Add per-link line width support

Extend LinkModel trait with line_width() method (default: 2.0px) and
add line_width field to SimpleLink, LinkData, and the rendering pipeline.
This allows each link to have its own stroke width for visual distinction.

Author: tilladam

examples/advanced/src/main.rs

@@ -59,6 +59,9 @@ impl LinkModel for LinkData {
     fn end_pin_id(&self) -> i32 {
         self.end_pin_id
     }
+    fn line_width(&self) -> f32 {
+        self.line_width
+    }
 }
 
 /// Helper to remove items by ID from a model based on selection
@@ -224,12 +227,14 @@ fn main() {
             start_pin_id: 1002,
             end_pin_id: 2001,
             color: link_colors[0],
+            line_width: 1.5, // Thin link
         },
         LinkData {
             id: 2,
             start_pin_id: 2002,
             end_pin_id: 3001,
             color: link_colors[1],
+            line_width: 5.0, // Thick link to demonstrate feature
         },
     ]));
     window.set_links(ModelRc::from(links.clone()));
@@ -468,7 +473,7 @@ fn main() {
             let color = link_colors[idx];
 
             if let Some(_path) = cache.compute_link_path(output_pin, input_pin, w.get_zoom(), w.get_bezier_min_offset()) {
-                let data = LinkData { id, start_pin_id: output_pin, end_pin_id: input_pin, color };
+                let data = LinkData { id, start_pin_id: output_pin, end_pin_id: input_pin, color, line_width: 2.0 };
                 links.push(data);
             }
         }
@@ -550,28 +555,27 @@ fn main() {
 
     let filter_nodes_for_type = filter_nodes.clone();
     window.on_filter_type_changed(move |id, idx| {
-        for i in 0..filter_nodes_for_type.row_count() {
-            if let Some(mut node) = filter_nodes_for_type.row_data(i) {
-                if node.id == id { node.filter_type_index = idx; filter_nodes_for_type.set_row_data(i, node); break; }
-            }
+        if let Some((i, mut node)) = GraphLogic::find_node_by_id(&filter_nodes_for_type, id, |n| n.id) {
+            node.filter_type_index = idx;
+            filter_nodes_for_type.set_row_data(i, node);
         }
     });
 
     let filter_nodes_for_enable = filter_nodes.clone();
     window.on_filter_toggle_enabled(move |id| {
-        for i in 0..filter_nodes_for_enable.row_count() {
-            if let Some(mut node) = filter_nodes_for_enable.row_data(i) {
-                if node.id == id { node.enabled = !node.enabled; filter_nodes_for_enable.set_row_data(i, node); break; }
-            }
+        if let Some((i, mut node)) = GraphLogic::find_node_by_id(&filter_nodes_for_enable, id, |n| n.id) {
+            node.enabled = !node.enabled;
+            filter_nodes_for_enable.set_row_data(i, node);
         }
     });
 
     let filter_nodes_for_reset = filter_nodes.clone();
     window.on_filter_reset(move |id| {
-        for i in 0..filter_nodes_for_reset.row_count() {
-            if let Some(mut node) = filter_nodes_for_reset.row_data(i) {
-                if node.id == id { node.processed_count = 0; node.filter_type_index = 0; node.enabled = true; filter_nodes_for_reset.set_row_data(i, node); break; }
-            }
+        if let Some((i, mut node)) = GraphLogic::find_node_by_id(&filter_nodes_for_reset, id, |n| n.id) {
+            node.processed_count = 0;
+            node.filter_type_index = 0;
+            node.enabled = true;
+            filter_nodes_for_reset.set_row_data(i, node);
         }
     });
 

examples/custom-shapes/src/main.rs

@@ -49,12 +49,14 @@ fn main() {
             start_pin_id: 3, // Node 1 output
             end_pin_id: 4,   // Node 2 input
             color: Color::from_argb_u8(255, 100, 180, 255),
+            line_width: 2.0,
         },
         LinkData {
             id: 2,
             start_pin_id: 7, // Node 3 output
             end_pin_id: 4,   // Node 2 input
             color: Color::from_argb_u8(255, 255, 180, 100),
+            line_width: 3.0, // Thicker link
         },
     ]))));
 

examples/minimal/src/main.rs

@@ -23,6 +23,7 @@ fn main() {
             start_pin_id: 3, // Node 1 output (node_id * 2 + 1)
             end_pin_id: 4,   // Node 2 input (node_id * 2)
             color: Color::from_argb_u8(255, 100, 180, 255),
+            line_width: 2.0,
         },
     ]))));
 

node-editor-building-blocks.slint

@@ -117,6 +117,8 @@ export struct LinkData {
     start-pin-id: int,
     end-pin-id: int,
     color: color,
+    /// Line width in pixels (default: 2.0 if not specified)
+    line-width: float,
 }
 
