implement screens

1 files changed, 31 insertions, 0 deletions

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
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