implement screens

13 files changed, 252 insertions, 41 deletions

diff --git a/lib/nes/app/CMakeLists.txt b/lib/nes/app/CMakeLists.txt
index 98a0490..76ccb74 100644
--- a/lib/nes/app/CMakeLists.txt
+++ b/lib/nes/app/CMakeLists.txt
@@ -5,4 +5,5 @@ target_sources(
 		application.cc)
 
 add_subdirectory(input)
-add_subdirectory(graphics)
\ No newline at end of file
+add_subdirectory(graphics)
+add_subdirectory(ui)
\ No newline at end of file
diff --git a/lib/nes/app/application.cc b/lib/nes/app/application.cc
index 4da3848..0c1a4cb 100644
--- a/lib/nes/app/application.cc
+++ b/lib/nes/app/application.cc
@@ -1,11 +1,10 @@
 #include "nes/app/application.hh"
 #include "nes/app/input/input-device-keyboard.hh"
 #include "nes/app/input/input-device-controller.hh"
+#include "nes/app/ui/screen.hh"
 #include "nes/app/graphics/renderer.hh"
-#include "nes/app/graphics/color.hh"
-#include "nes/app/graphics/mask-tile.hh"
-#include "nes/app/graphics/image-tile.hh"
-#include "nes/common/display.hh"
+#include "ui/action.hh"
+
 #include <iostream>
 
 namespace nes::app
@@ -15,29 +14,76 @@ namespace nes::app
 		constexpr auto file = std::string_view{ "/Users/hannes/Documents/temp/supermario.nes" };
 	} // namespace
 
+	auto application::display_proxy::switch_buffers() -> void
+	{
+		if (screen)
+		{
+			auto r = renderer{ base };
+			screen->render(r);
+		}
+
+		base.switch_buffers();
+	}
+
 	application::application(display& display, input_device_keyboard& keyboard)
 		: display_{ display }
 		, input_manager_{ keyboard }
-		, console_{ sys::cartridge::from_file(file), display_ }
+		, screen_title_{ input_manager_ }
 	{
-		if (console_.get_status() != sys::status::success)
-		{
-			std::cerr << "Unable to load cartridge: " << to_string(console_.get_status()) << std::endl;
-			std::abort();
-		}
+		display_.screen = &screen_title_;
 	}
 
 	auto application::frame(std::chrono::microseconds const elapsed_time) -> void
 	{
-		console_.ref_controller_1().set_pressed(input_manager_.get_input_1().read_mask());
-		console_.ref_controller_2().set_pressed(input_manager_.get_input_2().read_mask());
+		if (display_.screen)
+		{
+			auto const a = display_.screen->process_events();
+			handle_action(a);
+		}
+
+		if (console_)
+		{
+			console_->ref_controller_1().set_pressed(input_manager_.get_input_1().read_mask());
+			console_->ref_controller_2().set_pressed(input_manager_.get_input_2().read_mask());
 
-		console_.step(elapsed_time);
+			// The scene is rendered by the console after the PPU requests a new frame (thus calling
+			// display_proxy::switch_buffers).
+			console_->step(elapsed_time);
+
+			if (console_->get_status() != sys::status::success)
+			{
+				std::cerr << "Invalid state: " << to_string(console_->get_status()) << std::endl;
+				std::abort();
+			}
+		}
+		else
+		{
+			// Directly let the scene render itself without rendering any gameplay (the scene is responsible for
+			// clearing the buffer).
+			display_.switch_buffers();
+		}
+	}
 
-		if (console_.get_status() != sys::status::success)
+	auto application::handle_action(action const a) -> void
+	{
+		switch (a)
 		{
-			std::cerr << "Invalid state: " << to_string(console_.get_status()) << std::endl;
-			std::abort();
+			case action::none:
+			{
+				break;
+			}
+			case action::load_game:
+			{
+				console_.emplace(sys::cartridge::from_file(file), display_);
+				if (console_->get_status() != sys::status::success)
+				{
+					std::cerr << "Unable to load cartridge: " << to_string(console_->get_status()) << std::endl;
+					std::abort();
+				}
+
+				display_.screen = nullptr;
+				break;
+			}
 		}
 	}
 } // namespace nes::app
\ No newline at end of file
diff --git a/lib/nes/app/application.hh b/lib/nes/app/application.hh
index 5cd6ac7..1fc1c6b 100644
--- a/lib/nes/app/application.hh
+++ b/lib/nes/app/application.hh
@@ -1,16 +1,16 @@
 #pragma once
 
