Introduce type parameter for plot points

demo/src/plot_demo.rs

@@ -1,8 +1,10 @@
+use std::collections::HashMap;
 use std::ops::RangeInclusive;
 use std::{f64::consts::TAU, sync::Arc};
 
+use egui::mutex::Mutex;
 use egui::{
-    Checkbox, Color32, ComboBox, NumExt as _, Pos2, Response, ScrollArea, Stroke, TextWrapMode,
+    Checkbox, Color32, ComboBox, Id, NumExt as _, Pos2, Response, ScrollArea, Stroke, TextWrapMode,
     Vec2b, WidgetInfo, WidgetType, remap, vec2,
 };
 
@@ -24,6 +26,7 @@ enum Panel {
     Interaction,
     CustomAxes,
     LinkedAxes,
+    Userdata,
 }
 
 impl Default for Panel {
@@ -44,6 +47,7 @@ pub struct PlotDemo {
     interaction_demo: InteractionDemo,
     custom_axes_demo: CustomAxesDemo,
     linked_axes_demo: LinkedAxesDemo,
+    userdata_demo: UserdataDemo,
     open_panel: Panel,
 }
 
@@ -131,6 +135,7 @@ impl PlotDemo {
                     ui.selectable_value(&mut self.open_panel, Panel::Interaction, "Interaction");
                     ui.selectable_value(&mut self.open_panel, Panel::CustomAxes, "Custom Axes");
                     ui.selectable_value(&mut self.open_panel, Panel::LinkedAxes, "Linked Axes");
+                    ui.selectable_value(&mut self.open_panel, Panel::Userdata, "Userdata");
                 });
         });
         ui.separator();
@@ -160,6 +165,9 @@ impl PlotDemo {
             Panel::LinkedAxes => {
                 self.linked_axes_demo.ui(ui);
             }
+            Panel::Userdata => {
+                self.userdata_demo.ui(ui);
+            }
         }
     }
 }
@@ -636,7 +644,7 @@ impl CustomAxesDemo {
             }
         };
 
-        let label_fmt = |_s: &str, val: &PlotPoint| {
+        let label_fmt = |_s: &str, val: &PlotPoint, _| {
             format!(
                 "Day {d}, {h}:{m:02}\n{p:.2}%",
                 d = day(val.x),
@@ -1191,6 +1199,62 @@ impl ChartsDemo {
     }
 }
 
+#[derive(PartialEq, serde::Deserialize, serde::Serialize, Default)]
+struct UserdataDemo {}
+
+struct DemoPoint {
+    x: f64,
+    y: f64,
+    custom_info: bool,
+}
+
+impl UserdataDemo {
+    #[allow(clippy::unused_self, clippy::significant_drop_tightening)]
+    fn ui(&self, ui: &mut egui::Ui) -> Response {
+        let points = (1..=1000)
+            .map(|i| DemoPoint {
+                x: i as f64 / 1000.0,
+                y: ((i as f64) / 1000.0 * std::f64::consts::PI * 2.0).sin(),
+                custom_info: i % 2 == 0,
+            })
+            .collect::<Vec<_>>();
+
+        let custom_things = Arc::new(Mutex::new(HashMap::<Id, Vec<bool>>::new()));
+
+        let custom_things_ = custom_things.clone();
+        Plot::new("Userdata Plot Demo")
+            .legend(Legend::default())
+            .label_formatter(|_, _, item| {
+                format!(
+                    "item: {:?}\ncustom_thing: {:?}",
+                    item,
+                    item.and_then(|(id, index)| custom_things_
+                        .lock()
+                        .get(&id)
+                        .and_then(|vec| vec.get(index).copied()))
+                )
+            })
+            .show(ui, |plot_ui| {
+                let id = Id::new(1234);
+                let mut lock = custom_things.lock();
+                let entry = lock.entry(id).or_default();
+
+                for p in &points {
+                    entry.push(p.custom_info);
+                }
+
+                plot_ui.line(
+                    Line::new(
+                        "test",
+                        points.iter().map(|p| [p.x, p.y]).collect::<Vec<_>>(),
+                    )
+                    .id(id),
+                );
+            })
+            .response
+    }
+}
+
 fn is_approx_zero(val: f64) -> bool {
     val.abs() < 1e-6
 }

egui_plot/src/items/mod.rs

@@ -138,7 +138,7 @@ pub trait PlotItem {
         match self.geometry() {
             PlotGeometry::None => None,
 
-            PlotGeometry::Points(points) => points
+            PlotGeometry::Points(points, _) => points
                 .iter()
                 .enumerate()
                 .map(|(index, value)| {
@@ -163,8 +163,8 @@ pub trait PlotItem {
         plot: &PlotConfig<'_>,
         label_formatter: &LabelFormatter<'_>,
     ) {
-        let points = match self.geometry() {
-            PlotGeometry::Points(points) => points,
+        let (points, id) = match self.geometry() {
+            PlotGeometry::Points(points, id) => (points, id),
             PlotGeometry::None => {
                 panic!("If the PlotItem has no geometry, on_hover() must not be called")
             }
@@ -187,6 +187,7 @@ pub trait PlotItem {
         rulers_and_tooltip_at_value(
             plot_area_response,
             value,
+            id.map(|id| (id, elem.index)),
             self.name(),
             plot,
             cursors,
@@ -590,7 +591,7 @@ impl PlotItem for Line<'_> {
     }
 
     fn geometry(&self) -> PlotGeometry<'_> {
-        PlotGeometry::Points(self.series.points())
+        PlotGeometry::Points(self.series.points(), Some(self.id()))
     }
 
