BufferPane: add ability to draw line number gutter

src/gui/BufferPane.cc

@@ -1,4 +1,5 @@
 #include "BufferPane.h"
+#include <cmath>
 
 int BufferPane::Cwd::operator()(uint32_t character)
 {
@@ -24,26 +25,53 @@ BufferPane::BufferPane(Window * window, std::shared_ptr<Buffer> buffer)
     m_buffer_view->set_scroll_offset(5);
     m_buffer_view->update();
     m_show_status_bar = true;
+    m_show_line_number_gutter = true;
     m_command_mode = false;
     m_focused = false;
+    m_rows = 0;
+    m_columns = 0;
 }
 
 void BufferPane::resize(int width, int height)
 {
     Pane::resize(width, height);
-    m_columns = std::max(1, m_width / m_window->font()->get_advance());
+    resize_buffer_view();
+}
+
+void BufferPane::resize_buffer_view()
+{
+    if (m_show_line_number_gutter)
+    {
+        int max_line_possible = 1;
+        if (m_iterator->valid())
+        {
+            max_line_possible = std::min(m_iterator->line() + m_rows - m_buffer_view->cursor_screen_row(), m_buffer->end().line());
+        }
+        m_line_number_gutter_width = log10(max_line_possible) + 1;
+    }
+    else
+    {
+        m_line_number_gutter_width = 0;
+    }
+    int columns = std::max(1, (m_width - col_x(0)) / m_window->font()->get_advance());
     int height_subtract = 0;
     if (m_show_status_bar)
     {
         height_subtract = m_window->font()->get_line_height() + 1;
     }
-    m_rows = std::max(1, (m_height - height_subtract) / m_window->font()->get_line_height());
+    int rows = std::max(1, (m_height - height_subtract) / m_window->font()->get_line_height());
+    if ((rows != m_rows) || (columns != m_columns))
+    {
+        m_rows = rows;
+        m_columns = columns;
         m_buffer_view->resize(m_columns, m_rows);
         m_buffer_view->update();
     }
+}
 
 void BufferPane::draw()
 {
+    resize_buffer_view();
     if (m_iterator->valid())
     {
         for (auto line_iterator = m_buffer_view->vert_iter();
@@ -57,6 +85,10 @@ void BufferPane::draw()
     {
         draw_cursor(col_x(0), row_y(0), 0, 1);
     }
+    if (m_show_line_number_gutter)
+    {
+        m_window->gl()->draw_rect(win_x(m_line_number_gutter_width * m_window->font()->get_advance() + 1), win_y(0), 1, m_height, 0.5, 0.5, 0.5, 1.0);
+    }
     if (m_show_status_bar)
     {
         draw_status_bar();
@@ -82,6 +114,10 @@ void BufferPane::scroll_window_down(Window::ScrollMode scroll_mode)
 
 void BufferPane::draw_buffer_line(int screen_row, std::shared_ptr<Buffer::Iterator> start_of_line)
 {
+    if (m_show_line_number_gutter)
+    {
+        draw_line_number(screen_row, start_of_line->line());
+    }
     int last_drawn_crosshair_row = -1;
     for (auto it = m_buffer_view->horiz_iter(start_of_line);
             it.is_valid();
@@ -96,7 +132,7 @@ void BufferPane::draw_buffer_line(int screen_row, std::shared_ptr<Buffer::Iterat
             if ((draw_row > last_drawn_crosshair_row) &&
                     ((!it.is_eol()) || (it.row_offset() == 0)))
             {
-                draw_crosshair(0, row_y(draw_row), col_x(m_columns));
+                draw_crosshair(col_x(0), row_y(draw_row), col_x(m_columns));
                 last_drawn_crosshair_row = draw_row;
             }
         }
@@ -130,7 +166,7 @@ void BufferPane::draw_buffer_line(int screen_row, std::shared_ptr<Buffer::Iterat
                      * did not do this then the draw_crosshair for the next
                      * character on the new row would overwrite the wrapped
                      * part of the cursor. */
-                    draw_crosshair(0, row_y(row), col_x(m_columns));
+                    draw_crosshair(col_x(0), row_y(row), col_x(m_columns));
                     last_drawn_crosshair_row = row;
                 }
             }
@@ -146,12 +182,12 @@ void BufferPane::draw_buffer_line(int screen_row, std::shared_ptr<Buffer::Iterat
         }
         else
         {
-            draw_character(it.code_point(), draw_row, it.screen_column());
+            draw_buffer_character(it.code_point(), draw_row, it.screen_column());
         }
     }
 }
 