 #include "nes/app/input/input-manager.hh"
+#include "nes/app/ui/screen-title.hh"
 #include "nes/sys/nes.hh"
+#include "nes/common/box.hh"
+#include "nes/common/display.hh"
 #include <chrono>
 
-namespace nes
-{
-	class display;
-} // namespace nes
-
 namespace nes::app
 {
+	class screen;
+
 	/// Entrypoint for the application.
 	///
 	/// This class takes care of presenting a UI screen or the emulator, handling any errors and implementing the main
@@ -19,9 +19,28 @@ namespace nes::app
 	/// It delegates some platform-specific tasks to interfaces.
 	class application
 	{
-		display& display_;
+		/// Acts like a regular display, but renders a screen on top of the back buffer when requested to switch
+		/// buffers.
+		class display_proxy final : public display
+		{
+		public:
+			display& base;
+			screen* screen{ nullptr };
+
+			explicit display_proxy(display& base)
+				: base{ base }
+			{
+			}
+
+			auto get(unsigned const x, unsigned const y) const -> rgb override { return base.get(x, y); }
+			auto set(unsigned const x, unsigned const y, rgb const value) -> void override { base.set(x, y, value); }
+			auto switch_buffers() -> void override;
+		};
+
+		display_proxy display_;
 		input_manager input_manager_;
-		sys::nes console_;
+		box<sys::nes> console_;
+		screen_title screen_title_;
 
 	public:
 		explicit application(display&, input_device_keyboard&);
@@ -36,5 +55,8 @@ namespace nes::app
 
 		auto add_controller(input_device_controller& c) -> void { input_manager_.add_controller(c); }
 		auto remove_controller(input_device_controller& c) -> void { input_manager_.remove_controller(c); }
+
+	private:
+		auto handle_action(action) -> void;
 	};
 } // namespace nes::app
\ No newline at end of file
diff --git a/lib/nes/app/graphics/image-tile.hh b/lib/nes/app/graphics/image-tile.hh
index 5633a0e..0663e3f 100644
--- a/lib/nes/app/graphics/image-tile.hh
+++ b/lib/nes/app/graphics/image-tile.hh
@@ -11,19 +11,4 @@ namespace nes::app
 	{
 		color data[8 * 8]{};
 	};
-
-	namespace tiles
-	{
-		inline constexpr auto test = image_tile
-		{
-			color{ 0 }, color{ 0 }, color{ 9 }, color{ 9 }, color{ 9 }, color{ 9 }, color{ 0 }, color{ 0 },
-			color{ 0 }, color{ 9 }, color{ 9 }, color{ 8 }, color{ 8 }, color{ 9 }, color{ 9 }, color{ 0 },
-			color{ 9 }, color{ 9 }, color{ 8 }, color{ 8 }, color{ 8 }, color{ 8 }, color{ 9 }, color{ 9 },
-			color{ 9 }, color{ 8 }, color{ 8 }, color{ 9 }, color{ 9 }, color{ 8 }, color{ 8 }, color{ 9 },
-			color{ 9 }, color{ 8 }, color{ 8 }, color{ 9 }, color{ 9 }, color{ 8 }, color{ 8 }, color{ 9 },
-			color{ 9 }, color{ 9 }, color{ 8 }, color{ 8 }, color{ 8 }, color{ 8 }, color{ 9 }, color{ 9 },
-			color{ 0 }, color{ 9 }, color{ 9 }, color{ 8 }, color{ 8 }, color{ 9 }, color{ 9 }, color{ 0 },
-			color{ 0 }, color{ 0 }, color{ 9 }, color{ 9 }, color{ 9 }, color{ 9 }, color{ 0 }, color{ 0 },
-		};
-	} // namespace tiles
 } // namespace nes::app
\ No newline at end of file
diff --git a/lib/nes/app/graphics/renderer.cc b/lib/nes/app/graphics/renderer.cc
index c53ea12..8d1a168 100644
--- a/lib/nes/app/graphics/renderer.cc
+++ b/lib/nes/app/graphics/renderer.cc
@@ -68,7 +68,7 @@ namespace nes::app
 
