simplify CellGrid

Signed-off-by: Fabrizio Iannetti <fabrizio.iannetti@gmail.com>

src/ui/basics.rs

@@ -1,118 +1,82 @@
 
-struct CellAxis {
-    min: f32,
-    max: f32,
-    num: u32,
-    idx: u32
-}
-
-impl CellAxis {
-    pub fn new(min: f32, len: f32, num: u32) -> Self {
-        Self {
-            min,
-            max: min + len,
-            num,
-            idx: 0
-        }
-    }
-
-    pub fn reset(&mut self) {
-        self.idx = 0;
-    }
-}
-
-impl Iterator for CellAxis {
-    type Item = (f32, f32);
-
-    fn next(&mut self) -> Option<Self::Item> {
-        if self.idx < self.num {
-            let beg: f32 = self.min + ((self.max - self.min) * self.idx as f32) / self.num as f32;
-            let end: f32 = self.min + ((self.max - self.min) * (self.idx + 1) as f32) / self.num as f32;
-            self.idx += 1;
-
-            return Some((beg.trunc(), end.trunc()));
-        }
-        return None;
-    }
-}
-
 #[derive(Copy, Clone)]
 pub struct Cell {
+    // display coordinates of the cell
     pub x : f32,
     pub y : f32,
     pub width : f32,
     pub height : f32,
 
+    // position of the cell in the grid (0-based)
     pub pos_x: u32,
     pub pos_y: u32,
 }
 
 pub struct CellGrid {
-    x_axis: CellAxis,
-    y_axis: CellAxis,
+    // display coordinates of the grid
+    x: f32,
+    y: f32,
+    width: f32,
+    height: f32,
+
+    // size fo the grid, in number of cells
+    num_x: u32,
+    num_y: u32,
+
+    // current position when iterating
+    pos_x: u32,
+    pos_y: u32,
+
+    // current cell when iterating
     curr: Cell,
 }
 
 impl CellGrid {
     pub fn new(x: f32, y: f32, width: f32, height: f32, num_x: u32, num_y: u32) -> Self {
-        let x_axis = CellAxis::new(x, width, num_x);
-        let y_axis = CellAxis::new(y, height, num_y);
         Self {
-            x_axis,
-            y_axis,
+            x,
+            y,
+            width,
+            height,
+            num_x,
+            num_y,
+            pos_x: 0,
+            pos_y: 0,
             curr: Cell {x, y, width, height, pos_x: 0, pos_y: 0}
         }
     }
+
+    fn compute_cell(&mut self) -> () {
+        self.curr.pos_x = self.pos_x;
+        self.curr.pos_y = self.pos_y;
+
+        let beg_x: f32 = self.x + (self.width * self.curr.pos_x as f32) / self.num_x as f32;
+        let end_x: f32 = self.x + (self.width * (self.curr.pos_x + 1) as f32) / self.num_x as f32;
+        self.curr.x = beg_x.trunc();
+        self.curr.width = end_x.trunc() - self.curr.x;
+
+        let beg_y: f32 = self.y + (self.height * self.curr.pos_y as f32) / self.num_y as f32;
+        let end_y: f32 = self.y + (self.height * (self.curr.pos_y + 1) as f32) / self.num_y as f32;
+        self.curr.y = beg_y.trunc();
+        self.curr.height = end_y.trunc() - self.curr.y;
+    }
 }
 
 impl Iterator for CellGrid {
     type Item = Cell;
 
     fn next(&mut self) -> Option<Self::Item> {
-        if self.y_axis.idx == 0 && self.x_axis.idx == 0 {
-            if self.y_axis.num == 0 || self.x_axis.num == 0 {
-                return None
-            }
-            self.curr.pos_y = self.y_axis.idx;
-            let y_next = self.y_axis.next().unwrap();
-            self.curr.y = y_next.0;
-            self.curr.height = y_next.1 - y_next.0;
-        }
-        self.curr.pos_x = self.x_axis.idx;
-        let x_next = self.x_axis.next();
-        match x_next {
-            None => {
-                // end of x-axis, move down the y-axis
-                self.curr.pos_y = self.y_axis.idx;
-                let y_next = self.y_axis.next();
-
-                match y_next {
-                    None => {
-                        None
-                    },
-                    Some(y_val) => {
-                        // set new vertical span
-                        self.curr.y = y_val.0;
-                        self.curr.height = y_val.1 - y_val.0;
-
-                        // reset iteration on x axis
-                        self.x_axis.reset();
-                        self.curr.pos_x = 0;
-
-                        // get first horizontal span
-                        let x_val = self.x_axis.next().unwrap();
-                        self.curr.x = x_val.0;
-                        self.curr.width = x_val.1 - x_val.0;
-
-                        Some(self.curr)
-                     }
-                }
-            },
-            Some(x_val) => {
-                self.curr.x = x_val.0;
-                self.curr.width = x_val.1 - x_val.0;
-                Some(self.curr)
+        if self.pos_y >= self.num_y {
+            None
+        } else {
+            self.compute_cell();
+
+            self.pos_x += 1;
+            if self.pos_x >= self.num_x {
+                self.pos_x = 0;
+                self.pos_y += 1;
             }
+            Some(self.curr)
         }
     }
 }