Add a Scroll Bar

doc/pages/faces.asciidoc

@@ -146,6 +146,12 @@ the user interface:
 *BufferPadding*::
     Face applied on the *~* characters that follow the last line of a buffer.
 
+*ScrollBarGutter*::
+    Face applied on the scroll bar's gutter.
+
+*ScrollBarHandle*::
+    Face applied on the scroll bar's handle.
+
 === Built-in highlighter faces
 
 The following faces are used by built-in highlighters if enabled.

doc/pages/options.asciidoc

@@ -388,6 +388,9 @@ are exclusively available to built-in options.
             set the maximum allowable width of an info box. set to zero for
             no limit.
 
+        *terminal_status_bar*:::
+            if *yes* or *true* a scroll bar will be displayed.
+
         *terminal_cursor_native*:::
             if *yes* or *true*, use native terminal cursor visibility control
             instead of Kakoune's cursor management (defaults to *false*)

src/client.cc

@@ -264,7 +264,20 @@ void Client::redraw_ifn()
     {
         auto& display_buffer = window.update_display_buffer(context());
         auto cursor_pos = window.display_coord(context().selections().main().cursor()).value_or(DisplayCoord{});
-        m_ui->draw(display_buffer, cursor_pos, faces["Default"], faces["BufferPadding"]);
+        auto selections = context().selections();
+        auto sel = selections.begin();
+        Vector<LineCount> selection_lines;
+        selection_lines.reserve(selections.size());
+        std::generate_n(std::back_inserter(selection_lines), selections.size(), [&sel] { return (sel++)->min().line; });
+        m_ui->draw(display_buffer,
+                   cursor_pos,
+                   {display_buffer.range().begin.line, display_buffer.range().end.line},
+                   context().buffer().line_count(),
+                   selection_lines,
+                   faces["Default"],
+                   faces["BufferPadding"],
+                   faces["ScrollBarGutter"],
+                   faces["ScrollBarHandle"]);
     }
 
     const bool update_menu_anchor = (m_ui_pending & Draw) and not (m_ui_pending & MenuHide) and

src/face_registry.cc

@@ -207,6 +207,8 @@ FaceRegistry::FaceRegistry()
         { "BufferPadding", {Face{ Color::Blue, Color::Default }} },
         { "Whitespace", {Face{ Color::Default, Color::Default, Attribute::FinalFg }} },
         { "WhitespaceIndent", {Face{}, "Whitespace"} },
+        { "ScrollBarGutter", {Face{ Color::Blue, Color::Default }} },
+        { "ScrollBarHandle", {Face{ Color::Blue, Color::Default, Attribute::Reverse }} },
       }
 {}
 

src/json_ui.cc

@@ -140,10 +140,27 @@ JsonUI::JsonUI()
     set_signal_handler(SIGINT, SIG_DFL);
 }
 
-void JsonUI::draw(const DisplayBuffer& display_buffer, DisplayCoord cursor_pos,
-                  const Face& default_face, const Face& padding_face)
+void JsonUI::draw(const DisplayBuffer& display_buffer,
+                  const DisplayCoord cursor_pos,
+                  const Range<LineCount> range,
+                  const LineCount buffer_line_count,
+                  const Vector<LineCount> selection_lines,
+                  const Face& default_face,
+                  const Face& padding_face,
+                  const Face& scroll_bar_gutter_face,
+                  const Face& scroll_bar_handle_face)
 {
-    rpc_call("draw", display_buffer.lines(), cursor_pos, default_face, padding_face);
+    rpc_call("draw",
+             display_buffer.lines(),
+             cursor_pos,
+             range.begin,
+             range.end,
+             buffer_line_count,
+             selection_lines,
+             default_face,
+             padding_face,
+             scroll_bar_gutter_face,
+             scroll_bar_handle_face);
 }
 