 /// Minimap component for bird's-eye view of the node graph.

node-editor.slint

@@ -497,6 +497,7 @@ export component NodeEditor {
     for link in root.links: Link {
         path-commands: root.compute-link-path(link.start-pin-id, link.end-pin-id, root.geometry-version);
         link-color: link.color;
+        line-width: link.line-width > 0 ? link.line-width * 1px : 2px;
         selected: root.is-link-selected(link.id, root.selection-version);
         hovered: root.hovered-link-id == link.id;
     }

src/graph.rs

@@ -17,6 +17,7 @@ use std::fmt;
 ///     from: i32,
 ///     to: i32,
 ///     color: Color,
+///     width: f32,
 ///     label: String,  // custom field
 /// }
 ///
@@ -25,6 +26,7 @@ use std::fmt;
 ///     fn start_pin_id(&self) -> i32 { self.from }
 ///     fn end_pin_id(&self) -> i32 { self.to }
 ///     fn color(&self) -> Color { self.color }
+///     fn line_width(&self) -> f32 { self.width }
 /// }
 /// ```
 pub trait LinkModel {
@@ -38,6 +40,10 @@ pub trait LinkModel {
     fn color(&self) -> Color {
         Color::from_rgb_u8(255, 255, 255)
     }
+    /// Line width in pixels for rendering the link (default: 2.0)
+    fn line_width(&self) -> f32 {
+        2.0
+    }
 }
 
 /// Simple link data structure implementing [`LinkModel`].
@@ -50,15 +56,21 @@ pub struct SimpleLink {
     pub start_pin_id: i32,
     pub end_pin_id: i32,
     pub color: Color,
+    pub line_width: f32,
 }
 
 impl SimpleLink {
-    /// Create a new link with the specified endpoints and color.
+    /// Create a new link with the specified endpoints, color, and line width.
     pub fn new(id: i32, start_pin_id: i32, end_pin_id: i32, color: Color) -> Self {
-        Self { id, start_pin_id, end_pin_id, color }
+        Self { id, start_pin_id, end_pin_id, color, line_width: 2.0 }
+    }
+
+    /// Create a new link with custom line width.
+    pub fn with_line_width(id: i32, start_pin_id: i32, end_pin_id: i32, color: Color, line_width: f32) -> Self {
+        Self { id, start_pin_id, end_pin_id, color, line_width }
     }
 
-    /// Create a new link with default white color.
+    /// Create a new link with default white color and default line width.
     pub fn with_default_color(id: i32, start_pin_id: i32, end_pin_id: i32) -> Self {
         Self::new(id, start_pin_id, end_pin_id, Color::from_rgb_u8(255, 255, 255))
     }
@@ -69,6 +81,7 @@ impl LinkModel for SimpleLink {
     fn start_pin_id(&self) -> i32 { self.start_pin_id }
     fn end_pin_id(&self) -> i32 { self.end_pin_id }
     fn color(&self) -> Color { self.color }
+    fn line_width(&self) -> f32 { self.line_width }
 }
 
 /// Trait for nodes that can be moved (dragged) in the editor.

