Merge pull request #710 from ClementTsang/consolidate_component_drawing

Cleans up some drawing code and unifies all time graph drawing.

24 files changed, 1765 insertions, 1297 deletions

diff --git a/src/app.rs b/src/app.rs
index 3aa3a9d0..5f9ac413 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -128,9 +128,6 @@ pub struct App {
     pub basic_mode_use_percent: bool,
 
     #[builder(default = false, setter(skip))]
-    pub is_config_open: bool,
-
-    #[builder(default = false, setter(skip))]
     pub did_config_fail_to_save: bool,
 
     #[cfg(target_family = "unix")]
@@ -218,8 +215,6 @@ impl App {
             }
 
             self.is_force_redraw = true;
-        } else if self.is_config_open {
-            self.close_config_screen();
         } else {
             match self.current_widget.widget_type {
                 BottomWidgetType::Proc => {
@@ -297,7 +292,7 @@ impl App {
     }
 
     fn ignore_normal_keybinds(&self) -> bool {
-        self.is_config_open || self.is_in_dialog()
+        self.is_in_dialog()
     }
 
     pub fn on_tab(&mut self) {
@@ -910,8 +905,7 @@ impl App {
     }
 
     pub fn on_up_key(&mut self) {
-        if self.is_config_open {
-        } else if !self.is_in_dialog() {
+        if !self.is_in_dialog() {
             self.decrement_position_count();
         } else if self.help_dialog_state.is_showing_help {
             self.help_scroll_up();
@@ -932,8 +926,7 @@ impl App {
     }
 
     pub fn on_down_key(&mut self) {
-        if self.is_config_open {
-        } else if !self.is_in_dialog() {
+        if !self.is_in_dialog() {
             self.increment_position_count();
         } else if self.help_dialog_state.is_showing_help {
             self.help_scroll_down();
@@ -954,8 +947,7 @@ impl App {
     }
 
     pub fn on_left_key(&mut self) {
-        if self.is_config_open {
-        } else if !self.is_in_dialog() {
+        if !self.is_in_dialog() {
             match self.current_widget.widget_type {
                 BottomWidgetType::ProcSearch => {
                     let is_in_search_widget = self.is_in_search_widget();
@@ -1026,8 +1018,7 @@ impl App {
     }
 
     pub fn on_right_key(&mut self) {
-        if self.is_config_open {
-        } else if !self.is_in_dialog() {
+        if !self.is_in_dialog() {
             match self.current_widget.widget_type {
                 BottomWidgetType::ProcSearch => {
                     let is_in_search_widget = self.is_in_search_widget();
@@ -1191,7 +1182,6 @@ impl App {
                     }
                 }
             }
-        } else if self.is_config_open {
         }
     }
 
@@ -1238,7 +1228,6 @@ impl App {
                     }
                 }
             }
-        } else if self.is_config_open {
         }
     }
 
@@ -1490,7 +1479,6 @@ impl App {
                 'G' => self.skip_to_last(),
                 _ => {}
             }
-        } else if self.is_config_open {
         }
     }
 
@@ -1673,16 +1661,6 @@ impl App {
 
     pub fn on_space(&mut self) {}
 
-    pub fn open_config_screen(&mut self) {
-        self.is_config_open = true;
-        self.is_force_redraw = true;
-    }
-
-    pub fn close_config_screen(&mut self) {
-        self.is_config_open = false;
-        self.is_force_redraw = true;
-    }
-
     /// TODO: Disabled.
     /// Call this whenever the config value is updated!
     // fn update_config_file(&mut self) -> anyhow::Result<()> {
@@ -2264,7 +2242,6 @@ impl App {
                 _ => {}
             }
             self.reset_multi_tap_keys();
-        } else if self.is_config_open {
         } else if self.help_dialog_state.is_showing_help {
             self.help_dialog_state.scroll_state.current_scroll_index = 0;
         } else if self.delete_dialog_state.is_showing_dd {
@@ -2343,7 +2320,6 @@ impl App {
                 _ => {}
             }
             self.reset_multi_tap_keys();
-        } else if self.is_config_open {
         } else if self.help_dialog_state.is_showing_help {
             self.help_dialog_state.scroll_state.current_scroll_index = self
                 .help_dialog_state
diff --git a/src/canvas.rs b/src/canvas.rs
index 217b68a8..2070327a 100644
--- a/src/canvas.rs
+++ b/src/canvas.rs
@@ -9,12 +9,7 @@ use tui::{
     Frame, Terminal,
 };
 
