From c36c2fab306b3f9c6c120d7d9e5d6eabee569cdc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?R=C3=A9mi=20Thebault?= <remi.thebault@gmail.com>
Date: Thu, 7 May 2026 18:42:20 +0200
Subject: [PATCH] custom ticks locator

---
 examples/gauss.rs    |  4 +++-
 src/des/axis.rs      | 24 ++++++++++++++++++++++++
 src/drawing/ticks.rs |  3 ++-
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/examples/gauss.rs b/examples/gauss.rs
index 1d40331..b6adc71 100644
--- a/examples/gauss.rs
+++ b/examples/gauss.rs
@@ -29,9 +29,11 @@ fn main() {
     let title: des::figure::Title =
         format!("Normal distribution (\u{03bc}={}, \u{03c3}={})", MU, SIGMA).into();
 
+    let ticks = vec![5.0, 9.0, 11.0, 13.0, 15.0, 17.0, 21.0];
+
     let x_axis = des::Axis::new()
         .with_title("x".into())
-        .with_ticks(Default::default());
+        .with_ticks(des::axis::Ticks::new().with_locator(ticks.into()));
     let y_axis = des::Axis::new().with_title("y".into()).with_ticks(
         des::axis::Ticks::new()
             .with_formatter(Some(des::axis::ticks::PercentFormatter::default().into())),
diff --git a/src/des/axis.rs b/src/des/axis.rs
index 27f5d5c..8b8ccad 100644
--- a/src/des/axis.rs
+++ b/src/des/axis.rs
@@ -385,6 +385,8 @@ pub mod ticks {
         /// on the axis data range (bounds) and whether the ticks are major or minor
         #[default]
         Auto,
+        /// Specifies the exact locations of the ticks in data space.
+        List(ListLocator),
         /// Places ticks automatically, using the specified number of bins and steps
         MaxN(MaxNLocator),
         /// Places the ticks automatically, using the specified number of bins and multiples of PI.
@@ -403,6 +405,28 @@ pub mod ticks {
         TimeDelta(TimeDeltaLocator),
     }
 
+    /// A locator that places ticks at the specified locations in data space
+    #[derive(Debug, Clone)]
+    pub struct ListLocator(pub Vec<f64>);
+
+    impl From<Vec<f64>> for Locator {
+        fn from(loc: Vec<f64>) -> Self {
+            Locator::List(ListLocator(loc))
+        }
+    }
+
+    impl From<Vec<f64>> for ListLocator {
+        fn from(loc: Vec<f64>) -> Self {
+            ListLocator(loc)
+        }
+    }
+
+    impl From<ListLocator> for Locator {
+        fn from(loc: ListLocator) -> Self {
+            Locator::List(loc)
+        }
+    }
+
     /// A locator that places ticks automatically, using the specified number of bins and steps
     #[derive(Debug, Clone)]
     pub struct MaxNLocator {
diff --git a/src/drawing/ticks.rs b/src/drawing/ticks.rs
index 0652382..464957e 100644
--- a/src/drawing/ticks.rs
+++ b/src/drawing/ticks.rs
@@ -22,6 +22,7 @@ pub fn locate_num(
         (Locator::Auto, Scale::Log(LogScale { base, .. })) => {
             Ok(LogLocator::new_major(*base).ticks(nb))
         }
+        (Locator::List(locator), _) => Ok(locator.0.clone()),
         (Locator::MaxN(locator), Scale::Auto | Scale::Linear { .. }) => {
             let ticker = MaxN::new(locator.bins, locator.steps.as_slice());
             Ok(ticker.ticks(nb))
@@ -530,7 +531,7 @@ fn auto_label_formatter(
         (Locator::Auto, Scale::Log(LogScale { base, .. })) if *base == 10.0 => {
             Arc::new(SciLabelFormat)
         }
-        (Locator::Auto, _) => {
+        (Locator::Auto, _) | (Locator::List(..), _) => {
             let max = ab.start().abs().max(ab.end().abs());
             if max >= 100000.0 || max < 0.001 {
                 Arc::new(SciLabelFormat)