Skipping the print of characters without changes

ChangeLog

@@ -1,3 +1,9 @@
+2016-12-18  Markus Gans  <guru.mail@muenster.de>
+	* Only perform VTerm updates on terminal updates
+	* Skipping the print of characters without changes
+	* Combined scrollAreaForward and scrollAreaReverse 
+	  with terminal scroll sequences
+
 2016-12-15  Markus Gans  <guru.mail@muenster.de>
 	* Reduce the character output by using character erase 
 	  and character repeat

src/fbutton.cpp

@@ -526,7 +526,6 @@ void FButton::draw()
   is_Flat = isFlat();
   is_NonFlatShadow = ((flags & (fc::shadow+fc::flat)) == fc::shadow);
   is_NoUnderline = ((flags & fc::no_underline) != 0);
-  updateVTerm(false);
 
   if ( isMonochron() )
     setReverse(true);
@@ -725,7 +724,6 @@ void FButton::draw()
   if ( isMonochron() )
     setReverse(false);
 
-  updateVTerm(true);
   delete[] ButtonText;
 
   if ( is_Focus && getStatusBar() )

src/fbuttongroup.cpp

@@ -447,8 +447,6 @@ void FButtonGroup::setHotkeyAccelerator()
 //----------------------------------------------------------------------
 void FButtonGroup::draw()
 {
-  updateVTerm(false);
-
   if ( isMonochron() )
     setReverse(true);
 
@@ -461,8 +459,6 @@ void FButtonGroup::draw()
 
   if ( isMonochron() )
     setReverse(false);
-
-  updateVTerm(true);
 }
 
 //----------------------------------------------------------------------

src/fcheckbox.cpp

@@ -40,10 +40,8 @@ void FCheckBox::init()
 //----------------------------------------------------------------------
 void FCheckBox::draw()
 {
-  updateVTerm(false);
   drawCheckButton();
   drawLabel();
-  updateVTerm(true);
   FToggleButton::draw();
 }
 

src/fdialog.cpp

@@ -1007,7 +1007,6 @@ void FDialog::draw()
     tooltip = 0;
   }
 
-  updateVTerm(false);
   // fill the background
   setColor();
 
@@ -1024,8 +1023,6 @@ void FDialog::draw()
 
   if ( isMonochron() )
     setReverse(false);
-
-  updateVTerm(true);
 }
 
 //----------------------------------------------------------------------

src/flabel.cpp

@@ -452,8 +452,6 @@ void FLabel::draw()
   if ( text.isNull() || text.isEmpty() )
     return;
 
-  updateVTerm(false);
-
   if ( isMonochron() )
   {
     setReverse(true);
@@ -529,6 +527,4 @@ void FLabel::draw()
     if ( hasEmphasis() )
       setBold(false);
   }
-
-  updateVTerm(true);
 }

src/flineedit.cpp

@@ -748,8 +748,6 @@ void FLineEdit::drawInputField()
   int active_focus = fc::active + fc::focus;
   isActiveFocus = ((flags & active_focus) == active_focus);
   isShadow = ((flags & fc::shadow) != 0 );
-
-  updateVTerm(false);
   setPrintPos (1, 1);
 
   if ( isMonochron() )
@@ -807,8 +805,6 @@ void FLineEdit::drawInputField()
 
   // set the cursor to the first pos.
   setCursorPos (2+cursor_pos-text_offset, 1);
-
-  updateVTerm(true);
 }
 
 //----------------------------------------------------------------------

src/flistbox.cpp

@@ -1453,7 +1453,6 @@ void FListBox::draw()
   if ( current < 1 )
     current = 1;
 
-  updateVTerm(false);
   setColor();
 
   if ( isMonochron() )
@@ -1480,8 +1479,6 @@ void FListBox::draw()
   if ( isMonochron() )
     setReverse(false);
 
-  updateVTerm(true);
-
   if ( vbar->isVisible() )
     vbar->redraw();
 
@@ -1561,8 +1558,6 @@ void FListBox::drawList()
     end = std::max(last_pos, current_pos)+1;
   }
 
