Separate out into another library

iced-tetris/Cargo.lock

@@ -998,6 +998,7 @@ dependencies = [
  "iced",
  "iced_native",
  "rand",
+ "tetris-logic",
 ]
 
 [[package]]
@@ -2099,6 +2100,13 @@ dependencies = [
  "winapi-util",
 ]
 
+[[package]]
+name = "tetris-logic"
+version = "0.1.0"
+dependencies = [
+ "rand",
+]
+
 [[package]]
 name = "thiserror"
 version = "1.0.29"

iced-tetris/Cargo.toml

@@ -11,3 +11,7 @@ iced = { git = "https://github.com/hecrj/iced", rev = "099981cfc2f61a1f37e841005
 iced_native = { git = "https://github.com/hecrj/iced", rev = "099981cfc2f61a1f37e84100592d65babb94fb82"}
 chrono = "0.4.19"
 rand = "0.8.4"
+tetris-logic = { path = "tetris-logic" }
+
+[workspace]
+members = ["tetris-logic"]

iced-tetris/src/main.rs

@@ -4,10 +4,7 @@ use iced::{
     Settings, Size, Subscription,
 };
 use iced_native::{event, subscription, Event};
-use rand::distributions::{Distribution, Standard};
+use tetris_logic::{BlockGrid, MoveDirection, Tetromino};
-
-const START_LOCATION: (u8, u8) = (5, 1);
-type PieceBlocks = [(i8, i8); 4];
 
 fn main() -> iced::Result {
     Tetris::run(Settings::default())
@@ -68,17 +65,14 @@ impl Application for Tetris {
             }
         };
 
-        match self.blocks.active_piece {
+        if self.blocks.piece_currently_active() {
-            None => {
+            if self.ticks % 10 == 0 {
-                let piece: Tetromino = rand::random();
+                self.blocks.move_active_piece(MoveDirection::SoftDrop);
-                self.blocks.drop_piece(piece);
             }
-            Some(_) => {
+        } else {
-                if self.ticks % 10 == 0 {
+            let piece: Tetromino = rand::random();
-                    self.blocks.move_active_piece(MoveDirection::SoftDrop);
+            self.blocks.drop_piece(piece);
-                }
+        }
-            }
-        };
 
         let lines_removed = self.blocks.clear_pieces();
         self.lines_removed += lines_removed;
@@ -135,6 +129,7 @@ impl<'a> canvas::Program<Message> for Tetris {
             );
             let block = Path::rectangle(point, block_size);
             let color = tetronimo.color();
+            let color = Color::from_rgb8(color.0, color.1, color.2);
             frame.fill(&block, color);
         }
 
