Add support for ECMA-48 escape sequence for crossed-out/strikethrough

ECMA-48 defines rendition mode 9 as: crossed-out (characters still legible but marked as to be deleted), and mode 29 as the inverse: not crossed out Modern terminals (including xterm, tmux, libvte, etc.) support rendering strikethrough. Further, ncurses since version 6.1 includes the smxx/rmxx user-defined terminal capabilities in the tmux and xterm-basic databases. Note that the new attribute still fits in the eight bits allocated for Renditions::attributes, so there is no need to increase the size of Cell. Signed-off-by: Stanislav Spassov <[email protected]>
jdrouhard · Aug 5, 2019 · a1cca09 · a1cca09
1 parent 481d45d
commit a1cca09
Show file tree

Hide file tree

Showing 3 changed files with 6 additions and 2 deletions.
diff --git a/src/terminal/terminalframebuffer.cc b/src/terminal/terminalframebuffer.cc
@@ -489,7 +489,7 @@ void Renditions::set_rendition( color_type num )
     return;
   }
 
-  bool value = num < 9;
+  bool value = num < 10;
   switch ( num ) {
   case 1: set_attribute(bold, value); break;
   case 2: set_attribute(faint, value); break;
@@ -502,6 +502,7 @@ void Renditions::set_rendition( color_type num )
   case 5: case 25: set_attribute(blink, value); break;
   case 7: case 27: set_attribute(inverse, value); break;
   case 8: case 28: set_attribute(invisible, value); break;
+  case 9: case 29: set_attribute(strikethrough, value); break;
   default: break; /* ignore unknown rendition */
   }
 }
@@ -537,6 +538,7 @@ std::string Renditions::sgr( void ) const
   if ( get_attribute( blink ) ) ret.append( ";5" );
   if ( get_attribute( inverse ) ) ret.append( ";7" );
   if ( get_attribute( invisible ) ) ret.append( ";8" );
+  if ( get_attribute( strikethrough ) ) ret.append( ";9" );
 
   if ( foreground_color ) {
     if ( is_true_color( foreground_color ) ) {

diff --git a/src/terminal/terminalframebuffer.h b/src/terminal/terminalframebuffer.h
@@ -53,7 +53,7 @@ namespace Terminal {
 
   class Renditions {
   public:
-    typedef enum { bold, faint, italic, underlined, blink, inverse, invisible, SIZE } attribute_type;
+    typedef enum { bold, faint, italic, underlined, blink, inverse, invisible, strikethrough, SIZE } attribute_type;
 
   private:
     static const uint64_t true_color_mask = 0x1000000;

diff --git a/src/tests/emulation-attributes.test b/src/tests/emulation-attributes.test
@@ -122,6 +122,8 @@ baseline()
             test_true_color 7
             echo "Invisible:"
             test_true_color 8
+            echo "Strikethrough:"
+            test_true_color 9
             echo "Bold, italic and underline:"
             test_true_color 1 3 4
             ;;