summaryrefslogtreecommitdiff
path: root/src/board-view.rs
diff options
context:
space:
mode:
Diffstat (limited to 'src/board-view.rs')
-rw-r--r--src/board-view.rs412
1 files changed, 412 insertions, 0 deletions
diff --git a/src/board-view.rs b/src/board-view.rs
new file mode 100644
index 0000000..d6eba71
--- /dev/null
+++ b/src/board-view.rs
@@ -0,0 +1,412 @@
+use ratatui::{buffer::Buffer, layout::Rect, style::{Color, Modifier, Style}, widgets::Widget};
+
+use crate::{board::{GameBoard, Move, PieceType, Pos}, player::Highlights};
+
+/// Columns between neighbouring points at scale 1. Twice `ROW_STEP`, since cells are about twice as tall as wide.
+const COL_STEP: u16 = 4;
+/// Rows between neighbouring points at scale 1.
+const ROW_STEP: u16 = 2;
+/// Columns taken by the rank labels on the left.
+const LEFT: u16 = 3;
+
+/// The spacing between points, in (columns, rows), at `scale`.
+const fn steps(scale: u16) -> (u16, u16)
+{
+ (COL_STEP * scale, ROW_STEP * scale)
+}
+
+/// How far a drawn piece reaches past its point, in (columns, rows), at `scale`:
+/// `T` at scale 1, `[T]` at scale 2, and a 3x3 box from scale 3 up.
+const fn reach(scale: u16) -> (u16, u16)
+{
+ match scale
+ {
+ 1 => (0, 0),
+ 2 => (1, 0),
+ _ => (1, 1),
+ }
+}
+
+/// The board with its lines, rank labels down the left and file labels underneath.
+/// It is drawn at the largest whole-number scale that fits its area; at scale 1 it looks like:
+///
+/// ```text
+/// 5 T───·───·───·───T
+/// │ ╲ │ ╱ │ ╲ │ ╱ │
+/// 4 ·───·───·───·───·
+/// …
+/// 1 T───·───·───·───T
+///
+/// a b c d e
+/// ```
+pub struct BoardView
+{
+ pub board: GameBoard,
+ pub highlights: Highlights,
+ pub last_move: Option<Move>,
+}
+
+impl BoardView
+{
+ /// The (width, height) the board needs at `scale` (1 or more): the grid, the pieces sticking
+ /// out past its edge, then a blank row and the file labels.
+ pub const fn size(scale: u16) -> (u16, u16)
+ {
+ let (cs, rs) = steps(scale);
+ let (rx, ry) = reach(scale);
+ (LEFT + 4 * cs + 1 + rx, ry + 4 * rs + 1 + ry + 2)
+ }
+
+ /// The largest scale whose board fits in `width` by `height`; 1 if even that doesn't fit.
+ pub fn scale_to_fit(width: u16, height: u16) -> u16
+ {
+ let fits = |scale| { let (w, h) = BoardView::size(scale); w <= width && h <= height };
+ let mut scale = 1;
+ while fits(scale + 1)
+ {
+ scale += 1;
+ }
+ scale
+ }
+
+ /// The screen cell a point is drawn at at `scale`, relative to the widget's top-left.
+ /// The grid sits below a row for the top pieces' boxes once they are boxed.
+ fn cell((x, y): Pos, scale: u16) -> (u16, u16)
+ {
+ let (cs, rs) = steps(scale);
+ (LEFT + x as u16 * cs, reach(scale).1 + y as u16 * rs)
+ }
+
+ fn piece_style(&self, pos: Pos, piece: &PieceType) -> Style
+ {
+ let mut style = match piece
+ {
+ PieceType::Tiger => Style::new().fg(Color::Yellow).add_modifier(Modifier::BOLD),
+ PieceType::Sheep => Style::new().fg(Color::White).add_modifier(Modifier::BOLD),
+ PieceType::Empty => Style::new().fg(Color::DarkGray),
+ };
+ let (from, to) = match self.last_move
+ {
+ Some(Move::PlaceSheep { pos }) => (None, Some(pos)),
+ Some(Move::MoveSheep { from, to } | Move::MoveTiger { from, to }) => (Some(from), Some(to)),
+ None => (None, None),
+ };
+ if from == Some(pos) || to == Some(pos)
+ {
+ style = style.add_modifier(Modifier::UNDERLINED);
+ }
+ if self.highlights.targets.contains(&pos)
+ {
+ style = style.fg(Color::Green).add_modifier(Modifier::BOLD);
+ }
+ if self.highlights.selected == Some(pos)
+ {
+ style = style.add_modifier(Modifier::REVERSED);
+ }
+ style
+ }
+}
+
+impl Widget for &BoardView
+{
+ fn render(self, area: Rect, buf: &mut Buffer)
+ {
+ let scale = BoardView::scale_to_fit(area.width, area.height);
+ let (cs, rs) = steps(scale);
+ let lines = Style::new().fg(Color::Gray);
+ let labels = Style::new().fg(Color::Cyan);
+ // Clip to the area so a small terminal doesn't index outside the buffer
+ let mut put = |cx: u16, cy: u16, s: &str, style: Style|
+ {
+ if cx < area.width && cy < area.height
+ {
+ buf.set_string(area.x + cx, area.y + cy, s, style);
+ }
+ };
+
+ // Lines first, so the pieces are drawn over them
+ for y in 0..5u8
+ {
+ for x in 0..5u8
+ {
+ let (cx, cy) = BoardView::cell((x, y), scale);
+ if x < 4
+ {
+ put(cx + 1, cy, &"─".repeat(cs as usize - 1), lines);
+ }
+ if y < 4
+ {
+ for k in 1..rs
+ {
+ put(cx, cy + k, "│", lines);
+ }
+ if x < 4
+ {
+ // Diagonals run through points where x + y is even (see `GameBoard::on_line`).