@@ -164,346 +159,3 @@ enum Message {
     Pause,
     Tick(chrono::DateTime<chrono::Local>),
 }
-
-struct BlockGrid {
-    state: [[Option<Block>; 20]; 10],
-    active_piece: Option<ActivePiece>,
-}
-
-#[derive(Debug, Copy, Clone)]
-struct ActivePiece {
-    location: (u8, u8),
-    tetromino: Tetromino,
-    orientation: Orientation,
-}
-
-impl ActivePiece {
-    fn move_piece(&self, direction: &MoveDirection) -> ActivePiece {
-        use MoveDirection::*;
-        let (cur_x, cur_y) = self.location;
-        ActivePiece {
-            tetromino: self.tetromino,
-            orientation: self.orientation,
-            location: match direction {
-                Left => (cur_x.checked_sub(1).unwrap_or(0), cur_y),
-                Right => (cur_x + 1, cur_y),
-                SoftDrop => (cur_x, cur_y + 1),
-                HardDrop => (cur_x, cur_y),
-            },
-        }
-    }
-
-    fn rotate_piece(&self) -> ActivePiece {
-        ActivePiece {
-            tetromino: self.tetromino,
-            location: self.location,
-            orientation: match self.orientation {
-                Orientation::A => Orientation::B,
-                Orientation::B => Orientation::C,
-                Orientation::C => Orientation::D,
-                Orientation::D => Orientation::A,
-            },
-        }
-    }
-}
-
-impl BlockGrid {
-    fn new() -> BlockGrid {
-        let mut state = [[None; 20]; 10];
-        BlockGrid {
-            state,
-            active_piece: None,
-        }
-    }
-
-    /// If it's impossible to drop a piece, return false
-    fn drop_piece(&mut self, tetromino: Tetromino) -> bool {
-        if let None = self.active_piece {
-            let piece = ActivePiece {
-                location: START_LOCATION,
-                tetromino,
-                orientation: Orientation::A,
-            };
-            let piece_blocks = Self::piece_blocks(&piece);
-            if self.piece_blocks_in_bounds(piece_blocks) {
-                self.active_piece = Some(piece);
-                true
-            } else {
-                false
-            }
-        } else {
-            false
-        }
-    }
-
-    fn piece_blocks_in_bounds(&self, piece_blocks: PieceBlocks) -> bool {
-        piece_blocks.iter().all(|(x, y)| {
-            let x = *x;
-            let y = *y;
-            x >= 0 && y >= 0 && x < 10 && y < 20 && self.state[x as usize][y as usize].is_none()
-        })
-    }
-
-    /// If there is an active piece, and the move is legal, move it. Return true if it was possible
-    /// to move an active piece, false otherwise.
-    fn move_active_piece(&mut self, direction: MoveDirection) -> bool {
-        let active = self.active_piece;
-        match (active, direction) {
-            (None, _) => false,
-            (Some(piece), MoveDirection::Left | MoveDirection::Right) => {
-                let new_piece = piece.move_piece(&direction);
-                let new_blocks = Self::piece_blocks(&new_piece);
-                if self.piece_blocks_in_bounds(new_blocks) {
-                    self.active_piece = Some(new_piece);
-                    true
-                } else {
-                    false
-                }
-            }
-            (Some(ref piece), MoveDirection::HardDrop) => {
-                let mut new_piece = *piece;
-                loop {
-                    let p = new_piece.move_piece(&MoveDirection::SoftDrop);
-                    let new_blocks = Self::piece_blocks(&p);
-                    if self.piece_blocks_in_bounds(new_blocks) {
-                        new_piece = p;
-                    } else {
-                        break;
-                    }
-                }
-
-                self.active_piece = Some(new_piece);
