Add a gradient interpolation space attribute with sRGB Gamma (existing) and sRGB Linear (new) (#4412)

* Build dropdown menu entries from choice type metadata

* Add a gradient interpolation color space attribute, blending stops in linear light by default

* Add a Space interpolation dropdown to the color picker popover

* Stamp legacy gradient ramps with their implicit gamma interpolation during deserialization

* Resolve color-interpolation from SVG style blocks and fix cascade order among repeated declarations

node-graph/nodes/graphic/src/graphic.rs

@@ -9,7 +9,7 @@ use rand::SeedableRng;
 use rand::seq::SliceRandom;
 use raster_types::{CPU, GPU, Raster};
 use std::cmp::Ordering;
-use vector_types::gradient::{GradientForm, GradientSpread};
+use vector_types::gradient::{GradientForm, GradientInterpolation, GradientSpread};
 use vector_types::{Gradient, ReferencePoint};
 
 /// Returns the list with the item at the specified index removed.
@@ -747,6 +747,23 @@ fn read_attribute_gradient_spread(
 	result
 }
 
+/// Reads a named `GradientInterpolation` attribute from the input list, outputting each value as an element of a new `GradientInterpolation[]`.
+#[node_macro::node(category("Attributes: Read"))]
+fn read_attribute_gradient_interpolation(
+	_: impl Ctx,
+	content: ListDyn,
+	/// The attribute name (key) to read.
+	name: Item<String>,
+) -> List<GradientInterpolation> {
+	let name = name.into_element();
+	let mut result = List::with_capacity(content.len());
+	for index in 0..content.len() {
+		let Some(value) = content.attribute::<GradientInterpolation>(&name, index) else { continue };
+		result.push(Item::new_from_element(*value));
+	}
+	result
+}
+
 /// Reads a named `Gradient` attribute from the input list, outputting each value as an element of a new `Gradient[]`.
 #[node_macro::node(category("Attributes: Read"))]
 fn read_attribute_gradient_stops(

node-graph/nodes/math/src/lib.rs

@@ -1393,6 +1393,14 @@ fn gradient_spread(_: impl Ctx, gradient: Item<Gradient>, gradient_spread: Item<
 	gradient
 }
 
+/// Sets the color space each gradient in the input list blends between its stops with: linear light or gamma-encoded sRGB.
+#[node_macro::node(category("Gradient"))]
+fn gradient_interpolation(_: impl Ctx, gradient: Item<Gradient>, gradient_interpolation: Item<vector_types::GradientInterpolation>) -> Item<Gradient> {
+	let mut gradient = gradient;
+	gradient.set_attribute(core_types::ATTR_GRADIENT_INTERPOLATION, *gradient_interpolation.element());
+	gradient
+}
+
 /// Sets the position of each of a gradient's stops, a factor from 0 to 1 along the gradient.
 ///
 /// A list shorter than the stop count repeats its last value, a longer list is truncated, and an empty list sets each stop to its default evenly spaced position.

node-graph/nodes/path-bool/src/lib.rs

@@ -1,10 +1,11 @@
 use core_types::list::{ATTR_FILL, Item, ItemAttributeValues, List};
 use core_types::{
-	ATTR_BLEND_MODE, ATTR_CLIPPING_MASK, ATTR_EDITOR_LAYER_PATH, ATTR_EDITOR_MERGED_LAYERS, ATTR_GRADIENT_FORM, ATTR_GRADIENT_SPREAD, ATTR_OPACITY, ATTR_OPACITY_FILL, ATTR_TRANSFORM, Color, Ctx,
+	ATTR_BLEND_MODE, ATTR_CLIPPING_MASK, ATTR_EDITOR_LAYER_PATH, ATTR_EDITOR_MERGED_LAYERS, ATTR_GRADIENT_FORM, ATTR_GRADIENT_INTERPOLATION, ATTR_GRADIENT_SPREAD, ATTR_OPACITY, ATTR_OPACITY_FILL,
+	ATTR_TRANSFORM, Color, Ctx,
 };
 use glam::{DAffine2, DVec2};
 use graphic_types::graphic::{bake_paint_transforms, set_paint_attribute};
-use graphic_types::vector_types::gradient::{GradientForm, GradientSpread};
+use graphic_types::vector_types::gradient::{GradientForm, GradientInterpolation, GradientSpread};
 use graphic_types::vector_types::subpath::{ManipulatorGroup, Subpath};
 use graphic_types::vector_types::vector::PointId;
 use graphic_types::vector_types::vector::algorithms::merge_by_distance::MergeByDistanceExt;
@@ -289,6 +290,9 @@ fn flatten_vector(graphic_list: &List<Graphic>) -> List<Vector> {
 						if let Some(gradient_spread) = attributes.remove::<GradientSpread>(ATTR_GRADIENT_SPREAD) {
 							gradient_paint.set_attribute(ATTR_GRADIENT_SPREAD, 0, gradient_spread);
 						}
+						if let Some(gradient_interpolation) = attributes.remove::<GradientInterpolation>(ATTR_GRADIENT_INTERPOLATION) {
+							gradient_paint.set_attribute(ATTR_GRADIENT_INTERPOLATION, 0, gradient_interpolation);
+						}
 						set_paint_attribute(&mut attributes, ATTR_FILL, gradient_paint);
 
 						let mut element = Vector::default();