From cbdf748a3b49ba4f516cfba6def9c9c6bbf40c89 Mon Sep 17 00:00:00 2001
From: Nicolas Riebesel <nagua@users.noreply.github.com>
Date: Wed, 9 Aug 2023 16:47:46 +0200
Subject: [PATCH] egui: Plot Arrows add method to specify tip_size (#3138)

Normally the tip_size will be dependent on the arrow length.
This patch adds a new method to explicitly set the arrow tip size.
---
 crates/egui/src/widgets/plot/items/mod.rs | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/crates/egui/src/widgets/plot/items/mod.rs b/crates/egui/src/widgets/plot/items/mod.rs
index e96d8b3b..c56de6bb 100644
--- a/crates/egui/src/widgets/plot/items/mod.rs
+++ b/crates/egui/src/widgets/plot/items/mod.rs
@@ -997,6 +997,7 @@ impl PlotItem for Points {
 pub struct Arrows {
     pub(super) origins: PlotPoints,
     pub(super) tips: PlotPoints,
+    pub(super) tip_length: Option<f32>,
     pub(super) color: Color32,
     pub(super) name: String,
     pub(super) highlight: bool,
@@ -1007,6 +1008,7 @@ impl Arrows {
         Self {
             origins: origins.into(),
             tips: tips.into(),
+            tip_length: None,
             color: Color32::TRANSPARENT,
             name: Default::default(),
             highlight: false,
@@ -1019,6 +1021,12 @@ impl Arrows {
         self
     }
 
+    /// Set the length of the arrow tips
+    pub fn tip_length(mut self, tip_length: f32) -> Self {
+        self.tip_length = Some(tip_length);
+        self
+    }
+
     /// Set the arrows' color.
     pub fn color(mut self, color: impl Into<Color32>) -> Self {
         self.color = color.into();
@@ -1044,6 +1052,7 @@ impl PlotItem for Arrows {
         let Self {
             origins,
             tips,
+            tip_length,
             color,
             highlight,
             ..
@@ -1062,7 +1071,11 @@ impl PlotItem for Arrows {
             .for_each(|(origin, tip)| {
                 let vector = tip - origin;
                 let rot = Rot2::from_angle(std::f32::consts::TAU / 10.0);
-                let tip_length = vector.length() / 4.0;
+                let tip_length = if let Some(tip_length) = tip_length {
+                    *tip_length
+                } else {
+                    vector.length() / 4.0
+                };
                 let tip = origin + vector;
                 let dir = vector.normalized();
                 shapes.push(Shape::line_segment([origin, tip], stroke));