feature: Rework network y-axis, linear interpolation for off-screen data (#437)

Rewrite of the y-axis labeling and scaling for the network widget, along with more customization. This still has one step to be optimized (cache results so we don't have to recalculate the legend each time), but will be done in another PR for sake of this one being too large already.

Furthermore, this change adds linear interpolation at the 0 point in the case a data point shoots too far back - this seems to have lead to ugly gaps to the left of graphs in some cases, because the left hand limit was not big enough for the data point. We address this by grabbing values just outside the time range and linearly interpolating at the leftmost limit. This affects all graph widgets (CPU, mem, network).

This can be optimized, and will hopefully be prior to release in a separate change.

1 files changed, 17 insertions, 0 deletions

diff --git a/src/canvas/drawing_utils.rs b/src/canvas/drawing_utils.rs
index 222ca852..6aee1aa7 100644
--- a/src/canvas/drawing_utils.rs
+++ b/src/canvas/drawing_utils.rs
@@ -117,6 +117,12 @@ pub fn get_column_widths(
     filtered_column_widths
 }
 
+/// FIXME: [command move] This is a greedy method of determining column widths.  This is reserved for columns where we are okay with
+/// shoving information as far right as required.
+// pub fn greedy_get_column_widths() -> Vec<u16> {
+//     vec![]
+// }
+
 pub fn get_search_start_position(
     num_columns: usize, cursor_direction: &app::CursorDirection, cursor_bar: &mut usize,
     current_cursor_position: usize, is_force_redraw: bool,
@@ -205,3 +211,14 @@ pub fn calculate_basic_use_bars(use_percentage: f64, num_bars_available: usize)
         num_bars_available,
     )
 }
+
+/// Interpolates between two points.  Mainly used to help fill in tui-rs blanks in certain situations.
+/// It is expected point_one is "further left" compared to point_two.
+/// A point is two floats, in (x, y) form.  x is time, y is value.
+pub fn interpolate_points(point_one: &(f64, f64), point_two: &(f64, f64), time: f64) -> f64 {
+    let delta_x = point_two.0 - point_one.0;
+    let delta_y = point_two.1 - point_one.1;
+    let slope = delta_y / delta_x;
+
+    (point_one.1 + (time - point_one.0) * slope).max(0.0)
+}