Final tab-related bugfix (of the morning). Now matches xterm more closely.

src/terminal/terminalframebuffer.cc

@@ -32,19 +32,25 @@ void Cell::reset( int background_color )
   wrap = false;
 }
 
+void DrawState::reinitialize_tabs( unsigned int start )
+{
+  assert( default_tabs );
+  for ( unsigned int i = start; i < tabs.size(); i++ ) {
+    tabs[ i ] = ( (i % 8) == 0 );
+  }
+}
+
 DrawState::DrawState( int s_width, int s_height )
   : width( s_width ), height( s_height ),
     cursor_col( 0 ), cursor_row( 0 ),
-    combining_char_col( 0 ), combining_char_row( 0 ), tabs( s_width ),
+    combining_char_col( 0 ), combining_char_row( 0 ), default_tabs( true ), tabs( s_width ),
     scrolling_region_top_row( 0 ), scrolling_region_bottom_row( height - 1 ),
     renditions( 0 ), save(),
     next_print_will_wrap( false ), origin_mode( false ), auto_wrap_mode( true ),
     insert_mode( false ), cursor_visible( true ), reverse_video( false ),
     application_mode_cursor_keys( false )
 {
-  for ( int i = 0; i < width; i++ ) {
-    tabs[ i ] = ( (i % 8) == 0 );
-  }
+  reinitialize_tabs( 0 );
 }
 
 Framebuffer::Framebuffer( int s_width, int s_height )
@@ -204,19 +210,6 @@ int DrawState::limit_bottom( void )
   return origin_mode ? scrolling_region_bottom_row : height - 1;
 }
 
-std::vector<int> DrawState::get_tabs( void )
-{
-  std::vector<int> ret;
-
-  for ( int i = 0; i < width; i++ ) {
-    if ( tabs[ i ] ) {
-      ret.push_back( i );
-    }
-  }
-
-  return ret;
-}
-
 void Framebuffer::apply_renditions_to_current_cell( void )
 {
   get_mutable_cell()->renditions = ds.get_renditions();
@@ -361,17 +354,16 @@ void DrawState::resize( int s_width, int s_height )
     scrolling_region_bottom_row = s_height - 1;
   }
 
+  tabs.resize( s_width );
+  if ( default_tabs ) {
+    reinitialize_tabs( width );
+  }
+
   width = s_width;
   height = s_height;
 
   snap_cursor_to_border();
 
-  /* reset tab stops */
-  tabs = std::vector< bool >( width );
-  for ( int i = 0; i < width; i++ ) {
-    tabs[ i ] = ( (i % 8) == 0 );
-  }
-
   /* saved cursor will be snapped to border on restore */
 
   /* invalidate combining char cell if necessary */

src/terminal/terminalframebuffer.h

@@ -157,8 +157,11 @@ namespace Terminal {
     int cursor_col, cursor_row;
     int combining_char_col, combining_char_row;
 
+    bool default_tabs;
     std::vector<bool> tabs;
 
+    void reinitialize_tabs( unsigned int start );
+
     int scrolling_region_top_row, scrolling_region_bottom_row;
 
     Renditions renditions;
@@ -189,10 +192,10 @@ namespace Terminal {
 
     void set_tab( void );
     void clear_tab( int col );
+    void clear_default_tabs( void ) { default_tabs = false; }
+    /* Default tabs can't be restored without resetting the draw state. */
     int get_next_tab( void );
 
-    std::vector<int> get_tabs( void );
-
     void set_scrolling_region( int top, int bottom );
 
     int get_scrolling_region_top_row( void ) const { return scrolling_region_top_row; }

src/terminal/terminalfunctions.cc

@@ -191,13 +191,20 @@ void Ctrl_HT( Framebuffer *fb, Dispatcher *dispatch __attribute((unused)) )
 {
   int col = fb->ds.get_next_tab();
   if ( col == -1 ) { /* no tabs, go to end of line */
-    fb->ds.move_col( fb->ds.get_width() - 1 );
+  /* A horizontal tab is the only operation that (1) can keep the wrap
+     flag but (2) starts a new grapheme. */
+    if ( fb->ds.get_cursor_col() == fb->ds.get_width() - 1 ) {
+      fb->ds.move_col( fb->ds.get_width() - 1, false );
+      fb->ds.move_col( 1, true, true );
     } else {
-    fb->ds.move_col( col );
+      fb->ds.move_col( fb->ds.get_width() - 1, false );
+    }
+  } else {
+    fb->ds.move_col( col, false );
   }
 }
 
-static Function func_Ctrl_HT( CONTROL, "\x09", Ctrl_HT );
+static Function func_Ctrl_HT( CONTROL, "\x09", Ctrl_HT, false );
 
 /* horizontal tab set */
 void Ctrl_HTS( Framebuffer *fb, Dispatcher *dispatch __attribute((unused)) )
@@ -216,6 +223,7 @@ void CSI_TBC( Framebuffer *fb, Dispatcher *dispatch )
     fb->ds.clear_tab( fb->ds.get_cursor_col() );    
     break;
   case 3: /* clear all tab stops */
+    fb->ds.clear_default_tabs();
     for ( int x = 0; x < fb->ds.get_width(); x++ ) {
       fb->ds.clear_tab( x );
     }