 		auto const resolved = resolve_color(c);
 		auto const x_stop = std::min(x + width, renderer::width);
-		auto const y_stop = std::min(y + width, renderer::height);
+		auto const y_stop = std::min(y + height, renderer::height);
 		for (auto y_px = unsigned{ y * 8 }; y_px < y_stop * 8; ++y_px)
 		{
 			for (auto x_px = unsigned{ x * 8 }; x_px < x_stop * 8; ++x_px)
diff --git a/lib/nes/app/ui/CMakeLists.txt b/lib/nes/app/ui/CMakeLists.txt
new file mode 100644
index 0000000..2faed29
--- /dev/null
+++ b/lib/nes/app/ui/CMakeLists.txt
@@ -0,0 +1,7 @@
+target_sources(
+	nes
+	PRIVATE
+		action.hh
+		screen.hh
+		screen-title.hh
+		screen-title.cc)
\ No newline at end of file
diff --git a/lib/nes/app/ui/action.hh b/lib/nes/app/ui/action.hh
new file mode 100644
index 0000000..2994f37
--- /dev/null
+++ b/lib/nes/app/ui/action.hh
@@ -0,0 +1,11 @@
+#pragma once
+
+namespace nes::app
+{
+	/// An action for the application to process after a scene has handled its events.
+	enum class action
+	{
+		none,
+		load_game,
+	};
+} // namespace nes::app
\ No newline at end of file
diff --git a/lib/nes/app/ui/screen-title.cc b/lib/nes/app/ui/screen-title.cc
new file mode 100644
index 0000000..2a7bc5c
--- /dev/null
+++ b/lib/nes/app/ui/screen-title.cc
@@ -0,0 +1,30 @@
+#include "nes/app/ui/screen-title.hh"
+#include "nes/app/graphics/renderer.hh"
+#include "nes/app/graphics/color.hh"
+#include "nes/app/graphics/mask-tile.hh"
+#include "nes/app/input/input-manager.hh"
+
+namespace nes::app
+{
+	screen_title::screen_title(input_manager& input_manager)
+		: input_manager_{ input_manager }
+	{
+	}
+
+	auto screen_title::render(renderer& renderer) -> void
+	{
+		renderer.render_fill(color::background_primary);
+		renderer.render_rect(2, 4, 28, 8, color::accent_primary);
+		renderer.render_mask_tile(10, 16, tiles::letter_a, color::foreground_primary);
+	}
+
+	auto screen_title::process_events() -> action
+	{
+		if (input_manager_.get_keyboard().read_key_start())
+		{
+			return action::load_game;
+		}
+
+		return action::none;
+	}
+} // namespace nes::app
\ No newline at end of file
diff --git a/lib/nes/app/ui/screen-title.hh b/lib/nes/app/ui/screen-title.hh
new file mode 100644
index 0000000..a8dfdc5
--- /dev/null
+++ b/lib/nes/app/ui/screen-title.hh
@@ -0,0 +1,22 @@
+#pragma once
+
+#include "nes/app/ui/screen.hh"
+
+namespace nes::app
+{
+	class input_manager;
+
+	/// The main title screen for the emulator, used as an entrypoint for the UI.
+	///
+	/// Presents options to load games, adjust settings, and more.
+	class screen_title final : public screen
+	{
+		input_manager& input_manager_;
+
+	public:
+		explicit screen_title(input_manager&);
+
+		auto render(renderer&) -> void override;
+		auto process_events() -> action override;
+	};
+} // namespace nes::app
\ No newline at end of file
diff --git a/lib/nes/app/ui/screen.hh b/lib/nes/app/ui/screen.hh
new file mode 100644
index 0000000..07e9d6f
--- /dev/null
+++ b/lib/nes/app/ui/screen.hh
@@ -0,0 +1,31 @@
+#pragma once
+
+#include "nes/app/ui/action.hh"
+
+namespace nes::app
+{
+	class renderer;
+
+	/// A part of the UI which takes care of rendering and handling input events.
+	///