-  updateVTerm(false);
-
   for (uInt y=start; y < end; y++)
   {
     setPrintPos (2, 2 + int(y));
@@ -1784,7 +1779,6 @@ void FListBox::drawList()
     setReverse(false);
 
   unsetBold();
-  updateVTerm(true);
   last_yoffset = yoffset;
   last_current = current;
 }

src/fmenu.cpp

@@ -1218,7 +1218,6 @@ void FMenu::draw()
 {
   // fill the background
   setColor (wc.menu_active_fg, wc.menu_active_bg);
-  updateVTerm(false);
 
   if ( isMonochron() )
     setReverse(true);
@@ -1230,8 +1229,6 @@ void FMenu::draw()
 
   if ( isMonochron() )
     setReverse(false);
-
-  updateVTerm(true);
 }
 
 //----------------------------------------------------------------------

src/fmenubar.cpp

@@ -744,7 +744,6 @@ void FMenuBar::drawItems()
   if ( item_list.empty() )
     return;
 
-  updateVTerm(false);
   setPrintPos (1,1);
 
   if ( isMonochron() )
@@ -826,7 +825,8 @@ void FMenuBar::drawItems()
 
       if ( ! std::iswprint(wint_t(item_text[z])) )
       {
-        if ( ! isNewFont() && (  int(item_text[z]) < fc::NF_rev_left_arrow2
+        if ( ! isNewFont()
+            && ( int(item_text[z]) < fc::NF_rev_left_arrow2
                 || int(item_text[z]) > fc::NF_check_mark ) )
         {
           item_text[z] = L' ';
@@ -885,8 +885,6 @@ void FMenuBar::drawItems()
 
   if ( isMonochron() )
     setReverse(false);
-
-  updateVTerm(true);
 }
 
 //----------------------------------------------------------------------

src/fmessagebox.cpp

@@ -421,7 +421,6 @@ void FMessageBox::draw()
   int head_offset = 0;
   int center_x = 0;
   int msg_x = int((getWidth() - int(max_line_width)) / 2);  // center the whole block
-  updateVTerm(false);
 
   if ( isMonochron() )
     setReverse(true);
@@ -454,8 +453,6 @@ void FMessageBox::draw()
 
   if ( isMonochron() )
     setReverse(false);
-
-  updateVTerm(true);
 }
 
 //----------------------------------------------------------------------

src/foptiattr.h

@@ -55,6 +55,9 @@ class FOptiAttr
      uChar transparent   : 1;  // transparent
      uChar trans_shadow  : 1;  // transparent shadow
      uChar inherit_bg    : 1;  // inherit background
+     uChar no_changes    : 1;  // no changes required
+     uChar restored      : 1;  // restored VTerm character
+     uChar               : 6;  // padding bits
    } char_data;
 
    // Constructor

src/fprogressbar.cpp

@@ -37,15 +37,12 @@ void FProgressbar::setPercentage (int percentage_value)
   else
     percentage = percentage_value;
 
-  updateVTerm(false);
-
   if ( isVisible() )
   {
     drawPercentage();
     drawBar();
   }
 
-  updateVTerm(true);
   updateTerminal();
 }
 
@@ -128,7 +125,6 @@ void FProgressbar::hide()
 //----------------------------------------------------------------------
 void FProgressbar::reset()
 {
-  updateVTerm(false);
   percentage = -1;
 
   if ( isVisible() )
@@ -137,7 +133,6 @@ void FProgressbar::reset()
     drawBar();
   }
 
-  updateVTerm(true);
   updateTerminal();
 }
 
@@ -146,14 +141,12 @@ void FProgressbar::reset()
 //----------------------------------------------------------------------
 void FProgressbar::draw()
 {
-  updateVTerm(false);
   drawPercentage();
   drawBar();
 
   if ( (flags & fc::shadow) != 0 )
     drawShadow ();
 