-// use ordered_float::OrderedFloat;
-
 use canvas_colours::*;
-use dialogs::*;
-use screens::*;
-use widgets::*;
 
 use crate::{
     app::{
@@ -30,15 +25,14 @@ use crate::{
     Pid,
 };
 
+pub use self::components::Point;
+
 mod canvas_colours;
+mod components;
 mod dialogs;
 mod drawing_utils;
-mod screens;
 mod widgets;
 
-/// Point is of time, data
-type Point = (f64, f64);
-
 #[derive(Default)]
 pub struct DisplayableData {
     pub rx_display: String,
@@ -207,6 +201,16 @@ impl Painter {
         Ok(painter)
     }
 
+    /// Determines the border style.
+    pub fn get_border_style(&self, widget_id: u64, selected_widget_id: u64) -> tui::style::Style {
+        let is_on_widget = widget_id == selected_widget_id;
+        if is_on_widget {
+            self.colours.highlighted_border_style
+        } else {
+            self.colours.border_style
+        }
+    }
+
     fn generate_config_colours(&mut self, config: &Config) -> anyhow::Result<()> {
         if let Some(colours) = &config.colors {
             self.colours.set_colours_from_palette(colours)?;
@@ -513,13 +517,6 @@ impl Painter {
                     ),
                     _ => {}
                 }
-            } else if app_state.is_config_open {
-                let rect = Layout::default()
-                    .margin(0)
-                    .constraints([Constraint::Percentage(100)])
-                    .split(f.size())[0];
-
-                self.draw_config_screen(f, app_state, rect)
             } else if app_state.app_config_fields.use_basic_mode {
                 // Basic mode.  This basically removes all graphs but otherwise
                 // the same info.
diff --git a/src/canvas/components.rs b/src/canvas/components.rs
new file mode 100644
index 00000000..219c6245
--- /dev/null
+++ b/src/canvas/components.rs
@@ -0,0 +1,10 @@
+//! Some common components to reuse when drawing widgets.
+
+pub mod time_chart;
+pub use time_chart::*;
+
+pub mod time_graph;
+pub use time_graph::*;
+
+pub mod text_table;
+pub use text_table::*;
diff --git a/src/canvas/components/text_table.rs b/src/canvas/components/text_table.rs
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/src/canvas/components/text_table.rs
@@ -0,0 +1 @@
+
diff --git a/src/canvas/components/time_chart.rs b/src/canvas/components/time_chart.rs
new file mode 100644
index 00000000..5bb0ff15
--- /dev/null
+++ b/src/canvas/components/time_chart.rs
@@ -0,0 +1,701 @@
+use std::{
+    borrow::Cow,
+    cmp::{max, Ordering},
+};
+use tui::{
+    buffer::Buffer,
+    layout::{Constraint, Rect},
+    style::{Color, Style},
+    symbols,
+    text::{Span, Spans},
+    widgets::{
+        canvas::{Canvas, Line, Points},
+        Block, Borders, GraphType, Widget,
+    },
+};
+use unicode_width::UnicodeWidthStr;
+
+/// An X or Y axis for the chart widget
+#[derive(Debug, Clone)]
+pub struct Axis<'a> {
+    /// Title displayed next to axis end
+    pub title: Option<Spans<'a>>,
+    /// Bounds for the axis (all data points outside these limits will not be represented)
+    pub bounds: [f64; 2],
+    /// A list of labels to put to the left or below the axis
+    pub labels: Option<Vec<Span<'a>>>,
+    /// The style used to draw the axis itself
+    pub style: Style,
+}
+
+impl<'a> Default for Axis<'a> {
+    fn default() -> Axis<'a> {
+        Axis {
+            title: None,
+            bounds: [0.0, 0.0],
+            labels: None,
+            style: Default::default(),
+        }
+    }
+}
+
+#[allow(dead_code)]
+impl<'a> Axis<'a> {
+    pub fn title<T>(mut self, title: T) -> Axis<'a>
+    where
+        T: Into<Spans<'a>>,
+    {
+        self.title = Some(title.into());
+        self
+    }
+
+    pub fn bounds(mut self, bounds: [f64; 2]) -> Axis<'a> {
+        self.bounds = bounds;
+        self
+    }
+
+    pub fn labels(mut self, labels: Vec<Span<'a>>) -> Axis<'a> {
+        self.labels = Some(labels);
+        self
+    }
+