+ // Each row down the diagonal moves cs / rs = 2 columns across.
+ let down_right = (x + y) % 2 == 0;
+ for k in 1..rs
+ {
+ let col = if down_right { cx + 2 * k } else { cx + cs - 2 * k };
+ put(col, cy + k, if down_right { "╲" } else { "╱" }, lines);
+ }
+ }
+ }
+ }
+ }
+
+ for y in 0..5u8
+ {
+ let (_, cy) = BoardView::cell((0, y), scale);
+ put(0, cy, &(5 - y).to_string(), labels);
+ for x in 0..5u8
+ {
+ let (cx, cy) = BoardView::cell((x, y), scale);
+ let piece = self.board.get((x, y));
+ let targeted = self.highlights.targets.contains(&(x, y));
+ let symbol = match piece
+ {
+ PieceType::Tiger => "T",
+ PieceType::Sheep => "S",
+ PieceType::Empty if targeted => "●",
+ PieceType::Empty => "·",
+ };
+ let style = self.piece_style((x, y), &piece);
+ // The last move's underline is only for the symbol, not the box around it
+ let frame = style.remove_modifier(Modifier::UNDERLINED);
+ let boxed = targeted || !matches!(piece, PieceType::Empty);
+ match scale
+ {
+ _ if !boxed => put(cx, cy, symbol, style),
+ 1 => put(cx, cy, symbol, style),
+ 2 =>
+ {
+ put(cx - 1, cy, "[", frame);
+ put(cx, cy, symbol, style);
+ put(cx + 1, cy, "]", frame);
+ }
+ _ =>
+ {
+ // Where a line meets the box, join it on
+ put(cx - 1, cy - 1, if y > 0 { "┌┴┐" } else { "┌─┐" }, frame);
+ put(cx - 1, cy, if x > 0 { "┤" } else { "│" }, frame);
+ put(cx, cy, symbol, style);
+ put(cx + 1, cy, if x < 4 { "├" } else { "│" }, frame);
+ put(cx - 1, cy + 1, if y < 4 { "└┬┘" } else { "└─┘" }, frame);
+ }
+ }
+ }
+ }
+ let files_row = BoardView::size(scale).1 - 1;
+ for x in 0..5u8
+ {
+ let (cx, _) = BoardView::cell((x, 0), scale);
+ put(cx, files_row, &((b'a' + x) as char).to_string(), labels);
+ }
+ }
+}
+
+/// The board point nearest a click at screen cell (`column`, `row`), for a `BoardView` drawn in `area`
+/// (at the same scale `render` picks for it). Clicks on the lines between points go to the nearest
+/// point; clicks off the grid give None.
