Merge pull request #69 from setzer22/feature/user_state_in_value_widget

Expose UserState and the node id to value_widget

egui_node_graph/src/editor_ui.rs

@@ -76,7 +76,8 @@ where
         ValueType = ValueType,
     >,
     UserResponse: UserResponseTrait,
-    ValueType: WidgetValueTrait<Response = UserResponse>,
+    ValueType:
+        WidgetValueTrait<Response = UserResponse, UserState = UserState, NodeData = NodeData>,
     NodeTemplate: NodeTemplateTrait<
         NodeData = NodeData,
         DataType = DataType,
@@ -152,10 +153,10 @@ where
                 node_finder_area = node_finder_area.current_pos(pos);
             }
             node_finder_area.show(ui.ctx(), |ui| {
-                if let Some(node_kind) = node_finder.show(ui, all_kinds) {
+                if let Some(node_kind) = node_finder.show(ui, all_kinds, user_state) {
                     let new_node = self.graph.add_node(
-                        node_kind.node_graph_label(),
-                        node_kind.user_data(),
+                        node_kind.node_graph_label(user_state),
+                        node_kind.user_data(user_state),
                         |graph, node_id| node_kind.build_node(graph, user_state, node_id),
                     );
                     self.node_positions.insert(
@@ -391,7 +392,8 @@ where
         ValueType = ValueType,
     >,
     UserResponse: UserResponseTrait,
-    ValueType: WidgetValueTrait<Response = UserResponse>,
+    ValueType:
+        WidgetValueTrait<Response = UserResponse, UserState = UserState, NodeData = NodeData>,
     DataType: DataTypeTrait<UserState>,
 {
     pub const MAX_NODE_SIZE: [f32; 2] = [200.0, 200.0];
@@ -469,13 +471,23 @@ where
                     if self.graph.connection(param_id).is_some() {
                         ui.label(param_name);
                     } else {
-                        responses.extend(
-                            self.graph[param_id]
-                                .value
-                                .value_widget(&param_name, ui)
-                                .into_iter()
-                                .map(NodeResponse::User),
+                        // NOTE: We want to pass the `user_data` to
+                        // `value_widget`, but we can't since that would require
+                        // borrowing the graph twice. Here, we make the
+                        // assumption that the value is cheaply replaced, and
+                        // use `std::mem::take` to temporarily replace it with a
+                        // dummy value. This requires `ValueType` to implement
+                        // Default, but results in a totally safe alternative.
+                        let mut value = std::mem::take(&mut self.graph[param_id].value);
+                        let node_responses = value.value_widget(
+                            &param_name,
+                            self.node_id,
+                            ui,
+                            user_state,
+                            &self.graph[self.node_id].user_data,
                         );
+                        self.graph[param_id].value = value;
+                        responses.extend(node_responses.into_iter().map(NodeResponse::User));
                     }
                     let height_after = ui.min_rect().bottom();
                     input_port_heights.push((height_before + height_after) / 2.0);

egui_node_graph/src/node_finder.rs

@@ -14,9 +14,9 @@ pub struct NodeFinder<NodeTemplate> {
     _phantom: PhantomData<NodeTemplate>,
 }
 
-impl<NodeTemplate, NodeData> NodeFinder<NodeTemplate>
+impl<NodeTemplate, NodeData, UserState> NodeFinder<NodeTemplate>
 where
-    NodeTemplate: NodeTemplateTrait<NodeData = NodeData>,
+    NodeTemplate: NodeTemplateTrait<NodeData = NodeData, UserState = UserState>,
 {
     pub fn new_at(pos: Pos2) -> Self {
         NodeFinder {
@@ -34,6 +34,7 @@ where
         &mut self,
         ui: &mut Ui,
         all_kinds: impl NodeTemplateIter<Item = NodeTemplate>,
+        user_state: &mut UserState,
     ) -> Option<NodeTemplate> {
         let background_color;
         let text_color;
@@ -68,7 +69,7 @@ where
                     .inner_margin(vec2(10.0, 10.0))
                     .show(ui, |ui| {
                         for kind in all_kinds.all_kinds() {
-                            let kind_name = kind.node_finder_label().to_string();
+                            let kind_name = kind.node_finder_label(user_state).to_string();
                             if kind_name
                                 .to_lowercase()
                                 .contains(self.query.to_lowercase().as_str())