 void JsonUI::draw_status(const DisplayLine& prompt,

src/json_ui.hh

@@ -22,9 +22,14 @@ public:
     bool is_ok() const override { return m_stdin_watcher.fd() != -1; }
 
     void draw(const DisplayBuffer& display_buffer,
-              DisplayCoord cursor_pos,
+              const DisplayCoord cursor_pos,
+              const Range<LineCount> range,
+              const LineCount buffer_line_count,
+              const Vector<LineCount> selection_lines,
               const Face& default_face,
-              const Face& buffer_padding) override;
+              const Face& padding_face,
+              const Face& scroll_bar_gutter_face,
+              const Face& scroll_bar_handle_face) override;
 
     void draw_status(const DisplayLine& prompt,
                      const DisplayLine& content,

src/main.cc

@@ -530,6 +530,7 @@ void register_options()
                        "    terminal_shift_function_key    int\n"
                        "    terminal_padding_char          codepoint\n"
                        "    terminal_padding_fill          bool\n"
+                       "    terminal_scroll_bar            bool\n"
                        "    terminal_cursor_native         bool\n"
                        "    terminal_info_max_width        int\n",
                        UserInterface::Options{});
@@ -582,7 +583,15 @@ UniquePtr<UserInterface> make_ui(UIType ui_type)
         void info_show(const DisplayLine&, const DisplayLineList&, DisplayCoord, Face, InfoStyle) override {}
         void info_hide() override {}
 
-        void draw(const DisplayBuffer&, DisplayCoord, const Face&, const Face&) override {}
+        void draw(const DisplayBuffer& display_buffer,
+                  const DisplayCoord,
+                  const Range<LineCount> range,
+                  const LineCount buffer_line_count,
+                  const Vector<LineCount> selection_lines,
+                  const Face& default_face,
+                  const Face& padding_face,
+                  const Face& scroll_bar_gutter_face,
+                  const Face& scroll_bar_handle_face) override {}
         void draw_status(const DisplayLine&, const DisplayLine&, const ColumnCount, const DisplayLine&, const Face&) override {}
         DisplayCoord dimensions() override { return {24,80}; }
         void refresh(bool) override {}

src/remote.cc

@@ -398,9 +398,14 @@ class RemoteUI : public UserInterface
     void info_hide() override;
 
     void draw(const DisplayBuffer& display_buffer,
-              DisplayCoord cursor_pos,
+              const DisplayCoord cursor_pos,
+              const Range<LineCount> range,
+              const LineCount buffer_line_count,
+              const Vector<LineCount> selection_lines,
               const Face& default_face,
-              const Face& padding_face) override;
+              const Face& padding_face,
+              const Face& scroll_bar_gutter_face,
+              const Face& scroll_bar_handle_face) override;
 
     void draw_status(const DisplayLine& prompt,
                      const DisplayLine& content,
@@ -563,11 +568,16 @@ void RemoteUI::info_hide()
 }
 
 void RemoteUI::draw(const DisplayBuffer& display_buffer,
-                    DisplayCoord cursor_pos,
+                    const DisplayCoord cursor_pos,
+                    const Range<LineCount> range,
+                    const LineCount buffer_line_count,
+                    const Vector<LineCount> selection_lines,
                     const Face& default_face,
-                    const Face& padding_face)
+                    const Face& padding_face,
+                    const Face& scroll_bar_gutter_face,
+                    const Face& scroll_bar_handle_face)
 {
-    send_message(MessageType::Draw, display_buffer, cursor_pos, default_face, padding_face);
+    send_message(MessageType::Draw, display_buffer, cursor_pos, range, buffer_line_count, selection_lines, default_face, padding_face, scroll_bar_gutter_face, scroll_bar_handle_face);
 }
 
 void RemoteUI::draw_status(const DisplayLine& prompt,

src/terminal_ui.cc

@@ -557,12 +557,27 @@ void TerminalUI::refresh(bool force)
     m_dirty = false;
 }
 
