1 files changed, 147 insertions, 0 deletions
diff --git a/src/element/errorbar.rs b/src/element/errorbar.rs
new file mode 100644
index 0000000..855cd72
--- /dev/null
+++ b/src/element/errorbar.rs
@@ -0,0 +1,147 @@
+use std::marker::PhantomData;
+
+use crate::drawing::backend::{BackendCoord, DrawingBackend, DrawingErrorKind};
+use crate::element::{Drawable, PointCollection};
+use crate::style::ShapeStyle;
+
+pub trait ErrorBarOrient<K, V> {
+    type XType;
+    type YType;
+
+    fn make_coord(key: K, val: V) -> (Self::XType, Self::YType);
+    fn ending_coord(coord: BackendCoord, w: u32) -> (BackendCoord, BackendCoord);
+}
+
+pub struct ErrorBarOrientH<K, V>(PhantomData<(K, V)>);
+
+pub struct ErrorBarOrientV<K, V>(PhantomData<(K, V)>);
+
+impl<K, V> ErrorBarOrient<K, V> for ErrorBarOrientH<K, V> {
+    type XType = V;
+    type YType = K;
+
+    fn make_coord(key: K, val: V) -> (V, K) {
+        (val, key)
+    }
+
+    fn ending_coord(coord: BackendCoord, w: u32) -> (BackendCoord, BackendCoord) {
+        (
+            (coord.0, coord.1 - w as i32 / 2),
+            (coord.0, coord.1 + w as i32 / 2),
+        )
+    }
+}
+
+impl<K, V> ErrorBarOrient<K, V> for ErrorBarOrientV<K, V> {
+    type XType = K;
+    type YType = V;
+
+    fn make_coord(key: K, val: V) -> (K, V) {
+        (key, val)
+    }
+
+    fn ending_coord(coord: BackendCoord, w: u32) -> (BackendCoord, BackendCoord) {
+        (
+            (coord.0 - w as i32 / 2, coord.1),
+            (coord.0 + w as i32 / 2, coord.1),
+        )
+    }
+}
+
+pub struct ErrorBar<K, V, O: ErrorBarOrient<K, V>> {
+    style: ShapeStyle,
+    width: u32,
+    key: K,
+    values: [V; 3],
+    _p: PhantomData<O>,
+}
+
+impl<K, V> ErrorBar<K, V, ErrorBarOrientV<K, V>> {
+    pub fn new_vertical<S: Into<ShapeStyle>>(
+        key: K,
+        min: V,
+        avg: V,
+        max: V,
+        style: S,
+        width: u32,
+    ) -> Self {
+        Self {
+            style: style.into(),
+            width,
+            key,
+            values: [min, avg, max],
+            _p: PhantomData,
+        }
+    }
+}
+
+impl<K, V> ErrorBar<K, V, ErrorBarOrientH<K, V>> {
+    pub fn new_horizontal<S: Into<ShapeStyle>>(
+        key: K,
+        min: V,
+        avg: V,
+        max: V,
+        style: S,
+        width: u32,
+    ) -> Self {
+        Self {
+            style: style.into(),
+            width,
+            key,
+            values: [min, avg, max],
+            _p: PhantomData,
+        }
+    }
+}
+
+impl<'a, K: 'a + Clone, V: 'a + Clone, O: ErrorBarOrient<K, V>>
+    PointCollection<'a, (O::XType, O::YType)> for &'a ErrorBar<K, V, O>
+{
+    type Borrow = (O::XType, O::YType);
+    type IntoIter = Vec<Self::Borrow>;
+    fn point_iter(self) -> Self::IntoIter {
+        self.values
+            .iter()
+            .map(|v| O::make_coord(self.key.clone(), v.clone()))
+            .collect()
+    }
+}
+
+impl<K, V, O: ErrorBarOrient<K, V>, DB: DrawingBackend> Drawable<DB> for ErrorBar<K, V, O> {
+    fn draw<I: Iterator<Item = BackendCoord>>(
+        &self,
+        points: I,
+        backend: &mut DB,
+        _: (u32, u32),
+    ) -> Result<(), DrawingErrorKind<DB::ErrorType>> {
+        let points: Vec<_> = points.take(3).collect();
+
+        let (from, to) = O::ending_coord(points[0], self.width);
+        backend.draw_line(from, to, &self.style)?;
+
+        let (from, to) = O::ending_coord(points[2], self.width);
+        backend.draw_line(from, to, &self.style)?;
+
+        backend.draw_line(points[0], points[2], &self.style)?;
+
+        backend.draw_circle(points[1], self.width / 2, &self.style, self.style.filled)?;
+
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+#[test]
+fn test_preserve_stroke_width() {
+    let v = ErrorBar::new_vertical(100, 20, 50, 70, WHITE.filled().stroke_width(5), 3);
+    let h = ErrorBar::new_horizontal(100, 20, 50, 70, WHITE.filled().stroke_width(5), 3);
+
+    use crate::prelude::*;
+    let da = crate::create_mocked_drawing_area(300, 300, |m| {
+        m.check_draw_line(|_, w, _, _| {
+            assert_eq!(w, 5);
+        });
+    });
+    da.draw(&h).expect("Drawing Failure");
+    da.draw(&v).expect("Drawing Failure");
+}