn make_ramp(stops: &[ColorStop]) -> impl Iterator<Item = u32> + '_ {
     let mut last_u = 0.0;
-    let mut last_c = ColorF64::from_color(stops[0].color.to_alpha_color::<Srgb>());
+    let mut last_c = stops[0].color.to_alpha_color::<Srgb>();
     let mut this_u = last_u;
     let mut this_c = last_c;
     let mut j = 0;
     (0..N_SAMPLES).map(move |i| {
-        let u = (i as f64) / (N_SAMPLES - 1) as f64;
+        let u = (i as f32) / (N_SAMPLES - 1) as f32;
         while u > this_u {
             last_u = this_u;
             last_c = this_c;
             if let Some(s) = stops.get(j + 1) {
-                this_u = s.offset as f64;
-                this_c = ColorF64::from_color(s.color.to_alpha_color::<Srgb>());
+                this_u = s.offset;
+                this_c = s.color.to_alpha_color::<Srgb>();
                 j += 1;
             } else {
                 break;
@@ -103,39 +103,8 @@ fn make_ramp(stops: &[ColorStop]) -> impl Iterator<Item = u32> + '_ {
         let c = if du < 1e-9 {
             this_c
         } else {
-            last_c.lerp(&this_c, (u - last_u) / du)
+            last_c.lerp(this_c, (u - last_u) / du, HueDirection::default())
         };
-        c.as_premul_u32()
+        c.premultiply().to_rgba8().to_u32()
     })
 }
-
-#[derive(Copy, Clone, Debug)]
-struct ColorF64([f64; 4]);
-
-impl ColorF64 {
-    fn from_color(color: Color) -> Self {
-        let [r, g, b, a] = color.components;
-        Self([r as f64, g as f64, b as f64, a as f64])
-    }
-
-    fn lerp(&self, other: &Self, a: f64) -> Self {
-        fn l(x: f64, y: f64, a: f64) -> f64 {
-            x * (1.0 - a) + y * a
-        }
-        Self([
-            l(self.0[0], other.0[0], a),
-            l(self.0[1], other.0[1], a),
-            l(self.0[2], other.0[2], a),
-            l(self.0[3], other.0[3], a),
-        ])
-    }
-
-    fn as_premul_u32(&self) -> u32 {
-        let a = self.0[3].clamp(0.0, 1.0);
-        let r = ((self.0[0] * a).clamp(0.0, 1.0) * 255.0) as u32;
-        let g = ((self.0[1] * a).clamp(0.0, 1.0) * 255.0) as u32;
-        let b = ((self.0[2] * a).clamp(0.0, 1.0) * 255.0) as u32;
-        let a = (a * 255.0) as u32;
-        r | (g << 8) | (b << 16) | (a << 24)
-    }
-}
diff --git a/vello_tests/snapshots/big_colr.png b/vello_tests/snapshots/big_colr.png
index 40386f9de..c7bc77824 100644
--- a/vello_tests/snapshots/big_colr.png
+++ b/vello_tests/snapshots/big_colr.png
@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:f10d642ad14b33815998273a8a44fb6ddb1d7b8e161b550d498200a584f8370f
-size 15853
+oid sha256:c43e1738715b4b4359bdda7831f4bedbac3db182884c78bdcabd44fc49fffd55
+size 15735
diff --git a/vello_tests/snapshots/gradient_extend.png b/vello_tests/snapshots/gradient_extend.png
index a0b738b10..f1cf71a9e 100644
--- a/vello_tests/snapshots/gradient_extend.png
+++ b/vello_tests/snapshots/gradient_extend.png
@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:b39d3054c979222c4030f76ed7045f5f82499a327e8a9e00af411d1b50b75b33
-size 55386
+oid sha256:b6a055128e09745f2ceedd753431f32602c2c5618bd8a563123ae7670a2f5932
+size 55394
diff --git a/vello_tests/snapshots/little_colr.png b/vello_tests/snapshots/little_colr.png
index 64a112292..69796d060 100644
--- a/vello_tests/snapshots/little_colr.png
+++ b/vello_tests/snapshots/little_colr.png
@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:4aabea4b8cbf754fdf29c9d454f0880bfb9b0d380818d2ddb1d9128aa80fddb9
-size 2039
+oid sha256:842fa191cb557818fc3ff5663801d297c22d71eb0eacafbd757a7cadf6aae1c7
+size 1938