broken scrolling

src/app/screen.rs

@@ -0,0 +1,80 @@
+use std::{collections::HashMap, sync::RwLock};
+
+use ratatui::{layout::Rect, prelude};
+
+use crate::app::calc::LEN;
+
+pub struct ScreenSpace {
+    /// This is measured in cells
+    scroll: (usize, usize),
+    default_cell_len: usize,
+    default_cell_hight: usize,
+    /// This is measured in chars
+    last_seen_screen_size: RwLock<(usize, usize)>
+}
+
+impl ScreenSpace {
+    pub fn new() -> Self {
+        Self {
+            scroll: (0, 0),
+            default_cell_len: 10,
+            default_cell_hight: 1,
+            last_seen_screen_size: RwLock::new((0,0))
+        }
+    }
+
+    pub fn scroll_based_on_cursor_location(&mut self, (cursor_x, cursor_y): (usize, usize), vars: &HashMap<String, String>) {
+        if let Ok(screen_size) = self.last_seen_screen_size.read() {
+            
+            // screen seems to be 2 cells smaller than it should be
+            let x_cells = (screen_size.0 / self.get_cell_width(vars) as usize)-2;
+
+            let lower_x = self.scroll_x();
+            let upper_x = self.scroll_x() + x_cells;
+
+            if cursor_x<=lower_x {
+                self.scroll.0 = self.scroll.0.saturating_sub(1);
+            }
+            if cursor_x > upper_x {
+                self.scroll.0 = self.scroll.0.saturating_add(1);
+            }
+
+        }
+    }
+
+    pub fn scroll_x(&self) -> usize {
+        self.scroll.0
+    }
+    pub fn y(&self) -> usize{
+        self.scroll.1
+    }
+    pub fn get_cell_height(&self, vars: &HashMap<String, String>) -> usize {
+        if let Some(h) = vars.get("height") {
+            if let Ok(p) = h.parse::<usize>() {
+                return p;
+            }
+        }
+        return self.default_cell_hight
+    }
+    pub fn get_cell_width(&self, vars: &HashMap<String, String>) -> usize {
+        if let Some(h) = vars.get("length") {
+            if let Ok(p) = h.parse::<usize>() {
+                return p;
+            }
+        }
+        self.default_cell_len
+    }
+    pub fn how_many_cells_fit_in(&self, area: &prelude::Rect, vars: &HashMap<String, String>) -> (u16, u16) {
+        if let Ok(mut l) = self.last_seen_screen_size.write() {
+            l.0 = area.width as usize;
+            l.1 = area.height as usize;
+        }
+
+        let x_max =
+            if area.width as usize / self.get_cell_width(vars) > LEN { LEN - 1 } else { area.width as usize / self.get_cell_width(vars)};
+        let y_max =
+            if area.height as usize / self.get_cell_height(vars) > LEN { LEN - 1 } else { area.height as usize / self.get_cell_height(vars)};
+        (x_max as u16, y_max as u16)
+    }
+}
+