GameOfLife: Switch from single indexed vector to rows+columns

This is not only easier to comprehend code-wise and avoids some function
overloads, but also makes resizing the board while preserving game state
*a lot* easier. We now no longer have to allocate a new board on every
resize, we just grow/shrink the individual row vectors.
Also fixes a crash when clicking the board widget outside of the drawn
board area.

5 files changed, 110 insertions, 112 deletions

diff --git a/Userland/Games/GameOfLife/Board.cpp b/Userland/Games/GameOfLife/Board.cpp
index 452c803776..897f30c340 100644
--- a/Userland/Games/GameOfLife/Board.cpp
+++ b/Userland/Games/GameOfLife/Board.cpp
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2021, Andres Crucitti <dasc495@gmail.com>
+ * Copyright (c) 2021, Linus Groh <linusg@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -9,13 +10,8 @@
 #include <time.h>
 
 Board::Board(size_t rows, size_t columns)
-    : m_columns(columns)
-    , m_rows(rows)
 {
-    m_cells.resize(total_size());
-    for (size_t i = 0; i < total_size(); ++i) {
-        m_cells[i] = false;
-    }
+    resize(rows, columns);
 }
 
 Board::~Board()
@@ -25,28 +21,27 @@ Board::~Board()
 void Board::run_generation()
 {
     m_stalled = true;
-    Vector<bool> new_cells;
-    new_cells.resize(total_size());
-
-    for (size_t i = 0; i < total_size(); ++i) {
-        bool old_val = m_cells[i];
-        new_cells[i] = calculate_next_value(i);
-        if (old_val != new_cells[i]) {
+    Vector<Vector<bool>> new_cells;
+    new_cells.resize(m_rows);
+    for (size_t row = 0; row < m_rows; ++row)
+        new_cells[row].resize(m_columns);
+
+    for_each_cell([&](auto row, auto column) {
+        bool old_value = m_cells[row][column];
+        bool new_value = calculate_next_value(row, column);
+        new_cells[row][column] = new_value;
+        if (old_value != new_value)
             m_stalled = false;
-        }
-    }
+    });
 
     if (m_stalled)
         return;
 
-    m_cells = new_cells;
+    m_cells = move(new_cells);
 }
 
-bool Board::calculate_next_value(size_t index) const
+bool Board::calculate_next_value(size_t row, size_t column) const
 {
-    size_t row = index / columns();
-    size_t column = index % columns();
-
     int top_left = cell(row - 1, column - 1);
     int top_mid = cell(row - 1, column);
     int top_right = cell(row - 1, column + 1);
@@ -58,10 +53,10 @@ bool Board::calculate_next_value(size_t index) const
 
     int sum = top_left + top_mid + top_right + left + right + bottom_left + bottom_mid + bottom_right;
 
-    bool current = m_cells[index];
-    bool new_value = current;
+    bool old_value = m_cells[row][column];
+    bool new_value = old_value;
 
-    if (current) {
+    if (old_value) {
         if (sum < 2 || sum > 3)
             new_value = false;
     } else {
@@ -74,59 +69,47 @@ bool Board::calculate_next_value(size_t index) const
 
 void Board::clear()
 {
-    for (size_t i = 0; i < total_size(); ++i)
-        set_cell(i, false);
+    for_each_cell([this](auto row, auto column) {
+        set_cell(row, column, false);
+    });
 }
 
 void Board::randomize()
 {
-    for (size_t i = 0; i < total_size(); ++i)
-        set_cell(i, get_random<u32>() % 2);
+    for_each_cell([this](auto row, auto column) {
+        set_cell(row, column, get_random<u32>() % 2);
+    });
 }
 
-void Board::toggle_cell(size_t index)
+void Board::resize(size_t rows, size_t columns)
 {
-    VERIFY(index < total_size());
+    m_rows = rows;
+    m_columns = columns;
 