-                self.place_active_piece();
-                true
-            }
-            (Some(ref piece), MoveDirection::SoftDrop) => {
-                let new_piece = piece.move_piece(&MoveDirection::SoftDrop);
-                let new_blocks = Self::piece_blocks(&new_piece);
-                if self.piece_blocks_in_bounds(new_blocks) {
-                    self.active_piece = Some(new_piece);
-                    true
-                } else {
-                    self.place_active_piece();
-                    false
-                }
-            }
-        }
-    }
-
-    fn rotate_active_piece(&mut self) -> bool {
-        let active = self.active_piece;
-        if let Some(piece) = active {
-            let new_piece = piece.rotate_piece();
-            let new_blocks = Self::piece_blocks(&new_piece);
-            if self.piece_blocks_in_bounds(new_blocks) {
-                self.active_piece = Some(new_piece);
-                true
-            } else {
-                false
-            }
-        } else {
-            false
-        }
-    }
-
-    /// Remove the currently active piece and place its blocks onto the board.
-    fn place_active_piece(&mut self) {
-        if let Some(piece) = self.active_piece {
-            let cur_blocks = Self::piece_blocks(&piece);
-            for (x, y) in cur_blocks.iter() {
-                self.state[*x as usize][*y as usize] = Some(Block {
-                    source: piece.tetromino,
-                });
-            }
-            self.active_piece = None;
-        }
-    }
-
-    fn piece_blocks(piece: &ActivePiece) -> PieceBlocks {
-        use Orientation::*;
-        use Tetromino::*;
-        let (x, y) = piece.location;
-        let (x, y) = (x as i8, y as i8);
-
-        // These use the "Original Rotation System" cf. Tetris wiki
-        match (piece.tetromino, piece.orientation) {
-            (I, A | C) => [(x - 2, y), (x - 1, y), (x, y), (x + 1, y)],
-            (I, B | D) => [(x, y - 1), (x, y), (x, y + 1), (x, y + 2)],
-            (J, A) => [(x - 1, y), (x, y), (x + 1, y), (x + 1, y + 1)],
-            (J, B) => [(x, y), (x + 1, y), (x, y + 1), (x, y + 2)],
-            (J, C) => [(x - 1, y), (x - 1, y + 1), (x, y + 1), (x + 1, y + 1)],
-            (J, D) => [(x, y), (x, y + 1), (x, y + 2), (x - 1, y + 2)],
-            (L, A) => [(x - 1, y + 1), (x - 1, y), (x, y), (x + 1, y)],
-            (L, B) => [(x, y), (x, y + 1), (x, y + 2), (x + 1, y + 2)],
-            (L, C) => [(x - 1, y + 1), (x, y + 1), (x + 1, y + 1), (x + 1, y)],
-            (L, D) => [(x - 1, y), (x, y), (x, y + 1), (x, y + 2)],
-            (O, _) => [(x, y), (x, y + 1), (x - 1, y), (x - 1, y + 1)],
-            (S, A | C) => [(x - 1, y + 1), (x, y + 1), (x, y), (x + 1, y)],
-            (S, B | D) => [(x, y), (x, y + 1), (x + 1, y + 1), (x + 1, y + 2)],
-            (T, A) => [(x - 1, y), (x, y), (x + 1, y), (x, y + 1)],
-            (T, B) => [(x, y), (x, y + 1), (x + 1, y + 1), (x, y + 2)],
-            (T, C) => [(x, y), (x - 1, y + 1), (x, y + 1), (x + 1, y + 1)],
-            (T, D) => [(x - 1, y + 1), (x, y), (x, y + 1), (x, y + 2)],
-            (Z, A | C) => [(x - 1, y + 1), (x, y + 1), (x, y + 2), (x + 1, y + 2)],
-            (Z, B | D) => [(x, y), (x, y + 1), (x + 1, y), (x + 1, y - 1)],
-        }
-    }
-
-    /// Returns number of lines removed
-    fn clear_pieces(&mut self) -> u32 {
-      let mut new_state = [[None; 20]; 10];
-      let mut offset = 0;
-      for row in (0..=19).rev() {
-        let mut all_filled = true;
-        let mut all_empty = true;
-        for col in 0..10 {
-          if self.state[col][row].is_none() {
-            all_filled = false;
-          }
