Fix gamma correction for colored glyphs in `iced_wgpu`

4 files changed, 44 insertions, 15 deletions

diff --git a/core/src/color.rs b/core/src/color.rs
index 1392f28b..cce8b340 100644
--- a/core/src/color.rs
+++ b/core/src/color.rs
@@ -89,6 +89,26 @@ impl Color {
         }
     }
 
+    /// Creates a [`Color`] from its linear RGBA components.
+    pub fn from_linear_rgba(r: f32, g: f32, b: f32, a: f32) -> Self {
+        // As described in:
+        // https://en.wikipedia.org/wiki/SRGB
+        fn gamma_component(u: f32) -> f32 {
+            if u < 0.0031308 {
+                12.92 * u
+            } else {
+                1.055 * u.powf(1.0 / 2.4) - 0.055
+            }
+        }
+
+        Self {
+            r: gamma_component(r),
+            g: gamma_component(g),
+            b: gamma_component(b),
+            a,
+        }
+    }
+
     /// Converts the [`Color`] into its RGBA8 equivalent.
     #[must_use]
     pub fn into_rgba8(self) -> [u8; 4] {
diff --git a/graphics/src/text.rs b/graphics/src/text.rs
index 5fcfc699..c10eacad 100644
--- a/graphics/src/text.rs
+++ b/graphics/src/text.rs
@@ -8,6 +8,7 @@ pub use paragraph::Paragraph;
 
 pub use cosmic_text;
 
+use crate::color;
 use crate::core::font::{self, Font};
 use crate::core::text::Shaping;
 use crate::core::{Color, Size};
@@ -131,7 +132,12 @@ pub fn to_shaping(shaping: Shaping) -> cosmic_text::Shaping {
 }
 
 pub fn to_color(color: Color) -> cosmic_text::Color {
-    let [r, g, b, a] = color.into_rgba8();
-
-    cosmic_text::Color::rgba(r, g, b, a)
+    let [r, g, b, a] = color::pack(color).components();
+
+    cosmic_text::Color::rgba(
+        (r * 255.0) as u8,
+        (g * 255.0) as u8,
+        (b * 255.0) as u8,
+        (a * 255.0) as u8,
+    )
 }
diff --git a/tiny_skia/src/text.rs b/tiny_skia/src/text.rs
index d1b33293..70e95d01 100644
--- a/tiny_skia/src/text.rs
+++ b/tiny_skia/src/text.rs
@@ -1,6 +1,7 @@
 use crate::core::alignment;
 use crate::core::text::{LineHeight, Shaping};
 use crate::core::{Color, Font, Pixels, Point, Rectangle};
+use crate::graphics::color;
 use crate::graphics::text::cache::{self, Cache};
 use crate::graphics::text::editor;
 use crate::graphics::text::font_system;
@@ -216,7 +217,18 @@ fn draw(
 fn from_color(color: cosmic_text::Color) -> Color {
     let [r, g, b, a] = color.as_rgba();
 
-    Color::from_rgba8(r, g, b, a as f32 / 255.0)
+    if color::GAMMA_CORRECTION {
+        // `cosmic_text::Color` is linear RGB in this case, so we
+        // need to convert back to sRGB
+        Color::from_linear_rgba(
+            r as f32 / 255.0,
+            g as f32 / 255.0,
+            b as f32 / 255.0,
+            a as f32 / 255.0,
+        )
+    } else {
+        Color::from_rgba8(r, g, b, a as f32 / 255.0)
+    }
 }
 
 #[derive(Debug, Clone, Default)]
diff --git a/wgpu/src/text.rs b/wgpu/src/text.rs
index 581df0cb..f746be63 100644
--- a/wgpu/src/text.rs
+++ b/wgpu/src/text.rs
@@ -2,7 +2,7 @@ use crate::core::alignment;
 use crate::core::{Rectangle, Size};
 use crate::graphics::color;
 use crate::graphics::text::cache::{self, Cache};
-use crate::graphics::text::{font_system, Editor, Paragraph};
+use crate::graphics::text::{font_system, to_color, Editor, Paragraph};
 use crate::layer::Text;
 
 use std::borrow::Cow;
@@ -214,16 +214,7 @@ impl Pipeline {
                         right: (clip_bounds.x + clip_bounds.width) as i32,
                         bottom: (clip_bounds.y + clip_bounds.height) as i32,
                     },
-                    default_color: {
-                        let [r, g, b, a] = color::pack(color).components();
-
-                        glyphon::Color::rgba(
-                            (r * 255.0) as u8,
-                            (g * 255.0) as u8,
-                            (b * 255.0) as u8,
-                            (a * 255.0) as u8,
-                        )
-                    },
+                    default_color: to_color(color),
                 })
             },
         );