add undo/redo for single tile placement/erasing

src/marble_engine/board.rs

@@ -13,6 +13,14 @@ pub struct Board {
 	height: usize,
 }
 
+#[derive(Debug, Clone)]
+pub struct ResizeDeltas {
+	pub x_pos: usize,
+	pub x_neg: usize,
+	pub y_pos: usize,
+	pub y_neg: usize,
+}
+
 impl Board {
 	pub fn parse(source: &str) -> Self {
 		let mut rows = Vec::new();
@@ -226,6 +234,34 @@ impl Board {
 		(offset_x, offset_y)
 	}
 
+	pub fn grow(&mut self, deltas: &ResizeDeltas) {
+		// dbg!(&deltas);
+		let new_width = self.width + deltas.x_neg + deltas.x_pos;
+		let new_height = self.height + deltas.y_neg + deltas.y_pos;
+		let mut new_board = Board::new_empty(new_width, new_height);
+		for x in 0..self.width {
+			for y in 0..self.height {
+				let tile = self.rows[y][x];
+				new_board.rows[y + deltas.y_neg][x + deltas.x_neg] = tile;
+			}
+		}
+		*self = new_board;
+	}
+
+	pub fn shrink(&mut self, deltas: &ResizeDeltas) {
+		// dbg!(&deltas);
+		let new_width = self.width - deltas.x_neg - deltas.x_pos;
+		let new_height = self.height - deltas.y_neg - deltas.y_pos;
+		let mut new_board = Board::new_empty(new_width, new_height);
+		for x in 0..new_width {
+			for y in 0..new_height {
+				let tile = self.rows[y + deltas.y_neg][x + deltas.x_neg];
+				new_board.rows[y][x] = tile;
+			}
+		}
+		*self = new_board;
+	}
+
 	pub fn width(&self) -> usize {
 		self.width
 	}