5 files changed, 101 insertions, 0 deletions
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