+    pub fn style(mut self, style: Style) -> Axis<'a> {
+        self.style = style;
+        self
+    }
+}
+
+/// A group of data points
+#[derive(Debug, Clone)]
+pub struct Dataset<'a> {
+    /// Name of the dataset (used in the legend if shown)
+    name: Cow<'a, str>,
+    /// A reference to the actual data
+    data: &'a [(f64, f64)],
+    /// Symbol used for each points of this dataset
+    marker: symbols::Marker,
+    /// Determines graph type used for drawing points
+    graph_type: GraphType,
+    /// Style used to plot this dataset
+    style: Style,
+}
+
+impl<'a> Default for Dataset<'a> {
+    fn default() -> Dataset<'a> {
+        Dataset {
+            name: Cow::from(""),
+            data: &[],
+            marker: symbols::Marker::Dot,
+            graph_type: GraphType::Scatter,
+            style: Style::default(),
+        }
+    }
+}
+
+#[allow(dead_code)]
+impl<'a> Dataset<'a> {
+    pub fn name<S>(mut self, name: S) -> Dataset<'a>
+    where
+        S: Into<Cow<'a, str>>,
+    {
+        self.name = name.into();
+        self
+    }
+
+    pub fn data(mut self, data: &'a [(f64, f64)]) -> Dataset<'a> {
+        self.data = data;
+        self
+    }
+
+    pub fn marker(mut self, marker: symbols::Marker) -> Dataset<'a> {
+        self.marker = marker;
+        self
+    }
+
+    pub fn graph_type(mut self, graph_type: GraphType) -> Dataset<'a> {
+        self.graph_type = graph_type;
+        self
+    }
+
+    pub fn style(mut self, style: Style) -> Dataset<'a> {
+        self.style = style;
+        self
+    }
+}
+
+/// A container that holds all the infos about where to display each elements of the chart (axis,
+/// labels, legend, ...).
+#[derive(Default, Debug, Clone, PartialEq)]
+struct ChartLayout {
+    /// Location of the title of the x axis
+    title_x: Option<(u16, u16)>,
+    /// Location of the title of the y axis
+    title_y: Option<(u16, u16)>,
+    /// Location of the first label of the x axis
+    label_x: Option<u16>,
+    /// Location of the first label of the y axis
+    label_y: Option<u16>,
+    /// Y coordinate of the horizontal axis
+    axis_x: Option<u16>,
+    /// X coordinate of the vertical axis
+    axis_y: Option<u16>,
+    /// Area of the legend
+    legend_area: Option<Rect>,
+    /// Area of the graph
+    graph_area: Rect,
+}
+
+/// A "custom" chart, just a slightly tweaked [`tui::widgets::Chart`] from tui-rs, but with greater control over the
+/// legend, and built with the idea of drawing data points relative to a time-based x-axis.
+///
+/// Main changes:
+/// - Styling option for the legend box
+/// - Automatically trimming out redundant draws in the x-bounds.
+/// - Automatic interpolation to points that fall *just* outside of the screen.
+///
+/// TODO: Support for putting the legend on the left side.
+#[derive(Debug, Clone)]
+pub struct TimeChart<'a> {
+    /// A block to display around the widget eventually
+    block: Option<Block<'a>>,
+    /// The horizontal axis
+    x_axis: Axis<'a>,
+    /// The vertical axis
+    y_axis: Axis<'a>,
+    /// A reference to the datasets
+    datasets: Vec<Dataset<'a>>,
+    /// The widget base style
+    style: Style,
+    /// The legend's style
+    legend_style: Style,
+    /// Constraints used to determine whether the legend should be shown or not
+    hidden_legend_constraints: (Constraint, Constraint),
+}
+
+pub const DEFAULT_LEGEND_CONSTRAINTS: (Constraint, Constraint) =
+    (Constraint::Ratio(1, 4), Constraint::Ratio(1, 4));
+
+#[allow(dead_code)]
+impl<'a> TimeChart<'a> {
+    /// Creates a new [`TimeChart`].
+    ///
+    /// **Note:** `datasets` **must** be sorted!
+    pub fn new(datasets: Vec<Dataset<'a>>) -> TimeChart<'a> {
+        TimeChart {
+            block: None,
+            x_axis: Axis::default(),
+            y_axis: Axis::default(),
+            style: Default::default(),
+            legend_style: Default::default(),
+            datasets,