-void BufferPane::draw_character(uint32_t character, int screen_row, int screen_column)
+void BufferPane::draw_buffer_character(uint32_t character, int screen_row, int screen_column)
 {
     if ((character != ' ') &&
         (character != '\t') &&
@@ -221,6 +257,33 @@ void BufferPane::draw_crosshair(int x, int y, int width, int height)
     }
 }
 
+void BufferPane::draw_line_number(int screen_row, size_t line_number)
+{
+    if (screen_row >= 0)
+    {
+        char line_number_string[20];
+        int length = snprintf(line_number_string, sizeof(line_number_string), "%lu", line_number + 1u);
+        int x = (m_line_number_gutter_width - length) * m_window->font()->get_advance();
+        int y = row_y(screen_row);
+        float r, g;
+        if (line_number == m_iterator->line())
+        {
+            r = 1.0;
+            g = 1.0;
+        }
+        else
+        {
+            r = 0.6;
+            g = 0.6;
+        }
+        for (int i = 0; i < length; i++)
+        {
+            m_window->gl()->draw_character(win_x(x), win_y(y), line_number_string[i], *m_window->font(), r, g, 0.0, 1.0);
+            x += m_window->font()->get_advance();
+        }
+    }
+}
+
 void BufferPane::exit_insert_mode()
 {
     if (insert_mode())
@@ -408,6 +471,7 @@ void BufferPane::set_command_mode()
 {
     m_command_mode = true;
     set_show_status_bar(false);
+    set_show_line_number_gutter(false);
     enter_insert_mode(Window::EnterInsertModeMode::START_OF_CHAR);
 }
 

src/gui/BufferPane.h

@@ -45,6 +45,10 @@ public:
     {
         m_show_status_bar = show_status_bar;
     }
+    void set_show_line_number_gutter(bool show_line_number_gutter)
+    {
+        m_show_line_number_gutter = show_line_number_gutter;
+    }
     void set_command_mode();
     void set_focused(bool focused)
     {
@@ -55,12 +59,13 @@ public:
 
 protected:
     void draw_buffer_line(int screen_row, std::shared_ptr<Buffer::Iterator> start_of_line);
-    void draw_character(uint32_t character, int screen_row, int screen_column);
+    void draw_buffer_character(uint32_t character, int screen_row, int screen_column);
     void draw_cursor(int x, int y, int i, int columns);
     void draw_crosshair(int x, int y, int width = -1, int height = -1);
+    void draw_line_number(int screen_row, size_t line_number);
     int col_x(int col)
     {
-        return col * m_window->font()->get_advance();
+        return (m_line_number_gutter_width + col) * m_window->font()->get_advance() + (m_show_line_number_gutter ? 3 : 0);
     }
     int row_y(int row)
     {
@@ -70,6 +75,7 @@ protected:
     size_t display_column() const;
     void draw_status_bar();
     int calculate_lines_to_scroll(Window::ScrollMode scroll_mode);
+    void resize_buffer_view();
 
     Window * m_window;
     std::shared_ptr<Buffer> m_buffer;
@@ -77,9 +83,11 @@ protected:
     std::shared_ptr<BufferView> m_buffer_view;
     int m_rows;
     int m_columns;
+    int m_line_number_gutter_width;
     std::shared_ptr<Buffer::Iterator> m_iterator;
     std::list<std::pair<int, Buffer::Iterator>> m_screen_lines;
     bool m_show_status_bar;
+    bool m_show_line_number_gutter;
     bool m_command_mode;
     bool m_focused;
 };