src/links.rs

@@ -16,8 +16,13 @@
 //!
 //! // Set up link management
 //! let mut links = LinkManager::new(tracker.cache());
+//!
+//! // Add a link with default line width (2.0)
 //! links.add(SimpleLink::new(1, output_pin, input_pin, Color::from_rgb_u8(100, 180, 255)));
 //!
+//! // Or add a link with custom line width
+//! links.add(SimpleLink::with_line_width(2, output_pin, input_pin, Color::from_rgb_u8(255, 100, 100), 4.0));
+//!
 //! // Connect to Slint
 //! window.set_link_paths(links.paths());
 //!
@@ -46,12 +51,12 @@ struct ConcreteModelSyncer<P, F> {
 impl<P, F> ModelSyncer for ConcreteModelSyncer<P, F>
 where
     P: Clone + 'static,
-    F: Fn(i32, SharedString, slint::Color) -> P,
+    F: Fn(i32, SharedString, slint::Color, f32) -> P,
 {
     fn sync(&self, paths: &[LinkPathData]) {
         // Update existing rows or add new ones
         for (i, path) in paths.iter().enumerate() {
-            let item = (self.constructor)(path.id, path.path_commands.clone().into(), path.color);
+            let item = (self.constructor)(path.id, SharedString::from(path.path_commands.as_str()), path.color, path.line_width);
             if i < self.model.row_count() {
                 self.model.set_row_data(i, item);
             } else {
@@ -114,6 +119,7 @@ struct LinkPathData {
     id: i32,
     path_commands: String,
     color: slint::Color,
+    line_width: f32,
 }
 
 impl<L, N> LinkManager<L, N>
@@ -145,11 +151,11 @@ where
     /// # Arguments
     ///
     /// * `model` - The VecModel to sync to
-    /// * `constructor` - Function to create path items from (id, path_commands, color)
+    /// * `constructor` - Function to create path items from (id, path_commands, color, line_width)
     pub fn bind_model<P, F>(&mut self, model: Rc<VecModel<P>>, constructor: F)
     where
         P: Clone + 'static,
-        F: Fn(i32, SharedString, slint::Color) -> P + 'static,
+        F: Fn(i32, SharedString, slint::Color, f32) -> P + 'static,
     {
         self.syncer = Some(Box::new(ConcreteModelSyncer { model, constructor }));
     }
@@ -230,6 +236,7 @@ where
                     id: link.id(),
                     path_commands: path,
                     color: link.color(),
+                    line_width: link.line_width(),
                 });
             }
         }
@@ -270,19 +277,19 @@ pub trait LinkPathProvider {
     /// Create a Slint-compatible model of link paths.
     ///
     /// The returned closure takes a constructor function that creates
-    /// the Slint LinkPath type from (id, path_commands, color).
+    /// the Slint LinkPath type from (id, path_commands, color, line_width).
     fn create_paths_model<P, F>(&self, constructor: F) -> ModelRc<P>
     where
         P: Clone + 'static,
-        F: Fn(i32, slint::SharedString, slint::Color) -> P + 'static;
+        F: Fn(i32, slint::SharedString, slint::Color, f32) -> P + 'static;
 
     /// Update an existing paths model in place.
     ///
     /// This is more efficient than creating a new model each time.
     fn update_paths_model<P, F>(&self, model: &VecModel<P>, constructor: F)
     where
         P: Clone + 'static,
-        F: Fn(i32, slint::SharedString, slint::Color) -> P;
+        F: Fn(i32, slint::SharedString, slint::Color, f32) -> P;
 }
 
 impl<L, N> LinkPathProvider for LinkManager<L, N>
@@ -293,26 +300,26 @@ where
     fn create_paths_model<P, F>(&self, constructor: F) -> ModelRc<P>
     where
         P: Clone + 'static,
-        F: Fn(i32, slint::SharedString, slint::Color) -> P + 'static,
+        F: Fn(i32, slint::SharedString, slint::Color, f32) -> P + 'static,
     {
         let paths = self.paths.borrow();
         let items: Vec<P> = paths
             .iter()
-            .map(|p| constructor(p.id, p.path_commands.clone().into(), p.color))
+            .map(|p| constructor(p.id, SharedString::from(p.path_commands.as_str()), p.color, p.line_width))
             .collect();
         ModelRc::from(Rc::new(VecModel::from(items)))
     }
 
     fn update_paths_model<P, F>(&self, model: &VecModel<P>, constructor: F)
     where
         P: Clone + 'static,
-        F: Fn(i32, slint::SharedString, slint::Color) -> P,
+        F: Fn(i32, slint::SharedString, slint::Color, f32) -> P,
     {
         let paths = self.paths.borrow();
 
         // Update existing rows or add new ones
         for (i, path) in paths.iter().enumerate() {
-            let item = constructor(path.id, path.path_commands.clone().into(), path.color);
+            let item = constructor(path.id, SharedString::from(path.path_commands.as_str()), path.color, path.line_width);
             if i < model.row_count() {
                 model.set_row_data(i, item);
             } else {