+            hidden_legend_constraints: DEFAULT_LEGEND_CONSTRAINTS,
+        }
+    }
+
+    pub fn block(mut self, block: Block<'a>) -> TimeChart<'a> {
+        self.block = Some(block);
+        self
+    }
+
+    pub fn style(mut self, style: Style) -> TimeChart<'a> {
+        self.style = style;
+        self
+    }
+
+    pub fn legend_style(mut self, legend_style: Style) -> TimeChart<'a> {
+        self.legend_style = legend_style;
+        self
+    }
+
+    pub fn x_axis(mut self, axis: Axis<'a>) -> TimeChart<'a> {
+        self.x_axis = axis;
+        self
+    }
+
+    pub fn y_axis(mut self, axis: Axis<'a>) -> TimeChart<'a> {
+        self.y_axis = axis;
+        self
+    }
+
+    /// Set the constraints used to determine whether the legend should be shown or not.
+    pub fn hidden_legend_constraints(
+        mut self, constraints: (Constraint, Constraint),
+    ) -> TimeChart<'a> {
+        self.hidden_legend_constraints = constraints;
+        self
+    }
+
+    /// Compute the internal layout of the chart given the area. If the area is too small some
+    /// elements may be automatically hidden
+    fn layout(&self, area: Rect) -> ChartLayout {
+        let mut layout = ChartLayout::default();
+        if area.height == 0 || area.width == 0 {
+            return layout;
+        }
+        let mut x = area.left();
+        let mut y = area.bottom() - 1;
+
+        if self.x_axis.labels.is_some() && y > area.top() {
+            layout.label_x = Some(y);
+            y -= 1;
+        }
+
+        layout.label_y = self.y_axis.labels.as_ref().and(Some(x));
+        x += self.max_width_of_labels_left_of_y_axis(area);
+
+        if self.x_axis.labels.is_some() && y > area.top() {
+            layout.axis_x = Some(y);
+            y -= 1;
+        }
+
+        if self.y_axis.labels.is_some() && x + 1 < area.right() {
+            layout.axis_y = Some(x);
+            x += 1;
+        }
+
+        if x < area.right() && y > 1 {
+            layout.graph_area = Rect::new(x, area.top(), area.right() - x, y - area.top() + 1);
+        }
+
+        if let Some(ref title) = self.x_axis.title {
+            let w = title.width() as u16;
+            if w < layout.graph_area.width && layout.graph_area.height > 2 {
+                layout.title_x = Some((x + layout.graph_area.width - w, y));
+            }
+        }
+
+        if let Some(ref title) = self.y_axis.title {
+            let w = title.width() as u16;
+            if w + 1 < layout.graph_area.width && layout.graph_area.height > 2 {
+                layout.title_y = Some((x, area.top()));
+            }
+        }
+
+        if let Some(inner_width) = self.datasets.iter().map(|d| d.name.width() as u16).max() {
+            let legend_width = inner_width + 2;
+            let legend_height = self.datasets.len() as u16 + 2;
+            let max_legend_width = self
+                .hidden_legend_constraints
+                .0
+                .apply(layout.graph_area.width);
+            let max_legend_height = self
+                .hidden_legend_constraints
+                .1
+                .apply(layout.graph_area.height);
+            if inner_width > 0
+                && legend_width < max_legend_width
+                && legend_height < max_legend_height
+            {
+                layout.legend_area = Some(Rect::new(
+                    layout.graph_area.right() - legend_width,
+                    layout.graph_area.top(),
+                    legend_width,
+                    legend_height,
+                ));
+            }
+        }
+        layout
+    }
+
+    fn max_width_of_labels_left_of_y_axis(&self, area: Rect) -> u16 {
+        let mut max_width = self
+            .y_axis
+            .labels
+            .as_ref()
+            .map(|l| l.iter().map(Span::width).max().unwrap_or_default() as u16)
+            .unwrap_or_default();
+        if let Some(ref x_labels) = self.x_axis.labels {