-  updateVTerm(true);
   flush_out();
 }
 

src/fradiobutton.cpp

@@ -41,10 +41,8 @@ void FRadioButton::init()
 //----------------------------------------------------------------------
 void FRadioButton::draw()
 {
-  updateVTerm(false);
   drawRadioButton();
   drawLabel();
-  updateVTerm(true);
   FToggleButton::draw();
 }
 

src/fscrollbar.cpp

@@ -289,7 +289,6 @@ void FScrollbar::drawBar()
   if ( slider_pos != current_slider_pos )
   {
     int z;
-    updateVTerm(false);
 
     if ( bar_orientation == fc::vertical )
     {
@@ -392,8 +391,6 @@ void FScrollbar::drawBar()
 
     if ( isMonochron() )
       setReverse(false);
-
-    updateVTerm(true);
   }
 }
 
@@ -604,11 +601,9 @@ void FScrollbar::init()
 //----------------------------------------------------------------------
 void FScrollbar::draw()
 {
-  updateVTerm(false);
   drawButtons();
   current_slider_pos = -1;
   drawBar();
-  updateVTerm(true);
 }
 
 //----------------------------------------------------------------------

src/fstatusbar.cpp

@@ -259,7 +259,6 @@ void FStatusBar::drawMessage()
   if ( isLastActiveFocus )
     space_offset = 0;
 
-  updateVTerm(false);
   setColor (wc.statusbar_fg, wc.statusbar_bg);
   setPrintPos (x, 1);
 
@@ -301,8 +300,6 @@ void FStatusBar::drawMessage()
 
   if ( isMonochron() )
     setReverse(false);
-
-  updateVTerm(true);
 }
 
 //----------------------------------------------------------------------
@@ -604,7 +601,6 @@ void FStatusBar::drawKeys()
     return;
   }
 
-  updateVTerm(false);
   setPrintPos (1, 1);
 
   if ( isMonochron() )
@@ -721,6 +717,5 @@ void FStatusBar::drawKeys()
   if ( isMonochron() )
     setReverse(false);
 
-  updateVTerm(true);
   x_msg = x;
 }

src/fswitch.cpp

@@ -97,10 +97,8 @@ void FSwitch::onMouseUp (FMouseEvent* ev)
 //----------------------------------------------------------------------
 void FSwitch::draw()
 {
-  updateVTerm(false);
   drawLabel();
   drawCheckButton();
-  updateVTerm(true);
   FToggleButton::draw();
   updateTerminal();
   flush_out();

src/fterm.cpp

@@ -430,7 +430,7 @@ int FTerm::parseKeyString ( char buffer[]
       {
         if ( len == 2 && ( buffer[1] == 'O'
                           || buffer[1] == '['
-                         || buffer[1] == ']') )
+                          || buffer[1] == ']' ) )
         {
           if ( ! isKeyTimeout(time_keypressed, key_timeout) )
             return NEED_MORE_DATA;
@@ -932,7 +932,8 @@ const FString FTerm::getXTermColorName (int color)
 void FTerm::setXTermCursorStyle (fc::xtermCursorStyle style)
 {
   // Set the xterm cursor style
-  if ( (xterm_terminal || mintty_terminal) && ! (gnome_terminal || kde_konsole) )
+  if ( (xterm_terminal || mintty_terminal)
+      && ! (gnome_terminal || kde_konsole) )
   {
     putstringf (CSI "%d q", style);
     std::fflush(stdout);
@@ -2712,6 +2713,8 @@ void FTerm::init_termcaps()
         const_cast<char*>(CSI "48;5;%p1%dm");
       tcap[fc::t_exit_attribute_mode].string = \
         const_cast<char*>(CSI "0m" SI);
+      tcap[fc::t_orig_pair].string = \
+        const_cast<char*>(CSI "39;49m");
     }
     else if ( putty_terminal )
     {
@@ -2858,7 +2861,7 @@ void FTerm::init_termcaps()
 
     if ( (key_up_string && (std::strcmp(key_up_string, CSI "A") == 0))
         || ( tcap[fc::t_cursor_up].string
-          && (std::strcmp(tcap[fc::t_cursor_up].string, CSI "A") == 0)) )
+            && (std::strcmp(tcap[fc::t_cursor_up].string, CSI "A") == 0) ) )
     {
       for (int i=0; Fkey[i].tname[0] != 0; i++)
       {
@@ -2975,7 +2978,8 @@ void FTerm::init_encoding()
 {
   // detect encoding and set the Fputchar function pointer
 