-          if self.state[col][row].is_some() {
-            all_empty = false;
-          }
-        }
-
-        if all_filled && !all_empty {
-          offset += 1;
-        } else {
-          if offset != 0 {
-            println!("Offset {} row {}", offset, row);
-          }
-          for col in 0..10 {
-            new_state[col][row+offset] = self.state[col][row];
-          }
-        }
-      }
-
-      self.state = new_state;
-      println!("OFFSET: {}", offset);
-      offset as u32
-    }
-
-    fn iter<'a>(&'a self) -> BlockGridIter<'a> {
-        let active_piece_blocks = self.active_piece.as_ref().map(|piece| {
-            let b = Self::piece_blocks(piece);
-            let blocks = [
-                (b[0].0 as u8, b[0].1 as u8),
-                (b[1].0 as u8, b[1].1 as u8),
-                (b[2].0 as u8, b[2].1 as u8),
-                (b[3].0 as u8, b[3].1 as u8),
-            ];
-
-            (piece.tetromino, blocks)
-        });
-        BlockGridIter::new(&self.state, active_piece_blocks)
-    }
-}
-
-struct BlockGridIter<'a> {
-    outer_state: &'a [[Option<Block>; 20]; 10],
-    outer_active: Option<(Tetromino, [(u8, u8); 4])>,
-    idx: usize,
-    active_pice_idx: usize,
-}
-
-impl<'a> BlockGridIter<'a> {
-    fn new(
-        state: &'a [[Option<Block>; 20]; 10],
-        outer_active: Option<(Tetromino, [(u8, u8); 4])>,
-    ) -> Self {
-        BlockGridIter {
-            outer_state: state,
-            idx: 0,
-            active_pice_idx: 0,
-            outer_active,
-        }
-    }
-}
-
-impl<'a> std::iter::Iterator for BlockGridIter<'a> {
-    type Item = (u8, u8, Tetromino);
-    fn next(&mut self) -> Option<Self::Item> {
-        loop {
-            if self.idx >= 200 {
-                return self.outer_active.and_then(|(tetromino, block_array)| {
-                    let i = self.active_pice_idx;
-                    self.active_pice_idx += 1;
-                    block_array.get(i).map(|(x, y)| (*x, *y, tetromino))
-                });
-            }
-            let i = self.idx % 10;
-            let j = self.idx / 10;
-            match self.outer_state[i][j] {
-                Some(block) => {
-                    self.idx += 1;
-                    return Some((i as u8, j as u8, block.source));
-                }
-                None => {
-                    self.idx += 1;
-                }
-            }
-        }
-    }
-}
-
-#[derive(Debug, Clone, Copy)]
-struct Block {
-    source: Tetromino,
-}
-
-#[derive(Debug, Copy, Clone)]
-enum MoveDirection {
-    Left,
-    Right,
-    HardDrop,
-    SoftDrop,
-}
-
-#[derive(Debug, Copy, Clone)]
-enum Orientation {
-    A,
-    B,
-    C,
-    D,
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-enum Tetromino {
-    I,
-    J,
-    L,
-    O,
-    S,
-    T,
-    Z,
-}
-
-impl Tetromino {
-    fn color(self) -> Color {
-        use Tetromino::*;
-        match self {
-            I => Color::from_rgb8(0, 255, 255),
-            J => Color::from_rgb8(0, 0, 255),
-            L => Color::from_rgb8(255, 165, 0),
-            O => Color::from_rgb8(255, 255, 0),
-            S => Color::from_rgb8(0, 255, 0),
-            T => Color::from_rgb8(255, 255, 0),
-            Z => Color::from_rgb8(128, 0, 128),
-        }
-    }
-}
-
-impl Distribution<Tetromino> for Standard {
-    fn sample<R: rand::Rng + ?Sized>(&self, rng: &mut R) -> Tetromino {
-        let index: u8 = rng.gen_range(0..=6);
-        match index {
-            0 => Tetromino::I,
-            1 => Tetromino::J,
-            2 => Tetromino::L,
-            3 => Tetromino::O,
-            4 => Tetromino::S,
-            5 => Tetromino::T,
-            6 => Tetromino::Z,
-            _ => unreachable!(),
-        }
-    }
-}

