Add custom pin drawing functionality to PinInfo struct

examples/demo.rs

@@ -95,6 +95,8 @@ impl DemoNode {
 struct DemoViewer;
 
 impl SnarlViewer<DemoNode> for DemoViewer {
+    type Drawer = egui_snarl::ui::PinShape;
+
     #[inline]
     fn connect(&mut self, from: &OutPin, to: &InPin, snarl: &mut Snarl<DemoNode>) {
         // Validate connection
@@ -179,7 +181,7 @@ impl SnarlViewer<DemoNode> for DemoViewer {
         ui: &mut Ui,
         scale: f32,
         snarl: &mut Snarl<DemoNode>,
-    ) -> PinInfo {
+    ) -> PinInfo<Self::Drawer> {
         match snarl[pin.id.node] {
             DemoNode::Sink => {
                 assert_eq!(pin.id.input, 0, "Sink node has only one input");
@@ -394,7 +396,7 @@ impl SnarlViewer<DemoNode> for DemoViewer {
         ui: &mut Ui,
         _scale: f32,
         snarl: &mut Snarl<DemoNode>,
-    ) -> PinInfo {
+    ) -> PinInfo<Self::Drawer> {
         match snarl[pin.id.node] {
             DemoNode::Sink => {
                 unreachable!("Sink node has no outputs")

src/ui.rs

@@ -26,7 +26,7 @@ use self::{
 
 pub use self::{
     background_pattern::{BackgroundPattern, Grid, Viewport},
-    pin::{AnyPins, PinInfo, PinShape},
+    pin::{AnyPins, PinDrawer, PinInfo, PinShape},
     viewer::SnarlViewer,
     wire::{WireLayer, WireStyle},
 };

src/ui/pin.rs

@@ -44,9 +44,9 @@ pub enum PinShape {
 /// All fields are optional.
 /// If a field is `None`, the default value is used derived from the graph style.
 #[derive(Default)]
-pub struct PinInfo {
+pub struct PinInfo<T: PinDrawer> {
     /// Shape of the pin.
-    pub shape: Option<PinShape>,
+    pub shape: Option<T>,
 
     /// Size of the pin.
     pub size: Option<f32>,
@@ -61,10 +61,17 @@ pub struct PinInfo {
     pub wire_style: Option<WireStyle>,
 }
 
-impl PinInfo {
+/// Customization for the pin.
+/// This trait is used to customize the appearance of the pin.
+pub trait PinDrawer: Sync + Send + From<PinShape> + Clone {
+    /// Draws the pin.
+    fn draw(&self, painter: &Painter, fill: Color32, stroke: Stroke, pos: Pos2, size: f32);
+}
+
+impl<T: PinDrawer> PinInfo<T> {
     /// Sets the shape of the pin.
     #[must_use]
-    pub const fn with_shape(mut self, shape: PinShape) -> Self {
+    pub fn with_shape(mut self, shape: T) -> Self {
         self.shape = Some(shape);
         self
     }
@@ -101,42 +108,66 @@ impl PinInfo {
     #[must_use]
     pub fn circle() -> Self {
         PinInfo {
-            shape: Some(PinShape::Circle),
-            ..Default::default()
+            shape: Some(PinShape::Circle.into()),
+            size: Default::default(),
+            fill: Default::default(),
+            stroke: Default::default(),
+            wire_style: Default::default(),
         }
     }
 
     /// Creates a triangle pin.
     #[must_use]
     pub fn triangle() -> Self {
         PinInfo {
-            shape: Some(PinShape::Triangle),
-            ..Default::default()
+            shape: Some(PinShape::Triangle.into()),
+            size: Default::default(),
+            fill: Default::default(),
+            stroke: Default::default(),
+            wire_style: Default::default(),
         }
     }
 
     /// Creates a square pin.
     #[must_use]
     pub fn square() -> Self {
         PinInfo {
-            shape: Some(PinShape::Square),
-            ..Default::default()
+            shape: Some(PinShape::Square.into()),
+            size: Default::default(),
+            fill: Default::default(),
+            stroke: Default::default(),
+            wire_style: Default::default(),
         }
     }
 
