Fix the blend mode and opacity widgets of the Layers panel (#1506)

* Fix blend mode and opacity

* Cleanup and bug fixes

---------

Co-authored-by: Keavon Chambers <keavon@keavon.com>

editor/src/messages/tool/common_functionality/graph_modification_utils.rs

@@ -4,7 +4,7 @@ use crate::messages::prelude::*;
 use bezier_rs::{ManipulatorGroup, Subpath};
 use document_legacy::{document::Document, document_metadata::LayerNodeIdentifier, LayerId, Operation};
 use graph_craft::document::{value::TaggedValue, DocumentNode, NodeId, NodeInput, NodeNetwork};
-use graphene_core::raster::ImageFrame;
+use graphene_core::raster::{BlendMode, ImageFrame};
 use graphene_core::text::Font;
 use graphene_core::uuid::ManipulatorGroupId;
 use graphene_core::vector::style::{FillType, Gradient};
@@ -98,7 +98,7 @@ pub fn get_mirror_handles(layer: LayerNodeIdentifier, document: &Document) -> Op
 	}
 }
 
-/// Get the current gradient of a layer from the closest fill node
+/// Get the current gradient of a layer from the closest Fill node
 pub fn get_gradient(layer: LayerNodeIdentifier, document: &Document) -> Option<Gradient> {
 	let inputs = NodeGraphLayer::new(layer, document)?.find_node_inputs("Fill")?;
 	let TaggedValue::FillType(FillType::Gradient) = inputs.get(1)?.as_value()? else {
@@ -128,7 +128,7 @@ pub fn get_gradient(layer: LayerNodeIdentifier, document: &Document) -> Option<G
 	})
 }
 
-/// Get the current fill of a layer from the closest fill node
+/// Get the current fill of a layer from the closest Fill node
 pub fn get_fill_color(layer: LayerNodeIdentifier, document: &Document) -> Option<Color> {
 	let inputs = NodeGraphLayer::new(layer, document)?.find_node_inputs("Fill")?;
 	let TaggedValue::Color(color) = inputs.get(2)?.as_value()? else {
@@ -137,14 +137,39 @@ pub fn get_fill_color(layer: LayerNodeIdentifier, document: &Document) -> Option
 	Some(*color)
 }
 
-pub fn get_text_id(layer: LayerNodeIdentifier, document: &Document) -> Option<NodeId> {
-	NodeGraphLayer::new(layer, document)?.node_id("Text")
+/// Get the current blend mode of a layer from the closest Blend Mode node
+pub fn get_blend_mode(layer: LayerNodeIdentifier, document: &Document) -> Option<BlendMode> {
+	let inputs = NodeGraphLayer::new(layer, document)?.find_node_inputs("Blend Mode")?;
+	let TaggedValue::BlendMode(blend_mode) = inputs.get(1)?.as_value()? else {
+		return None;
+	};
+	Some(*blend_mode)
 }
+
+/// Get the current opacity of a layer from the closest Opacity node.
+/// This may differ from the actual opacity contained within the data type reaching this layer, because that actual opacity may be:
+/// - Multiplied with additional opacity nodes earlier in the chain
+/// - Set by an Opacity node with an exposed parameter value driven by another node
+/// - Already factored into the pixel alpha channel of an image
+/// - The default value of 100% if no Opacity node is present, but this function returns None in that case
+/// With those limitations in mind, the intention of this function is to show just the value already present in an upstream Opacity node so that value can be directly edited.
+pub fn get_opacity(layer: LayerNodeIdentifier, document: &Document) -> Option<f32> {
+	let inputs = NodeGraphLayer::new(layer, document)?.find_node_inputs("Opacity")?;
+	let TaggedValue::F32(opacity) = inputs.get(1)?.as_value()? else {
+		return None;
+	};
+	Some(*opacity)
+}
+
 pub fn get_fill_id(layer: LayerNodeIdentifier, document: &Document) -> Option<NodeId> {
 	NodeGraphLayer::new(layer, document)?.node_id("Fill")
 }
 
-/// Gets properties from the text node
+pub fn get_text_id(layer: LayerNodeIdentifier, document: &Document) -> Option<NodeId> {
+	NodeGraphLayer::new(layer, document)?.node_id("Text")
+}
+
+/// Gets properties from the Text node
 pub fn get_text(layer: LayerNodeIdentifier, document: &Document) -> Option<(&String, &Font, f64)> {
 	let inputs = NodeGraphLayer::new(layer, document)?.find_node_inputs("Text")?;
 	let NodeInput::Value {
@@ -174,19 +199,9 @@ pub fn get_text(layer: LayerNodeIdentifier, document: &Document) -> Option<(&Str
 	Some((text, font, font_size))
 }
 
-/// Is a specified layer an artboard?
-pub fn is_artboard(layer: LayerNodeIdentifier, document: &Document) -> bool {
-	NodeGraphLayer::new(layer, document).is_some_and(|layer| layer.uses_node("Artboard"))
-}
-
-/// Is a specified layer a shape?
-pub fn is_shape_layer(layer: LayerNodeIdentifier, document: &Document) -> bool {
-	NodeGraphLayer::new(layer, document).is_some_and(|layer| layer.uses_node("Shape"))
-}
-
-/// Is a specified layer text?
-pub fn is_text_layer(layer: LayerNodeIdentifier, document: &Document) -> bool {
-	NodeGraphLayer::new(layer, document).is_some_and(|layer| layer.uses_node("Text"))
+/// Checks if a specified layer uses an upstream node matching the given name.
+pub fn is_layer_fed_by_node_of_name(layer: LayerNodeIdentifier, document: &Document, node_name: &str) -> bool {
+	NodeGraphLayer::new(layer, document).is_some_and(|layer| layer.find_node_inputs(node_name).is_some())
 }
 
 /// Convert subpaths to an iterator of manipulator groups
@@ -243,19 +258,18 @@ impl<'a> NodeGraphLayer<'a> {
 		self.node_graph.upstream_flow_back_from_nodes(vec![self.layer_node], true)
 	}
 
-	/// Does a node exist in the layer's primary flow
-	pub fn uses_node(&self, node_name: &str) -> bool {
-		self.primary_layer_flow().any(|(node, _id)| node.name == node_name)
-	}
-
 	/// Node id of a node if it exists in the layer's primary flow
 	pub fn node_id(&self, node_name: &str) -> Option<NodeId> {
 		self.primary_layer_flow().find(|(node, _id)| node.name == node_name).map(|(_node, id)| id)
 	}
 
-	/// Find all of the inputs of a specific node within the layer's primary flow
+	/// Find all of the inputs of a specific node within the layer's primary flow, up until the next layer is reached.
 	pub fn find_node_inputs(&self, node_name: &str) -> Option<&'a Vec<NodeInput>> {
-		self.primary_layer_flow().find(|(node, _id)| node.name == node_name).map(|(node, _id)| &node.inputs)
+		self.primary_layer_flow()
+			.skip(1)
+			.take_while(|(node, _)| !node.is_layer())
+			.find(|(node, _)| node.name == node_name)
+			.map(|(node, _id)| &node.inputs)
 	}
 
 	/// Find a specific input of a node within the layer's primary flow