iced-tetris/tetris-logic/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "tetris-logic"
+version = "0.1.0"
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+rand = "0.8.4"

iced-tetris/tetris-logic/src/lib.rs

@@ -0,0 +1,347 @@
+use rand::distributions::{Distribution, Standard};
+
+const START_LOCATION: (u8, u8) = (5, 1);
+type PieceBlocks = [(i8, i8); 4];
+
+pub struct BlockGrid {
+    state: [[Option<Block>; 20]; 10],
+    active_piece: Option<ActivePiece>,
+}
+
+impl BlockGrid {
+    pub fn new() -> BlockGrid {
+        let mut state = [[None; 20]; 10];
+        BlockGrid {
+            state,
+            active_piece: None,
+        }
+    }
+
+    pub fn piece_currently_active(&self) -> bool {
+        self.active_piece.is_some()
+    }
+
+    /// If it's impossible to drop a piece, return false
+    pub fn drop_piece(&mut self, tetromino: Tetromino) -> bool {
+        if let None = self.active_piece {
+            let piece = ActivePiece {
+                location: START_LOCATION,
+                tetromino,
+                orientation: Orientation::A,
+            };
+            let piece_blocks = Self::piece_blocks(&piece);
+            if self.piece_blocks_in_bounds(piece_blocks) {
+                self.active_piece = Some(piece);
+                true
+            } else {
+                false
+            }
+        } else {
+            false
+        }
+    }
+
+    fn piece_blocks_in_bounds(&self, piece_blocks: PieceBlocks) -> bool {
+        piece_blocks.iter().all(|(x, y)| {
+            let x = *x;
+            let y = *y;
+            x >= 0 && y >= 0 && x < 10 && y < 20 && self.state[x as usize][y as usize].is_none()
+        })
+    }
+
+    /// If there is an active piece, and the move is legal, move it. Return true if it was possible
+    /// to move an active piece, false otherwise.
+    pub fn move_active_piece(&mut self, direction: MoveDirection) -> bool {
+        let active = self.active_piece;
+        match (active, direction) {
+            (None, _) => false,
+            (Some(piece), MoveDirection::Left | MoveDirection::Right) => {
+                let new_piece = piece.move_piece(&direction);
+                let new_blocks = Self::piece_blocks(&new_piece);
+                if self.piece_blocks_in_bounds(new_blocks) {
+                    self.active_piece = Some(new_piece);
+                    true
+                } else {
+                    false
+                }
+            }
+            (Some(ref piece), MoveDirection::HardDrop) => {
+                let mut new_piece = *piece;
+                loop {
+                    let p = new_piece.move_piece(&MoveDirection::SoftDrop);
+                    let new_blocks = Self::piece_blocks(&p);
+                    if self.piece_blocks_in_bounds(new_blocks) {
+                        new_piece = p;
+                    } else {
+                        break;
+                    }
+                }
+
+                self.active_piece = Some(new_piece);
+                self.place_active_piece();
+                true
+            }
+            (Some(ref piece), MoveDirection::SoftDrop) => {
+                let new_piece = piece.move_piece(&MoveDirection::SoftDrop);
+                let new_blocks = Self::piece_blocks(&new_piece);
+                if self.piece_blocks_in_bounds(new_blocks) {
+                    self.active_piece = Some(new_piece);
+                    true
+                } else {
+                    self.place_active_piece();
+                    false
+                }
+            }
+        }
+    }
+
+    pub fn rotate_active_piece(&mut self) -> bool {
+        let active = self.active_piece;
+        if let Some(piece) = active {
+            let new_piece = piece.rotate_piece();
+            let new_blocks = Self::piece_blocks(&new_piece);