-    m_cells[index] = !m_cells[index];
+    // Vector values get default-initialized, we don't need to set them to false explicitly.
+    m_cells.resize(rows);
+    for (size_t row = 0; row < rows; ++row)
+        m_cells[row].resize(columns);
 }
 
 void Board::toggle_cell(size_t row, size_t column)
 {
-    VERIFY(column < total_size() && row < total_size());
+    VERIFY(row < m_rows && column < m_columns);
 
-    size_t index = calculate_index(row, column);
-    set_cell(index, !m_cells[index]);
-}
-
-void Board::set_cell(size_t index, bool on)
-{
-    VERIFY(index < total_size());
-
-    m_cells[index] = on;
+    m_cells[row][column] = !m_cells[row][column];
 }
 
 void Board::set_cell(size_t row, size_t column, bool on)
 {
-    VERIFY(column < total_size() && row < total_size());
-
-    size_t index = calculate_index(row, column);
-    set_cell(index, on);
-}
-
-bool Board::cell(size_t index) const
-{
-    if (index > total_size() - 1)
-        return false;
+    VERIFY(row < m_rows && column < m_columns);
 
-    return m_cells[index];
+    m_cells[row][column] = on;
 }
 
 bool Board::cell(size_t row, size_t column) const
 {
-    if (column > total_size() - 1 || row > total_size() - 1)
+    if (row >= m_rows || column >= m_columns)
         return false;
 
-    size_t index = calculate_index(row, column);
-    return cell(index);
+    return m_cells[row][column];
 }
diff --git a/Userland/Games/GameOfLife/Board.h b/Userland/Games/GameOfLife/Board.h
index 86fe40c807..bcd3425e99 100644
--- a/Userland/Games/GameOfLife/Board.h
+++ b/Userland/Games/GameOfLife/Board.h
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2021, Andres Crucitti <dasc495@gmail.com>
+ * Copyright (c) 2021, Linus Groh <linusg@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -12,39 +13,45 @@
 
 class Board {
 public:
-    Board(size_t rows, size_t column);
+    Board(size_t rows, size_t columns);
     ~Board();
 
-    size_t total_size() const { return m_columns * m_rows; }
     size_t columns() const { return m_columns; }
     size_t rows() const { return m_rows; }
 
-    size_t calculate_index(size_t row, size_t column) const { return row * m_columns + column; };
-
-    void toggle_cell(size_t index);
     void toggle_cell(size_t row, size_t column);
-
     void set_cell(size_t row, size_t column, bool on);
-    void set_cell(size_t index, bool on);
-
     bool cell(size_t row, size_t column) const;
-    bool cell(size_t index) const;
-
-    const Vector<bool>& cells() const { return m_cells; }
+    const Vector<Vector<bool>>& cells() const { return m_cells; }
 
     void run_generation();
     bool is_stalled() const { return m_stalled; }
 
     void clear();
     void randomize();
+    void resize(size_t rows, size_t columns);
+
+    struct RowAndColumn {
+        size_t row { 0 };
+        size_t column { 0 };
+    };
 
 private:
-    bool calculate_next_value(size_t index) const;
+    bool calculate_next_value(size_t row, size_t column) const;
+
+    template<typename Callback>
+    void for_each_cell(Callback callback)
+    {
+        for (size_t row = 0; row < m_rows; ++row) {
+            for (size_t column = 0; column < m_columns; ++column)
+                callback(row, column);
+        }
+    }
 
-    size_t m_columns { 1 };
-    size_t m_rows { 1 };
+    size_t m_rows { 0 };
+    size_t m_columns { 0 };
 
     bool m_stalled { false };
 
-    Vector<bool> m_cells;
+    Vector<Vector<bool>> m_cells;
 };
diff --git a/Userland/Games/GameOfLife/BoardWidget.cpp b/Userland/Games/GameOfLife/BoardWidget.cpp
index eb7051bcd4..a8a7c1fb45 100644
--- a/Userland/Games/GameOfLife/BoardWidget.cpp
+++ b/Userland/Games/GameOfLife/BoardWidget.cpp
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2021, Andres Crucitti <dasc495@gmail.com>
+ * Copyright (c) 2021, Linus Groh <linusg@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -8,6 +9,7 @@
 #include <LibGUI/Painter.h>
 
