Refactor cursor memory to deal with removal of plots

egui/src/widgets/plot/items/mod.rs

@@ -7,7 +7,7 @@ use epaint::Mesh;
 
 use crate::*;
 
-use super::{LabelFormatter, PlotBounds, ScreenTransform};
+use super::{Cursor, LabelFormatter, PlotBounds, ScreenTransform};
 use rect_elem::*;
 use values::{ClosestElem, PlotGeometry};
 
@@ -28,7 +28,7 @@ pub(super) struct PlotConfig<'a> {
  pub transform: &'a ScreenTransform,
  pub show_x: bool,
  pub show_y: bool,
- pub cursors: &'a RefCell<Vec<(Orientation, f64)>>,
+ pub cursors: &'a RefCell<Vec<Cursor>>,
 }
 
 /// Trait shared by things that can be drawn in the plot.
@@ -1663,15 +1663,17 @@ pub(super) fn rulers_at_value(
  let line_color = rulers_color(plot.ui);
  if plot.show_x {
  shapes.push(vertical_line(pointer, plot.transform, line_color));
- plot.cursors
- .borrow_mut()
- .push((Orientation::Vertical, value.x));
+ plot.cursors.borrow_mut().push(Cursor {
+ orientation: Orientation::Vertical,
+ point: value.x,
+ });
  }
  if plot.show_y {
  shapes.push(horizontal_line(pointer, plot.transform, line_color));
- plot.cursors
- .borrow_mut()
- .push((Orientation::Horizontal, value.y));
+ plot.cursors.borrow_mut().push(Cursor {
+ orientation: Orientation::Horizontal,
+ point: value.y,
+ });
  }
 
  let mut prefix = String::new();

egui/src/widgets/plot/mod.rs

@@ -2,7 +2,6 @@
 
 use std::{
  cell::{Cell, RefCell},
- collections::HashMap,
  ops::RangeInclusive,
  rc::Rc,
 };
@@ -122,6 +121,12 @@ impl PlotMemory {
 
 // ----------------------------------------------------------------------------
 
+#[derive(Copy, Clone, PartialEq)]
+struct Cursor {
+ orientation: Orientation,
+ point: f64,
+}
+
 /// Defines how multiple plots share the same range for one or both of their axes. Can be added while building
 /// a plot with [`Plot::link_axis`]. Contains an internal state, meaning that this object should be stored by
 /// the user between frames.
@@ -131,7 +136,7 @@ pub struct LinkedAxisGroup {
  pub(crate) link_y: bool,
  pub(crate) link_cursor: bool,
  pub(crate) bounds: Rc<Cell<Option<PlotBounds>>>,
- pub(crate) cursors: Rc<RefCell<HashMap<Id, Vec<(Orientation, f64)>>>>,
+ cursors: Rc<RefCell<Vec<(Id, Vec<Cursor>)>>>,
 }
 
 impl LinkedAxisGroup {
@@ -141,7 +146,7 @@ impl LinkedAxisGroup {
  link_y,
  link_cursor: false,
  bounds: Rc::new(Cell::new(None)),
- cursors: Rc::new(RefCell::new(HashMap::new())),
+ cursors: Rc::new(RefCell::new(Vec::new())),
  }
  }
 
@@ -677,12 +682,24 @@ impl Plot {
  // --- Bound computation ---
  let mut bounds = *last_screen_transform.bounds();
 
- let mut cursors = HashMap::new();
+ let mut draw_cursors: Vec<Cursor> = Vec::new();
 
  // Transfer the bounds from a link group.
  if let Some(axes) = linked_axes.as_ref() {
  if axes.link_cursor {
- cursors = axes.cursors.borrow().clone();
+ let mut cursors = axes.cursors.borrow_mut();
+
+ // Look for our previous entry
+ let index = cursors
+ .iter()
+ .enumerate()
+ .find(|(_, e)| e.0 == plot_id)
+ .map(|(i, _)| i);
+
+ // Remove our previous entry and all older entries as these are no longer displayed.
+ index.map(|index| cursors.drain(0..=index));
+
+ draw_cursors = cursors.iter().flat_map(|e| e.1.iter().copied()).collect();
  }
  if let Some(linked_bounds) = axes.get() {
  if axes.link_x {
@@ -842,9 +859,9 @@ impl Plot {
  grid_spacers,
  draw_cursor_x: linked_axes.as_ref().map_or(false, |axes| axes.link_x),
  draw_cursor_y: linked_axes.as_ref().map_or(false, |axes| axes.link_y),
- draw_cursors: cursors,
+ draw_cursors,
  };
- let cursors = prepared.ui(ui, &response);
+ let plot_cursors = prepared.ui(ui, &response);
 
  if let Some(boxed_zoom_rect) = boxed_zoom_rect {
  ui.painter().with_clip_rect(rect).add(boxed_zoom_rect.0);
@@ -858,12 +875,7 @@ impl Plot {
  }
 
  if let Some(group) = linked_axes.as_ref() {
- let cursors_map = &mut *group.cursors.borrow_mut();
- if response.hovered() {
- cursors_map.insert(id_source, cursors);
- } else {
- cursors_map.remove(&id_source);
- }
+ group.cursors.borrow_mut().push((plot_id, plot_cursors));
  group.set(*transform.bounds());
  }
 
@@ -1151,11 +1163,11 @@ struct PreparedPlot {
  grid_spacers: [GridSpacer; 2],
  draw_cursor_x: bool,
  draw_cursor_y: bool,
- draw_cursors: HashMap<Id, Vec<(Orientation, f64)>>,
+ draw_cursors: Vec<Cursor>,
 }
 
 impl PreparedPlot {
- fn ui(self, ui: &mut Ui, response: &Response) -> Vec<(Orientation, f64)> {
+ fn ui(self, ui: &mut Ui, response: &Response) -> Vec<Cursor> {
  let mut shapes = Vec::new();
 
  for d in 0..2 {
@@ -1177,16 +1189,12 @@ impl PreparedPlot {
  } else {
  // Draw cursors from other plots
  let line_color = rulers_color(ui);
- for &(orientation, value) in self
- .draw_cursors
- .values()
- .flat_map(|cursors| cursors.iter())
- {
- match orientation {
+ for cursor in &self.draw_cursors {
+ match cursor.orientation {
  Orientation::Horizontal => {
  if self.draw_cursor_y {
  shapes.push(horizontal_line(
- transform.position_from_point(&PlotPoint::new(0.0, value)),
+ transform.position_from_point(&PlotPoint::new(0.0, cursor.point)),
  &self.transform,
  line_color,
  ));
@@ -1195,7 +1203,7 @@ impl PreparedPlot {
  Orientation::Vertical => {
  if self.draw_cursor_x {
  shapes.push(vertical_line(
- transform.position_from_point(&PlotPoint::new(value, 0.0)),
+ transform.position_from_point(&PlotPoint::new(cursor.point, 0.0)),
  &self.transform,
  line_color,
  ));
@@ -1320,7 +1328,7 @@ impl PreparedPlot {
  }
  }
 
- fn hover(&self, ui: &Ui, pointer: Pos2, shapes: &mut Vec<Shape>) -> Vec<(Orientation, f64)> {
+ fn hover(&self, ui: &Ui, pointer: Pos2, shapes: &mut Vec<Shape>) -> Vec<Cursor> {
  let Self {
  transform,
  show_x,