Snake: Flesh out a basic snake game :^)

Games/Snake/SnakeGame.cpp

@@ -0,0 +1,151 @@
+#include "SnakeGame.h"
+#include <LibGUI/GPainter.h>
+#include <stdlib.h>
+#include <time.h>
+
+SnakeGame::SnakeGame(GWidget* parent)
+    : GWidget(parent)
+{
+    srand(time(nullptr));
+    reset();
+}
+
+SnakeGame::~SnakeGame()
+{
+}
+
+void SnakeGame::reset()
+{
+    m_head = { m_rows / 2, m_columns / 2 };
+    m_tail.clear_with_capacity();
+    m_length = 2;
+    stop_timer();
+    start_timer(120);
+    spawn_fruit();
+}
+
+bool SnakeGame::is_available(const Coordinate& coord)
+{
+    for (int i = 0; i < m_tail.size(); ++i) {
+        if (m_tail[i] == coord)
+            return false;
+    }
+    if (m_head == coord)
+        return false;
+    if (m_fruit == coord)
+        return false;
+    return true;
+}
+
+void SnakeGame::spawn_fruit()
+{
+    Coordinate coord;
+    for (;;) {
+        coord.row = rand() % m_rows;
+        coord.column = rand() % m_columns;
+        if (is_available(coord))
+            break;
+    }
+    m_fruit = coord;
+}
+
+void SnakeGame::timer_event(CTimerEvent&)
+{
+    m_tail.prepend(m_head);
+
+    if (m_tail.size() > m_length)
+        m_tail.take_last();
+
+    m_head.row += m_vertical_velocity;
+    m_head.column += m_horizontal_velocity;
+
+    m_last_vertical_velocity = m_vertical_velocity;
+    m_last_horizontal_velocity = m_horizontal_velocity;
+
+    if (m_head.row >= m_rows)
+        m_head.row = 0;
+    if (m_head.row < 0)
+        m_head.row = m_rows - 1;
+    if (m_head.column >= m_columns)
+        m_head.column = 0;
+    if (m_head.column < 0)
+        m_head.column = m_columns - 1;
+
+    for (int i = 0; i < m_tail.size(); ++i) {
+        if (m_head == m_tail[i]) {
+            game_over();
+            return;
+        }
+    }
+
+    if (m_head == m_fruit) {
+        ++m_length;
+        spawn_fruit();
+    }
+    update();
+}
+
+void SnakeGame::keydown_event(GKeyEvent& event)
+{
+    switch (event.key()) {
+    case KeyCode::Key_A:
+    case KeyCode::Key_Left:
+        if (m_last_horizontal_velocity == 1)
+            break;
+        m_vertical_velocity = 0;
+        m_horizontal_velocity = -1;
+        break;
+    case KeyCode::Key_D:
+    case KeyCode::Key_Right:
+        if (m_last_horizontal_velocity == -1)
+            break;
+        m_vertical_velocity = 0;
+        m_horizontal_velocity = 1;
+        break;
+    case KeyCode::Key_W:
+    case KeyCode::Key_Up:
+        if (m_last_vertical_velocity == 1)
+            break;
+        m_vertical_velocity = -1;
+        m_horizontal_velocity = 0;
+        break;
+    case KeyCode::Key_S:
+    case KeyCode::Key_Down:
+        if (m_last_vertical_velocity == -1)
+            break;
+        m_vertical_velocity = 1;
+        m_horizontal_velocity = 0;
+        break;
+    default:
+        break;
+    }
+}
+
+void SnakeGame::paint_event(GPaintEvent& event)
+{
+    GPainter painter(*this);
+    painter.fill_rect(event.rect(), Color::Black);
+
+    auto game_rect = rect();
+    auto cell_size = Size(game_rect.width() / m_columns, game_rect.height() / m_rows);
+
+    auto cell_rect = [&] (const Coordinate& coord) -> Rect {
+        return {
+            coord.column * cell_size.width(),
+            coord.row * cell_size.height(),
+            cell_size.width(),
+            cell_size.height()
+        };
+    };
+
+    painter.fill_rect(cell_rect(m_head), Color::Yellow);
+    for (auto& coord : m_tail)
+        painter.fill_rect(cell_rect(coord), Color::from_rgb(0xaaaa00));
+
+    painter.fill_rect(cell_rect(m_fruit), Color::Red);
+}
+
+void SnakeGame::game_over()
+{
+    reset();
+}