+            if self.piece_blocks_in_bounds(new_blocks) {
+                self.active_piece = Some(new_piece);
+                true
+            } else {
+                false
+            }
+        } else {
+            false
+        }
+    }
+
+    /// Remove the currently active piece and place its blocks onto the board.
+    fn place_active_piece(&mut self) {
+        if let Some(piece) = self.active_piece {
+            let cur_blocks = Self::piece_blocks(&piece);
+            for (x, y) in cur_blocks.iter() {
+                self.state[*x as usize][*y as usize] = Some(Block {
+                    source: piece.tetromino,
+                });
+            }
+            self.active_piece = None;
+        }
+    }
+
+    fn piece_blocks(piece: &ActivePiece) -> PieceBlocks {
+        use Orientation::*;
+        use Tetromino::*;
+        let (x, y) = piece.location;
+        let (x, y) = (x as i8, y as i8);
+
+        // These use the "Original Rotation System" cf. Tetris wiki
+        match (piece.tetromino, piece.orientation) {
+            (I, A | C) => [(x - 2, y), (x - 1, y), (x, y), (x + 1, y)],
+            (I, B | D) => [(x, y - 1), (x, y), (x, y + 1), (x, y + 2)],
+            (J, A) => [(x - 1, y), (x, y), (x + 1, y), (x + 1, y + 1)],
+            (J, B) => [(x, y), (x + 1, y), (x, y + 1), (x, y + 2)],
+            (J, C) => [(x - 1, y), (x - 1, y + 1), (x, y + 1), (x + 1, y + 1)],
+            (J, D) => [(x, y), (x, y + 1), (x, y + 2), (x - 1, y + 2)],
+            (L, A) => [(x - 1, y + 1), (x - 1, y), (x, y), (x + 1, y)],
+            (L, B) => [(x, y), (x, y + 1), (x, y + 2), (x + 1, y + 2)],
+            (L, C) => [(x - 1, y + 1), (x, y + 1), (x + 1, y + 1), (x + 1, y)],
+            (L, D) => [(x - 1, y), (x, y), (x, y + 1), (x, y + 2)],
+            (O, _) => [(x, y), (x, y + 1), (x - 1, y), (x - 1, y + 1)],
+            (S, A | C) => [(x - 1, y + 1), (x, y + 1), (x, y), (x + 1, y)],
+            (S, B | D) => [(x, y), (x, y + 1), (x + 1, y + 1), (x + 1, y + 2)],
+            (T, A) => [(x - 1, y), (x, y), (x + 1, y), (x, y + 1)],
+            (T, B) => [(x, y), (x, y + 1), (x + 1, y + 1), (x, y + 2)],
+            (T, C) => [(x, y), (x - 1, y + 1), (x, y + 1), (x + 1, y + 1)],
+            (T, D) => [(x - 1, y + 1), (x, y), (x, y + 1), (x, y + 2)],
+            (Z, A | C) => [(x - 1, y + 1), (x, y + 1), (x, y + 2), (x + 1, y + 2)],
+            (Z, B | D) => [(x, y), (x, y + 1), (x + 1, y), (x + 1, y - 1)],
+        }
+    }
+
+    /// Returns number of lines removed
+    pub fn clear_pieces(&mut self) -> u32 {
+        let mut new_state = [[None; 20]; 10];
+        let mut offset = 0;
+        for row in (0..=19).rev() {
+            let mut all_filled = true;
+            let mut all_empty = true;
+            for col in 0..10 {
+                if self.state[col][row].is_none() {
+                    all_filled = false;
+                }
+                if self.state[col][row].is_some() {
+                    all_empty = false;
+                }
+            }
+
+            if all_filled && !all_empty {
+                offset += 1;
+            } else {
+                for col in 0..10 {
+                    new_state[col][row + offset] = self.state[col][row];
+                }
+            }
+        }
+
+        self.state = new_state;
+        offset as u32
+    }
+
+    pub fn iter<'a>(&'a self) -> BlockGridIter<'a> {
+        let active_piece_blocks = self.active_piece.as_ref().map(|piece| {
+            let b = Self::piece_blocks(piece);
+            let blocks = [
+                (b[0].0 as u8, b[0].1 as u8),
+                (b[1].0 as u8, b[1].1 as u8),
+                (b[2].0 as u8, b[2].1 as u8),
+                (b[3].0 as u8, b[3].1 as u8),
+            ];
+
+            (piece.tetromino, blocks)
+        });