-  if ( isatty(stdout_no) && ! std::strcmp(nl_langinfo(CODESET), "UTF-8") )
+  if ( isatty(stdout_no)
+      && ! std::strcmp(nl_langinfo(CODESET), "UTF-8") )
   {
     utf8_console = true;
     Encoding = fc::UTF8;

src/ftextview.cpp

@@ -631,7 +631,6 @@ void FTextView::draw()
 {
   FWidget* parent = getParentWidget();
   bool is_text_dialog;
-  updateVTerm(false);
   setColor();
 
   if ( isMonochron() )
@@ -662,7 +661,6 @@ void FTextView::draw()
   if ( hbar->isVisible() )
     hbar->redraw();
 
-  updateVTerm(true);
   drawText();
 
   if ( hasFocus() && getStatusBar() )
@@ -672,10 +670,8 @@ void FTextView::draw()
 
     if ( curMsg != msg )
     {
-      updateVTerm(false);
       getStatusBar()->setMessage(msg);
       getStatusBar()->drawMessage();
-      updateVTerm(true);
     }
   }
 
@@ -698,7 +694,6 @@ void FTextView::drawText()
   if ( end > getRows() )
     end = getRows();
 
-  updateVTerm(false);
   setColor();
 
   if ( isMonochron() )
@@ -737,8 +732,6 @@ void FTextView::drawText()
 
   if ( isMonochron() )
     setReverse(false);
-
-  updateVTerm(true);
 }
 
 //----------------------------------------------------------------------

src/ftooltip.cpp

@@ -79,7 +79,6 @@ void FToolTip::setText (const char* txt)
 //----------------------------------------------------------------------
 void FToolTip::draw()
 {
-  updateVTerm(false);
   setColor();
 
   if ( getMaxColor() < 16 )
@@ -95,7 +94,6 @@ void FToolTip::draw()
   }
 
   unsetBold();
-  updateVTerm(true);
 }
 
 //----------------------------------------------------------------------

src/fvterm.cpp

@@ -15,13 +15,11 @@ bool                 FVTerm::terminal_update_complete;
 bool                 FVTerm::terminal_update_pending;
 bool                 FVTerm::force_terminal_update;
 bool                 FVTerm::stop_terminal_updates;
-bool                 FVTerm::vterm_updates;
 int                  FVTerm::skipped_terminal_update = 0;
 std::queue<int>*     FVTerm::output_buffer           = 0;
 FPoint*              FVTerm::term_pos                = 0;
 FVTerm::term_area*   FVTerm::vterm                   = 0;
 FVTerm::term_area*   FVTerm::vdesktop                = 0;
-FVTerm::term_area*   FVTerm::last_area               = 0;
 FVTerm::term_area*   FVTerm::active_area             = 0;
 FVTerm::termcap_map* FVTerm::tcap                    = 0;
 FTermcap::tcap_map*  FTermcap::tcap                  = 0;
@@ -41,7 +39,6 @@ FVTerm::FVTerm (FVTerm* parent)
   , vwin(0)
 {
   terminal_update_complete = false;
-  vterm_updates    = true;
 
   if ( ! parent )
   {
@@ -131,7 +128,7 @@ void FVTerm::clearTerm (int fillchar)
       vdesktop->changes[i].trans_count = 0;
     }
 
-    updateVTerm (vdesktop);
+    vdesktop->has_changes = true;
     setTermXY (0,0);
   }
   else if ( cl )
@@ -279,6 +276,9 @@ void FVTerm::updateTerminal()
     }
   }
 
+  // Update data on VTerm
+  updateVTerm();
+
   for (register uInt y=0; y < uInt(vterm->height); y++)
     updateTerminalLine (y);
 
@@ -318,7 +318,9 @@ void FVTerm::updateTerminalLine (uInt y)
 
       for (uInt x=xmin+1; x < uInt(vt->width); x++)
       {
-        if ( *min_char == vt->text[y * uInt(vt->width) + x] )
+        char_data* ch = &vt->text[y * uInt(vt->width) + x];
+
+        if ( *min_char == *ch )
           beginning_whitespace++;
         else
           break;
@@ -340,7 +342,9 @@ void FVTerm::updateTerminalLine (uInt y)
 
         for (uInt x=1; x < uInt(vt->width); x++)
         {
-          if ( *first_char == vt->text[y * uInt(vt->width) + x] )
+          char_data* ch = &vt->text[y * uInt(vt->width) + x];
+
+          if ( *first_char == *ch )
             leading_whitespace++;
           else
             break;
@@ -363,7 +367,9 @@ void FVTerm::updateTerminalLine (uInt y)
 