+            if !x_labels.is_empty() {
+                max_width = max(max_width, x_labels[0].content.width() as u16);
+            }
+        }
+        // labels of y axis and first label of x axis can take at most 1/3rd of the total width
+        max_width.min(area.width / 3)
+    }
+
+    fn render_x_labels(
+        &mut self, buf: &mut Buffer, layout: &ChartLayout, chart_area: Rect, graph_area: Rect,
+    ) {
+        let y = match layout.label_x {
+            Some(y) => y,
+            None => return,
+        };
+        let labels = self.x_axis.labels.as_ref().unwrap();
+        let labels_len = labels.len() as u16;
+        if labels_len < 2 {
+            return;
+        }
+        let width_between_ticks = graph_area.width / (labels_len - 1);
+        for (i, label) in labels.iter().enumerate() {
+            let label_width = label.width() as u16;
+            let label_width = if i == 0 {
+                // the first label is put between the left border of the chart and the y axis.
+                graph_area
+                    .left()
+                    .saturating_sub(chart_area.left())
+                    .min(label_width)
+            } else {
+                // other labels are put on the left of each tick on the x axis
+                width_between_ticks.min(label_width)
+            };
+            buf.set_span(
+                graph_area.left() + i as u16 * width_between_ticks - label_width,
+                y,
+                label,
+                label_width,
+            );
+        }
+    }
+
+    fn render_y_labels(
+        &mut self, buf: &mut Buffer, layout: &ChartLayout, chart_area: Rect, graph_area: Rect,
+    ) {
+        let x = match layout.label_y {
+            Some(x) => x,
+            None => return,
+        };
+        let labels = self.y_axis.labels.as_ref().unwrap();
+        let labels_len = labels.len() as u16;
+        let label_width = graph_area.left().saturating_sub(chart_area.left());
+        for (i, label) in labels.iter().enumerate() {
+            let dy = i as u16 * (graph_area.height - 1) / (labels_len - 1);
+            if dy < graph_area.bottom() {
+                buf.set_span(x, graph_area.bottom() - 1 - dy, label, label_width as u16);
+            }
+        }
+    }
+}
+
+impl<'a> Widget for TimeChart<'a> {
+    fn render(mut self, area: Rect, buf: &mut Buffer) {
+        if area.area() == 0 {
+            return;
+        }
+        buf.set_style(area, self.style);
+        // Sample the style of the entire widget. This sample will be used to reset the style of
+        // the cells that are part of the components put on top of the graph area (i.e legend and
+        // axis names).
+        let original_style = buf.get(area.left(), area.top()).style();
+
+        let chart_area = match self.block.take() {
+            Some(b) => {
+                let inner_area = b.inner(area);
+                b.render(area, buf);
+                inner_area
+            }
+            None => area,
+        };
+
+        let layout = self.layout(chart_area);
+        let graph_area = layout.graph_area;
+        if graph_area.width < 1 || graph_area.height < 1 {
+            return;
+        }
+
+        self.render_x_labels(buf, &layout, chart_area, graph_area);
+        self.render_y_labels(buf, &layout, chart_area, graph_area);
+
+        if let Some(y) = layout.axis_x {
+            for x in graph_area.left()..graph_area.right() {
+                buf.get_mut(x, y)
+                    .set_symbol(symbols::line::HORIZONTAL)
+                    .set_style(self.x_axis.style);
+            }
+        }
+
+        if let Some(x) = layout.axis_y {
+            for y in graph_area.top()..graph_area.bottom() {
+                buf.get_mut(x, y)
+                    .set_symbol(symbols::line::VERTICAL)
+                    .set_style(self.y_axis.style);
+            }
+        }
+
+        if let Some(y) = layout.axis_x {