egui_node_graph/src/traits.rs

@@ -3,13 +3,28 @@ use super::*;
 /// This trait must be implemented by the `ValueType` generic parameter of the
 /// [`Graph`]. The trait allows drawing custom inline widgets for the different
 /// types of the node graph.
-pub trait WidgetValueTrait {
+///
+/// The [`Default`] trait bound is required to circumvent borrow checker issues
+/// using `std::mem::take` Otherwise, it would be impossible to pass the
+/// `node_data` parameter during `value_widget`. The default value is never
+/// used, so the implementation is not important, but it should be reasonably
+/// cheap to construct.
+pub trait WidgetValueTrait: Default {
     type Response;
+    type UserState;
+    type NodeData;
     /// This method will be called for each input parameter with a widget. The
     /// return value is a vector of custom response objects which can be used
     /// to implement handling of side effects. If unsure, the response Vec can
     /// be empty.
-    fn value_widget(&mut self, param_name: &str, ui: &mut egui::Ui) -> Vec<Self::Response>;
+    fn value_widget(
+        &mut self,
+        param_name: &str,
+        node_id: NodeId,
+        ui: &mut egui::Ui,
+        user_state: &mut Self::UserState,
+        node_data: &Self::NodeData,
+    ) -> Vec<Self::Response>;
 }
 
 /// This trait must be implemented by the `DataType` generic parameter of the
@@ -112,13 +127,17 @@ pub trait NodeTemplateTrait: Clone {
     type UserState;
 
     /// Returns a descriptive name for the node kind, used in the node finder.
-    fn node_finder_label(&self) -> &str;
+    ///
+    /// The return type is Cow<str> to allow returning owned or borrowed values
+    /// more flexibly. Refer to the documentation for `DataTypeTrait::name` for
+    /// more information
+    fn node_finder_label(&self, user_state: &mut Self::UserState) -> std::borrow::Cow<str>;
 
     /// Returns a descriptive name for the node kind, used in the graph.
-    fn node_graph_label(&self) -> String;
+    fn node_graph_label(&self, user_state: &mut Self::UserState) -> String;
 
     /// Returns the user data for this node kind.
-    fn user_data(&self) -> Self::NodeData;
+    fn user_data(&self, user_state: &mut Self::UserState) -> Self::NodeData;
 
     /// This function is run when this node kind gets added to the graph. The
     /// node will be empty by default, and this function can be used to fill its

egui_node_graph_example/src/app.rs

@@ -37,6 +37,14 @@ pub enum MyValueType {
     Scalar { value: f32 },
 }
 
+impl Default for MyValueType {
+    fn default() -> Self {
+        // NOTE: This is just a dummy `Default` implementation. The library
+        // requires it to circumvent some internal borrow checker issues.
+        Self::Scalar { value: 0.0 }
+    }
+}
+
 impl MyValueType {
     /// Tries to downcast this value type to a vector
     pub fn try_to_vec2(self) -> anyhow::Result<egui::Vec2> {
@@ -118,8 +126,8 @@ impl NodeTemplateTrait for MyNodeTemplate {
     type ValueType = MyValueType;
     type UserState = MyGraphState;
 
-    fn node_finder_label(&self) -> &str {
-        match self {
+    fn node_finder_label(&self, _user_state: &mut Self::UserState) -> Cow<'_, str> {
+        Cow::Borrowed(match self {
             MyNodeTemplate::MakeVector => "New vector",
             MyNodeTemplate::MakeScalar => "New scalar",
             MyNodeTemplate::AddScalar => "Scalar add",
@@ -127,16 +135,16 @@ impl NodeTemplateTrait for MyNodeTemplate {
             MyNodeTemplate::AddVector => "Vector add",
             MyNodeTemplate::SubtractVector => "Vector subtract",
             MyNodeTemplate::VectorTimesScalar => "Vector times scalar",
-        }
+        })
     }
 
-    fn node_graph_label(&self) -> String {
+    fn node_graph_label(&self, user_state: &mut Self::UserState) -> String {
         // It's okay to delegate this to node_finder_label if you don't want to
         // show different names in the node finder and the node itself.
-        self.node_finder_label().into()
+        self.node_finder_label(user_state).into()
     }
 
-    fn user_data(&self) -> Self::NodeData {
+    fn user_data(&self, _user_state: &mut Self::UserState) -> Self::NodeData {
         MyNodeData { template: *self }
     }
 
@@ -258,7 +266,16 @@ impl NodeTemplateIter for AllMyNodeTemplates {
 
 impl WidgetValueTrait for MyValueType {
     type Response = MyResponse;
-    fn value_widget(&mut self, param_name: &str, ui: &mut egui::Ui) -> Vec<MyResponse> {
+    type UserState = MyGraphState;
+    type NodeData = MyNodeData;
+    fn value_widget(
+        &mut self,
+        param_name: &str,
+        _node_id: NodeId,
+        ui: &mut egui::Ui,
+        _user_state: &mut MyGraphState,
+        _node_data: &MyNodeData,
+    ) -> Vec<MyResponse> {
         // This trait is used to tell the library which UI to display for the
         // inline parameter widgets.
         match self {