         for (uInt x=uInt(vt->width)-1; x >  0 ; x--)
         {
-          if ( *last_char == vt->text[y * uInt(vt->width) + x] )
+          char_data* ch = &vt->text[y * uInt(vt->width) + x];
+
+          if ( *last_char == *ch )
             tailing_whitespace++;
           else
             break;
@@ -399,6 +405,31 @@ void FVTerm::updateTerminalLine (uInt y)
         char_data* print_char;
         print_char = &vt->text[y * uInt(vt->width) + x];
 
+        // skip character with no changes
+        if ( ! terminal_update_pending
+            && print_char->no_changes
+            && ! print_char->restored )
+        {
+          uInt count = 1;
+
+          for (uInt i=x+1; i <= xmax; i++)
+          {
+            char_data* ch = &vt->text[y * uInt(vt->width) + i];
+
+            if ( ch->no_changes && ! ch->restored )
+              count++;
+            else
+              break;
+          }
+
+          if ( count > uInt(cursor_addres_lengths) )
+          {
+            setTermXY (int(x + count), int(y));
+            x = x + count - 1;
+            continue;
+          }
+        }
+
         // Erase a number of characters to draw simple whitespaces
         if ( ec && print_char->code == ' ' )
         {
@@ -407,7 +438,9 @@ void FVTerm::updateTerminalLine (uInt y)
 
           for (uInt i=x+1; i <= xmax; i++)
           {
-            if ( *print_char == vt->text[y * uInt(vt->width) + i] )
+            char_data* ch = &vt->text[y * uInt(vt->width) + i];
+
+            if ( *print_char == *ch )
               whitespace++;
             else
               break;
@@ -440,7 +473,9 @@ void FVTerm::updateTerminalLine (uInt y)
 
           for (uInt i=x+1; i <= xmax; i++)
           {
-            if ( *print_char == vt->text[y * uInt(vt->width) + i] )
+            char_data* ch = &vt->text[y * uInt(vt->width) + i];
+
+            if ( *print_char == *ch )
               repetitions++;
             else
               break;
@@ -704,6 +739,9 @@ int FVTerm::print (term_area* area, FString& s)
 
   if ( p )
   {
+    if ( *p )
+      area->has_changes = true;
+
     while ( *p )
     {
       int width, height, rsh, bsh;
@@ -762,6 +800,8 @@ int FVTerm::print (term_area* area, FString& s)
           nc.transparent   = next_attribute.transparent;
           nc.trans_shadow  = next_attribute.trans_shadow;
           nc.inherit_bg    = next_attribute.inherit_bg;
+          nc.no_changes    = false;
+          nc.restored      = false;
 
           if ( area
               && area->cursor_x > 0
@@ -820,8 +860,6 @@ int FVTerm::print (term_area* area, FString& s)
       p++;
       len++;
     } // end of while
-
-    updateVTerm (area);
   }
 
   return len;
@@ -878,6 +916,8 @@ int FVTerm::print (term_area* area, register int c)
   nc.transparent   = next_attribute.transparent;
   nc.trans_shadow  = next_attribute.trans_shadow;
   nc.inherit_bg    = next_attribute.inherit_bg;
+  nc.no_changes    = false;
+  nc.restored      = false;
 
   if ( area->cursor_x > 0
       && area->cursor_y > 0
@@ -918,6 +958,7 @@ int FVTerm::print (term_area* area, register int c)
   }
 
   area->cursor_x++;
+  area->has_changes = true;
 
   if ( area->cursor_x > width + rsh )
   {
@@ -928,11 +969,9 @@ int FVTerm::print (term_area* area, register int c)
   if ( area->cursor_y > height + bsh )
   {
     area->cursor_y--;
-    updateVTerm (area);
     return -1;
   }
 