+            if let Some(x) = layout.axis_y {
+                buf.get_mut(x, y)
+                    .set_symbol(symbols::line::BOTTOM_LEFT)
+                    .set_style(self.x_axis.style);
+            }
+        }
+
+        for dataset in &self.datasets {
+            Canvas::default()
+                .background_color(self.style.bg.unwrap_or(Color::Reset))
+                .x_bounds(self.x_axis.bounds)
+                .y_bounds(self.y_axis.bounds)
+                .marker(dataset.marker)
+                .paint(|ctx| {
+                    let start_bound = self.x_axis.bounds[0];
+                    let end_bound = self.x_axis.bounds[1];
+
+                    let (start_index, interpolate_start) = get_start(dataset, start_bound);
+                    let (end_index, interpolate_end) = get_end(dataset, end_bound);
+
+                    let data_slice = &dataset.data[start_index..end_index];
+
+                    ctx.draw(&Points {
+                        coords: data_slice,
+                        color: dataset.style.fg.unwrap_or(Color::Reset),
+                    });
+
+                    if let Some(interpolate_start) = interpolate_start {
+                        if let (Some(older_point), Some(newer_point)) = (
+                            dataset.data.get(interpolate_start),
+                            dataset.data.get(interpolate_start + 1),
+                        ) {
+                            let interpolated_point = (
+                                self.x_axis.bounds[0],
+                                interpolate_point(older_point, newer_point, self.x_axis.bounds[0]),
+                            );
+
+                            ctx.draw(&Points {
+                                coords: &[interpolated_point],
+                                color: dataset.style.fg.unwrap_or(Color::Reset),
+                            });
+
+                            if let GraphType::Line = dataset.graph_type {
+                                ctx.draw(&Line {
+                                    x1: interpolated_point.0,
+                                    y1: interpolated_point.1,
+                                    x2: newer_point.0,
+                                    y2: newer_point.1,
+                                    color: dataset.style.fg.unwrap_or(Color::Reset),
+                                });
+                            }
+                        }
+                    }
+
+                    if let GraphType::Line = dataset.graph_type {
+                        for data in data_slice.windows(2) {
+                            ctx.draw(&Line {
+                                x1: data[0].0,
+                                y1: data[0].1,
+                                x2: data[1].0,
+                                y2: data[1].1,
+                                color: dataset.style.fg.unwrap_or(Color::Reset),
+                            });
+                        }
+                    }
+
+                    if let Some(interpolate_end) = interpolate_end {
+                        if let (Some(older_point), Some(newer_point)) = (
+                            dataset.data.get(interpolate_end - 1),
+                            dataset.data.get(interpolate_end),
+                        ) {
+                            let interpolated_point = (
+                                self.x_axis.bounds[1],
+                                interpolate_point(older_point, newer_point, self.x_axis.bounds[1]),
+                            );
+
+                            ctx.draw(&Points {
+                                coords: &[interpolated_point],
+                                color: dataset.style.fg.unwrap_or(Color::Reset),
+                            });
+
+                            if let GraphType::Line = dataset.graph_type {
+                                ctx.draw(&Line {
+                                    x1: older_point.0,