+template<typename T>
+T scale_to(T val, Range<T> from, Range<T> to)
+{
+    T from_size = from.end - from.begin + 1;
+    T to_size = to.end - to.begin + 1;
+
+    return ((val - from.begin) * to_size + from_size / 2) / from_size + to.begin;
+}
+
 static const DisplayLine empty_line = { String(" "), {} };
 
+
 void TerminalUI::draw(const DisplayBuffer& display_buffer,
-                      DisplayCoord cursor_pos,
+                      const DisplayCoord cursor_pos,
+                      const Range<LineCount> range,
+                      const LineCount buffer_line_count,
+                      const Vector<LineCount> selection_lines,
                       const Face& default_face,
-                      const Face& padding_face)
+                      const Face& padding_face,
+                      const Face& scroll_bar_gutter_face,
+                      const Face& scroll_bar_handle_face)
 {
     check_resize();
 
@@ -576,9 +591,40 @@ void TerminalUI::draw(const DisplayBuffer& display_buffer,
 
     DisplayAtom padding{String{m_padding_char, m_padding_fill ? dim.column : 1}};
 
+    const auto padding_lines = (dim.line + line_offset) - line_index;
     while (line_index < dim.line + line_offset)
         m_window.draw(line_index++, padding, face);
 
+    if (m_scroll_bar)
+    {
+        Range<LineCount> gutter_range = {0_line, dim.line - 1};
+        Range<LineCount> buffer_range = {0_line, buffer_line_count - 1 + dim.line - 1};
+
+        std::fill(m_scroll_bar_scratch.begin(), m_scroll_bar_scratch.end(), 0);
+
+        for (const LineCount selection_line : selection_lines)
+            m_scroll_bar_scratch[(int) scale_to(selection_line, buffer_range, gutter_range)]++;
+
+        const auto visible_lines = range.end - range.begin + padding_lines;
+        const auto mark_height = scale_to(visible_lines, buffer_range, gutter_range);
+
+        const auto mark_begin = scale_to(range.begin, buffer_range, gutter_range);
+        const auto mark_end = mark_begin + mark_height;
+
+        for (auto line = 0_line; line < dim.line; ++line) {
+            const bool is_mark = line >= mark_begin and line <= mark_end;
+            String selections;
+            switch (m_scroll_bar_scratch[(int)line]) {
+                case 0: selections = " "; break;
+                case 1: selections = "-"; break;
+                case 2: selections = "="; break;
+                default: selections = "≡"; break;
+            }
+
+            m_window.draw({line + line_offset, m_window.size.column - 1}, DisplayAtom(selections), is_mark ? scroll_bar_handle_face : scroll_bar_gutter_face);
+        }
+    }
+
     m_cursor_pos = cursor_pos;
 
     m_dirty = true;
@@ -605,12 +651,13 @@ void TerminalUI::draw_status(const DisplayLine& prompt,
     m_window.draw(status_line_pos, prompt.atoms(), default_face);
     m_window.draw(DisplayCoord{status_line_pos, prompt.length()}, trimmed_content.atoms(), default_face);
 
+    const auto scroll_bar_gutter = m_scroll_bar ? 1 : 0;
     const auto mode_len = mode_line.length();
     m_status_len = prompt.length() + trimmed_content.length();
     const auto remaining = m_dimensions.column - m_status_len;
     if (mode_len < remaining)
     {
-        ColumnCount col = m_dimensions.column - mode_len;
+        ColumnCount col = m_dimensions.column - mode_len + scroll_bar_gutter;
         m_window.draw({status_line_pos, col}, mode_line.atoms(), default_face);
     }
     else if (remaining > 2)
@@ -620,7 +667,7 @@ void TerminalUI::draw_status(const DisplayLine& prompt,
         trimmed_mode_line.insert(trimmed_mode_line.begin(), { "…", {} });
         kak_assert(trimmed_mode_line.length() == remaining - 1);
 
