fix BarChart

TODO.md

@@ -2,7 +2,6 @@
 1. Port to [egui](https://github.com/emilk/egui)
     - Proper support for dynamic chart display size.
     - Don't re-render plot on mouse movement
-    - Fix interval display
     - Fix crashes in parsing strings (`TextDecoder.decode: Decoding failed.`)
 2. Multiple functions in one graph.
 3. Non `y=` functions.

src/chart_manager.rs

@@ -56,6 +56,10 @@ impl ChartManager {
         (filtered_data, rect_data, area)
     }
 
+    pub fn get_step(&self) -> f64 {
+        (self.max_x - self.min_x).abs() / (self.num_interval as f64)
+    }
+
     pub fn do_update_front(&self, resolution: usize, num_interval: usize) -> bool {
         (self.resolution != resolution) | (num_interval != self.num_interval)
     }
@@ -100,6 +104,7 @@ impl ChartManager {
     // Creates and does the math for creating all the rectangles under the graph
     #[inline]
     fn integral_rectangles(&self, step: f64) -> (Vec<(f64, f64)>, f64) {
+        let half_step = step/2.0;
         let data2: Vec<(f64, f64)> = (0..self.num_interval)
             .map(|e| {
                 let x: f64 = ((e as f64) * step) + self.min_x;
@@ -114,12 +119,19 @@ impl ChartManager {
                 let tmp2: f64 = self.function.run(x2);
 
                 // Chooses the y value who's absolute value is the smallest
+                let mut output = match tmp2.abs() > tmp1.abs() {
+                    true => (x, tmp1),
+                    false => (x2, tmp2),
+                };
                 
-
-                match tmp2.abs() > tmp1.abs() {
-                    true => (x2, tmp1),
-                    false => (x, tmp2),
+                // Applies `half_step` in order to make the bar graph display properly
+                if output.0 > 0.0 {
+                    output.0 = output.0+half_step;
+                } else {
+                    output.0 = output.0-half_step;
                 }
+
+                output
             })
             .filter(|(_, y)| !y.is_nan())
             .collect();

src/egui_app.rs

@@ -88,7 +88,7 @@ impl epi::App for MathApp {
                 }
             }
 
-            ui.add(egui::Slider::new(num_interval, 1..=usize::MAX).text("Interval"));
+            ui.add(egui::Slider::new(num_interval, 10..=usize::MAX).text("Interval"));
         });
 
         let _update_back = chart_manager.do_update_back(func_str.clone(), *min_x, *max_x);
@@ -134,7 +134,7 @@ impl epi::App for MathApp {
                     }
                 }
             };
-            let bar_chart = BarChart::new(bars).color(Color32::BLUE);
+            let bar_chart = BarChart::new(bars).color(Color32::BLUE).width(chart_manager.get_step());
 
             Plot::new("plot")
                 .view_aspect(1.0)

src/misc.rs

@@ -133,6 +133,7 @@ impl Function {
 
     pub fn str_compare(&self, other_string: String) -> bool { self.func_str == other_string }
 
+    #[allow(dead_code)]
     pub fn get_string(&self) -> String { self.func_str.clone() }
 }