Add ability to style histograms

Author: milliams

examples/histogram_svg.rs

@@ -1,8 +1,11 @@
 extern crate plotlib;
 
+use plotlib::style::Bar;
+
 fn main() {
     let data = [0.3, 0.5, 6.4, 5.3, 3.6, 3.6, 3.5, 7.5, 4.0];
-    let h = plotlib::histogram::Histogram::from_vec(&data, 10);
+    let h = plotlib::histogram::Histogram::from_vec(&data, 10)
+        .style(plotlib::histogram::Style::new().fill("olive"));
     let v = plotlib::view::View::new().add(&h);
     plotlib::page::Page::single(&v).save("histogram.svg");
 }

src/histogram.rs

@@ -27,6 +27,39 @@ use utils::PairWise;
 use svg_render;
 use text_render;
 use representation::Representation;
+use style;
+
+#[derive(Debug, Default)]
+pub struct Style {
+    fill: Option<String>,
+}
+
+impl Style {
+    pub fn new() -> Self {
+        Style { fill: None }
+    }
+
+    pub fn overlay(&mut self, other: &Self) {
+        match other.fill {
+            Some(ref v) => self.fill = Some(v.clone()),
+            None => {}
+        }
+    }
+}
+
+impl style::Bar for Style {
+    fn fill<T>(&mut self, value: T) -> &mut Self
+    where
+        T: Into<String>,
+    {
+        self.fill = Some(value.into());
+        self
+    }
+
+    fn get_fill(&self) -> &Option<String> {
+        &self.fill
+    }
+}
 
 /**
 A one-dimensional histogram with equal binning.
@@ -36,6 +69,7 @@ pub struct Histogram {
     pub bin_bounds: Vec<f64>,    // will have N_bins + 1 entries
     pub bin_counts: Vec<u32>,    // will have N_bins entries
     pub bin_densities: Vec<f64>, // will have N_bins entries
+    style: Style,
 }
 
 impl Histogram {
@@ -81,6 +115,7 @@ impl Histogram {
             bin_bounds: bounds,
             bin_counts: bins,
             bin_densities: density_per_bin,
+            style: Style::new(),
         }
     }
 
@@ -99,6 +134,15 @@ impl Histogram {
         let max = *self.bin_counts.iter().max().unwrap();
         (0., max as f64)
     }
+
+    pub fn style(mut self, style: &Style) -> Self {
+        self.style.overlay(&style);
+        self
+    }
+
+    pub fn get_style(&self) -> &Style {
+        &self.style
+    }
 }
 
 impl Representation for Histogram {
@@ -117,7 +161,7 @@ impl Representation for Histogram {
         face_width: f64,
         face_height: f64,
     ) -> svg::node::element::Group {
-        svg_render::draw_face_bars(self, x_axis, y_axis, face_width, face_height)
+        svg_render::draw_face_bars(self, x_axis, y_axis, face_width, face_height, &self.style)
     }
 
     fn to_text(

src/style.rs

@@ -47,3 +47,11 @@ pub trait Point {
 
     fn get_size(&self) -> &Option<f32>;
 }
+
+pub trait Bar {
+    fn fill<T>(&mut self, value: T) -> &mut Self
+    where
+        T: Into<String>;
+
+    fn get_fill(&self) -> &Option<String>;
+}

src/svg_render.rs

@@ -168,13 +168,17 @@ where
     group
 }
 
-pub fn draw_face_bars(
+pub fn draw_face_bars<S>(
     h: &histogram::Histogram,
     x_axis: &axis::Axis,
     y_axis: &axis::Axis,
     face_width: f64,
     face_height: f64,
-) -> node::element::Group {
+    style: &S,
+) -> node::element::Group
+where
+    S: style::Bar,
+{
     let mut group = node::element::Group::new();
 
     for ((&l, &u), &count) in h.bin_bounds.pairwise().zip(h.bin_counts.iter()) {
@@ -187,7 +191,10 @@ pub fn draw_face_bars(
             .set("y", -count_scaled)
             .set("width", width)
             .set("height", count_scaled)
-            .set("fill", "burlywood")
+            .set(
+                "fill",
+                style.get_fill().clone().unwrap_or("burlywood".into()),
+            )
             .set("stroke", "black");
         group.append(rect);
     }