Chess: Add pawn promotion to any piece

Games/Chess/CMakeLists.txt

@@ -2,6 +2,7 @@ set(SOURCES
     main.cpp
     Chess.cpp
     ChessWidget.cpp
+    PromotionDialog.cpp
 )
 
 serenity_bin(Chess)

Games/Chess/Chess.cpp

@@ -153,6 +153,9 @@ bool Chess::is_legal_no_check(const Move& move, Colour colour) const
     if (move.to.rank > 7 || move.to.file > 7)
         return false;
 
+    if (move.promote_to == Type::Pawn || move.promote_to == Type::King || move.promote_to == Type::None)
+        return false;
+
     if (piece.type == Type::Pawn) {
         int dir = (colour == Colour::White) ? +1 : -1;
         unsigned start_rank = (colour == Colour::White) ? 1 : 6;
@@ -304,8 +307,6 @@ bool Chess::apply_illegal_move(const Move& move, Colour colour)
 {
     m_turn = opposing_colour(colour);
 
-    // FIXME: pawn promotion
-
     m_last_move = move;
 
     if (move.from == Square("a1") || move.to == Square("a1") || move.from == Square("e1"))
@@ -347,6 +348,13 @@ bool Chess::apply_illegal_move(const Move& move, Colour colour)
         }
     }
 
+    if (get_piece(move.from).type == Type::Pawn && ((colour == Colour::Black && move.to.rank == 0) || (colour == Colour::White && move.to.rank == 7))) {
+        // Pawn Promotion
+        set_piece(move.to, { colour, move.promote_to });
+        set_piece(move.from, EmptyPiece);
+        return true;
+    }
+
     if (get_piece(move.from).type == Type::Pawn && move.from.file != move.to.file && get_piece(move.to).type == Type::None) {
         // En passant.
         if (colour == Colour::White) {
@@ -379,3 +387,17 @@ Chess::Result Chess::game_result() const
 
     return Result::StaleMate;
 }
+
+bool Chess::is_promotion_move(const Move& move, Colour colour) const
+{
+    if (colour == Colour::None)
+        colour = turn();
+
+    if (!is_legal(move, colour))
+        return false;
+
+    if (get_piece(move.from).type == Type::Pawn && ((colour == Colour::Black && move.to.rank == 0) || (colour == Colour::White && move.to.rank == 7)))
+        return true;
+
+    return false;
+}

Games/Chess/Chess.h

@@ -87,13 +87,15 @@ public:
     struct Move {
         Square from;
         Square to;
+        Type promote_to;
         Move(const StringView& algebraic);
-        Move(const Square& from, const Square& to)
+        Move(const Square& from, const Square& to, const Type& promote_to = Type::Queen)
             : from(from)
             , to(to)
+            , promote_to(promote_to)
         {
         }
-        bool operator==(const Move& other) const { return from == other.from && to == other.to; }
+        bool operator==(const Move& other) const { return from == other.from && to == other.to && promote_to == other.promote_to; }
     };
 
     Chess();
@@ -104,6 +106,8 @@ public:
     bool is_legal(const Move&, Colour colour = Colour::None) const;
     bool in_check(Colour colour) const;
 
+    bool is_promotion_move(const Move&, Colour colour = Colour::None) const;
+
     bool apply_move(const Move&, Colour colour = Colour::None);
     const Optional<Move>& last_move() const { return m_last_move; }
 

Games/Chess/ChessWidget.cpp

@@ -25,6 +25,7 @@
  */
 
 #include "ChessWidget.h"
+#include "PromotionDialog.h"
 #include <AK/String.h>
 #include <LibGUI/MessageBox.h>
 #include <LibGUI/Painter.h>
@@ -114,7 +115,14 @@ void ChessWidget::mouseup_event(GUI::MouseEvent& event)
 
     auto target_square = mouse_to_square(event);
 
-    if (board().apply_move({ m_moving_square, target_square })) {
+    Chess::Move move = { m_moving_square, target_square };
+    if (board().is_promotion_move(move)) {
+        auto promotion_dialog = PromotionDialog::construct(*this);
+        if (promotion_dialog->exec() == PromotionDialog::ExecOK)
+            move.promote_to = promotion_dialog->selected_piece();
+    }
+
+    if (board().apply_move(move)) {
         if (board().game_result() != Chess::Result::NotFinished) {
             set_drag_enabled(false);
             update();
@@ -198,6 +206,11 @@ Chess::Square ChessWidget::mouse_to_square(GUI::MouseEvent& event) const
     }
 }
 
+RefPtr<Gfx::Bitmap> ChessWidget::get_piece_graphic(const Chess::Piece& piece) const
+{
+    return m_pieces.get(piece).value();
+}
+
 void ChessWidget::reset()
 {
     m_board = Chess();

Games/Chess/ChessWidget.h

@@ -59,6 +59,7 @@ public:
 
     bool drag_enabled() const { return m_drag_enabled; }
     void set_drag_enabled(bool e) { m_drag_enabled = e; }
+    RefPtr<Gfx::Bitmap> get_piece_graphic(const Chess::Piece& piece) const;
 
     void reset();
 

Games/Chess/PromotionDialog.cpp

@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "PromotionDialog.h"
+#include <LibGUI/BoxLayout.h>
+#include <LibGUI/Button.h>
+#include <LibGUI/Frame.h>
+
+PromotionDialog::PromotionDialog(ChessWidget& chess_widget)
+    : Dialog(chess_widget.window())
+{
+    set_title("Choose piece to promote to");
+    resize(70 * 4, 70);
+
+    auto& main_widget = set_main_widget<GUI::Frame>();
+    main_widget.set_frame_shape(Gfx::FrameShape::Container);
+    main_widget.set_fill_with_background_color(true);
+    main_widget.set_layout<GUI::HorizontalBoxLayout>();
+
+    for (auto& type : Vector({ Chess::Type::Queen, Chess::Type::Knight, Chess::Type::Rook, Chess::Type::Bishop })) {
+        auto& button = main_widget.add<GUI::Button>("");
+        button.set_icon(chess_widget.get_piece_graphic({ chess_widget.board().turn(), type }));
+        button.on_click = [this, type](auto) {
+            m_selected_piece = type;
+            done(ExecOK);
+        };
+    }
+}
+
+void PromotionDialog::event(Core::Event& event)
+{
+    Dialog::event(event);
+}

Games/Chess/PromotionDialog.h

@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include "ChessWidget.h"
+#include <LibGUI/Dialog.h>
+
+class PromotionDialog final : public GUI::Dialog {
+    C_OBJECT(PromotionDialog)
+public:
+    Chess::Type selected_piece() const { return m_selected_piece; }
+
+private:
+    explicit PromotionDialog(ChessWidget& chess_widget);
+    virtual void event(Core::Event&) override;
+
+    Chess::Type m_selected_piece;
+};