     /// Creates a star pin.
     #[must_use]
     pub fn star() -> Self {
         PinInfo {
-            shape: Some(PinShape::Star),
-            ..Default::default()
+            shape: Some(PinShape::Star.into()),
+            size: Default::default(),
+            fill: Default::default(),
+            stroke: Default::default(),
+            wire_style: Default::default(),
+        }
+    }
+
+    /// Creates a pin with the custom drawer.
+    #[must_use]
+    pub fn shape(drawer: T) -> PinInfo<T> {
+        PinInfo {
+            shape: Some(drawer),
+            size: Default::default(),
+            fill: Default::default(),
+            stroke: Default::default(),
+            wire_style: Default::default(),
         }
     }
 
     /// Returns the shape of the pin.
     #[must_use]
-    pub fn get_shape(&self, snarl_style: &SnarlStyle) -> PinShape {
-        self.shape.unwrap_or_else(|| snarl_style.get_pin_shape())
+    pub fn get_shape(&self, snarl_style: &SnarlStyle) -> T {
+        self.shape.clone().unwrap_or_else(|| Into::<T>::into(snarl_style.get_pin_shape()))
     }
 
     /// Returns fill color of the pin.
@@ -170,12 +201,19 @@ impl PinInfo {
         let fill = self.get_fill(snarl_style, style);
         let stroke = self.get_stroke(snarl_style, style, scale);
         let size = self.size.zoomed(scale).unwrap_or(size);
-        draw_pin(painter, shape, fill, stroke, pos, size);
+
+        shape.draw(painter, fill, stroke, pos, size);
 
         fill
     }
 }
 
+impl PinDrawer for PinShape {
+    fn draw(&self, painter: &Painter, fill: Color32, stroke: Stroke, pos: Pos2, size: f32) {
+        draw_pin(painter, *self, fill, stroke, pos, size);
+    }
+}
+
 pub fn draw_pin(
     painter: &Painter,
     shape: PinShape,

src/ui/viewer.rs

@@ -2,13 +2,19 @@ use egui::{Color32, Painter, Pos2, Rect, Style, Ui};
 
 use crate::{InPin, InPinId, NodeId, OutPin, OutPinId, Snarl};
 
-use super::{pin::AnyPins, BackgroundPattern, NodeLayout, PinInfo, SnarlStyle, Viewport};
+use super::{
+    pin::AnyPins, BackgroundPattern, NodeLayout, PinDrawer, PinInfo, SnarlStyle, Viewport,
+};
 
 /// `SnarlViewer` is a trait for viewing a Snarl.
 ///
 /// It can extract necessary data from the nodes and controls their
 /// response to certain events.
 pub trait SnarlViewer<T> {
+    /// The drawer type for the pins.
+    /// If you use the default pin drawer, you can use `PinShape` as the drawer type.
+    type Drawer: PinDrawer;
+
     /// Returns title of the node.
     fn title(&mut self, node: &T) -> String;
 
@@ -76,8 +82,13 @@ pub trait SnarlViewer<T> {
     fn inputs(&mut self, node: &T) -> usize;
 
     /// Renders the node's input.
-    fn show_input(&mut self, pin: &InPin, ui: &mut Ui, scale: f32, snarl: &mut Snarl<T>)
-        -> PinInfo;
+    fn show_input(
+        &mut self,
+        pin: &InPin,
+        ui: &mut Ui,
+        scale: f32,
+        snarl: &mut Snarl<T>,
+    ) -> PinInfo<Self::Drawer>;
 
     /// Returns number of output pins of the node.
     ///
@@ -91,7 +102,7 @@ pub trait SnarlViewer<T> {
         ui: &mut Ui,
         scale: f32,
         snarl: &mut Snarl<T>,
-    ) -> PinInfo;
+    ) -> PinInfo<Self::Drawer>;
 
     /// Checks if node has something to show in body - between input and output pins.
     #[inline]
@@ -298,7 +309,7 @@ pub trait SnarlViewer<T> {
     fn draw_input_pin(
         &mut self,
         pin: &InPin,
-        pin_info: &PinInfo,
+        pin_info: &PinInfo<Self::Drawer>,
         pos: Pos2,
         size: f32,
         snarl_style: &SnarlStyle,
@@ -322,7 +333,7 @@ pub trait SnarlViewer<T> {
     fn draw_output_pin(
         &mut self,
         pin: &OutPin,
-        pin_info: &PinInfo,
+        pin_info: &PinInfo<Self::Drawer>,
         pos: Pos2,
         size: f32,
         snarl_style: &SnarlStyle,