+                                    y1: older_point.1,
+                                    x2: interpolated_point.0,
+                                    y2: interpolated_point.1,
+                                    color: dataset.style.fg.unwrap_or(Color::Reset),
+                                });
+                            }
+                        }
+                    }
+                })
+                .render(graph_area, buf);
+        }
+
+        if let Some(legend_area) = layout.legend_area {
+            buf.set_style(legend_area, original_style);
+            Block::default()
+                .borders(Borders::ALL)
+                .border_style(self.legend_style)
+                .render(legend_area, buf);
+            for (i, dataset) in self.datasets.iter().enumerate() {
+                buf.set_string(
+                    legend_area.x + 1,
+                    legend_area.y + 1 + i as u16,
+                    &dataset.name,
+                    dataset.style,
+                );
+            }
+        }
+
+        if let Some((x, y)) = layout.title_x {
+            let title = self.x_axis.title.unwrap();
+            let width = graph_area.right().saturating_sub(x);
+            buf.set_style(
+                Rect {
+                    x,
+                    y,
+                    width,
+                    height: 1,
+                },
+                original_style,
+            );
+            buf.set_spans(x, y, &title, width);
+        }
+
+        if let Some((x, y)) = layout.title_y {
+            let title = self.y_axis.title.unwrap();
+            let width = graph_area.right().saturating_sub(x);
+            buf.set_style(
+                Rect {
+                    x,
+                    y,
+                    width,
+                    height: 1,
+                },
+                original_style,
+            );
+            buf.set_spans(x, y, &title, width);
+        }
+    }
+}
+
+fn bin_cmp(a: &f64, b: &f64) -> Ordering {
+    // TODO: Switch to `total_cmp` on 1.62
+    a.partial_cmp(b).unwrap_or(Ordering::Equal)
+}
+
+/// Returns the start index and potential interpolation index given the start time and the dataset.
+fn get_start(dataset: &Dataset<'_>, start_bound: f64) -> (usize, Option<usize>) {
+    match dataset
+        .data
+        .binary_search_by(|(x, _y)| bin_cmp(x, &start_bound))
+    {
+        Ok(index) => (index, None),
+        Err(index) => (index, index.checked_sub(1)),
+    }
+}
+
+/// Returns the end position and potential interpolation index given the end time and the dataset.
+fn get_end(dataset: &Dataset<'_>, end_bound: f64) -> (usize, Option<usize>) {
+    match dataset
+        .data
+        .binary_search_by(|(x, _y)| bin_cmp(x, &end_bound))
+    {
+        // In the success case, this means we found an index. Add one since we want to include this index and we
+        // expect to use the returned index as part of a (m..n) range.
+        Ok(index) => (index.saturating_add(1), None),
+        // In the fail case, this means we did not find an index, and the returned index is where one would *insert*
+        // the location. This index is where one would insert to fit inside the dataset - and since this is an end
+        // bound, index is, in a sense, already "+1" for our range later.
+        Err(index) => (index, {
+            let sum = index.checked_add(1);
+            match sum {
+                Some(s) if s < dataset.data.len() => sum,
+                _ => None,
+            }
+        }),
+    }
+}
+
+/// Returns the y-axis value for a given `x`, given two points to draw a line between.
+fn interpolate_point(older_point: &(f64, f64), newer_point: &(f64, f64), x: f64) -> f64 {
+    let delta_x = newer_point.0 - older_point.0;
+    let delta_y = newer_point.1 - older_point.1;
+    let slope = delta_y / delta_x;
+
+    (older_point.1 + (x - older_point