-        ColumnCount col = m_dimensions.column - remaining + 1;
+        ColumnCount col = m_dimensions.column - remaining + 1 + scroll_bar_gutter;
         m_window.draw({status_line_pos, col}, trimmed_mode_line.atoms(), default_face);
     }
 
@@ -675,6 +722,11 @@ void TerminalUI::check_resize(bool force)
 
     m_dimensions = terminal_size - 1_line;
 
+    if (m_scroll_bar) {
+        m_dimensions -= {0_line, 1_col};
+        m_scroll_bar_scratch.resize((size_t)m_dimensions.line);
+    }
+
     // if (char* csr = tigetstr((char*)"csr"))
     //     putp(tparm(csr, 0, ws.ws_row));
 
@@ -1593,7 +1645,7 @@ void TerminalUI::set_ui_options(const Options& options)
 
     m_padding_char = find("terminal_padding_char").map([](StringView s) { return s.column_length() < 1 ? ' ' : s[0_char]; }).value_or(Codepoint{'~'});
     m_padding_fill = find("terminal_padding_fill").map(to_bool).value_or(false);
-    
+
     bool new_cursor_native = find("terminal_cursor_native").map(to_bool).value_or(false);
     if (new_cursor_native != m_cursor_native)
     {
@@ -1602,6 +1654,13 @@ void TerminalUI::set_ui_options(const Options& options)
     }
 
     m_info_max_width = find("terminal_info_max_width").map(str_to_int_ifp).value_or(0);
+
+    bool new_scroll_bar = find("terminal_scroll_bar").map(to_bool).value_or(false);
+
+    if (m_scroll_bar != new_scroll_bar) {
+      m_scroll_bar = new_scroll_bar;
+      check_resize(true);
+    }
 }
 
 }

src/terminal_ui.hh

@@ -31,9 +31,14 @@ public:
     bool is_ok() const override { return (bool)m_window; }
 
     void draw(const DisplayBuffer& display_buffer,
-              DisplayCoord cursor_pos,
+              const DisplayCoord cursor_pos,
+              const Range<LineCount> range,
+              const LineCount buffer_line_count,
+              const Vector<LineCount> selection_lines,
               const Face& default_face,
-              const Face& padding_face) override;
+              const Face& padding_face,
+              const Face& scroll_bar_gutter_face,
+              const Face& scroll_bar_handle_face) override;
 
     void draw_status(const DisplayLine& prompt,
                      const DisplayLine& content,
@@ -167,6 +172,9 @@ private:
     bool m_padding_fill = false;
     bool m_cursor_native = false;
 
+    bool m_scroll_bar = false;
+    Vector<char> m_scroll_bar_scratch;
+
     bool m_dirty = false;
 
     bool m_resize_pending = false;

src/user_interface.hh

@@ -2,8 +2,13 @@
 #define user_interface_hh_INCLUDED
 
 #include "array_view.hh"
-#include "hash_map.hh"
 #include "function.hh"
+#include "hash_map.hh"
+#include "range.hh"
+#include "selection.hh"
+#include "units.hh"
+
+#include <functional>
 
 namespace Kakoune
 {
@@ -58,9 +63,14 @@ public:
     virtual void info_hide() = 0;
 
     virtual void draw(const DisplayBuffer& display_buffer,
-                      DisplayCoord cursor_pos,
+                      const DisplayCoord cursor_pos,
+                      const Range<LineCount> range,
+                      const LineCount buffer_line_count,
+                      const Vector<LineCount> selection_lines,
                       const Face& default_face,
-                      const Face& padding_face) = 0;
+                      const Face& padding_face,
+                      const Face& scroll_bar_gutter_face,
+                      const Face& scroll_bar_handle_face) = 0;
 
     virtual void draw_status(const DisplayLine& prompt,
                              const DisplayLine& content,