+	/// One screen may be shown at a time. It may be used as an overlay over an active game.
+	class screen
+	{
+	public:
+		virtual ~screen() = default;
+
+		screen(screen const&) = delete;
+		screen(screen&&) = delete;
+		auto operator=(screen const&) -> screen& = delete;
+		auto operator=(screen&&) -> screen& = delete;
+
+		/// Render a frame with the current UI state.
+		virtual auto render(renderer&) -> void = 0;
+
+		/// Handle events and return an action for the application to execute.
+		virtual auto process_events() -> action = 0;
+
+	protected:
+		explicit screen() = default;
+	};
+} // namespace nes::app
\ No newline at end of file
diff --git a/lib/nes/common/CMakeLists.txt b/lib/nes/common/CMakeLists.txt
index 553d468..1a66929 100644
--- a/lib/nes/common/CMakeLists.txt
+++ b/lib/nes/common/CMakeLists.txt
@@ -4,4 +4,5 @@ target_sources(
 		debug.hh
 		rgb.hh
 		list.hh
+		box.hh
 		display.hh)
\ No newline at end of file
diff --git a/lib/nes/common/box.hh b/lib/nes/common/box.hh
new file mode 100644
index 0000000..442d60f
--- /dev/null
+++ b/lib/nes/common/box.hh
@@ -0,0 +1,55 @@
+#pragma once
+
+namespace nes
+{
+	/// Wrapper around an object, allowing for it to be uninitialized or reassigned even if the object type doesn't
+	/// support it.
+	///
+	/// Basically a std::unique_ptr but stored in-place (and thus not movable).
+	template<typename T>
+	class box
+	{
+		bool initialized_{ false };
+		alignas(T) unsigned char buffer_[sizeof(T)];
+
+	public:
+		/// Create an empty box.
+		explicit box() = default;
+
+		~box()
+		{
+			clear();
+		}
+
+		box(box const&) = delete;
+		box(box&&) = delete;
+		auto operator=(box const&) -> box& = delete;
+		auto operator=(box&&) -> box& = delete;
+
+		auto operator*() -> T& { return *get(); }
+		auto operator*() const -> T const& { return *get(); }
+		auto operator->() -> T* { return get(); }
+		auto operator->() const -> T const* { return get(); }
+		operator bool() const { return has_value(); }
+
+		auto has_value() const -> bool { return initialized_; }
+		auto get() -> T* { return has_value() ? std::launder(reinterpret_cast<T*>(buffer_)) : nullptr; }
+		auto get() const -> T const* { return has_value() ? std::launder(reinterpret_cast<T const *>(buffer_)) : nullptr; }
+
+		/// Construct a new value in-place, potentially replacing the old value.
+		template<typename... Args>
+		auto emplace(Args&&... args) -> void
+		{
+			clear();
+			new (buffer_) T(std::forward<Args>(args)...);
+			initialized_ = true;
+		}
+
+		/// Clear the boxed value.
+		auto clear() -> void
+		{
+			if (initialized_) { (*this)->~T(); }
+			initialized_ = false;
+		}
+	};
+} // namespace nes
\ No newline at end of file
diff --git a/lib/nes/common/list.hh b/lib/nes/common/list.hh
index 5f0d258..d7a7d9b 100644
--- a/lib/nes/common/list.hh
+++ b/lib/nes/common/list.hh
@@ -39,7 +39,7 @@ namespace nes
 			auto operator==(iterator const& other) -> bool { return current_ == other.current_; }
 			auto operator!=(iterator const& other) -> bool { return current_ != other.current_; }
 
-			auto operator*() -> T* { return current_; }
+			auto operator*() const -> T* { return current_; }
 
 			auto operator++() -> iterator&
 			{