 BoardWidget::BoardWidget(size_t rows, size_t columns)
+    : m_board(make<Board>(rows, columns))
 {
     m_timer = add<Core::Timer>();
     m_timer->stop();
@@ -15,8 +17,6 @@ BoardWidget::BoardWidget(size_t rows, size_t columns)
         run_generation();
     };
     m_timer->set_interval(m_running_timer_interval);
-
-    update_board(rows, columns);
 }
 
 void BoardWidget::run_generation()
@@ -30,19 +30,12 @@ void BoardWidget::run_generation()
     };
 }
 
-void BoardWidget::update_board(size_t rows, size_t columns)
+void BoardWidget::resize_board(size_t rows, size_t columns)
 {
-    set_running(false);
-
-    m_last_cell_toggled = columns * rows;
-
-    if (m_board) {
-        if (columns == m_board->columns() && rows == m_board->rows()) {
-            return;
-        }
-    }
-
-    m_board = make<Board>(rows, columns);
+    if (columns == m_board->columns() && rows == m_board->rows())
+        return;
+    m_board->resize(rows, columns);
+    m_last_cell_toggled = { rows, columns };
 }
 
 void BoardWidget::set_running_timer_interval(int interval)
@@ -76,16 +69,16 @@ void BoardWidget::set_running(bool running)
     update();
 }
 
-void BoardWidget::toggle_cell(size_t index)
+void BoardWidget::toggle_cell(size_t row, size_t column)
 {
-    if (m_running || !m_toggling_cells || m_last_cell_toggled == index)
+    if (m_running || !m_toggling_cells || (m_last_cell_toggled.row == row && m_last_cell_toggled.column == column))
         return;
 
-    m_last_cell_toggled = index;
-    m_board->toggle_cell(index);
+    m_last_cell_toggled = { row, column };
+    m_board->toggle_cell(row, column);
 
     if (on_cell_toggled)
-        on_cell_toggled(m_board, index);
+        on_cell_toggled(m_board, row, column);
 
     update();
 }
@@ -145,17 +138,23 @@ void BoardWidget::paint_event(GUI::PaintEvent& event)
 
 void BoardWidget::mousedown_event(GUI::MouseEvent& event)
 {
-    size_t index = get_index_for_point(event.x(), event.y());
     set_toggling_cells(true);
-    toggle_cell(index);
+    auto row_and_column = get_row_and_column_for_point(event.x(), event.y());
+    if (!row_and_column.has_value())
+        return;
+    auto [row, column] = row_and_column.value();
+    toggle_cell(row, column);
 }
 
 void BoardWidget::mousemove_event(GUI::MouseEvent& event)
 {
-    size_t index = get_index_for_point(event.x(), event.y());
-    if (is_toggling()) {
-        if (last_toggled() != index)
-            toggle_cell(index);
+    auto row_and_column = get_row_and_column_for_point(event.x(), event.y());
+    if (!row_and_column.has_value())
+        return;
+    auto [row, column] = row_and_column.value();
+    if (m_toggling_cells) {
+        if (m_last_cell_toggled.row != row || m_last_cell_toggled.column != column)
+            toggle_cell(row, column);
     }
 }
 
@@ -164,9 +163,18 @@ void BoardWidget::mouseup_event(GUI::MouseEvent&)
     set_toggling_cells(false);
 }
 