+        BlockGridIter::new(&self.state, active_piece_blocks)
+    }
+}
+
+#[derive(Debug, Copy, Clone)]
+struct ActivePiece {
+    location: (u8, u8),
+    tetromino: Tetromino,
+    orientation: Orientation,
+}
+
+impl ActivePiece {
+    fn move_piece(&self, direction: &MoveDirection) -> ActivePiece {
+        use MoveDirection::*;
+        let (cur_x, cur_y) = self.location;
+        ActivePiece {
+            tetromino: self.tetromino,
+            orientation: self.orientation,
+            location: match direction {
+                Left => (cur_x.checked_sub(1).unwrap_or(0), cur_y),
+                Right => (cur_x + 1, cur_y),
+                SoftDrop => (cur_x, cur_y + 1),
+                HardDrop => (cur_x, cur_y),
+            },
+        }
+    }
+
+    fn rotate_piece(&self) -> ActivePiece {
+        ActivePiece {
+            tetromino: self.tetromino,
+            location: self.location,
+            orientation: match self.orientation {
+                Orientation::A => Orientation::B,
+                Orientation::B => Orientation::C,
+                Orientation::C => Orientation::D,
+                Orientation::D => Orientation::A,
+            },
+        }
+    }
+}
+
+pub struct BlockGridIter<'a> {
+    outer_state: &'a [[Option<Block>; 20]; 10],
+    outer_active: Option<(Tetromino, [(u8, u8); 4])>,
+    idx: usize,
+    active_pice_idx: usize,
+}
+
+impl<'a> BlockGridIter<'a> {
+    fn new(
+        state: &'a [[Option<Block>; 20]; 10],
+        outer_active: Option<(Tetromino, [(u8, u8); 4])>,
+    ) -> Self {
+        BlockGridIter {
+            outer_state: state,
+            idx: 0,
+            active_pice_idx: 0,
+            outer_active,
+        }
+    }
+}
+
+impl<'a> std::iter::Iterator for BlockGridIter<'a> {
+    type Item = (u8, u8, Tetromino);
+    fn next(&mut self) -> Option<Self::Item> {
+        loop {
+            if self.idx >= 200 {
+                return self.outer_active.and_then(|(tetromino, block_array)| {
+                    let i = self.active_pice_idx;
+                    self.active_pice_idx += 1;
+                    block_array.get(i).map(|(x, y)| (*x, *y, tetromino))
+                });
+            }
+            let i = self.idx % 10;
+            let j = self.idx / 10;
+            match self.outer_state[i][j] {
+                Some(block) => {
+                    self.idx += 1;
+                    return Some((i as u8, j as u8, block.source));
+                }
+                None => {
+                    self.idx += 1;
+                }
+            }
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+struct Block {
+    source: Tetromino,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum Tetromino {
+    I,
+    J,
+    L,
+    O,
+    S,
+    T,
+    Z,
+}
+
+#[derive(Debug, Copy, Clone)]
+pub enum Orientation {
+    A,
+    B,
+    C,
+    D,
+}
+
+#[derive(Debug, Copy, Clone)]
+pub enum MoveDirection {
+    Left,
+    Right,
+    HardDrop,
+    SoftDrop,
+}
+
+impl Tetromino {
+    pub fn color(self) -> (u8, u8, u8) {
+        use Tetromino::*;
+        match self {
+            I => (0, 255, 255),
+            J => (0, 0, 255),
+            L => (255, 165, 0),
+            O => (255, 255, 0),
+            S => (0, 255, 0),
+            T => (255, 255, 0),
+            Z => (128, 0, 128),
+        }
+    }
+}
+
+impl Distribution<Tetromino> for Standard {
+    fn sample<R: rand::Rng + ?Sized>(&self, rng: &mut R) -> Tetromino {
+        let index: u8 = rng.gen_range(0..=6);
+        match index {
+            0 => Tetromino::I,
+            1 => Tetromino::J,
+            2 => Tetromino::L,
+            3 => Tetromino::O,
+            4 => Tetromino::S,
+            5 => Tetromino::T,
+            6 => Tetromino::Z,
+            _ => unreachable!(),
+        }
+    }
+}