+pub fn pos_at(area: Rect, column: u16, row: u16) -> Option<Pos>
+{
+ let scale = BoardView::scale_to_fit(area.width, area.height);
+ let (cs, rs) = steps(scale);
+ let (rx, ry) = reach(scale);
+ // Offsets from the top-left point, letting clicks land on the edge pieces' boxes
+ let cx = column.checked_sub(area.x + LEFT - rx)?;
+ let cy = row.checked_sub(area.y)?;
+ if cx > 4 * cs + 1 + rx || cy > 4 * rs + 2 * ry
+ {
+ return None;
+ }
+ // Shifted by the reach, so (cx, cy) are offsets from one column/row before the first point
+ let x = ((cx + cs / 2 - rx) / cs).min(4);
+ let y = ((cy + rs / 2 - ry) / rs).min(4);
+ Some((x as u8, y as u8))
+}
+
+#[cfg(test)]
+mod tests
+{
+ use super::*;
+
+ fn rendered(view: &BoardView, area: Rect) -> Buffer
+ {
+ let mut buf = Buffer::empty(Rect::new(0, 0, area.right() + 2, area.bottom() + 2));
+ view.render(area, &mut buf);
+ buf
+ }
+
+ fn symbol(buf: &Buffer, x: u16, y: u16) -> &str
+ {
+ buf[(x, y)].symbol()
+ }
+
+ #[test]
+ fn renders_default_board_with_labels()
+ {
+ let area = Rect::new(1, 1, BoardView::size(1).0, BoardView::size(1).1);
+ let view = BoardView { board: GameBoard::default(), highlights: Highlights::default(), last_move: None };
+ let buf = rendered(&view, area);
+ for (pos, s) in [((0, 0), "T"), ((4, 0), "T"), ((0, 4), "T"), ((4, 4), "T"), ((2, 2), "·")]
+ {
+ let (cx, cy) = BoardView::cell(pos, 1);
+ assert_eq!(symbol(&buf, area.x + cx, area.y + cy), s, "{pos:?}");
+ }
+ assert_eq!(symbol(&buf, area.x, area.y), "5");
+ assert_eq!(symbol(&buf, area.x, area.y + 8), "1");
+ assert_eq!(symbol(&buf, area.x + LEFT, area.y + BoardView::size(1).1 - 1), "a");
+ assert_eq!(symbol(&buf, area.x + LEFT + 16, area.y + BoardView::size(1).1 - 1), "e");
+ // (0, 0) has an even sum, so its diagonal runs down-right
+ assert_eq!(symbol(&buf, area.x + LEFT + 2, area.y + 1), "╲");
+ assert_eq!(symbol(&buf, area.x + LEFT + 6, area.y + 1), "╱");
+ }
+
+ #[test]
+ fn renders_target_highlights()
+ {
+ let area = Rect::new(0, 0, BoardView::size(1).0, BoardView::size(1).1);
+ let highlights = Highlights { selected: Some((0, 0)), targets: vec![(1, 1)] };
+ let view = BoardView { board: GameBoard::default(), highlights, last_move: None };
+ let buf = rendered(&view, area);
+ let (cx, cy) = BoardView::cell((1, 1), 1);
+ assert_eq!(symbol(&buf, cx, cy), "●");
+ let (cx, cy) = BoardView::cell((0, 0), 1);
+ assert!(buf[(cx, cy)].modifier.contains(Modifier::REVERSED));
+ }
+
+ #[test]
+ fn renders_into_a_small_area_without_panicking()
+ {
+ let view = BoardView { board: GameBoard::default(), highlights: Highlights::default(), last_move: None };
+ rendered(&view, Rect::new(0, 0, 5, 3));
+ }
+
+ #[test]
+ fn scale_to_fit_picks_the_largest_board_that_fits()
+ {
+ for scale in 1..5
+ {
+ let (w, h) = BoardView::size(scale);
+ assert_eq!(BoardView::scale_to_fit(w, h), scale);
+ assert_eq!(BoardView::scale_to_fit(w + 5, h + 5), scale);
+ assert_eq!(BoardView::scale_to_fit(w - 1, h), (scale - 1).max(1));
+ assert_eq!(BoardView::scale_to_fit(w, h - 1), (scale - 1).max(1));
+ }
+ assert_eq!(BoardView::scale_to_fit(0, 0), 1);
+ }
+
+ #[test]
+ fn renders_bigger_when_there_is_room()
+ {
+ let (w, h) = BoardView::size(2);
+ let area = Rect::new(0, 0, w, h);
+ let view = BoardView { board: GameBoard::default(), highlights: Highlights::default(), last_move: None };
+ let buf = rendered(&view, area);
+ let (cx, cy) = BoardView::cell((4, 4), 2);
+ assert_eq!((cx, cy), (LEFT + 32, 16));
+ assert_eq!(symbol(&buf, cx, cy), "T");
+ assert_eq!(symbol(&buf, 0, 16), "1");