-size_t BoardWidget::get_index_for_point(int x, int y) const
+Optional<Board::RowAndColumn> BoardWidget::get_row_and_column_for_point(int x, int y) const
 {
-    int cell_size = get_cell_size();
-    Gfx::IntSize board_offset = get_board_offset();
-    return m_board->columns() * ((y - board_offset.height()) / cell_size) + (x - board_offset.width()) / cell_size;
+    auto board_offset = get_board_offset();
+    auto cell_size = get_cell_size();
+    auto board_width = m_board->columns() * cell_size;
+    auto board_height = m_board->rows() * cell_size;
+    if (x <= board_offset.width() || static_cast<size_t>(x) >= board_offset.width() + board_width)
+        return {};
+    if (y <= board_offset.height() || static_cast<size_t>(y) >= board_offset.height() + board_height)
+        return {};
+    return { {
+        .row = static_cast<size_t>((y - board_offset.height()) / cell_size),
+        .column = static_cast<size_t>((x - board_offset.width()) / cell_size),
+    } };
 }
diff --git a/Userland/Games/GameOfLife/BoardWidget.h b/Userland/Games/GameOfLife/BoardWidget.h
index 0d10e2daa2..7933c96e8f 100644
--- a/Userland/Games/GameOfLife/BoardWidget.h
+++ b/Userland/Games/GameOfLife/BoardWidget.h
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2021, Andres Crucitti <dasc495@gmail.com>
+ * Copyright (c) 2021, Linus Groh <linusg@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -7,6 +8,10 @@
 #pragma once
 
 #include "Board.h"
+#include <AK/Function.h>
+#include <AK/NonnullOwnPtr.h>
+#include <AK/Optional.h>
+#include <AK/RefPtr.h>
 #include <LibCore/Timer.h>
 #include <LibGUI/Widget.h>
 
@@ -23,29 +28,24 @@ public:
     {
         m_toggling_cells = toggling;
         if (!toggling)
-            m_last_cell_toggled = m_board->total_size();
+            m_last_cell_toggled = { m_board->rows(), m_board->columns() };
     }
 
-    size_t last_toggled() const { return m_last_cell_toggled; }
-    bool is_toggling() const { return m_toggling_cells; }
-
-    void toggle_cell(size_t index);
+    void toggle_cell(size_t row, size_t column);
     void clear_cells() { m_board->clear(); }
     void randomize_cells() { m_board->randomize(); }
 
     int get_cell_size() const;
     Gfx::IntSize get_board_offset() const;
 
-    size_t get_index_for_point(int x, int y) const;
+    Optional<Board::RowAndColumn> get_row_and_column_for_point(int x, int y) const;
 
-    void update_board(size_t rows, size_t columns);
+    void resize_board(size_t rows, size_t columns);
     const Board* board() const { return m_board.ptr(); }
 
     bool is_running() const { return m_running; }
     void set_running(bool r);
 
-    void set_toolbar_enabled(bool);
-
     void run_generation();
 
     int running_timer_interval() const { return m_running_timer_interval; }
@@ -53,15 +53,15 @@ public:
 
     Function<void()> on_running_state_change;
     Function<void()> on_stall;
-    Function<void(Board*, size_t)> on_cell_toggled;
+    Function<void(Board*, size_t row, size_t column)> on_cell_toggled;
 
 private:
     BoardWidget(size_t rows, size_t columns);
 
     bool m_toggling_cells { false };
-    size_t m_last_cell_toggled { 0 };
+    Board::RowAndColumn m_last_cell_toggled {};
 
-    OwnPtr<Board> m_board { nullptr };
+    NonnullOwnPtr<Board> m_board;
 
     bool m_running { false };
 
diff --git a/Userland/Games/GameOfLife/main.cpp b/Userland/Games/GameOfLife/main.cpp
index 9f0eb2ae74..040fae53b8 100644
--- a/Userland/Games/GameOfLife/main.cpp
+++ b/Userland/Games/GameOfLife/main.cpp
@@ -60,7 +60,7 @@ int main(int argc, char** argv)
 
     auto size_changed_function = [&] {
         statusbar.set_text(click_tip);
-        board_widget.update_board(rows_spinbox.value(), columns_spinbox.value());
+        board_widget.resize_board(rows_spinbox.value(), columns_spinbox.value());
         board_widget.randomize_cells();
         board_widget.update();
     };
@@ -159,7 +159,7 @@ int main(int argc, char** argv)
         statusbar.set_text("Stalled...");
     };
 
-    board_widget.on_cell_toggled = [&](auto, auto) {
+    board_widget.on_cell_toggled = [&](auto, auto, auto) {
         statusbar.set_text(click_tip);
     };