Add console escape sequences to draw headings

src/hulk/console.d

@@ -19,6 +19,9 @@ struct Console
     /** Border color. */
     private enum BORDER_COLOR = 0xFF8000u;
 
+    /** Heading color. */
+    private enum HEADING_COLOR = 0x0066FFu;
+
     /** Console page width in text columns. */
     private static __gshared size_t m_width;
 
@@ -37,6 +40,12 @@ struct Console
     /** Number of delayed newline characters. */
     private static __gshared size_t m_newlines;
 
+    /** Active console escape code. */
+    private static __gshared char m_escape_code;
+
+    /** Flag to indicate the previous character was an escape character. */
+    private static __gshared bool m_escape;
+
     /**
      * Initialize the console.
      */
@@ -68,6 +77,8 @@ struct Console
     {
         if (ch == '\n')
         {
+            render_heading_end();
+            m_escape_code = 0u;
             m_newlines++;
         }
         else
@@ -76,6 +87,46 @@ struct Console
         }
     }
 
+    private static void render_heading_start()
+    {
+        if ('0' <= m_escape_code && m_escape_code <= '9' && m_x < (m_width - 1))
+        {
+            size_t heading_level = m_escape_code - ('0' - 1);
+            size_t nx = m_x + heading_level;
+            if (nx >= m_width)
+            {
+                nx = m_width - 1;
+            }
+            size_t hx = fb_x(m_page, m_x);
+            size_t hy = fb_y(m_y) + Kfont.line_height / 2 - 1;
+            size_t hwidth = (nx - m_x - 1) * Kfont.advance + Kfont.advance / 2 - 1;
+            Fb.rect(hx, hy, hwidth, 2, HEADING_COLOR);
+            Fb.rect(hx + hwidth, fb_y(m_y) + Kfont.line_height / 8,
+                    2, Kfont.line_height * 3 / 4, HEADING_COLOR);
+            m_x = nx;
+        }
+    }
+
+    private static void render_heading_end()
+    {
+        if ('0' <= m_escape_code && m_escape_code <= '9' && m_x < (m_width - 1))
+        {
+            size_t heading_level = m_escape_code - ('0' - 1);
+            size_t nx = m_x + heading_level;
+            if (nx >= m_width)
+            {
+                nx = m_width - 1;
+            }
+            size_t hwidth = (nx - m_x - 1) * Kfont.advance + Kfont.advance / 2 - 1;
+            size_t hx = fb_x(m_page, nx) - hwidth;
+            size_t hy = fb_y(m_y) + Kfont.line_height / 2 - 1;
+            Fb.rect(hx, hy, hwidth, 2, HEADING_COLOR);
+            Fb.rect(hx - 2, fb_y(m_y) + Kfont.line_height / 8,
+                    2, Kfont.line_height * 3 / 4, HEADING_COLOR);
+            m_x = nx;
+        }
+    }
+
     /**
      * Write a character to the console (no newline buffering).
      *
@@ -92,6 +143,18 @@ struct Console
                 dowrite('\n');
             }
         }
+        if (m_escape)
+        {
+            m_escape_code = ch;
+            render_heading_start();
+            m_escape = false;
+            return;
+        }
+        if (ch == '\a')
+        {
+            m_escape = true;
+            return;
+        }
         if (ch == '\n')
         {
             m_x = 0u;