+ assert_eq!(symbol(&buf, cx, h - 1), "e");
+ // Lines fill the gaps: three rows of │ between points, a diagonal two columns per row
+ for k in 1..4
+ {
+ assert_eq!(symbol(&buf, LEFT, k), "│");
+ assert_eq!(symbol(&buf, LEFT + 2 * k, k), "╲");
+ }
+ assert_eq!(symbol(&buf, LEFT + 7, 0), "─");
+ }
+
+ fn row(buf: &Buffer, y: u16) -> String
+ {
+ (0..buf.area.width).map(|x| buf[(x, y)].symbol()).collect()
+ }
+
+ #[test]
+ fn pieces_get_brackets_at_scale_2()
+ {
+ let (w, h) = BoardView::size(2);
+ let highlights = Highlights { selected: None, targets: vec![(1, 1)] };
+ let view = BoardView { board: GameBoard::default(), highlights, last_move: None };
+ let buf = rendered(&view, Rect::new(0, 0, w, h));
+ assert!(row(&buf, 0).starts_with("5 [T]──────·"), "{}", row(&buf, 0));
+ assert!(row(&buf, 4).starts_with("4 ·──────[●]──────·"), "{}", row(&buf, 4));
+ }
+
+ #[test]
+ fn pieces_get_boxes_from_scale_3()
+ {
+ let (w, h) = BoardView::size(3);
+ let mut board = GameBoard::default();
+ board.make_move(Move::PlaceSheep { pos: (2, 2) }).unwrap();
+ let view = BoardView { board, highlights: Highlights::default(), last_move: None };
+ let buf = rendered(&view, Rect::new(0, 0, w, h));
+ // Corner tiger: lines only join on the sides that have them
+ assert!(row(&buf, 0).starts_with(" ┌─┐"), "{}", row(&buf, 0));
+ assert!(row(&buf, 1).starts_with("5 │T├───"), "{}", row(&buf, 1));
+ assert!(row(&buf, 2).starts_with(" └┬┘"), "{}", row(&buf, 2));
+ // Centre sheep: lines join on all four sides
+ let (cx, cy) = BoardView::cell((2, 2), 3);
+ let around = |dy: u16| (cx - 1..=cx + 1).map(|x| buf[(x, cy + dy - 1)].symbol()).collect::<String>();
+ assert_eq!([around(0), around(1), around(2)], ["┌┴┐", "┤S├", "└┬┘"]);
+ assert_eq!(symbol(&buf, cx, h - 1), "c");
+ }
+
+ #[test]
+ fn pos_at_takes_clicks_on_a_piece_box()
+ {
+ let (w, h) = BoardView::size(3);
+ let area = Rect::new(4, 3, w, h);
+ for pos in [(0, 0), (4, 4), (2, 2), (4, 0)]
+ {
+ let (cx, cy) = BoardView::cell(pos, 3);
+ for (dx, dy) in [(-1, -1), (1, 1), (-1, 1), (1, -1)]
+ {
+ let column = (area.x + cx).checked_add_signed(dx).unwrap();
+ let row = (area.y + cy).checked_add_signed(dy).unwrap();
+ assert_eq!(pos_at(area, column, row), Some(pos), "{pos:?} {dx},{dy}");
+ }
+ }
+ assert_eq!(pos_at(area, area.x + 1, area.y), None);
+ assert_eq!(pos_at(area, area.x + LEFT, area.y + h - 1), None); // file labels
+ }
+
+ #[test]
+ fn pos_at_finds_every_drawn_point()
+ {
+ for scale in 1..6
+ {
+ let (w, h) = BoardView::size(scale);
+ let area = Rect::new(3, 2, w, h);
+ for y in 0..5
+ {
+ for x in 0..5
+ {
+ let (cx, cy) = BoardView::cell((x, y), scale);
+ assert_eq!(pos_at(area, area.x + cx, area.y + cy), Some((x, y)), "scale {scale}");
+ }
+ }
+ }
+ }
+
+ #[test]
+ fn pos_at_snaps_line_clicks_to_nearest_point()
+ {
+ let area = Rect::new(0, 0, BoardView::size(1).0, BoardView::size(1).1);
+ assert_eq!(pos_at(area, LEFT + 1, 0), Some((0, 0)));
+ assert_eq!(pos_at(area, LEFT + 3, 0), Some((1, 0)));
+ assert_eq!(pos_at(area, LEFT + 16, 1), Some((4, 1)));
+ }
+
+ #[test]
+ fn pos_at_rejects_clicks_off_the_grid()
+ {
+ let area = Rect::new(2, 2, BoardView::size(1).0, BoardView::size(1).1);
+ assert_eq!(pos_at(area, 0, 0), None);
+ assert_eq!(pos_at(area, area.x, area.y), None); // rank label
+ assert_eq!(pos_at(area, area.x + LEFT, area.y + 9), None); // below the last rank
+ assert_eq!(pos_at(area, area.x + LEFT + 18, area.y), None);
+ }
+}
generated by cgit v1.3.1 (git 2.54.0) at 2026-11-09 21:14:36 +0000