Start working on a graphical Terminal program.

Terminal/Terminal.h

@@ -0,0 +1,70 @@
+#pragma once
+
+#include <AK/AKString.h>
+#include <AK/Types.h>
+#include <AK/Vector.h>
+#include <Widgets/GraphicsBitmap.h>
+
+
+class Terminal {
+public:
+    Terminal();
+    ~Terminal();
+
+    void create_window();
+    void paint();
+    void on_char(byte);
+
+private:
+    void scroll_up();
+    void set_cursor(unsigned row, unsigned column);
+    void put_character_at(unsigned row, unsigned column, byte ch);
+
+    void escape$A(const Vector<unsigned>&);
+    void escape$D(const Vector<unsigned>&);
+    void escape$H(const Vector<unsigned>&);
+    void escape$J(const Vector<unsigned>&);
+    void escape$m(const Vector<unsigned>&);
+    void escape$s(const Vector<unsigned>&);
+    void escape$u(const Vector<unsigned>&);
+
+    void clear();
+
+    void set_size(word columns, word rows);
+    word columns() const { return m_columns; }
+    word rows() const { return m_rows; }
+
+    void inject_string_at(word row, word column, const String&);
+
+    byte* m_buffer { nullptr };
+
+    word m_columns { 0 };
+    word m_rows { 0 };
+
+    byte m_cursor_row { 0 };
+    byte m_cursor_column { 0 };
+    byte m_saved_cursor_row { 0 };
+    byte m_saved_cursor_column { 0 };
+    byte m_current_attribute { 0x07 };
+
+    void execute_escape_sequence(byte final);
+
+    enum EscapeState {
+        Normal,
+        ExpectBracket,
+        ExpectParameter,
+        ExpectIntermediate,
+        ExpectFinal,
+    };
+    EscapeState m_escape_state { Normal };
+    Vector<byte> m_parameters;
+    Vector<byte> m_intermediates;
+    byte* m_horizontal_tabs { nullptr };
+    bool m_belling { false };
+
+    int m_window_id { 0 };
+    RetainPtr<GraphicsBitmap> m_backing;
+
+    int m_pixel_width { 0 };
+    int m_pixel_height { 0 };
+};