     fn bounds(&self) -> PlotBounds {
@@ -692,7 +693,7 @@ impl PlotItem for Polygon<'_> {
     }
 
     fn geometry(&self) -> PlotGeometry<'_> {
-        PlotGeometry::Points(self.series.points())
+        PlotGeometry::Points(self.series.points(), Some(self.id()))
     }
 
     fn bounds(&self) -> PlotBounds {
@@ -1013,7 +1014,7 @@ impl PlotItem for Points<'_> {
     }
 
     fn geometry(&self) -> PlotGeometry<'_> {
-        PlotGeometry::Points(self.series.points())
+        PlotGeometry::Points(self.series.points(), Some(self.id()))
     }
 
     fn bounds(&self) -> PlotBounds {
@@ -1124,7 +1125,7 @@ impl PlotItem for Arrows<'_> {
     }
 
     fn geometry(&self) -> PlotGeometry<'_> {
-        PlotGeometry::Points(self.origins.points())
+        PlotGeometry::Points(self.origins.points(), Some(self.id()))
     }
 
     fn bounds(&self) -> PlotBounds {
@@ -1694,6 +1695,7 @@ fn add_rulers_and_text(
 pub(super) fn rulers_and_tooltip_at_value(
     plot_area_response: &egui::Response,
     value: PlotPoint,
+    item: Option<(Id, usize)>,
     name: &str,
     plot: &PlotConfig<'_>,
     cursors: &mut Vec<Cursor>,
@@ -1707,7 +1709,7 @@ pub(super) fn rulers_and_tooltip_at_value(
     }
 
     let text = if let Some(custom_label) = label_formatter {
-        custom_label(name, &value)
+        custom_label(name, &value, None)
     } else {
         let prefix = if name.is_empty() {
             String::new()
@@ -1717,7 +1719,9 @@ pub(super) fn rulers_and_tooltip_at_value(
         let scale = plot.transform.dvalue_dpos();
         let x_decimals = ((-scale[0].abs().log10()).ceil().at_least(0.0) as usize).clamp(1, 6);
         let y_decimals = ((-scale[1].abs().log10()).ceil().at_least(0.0) as usize).clamp(1, 6);
-        if plot.show_x && plot.show_y {
+        if let Some(custom_label) = label_formatter {
+            custom_label(name, &value, item)
+        } else if plot.show_x && plot.show_y {
             format!(
                 "{}x = {:.*}\ny = {:.*}",
                 prefix, x_decimals, value.x, y_decimals, value.y

egui_plot/src/items/values.rs

@@ -1,7 +1,7 @@
 use std::ops::{Bound, RangeBounds, RangeInclusive};
 
 use egui::{
-    Pos2, Rect, Shape, Stroke, Vec2,
+    Id, Pos2, Rect, Shape, Stroke, Vec2,
     epaint::{ColorMode, PathStroke},
     lerp, pos2,
 };
@@ -397,7 +397,7 @@ pub enum PlotGeometry<'a> {
     None,
 
     /// Point values (X-Y graphs)
-    Points(&'a [PlotPoint]),
+    Points(&'a [PlotPoint], Option<Id>),
 
     /// Rectangles (examples: boxes or bars)
     // Has currently no data, as it would require copying rects or iterating a list of pointers.

egui_plot/src/lib.rs

@@ -42,7 +42,7 @@ use axis::AxisWidget;
 use items::{horizontal_line, rulers_color, vertical_line};
 use legend::LegendWidget;
 
-type LabelFormatterFn<'a> = dyn Fn(&str, &PlotPoint) -> String + 'a;
+type LabelFormatterFn<'a> = dyn Fn(&str, &PlotPoint, Option<(Id, usize)>) -> String + 'a;
 pub type LabelFormatter<'a> = Option<Box<LabelFormatterFn<'a>>>;
 
 type GridSpacerFn<'a> = dyn Fn(GridInput) -> Vec<GridMark> + 'a;
@@ -402,6 +402,10 @@ impl<'a> Plot<'a> {
     }
 
     /// Provide a function to customize the on-hover label for the x and y axis
+    /// ## `build_fn` parameter
+    /// The third parameter, `build_fn`, is a closure that is called with a mutable reference to a [`PlotUi`] instance.
+    /// Within this closure, you can add items (such as lines, points, bars, etc.) to the plot and interact with the plot UI.
+    /// The closure should return any value you wish to propagate from the plot construction (for example, a reference to a plot item, or a custom result).
     ///
     /// ```
     /// # egui::__run_test_ui(|ui| {
@@ -412,7 +416,7 @@ impl<'a> Plot<'a> {
     /// }).collect();
     /// let line = Line::new("sin", sin);
     /// Plot::new("my_plot").view_aspect(2.0)
-    /// .label_formatter(|name, value| {
+    /// .label_formatter(|name, value, _| {
     ///     if !name.is_empty() {
     ///         format!("{}: {:.*}%", name, 1, value.y)
     ///     } else {
@@ -424,7 +428,7 @@ impl<'a> Plot<'a> {
     /// ```
     pub fn label_formatter(
         mut self,
-        label_formatter: impl Fn(&str, &PlotPoint) -> String + 'a,
+        label_formatter: impl Fn(&str, &PlotPoint, Option<(Id, usize)>) -> String + 'a,
     ) -> Self {
         self.label_formatter = Some(Box::new(label_formatter));
         self
@@ -1858,6 +1862,7 @@ impl PreparedPlot<'_> {
             items::rulers_and_tooltip_at_value(
                 plot_area_response,
                 value,
+                None,
                 "",
                 &plot,
                 &mut cursors,