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+/*
+ * Copyright © 2018–2019 Egmont Koblinger
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#pragma once
+
+#include <glib.h>
+
+#include "ring.hh"
+#include "vterowdata.hh"
+#include "vtetypes.hh"
+#include "vteunistr.h"
+
+namespace vte {
+
+namespace base {
+
+/*
+ * RingView provides a "view" to a continuous segment of the Ring (or stream),
+ * typically the user visible area.
+ *
+ * It computes additional data that are needed to display the contents (or handle
+ * user events such as mouse click), but not needed for the terminal emulation logic.
+ * In order to save tons of resources, these data are computed when the Ring's
+ * contents are about to be displayed, rather than whenever they change.
+ *
+ * For computing these data, context lines (outside of the specified region of the
+ * Ring) are also taken into account up to the next hard newline or a safety limit.
+ *
+ * Currently RingView is used for BiDi: to figure out which logical character is
+ * mapped to which visual position.
+ *
+ * Future possible uses include "highlight all" for the search match, and
+ * syntax highlighting. URL autodetection might also be ported to this
+ * infrastructure one day.
+ */
+class RingView {
+public:
+        RingView();
+        ~RingView();
+
+        // prevent accidents
+        RingView(RingView& o) = delete;
+        RingView(RingView const& o) = delete;
+        RingView(RingView&& o) = delete;
+        RingView& operator= (RingView& o) = delete;
+        RingView& operator= (RingView const& o) = delete;
+        RingView& operator= (RingView&& o) = delete;
+
+        void set_ring(Ring *ring);
+        void set_rows(vte::grid::row_t start, vte::grid::row_t len);
+        void set_width(vte::grid::column_t width);
+        inline constexpr vte::grid::column_t get_width() const noexcept { return m_width; }
+
+        inline void invalidate() { m_invalid = true; }
+        inline constexpr bool is_updated() const noexcept { return !m_invalid; }
+        void update();
+        void pause();
+
+        VteRowData const* get_row(vte::grid::row_t row) const;
+
+private:
+        Ring *m_ring{nullptr};
+
+        VteRowData **m_rows{nullptr};
+        int m_rows_len{0};
+        int m_rows_alloc_len{0};
+
+        vte::grid::row_t m_top{0};  /* the row of the Ring corresponding to m_rows[0] */
+
+        vte::grid::row_t m_start{0};
+        vte::grid::row_t m_len{0};
+        vte::grid::column_t m_width{0};
+
+        bool m_invalid{true};
+        bool m_paused{true};
+
+        void resume();
+};
+
+}; /* namespace base */
+
+}; /* namespace vte */