-  updateVTerm (area);
   return 1;
 }
 
@@ -1180,6 +1219,7 @@ void FVTerm::createArea ( int x_offset, int y_offset
   area->input_cursor_x       = -1;
   area->input_cursor_y       = -1;
   area->input_cursor_visible = false;
+  area->has_changes          = false;
   area->changes              = 0;
   area->text                 = 0;
   area->visible              = false;
@@ -1244,6 +1284,7 @@ void FVTerm::resizeArea ( int x_offset, int y_offset
   area->height = height;
   area->right_shadow = rsw;
   area->bottom_shadow = bsh;
+  area->has_changes = false;
 
   default_char.code          = ' ';
   default_char.fg_color      = fc::Default;
@@ -1264,6 +1305,7 @@ void FVTerm::resizeArea ( int x_offset, int y_offset
   default_char.transparent   = 0;
   default_char.trans_shadow  = 0;
   default_char.inherit_bg    = 0;
+  default_char.no_changes    = 0;
 
   std::fill_n (area->text, area_size, default_char);
 
@@ -1413,6 +1455,7 @@ void FVTerm::restoreVTerm (int x, int y, int w, int h)
         }
       }
 
+      sc->restored = true;
       std::memcpy (tc, sc, sizeof(char_data));
 
       if ( short(vterm->changes[y+ty].xmin) > x )
@@ -1496,27 +1539,52 @@ FVTerm::covered_state FVTerm::isCovered ( int x, int y
 }
 
 //----------------------------------------------------------------------
-void FVTerm::updateVTerm (bool on)
+void FVTerm::updateVTerm()
 {
-  vterm_updates = on;
+  // Update data on VTerm
 
-  if ( on )
+  if ( vdesktop && vdesktop->has_changes )
-    updateVTerm (last_area);
+  {
+    updateVTerm(vdesktop);
+    vdesktop->has_changes = false;
+  }
+
+  FWidget* widget = static_cast<FWidget*>(vterm->widget);
+
+  if ( ! widget->window_list || widget->window_list->empty() )
+    return;
+
+  FWidget::widgetList::const_iterator iter, end;
+  iter = widget->window_list->begin();
+  end  = widget->window_list->end();
+
+  for (; iter != end; ++iter)
+  {
+    term_area* win = (*iter)->getVWin();
+
+    if ( ! win )
+      continue;
+
+    if ( ! win->visible )
+      continue;
+
+    if ( win->has_changes )
+    {
+      updateVTerm(win);
+      win->has_changes = false;
+    }
+  }
 }
 
 //----------------------------------------------------------------------
 void FVTerm::updateVTerm (term_area* area)
 {
+  // Update area data on VTerm
+
   int ax, ay, aw, ah, rsh, bsh, y_end, ol;
   char_data* tc; // terminal character
   char_data* ac; // area character
 
-  if ( ! vterm_updates )
-  {
-    last_area = area;
-    return;
-  }
-
   if ( ! area )
     return;
 
@@ -1542,7 +1610,7 @@ void FVTerm::updateVTerm (term_area* area)
   else
     y_end = ah + bsh;
 
-  for (register int y=0; y < y_end; y++)  // line loop
+  for (int y=0; y < y_end; y++)  // line loop
   {
     int line_xmin = int(area->changes[y].xmin);
     int line_xmax = int(area->changes[y].xmax);
@@ -1561,7 +1629,7 @@ void FVTerm::updateVTerm (term_area* area)
       if ( ax + line_xmin >= vterm->width )
         continue;
 
-      for (register int x=line_xmin; x <= line_xmax; x++)  // column loop
+      for (int x=line_xmin; x <= line_xmax; x++)  // column loop
       {
         int gx, gy, line_len;
         covered_state is_covered;
@@ -1599,6 +1667,7 @@ void FVTerm::updateVTerm (term_area* area)
                 || ch.code == fc::FullBlock )
               ch.code = ' ';
 
+            ch.no_changes = bool(! tc->restored && *tc == ch);
             std::memcpy (tc, &ch, sizeof(char_data));
           }
           else if ( ac->transparent )   // transparent
@@ -1606,6 +1675,7 @@ void FVTerm::updateVTerm (term_area* area)
             // restore one character on vterm
             char_data ch;
             ch = getCoveredCharacter (gx+1 - ol, gy+1, area->widget);
+            ch.no_changes = bool(! tc->restored && *tc == ch);
             std::memcpy (tc, &ch, sizeof(char_data));
           }
           else  // not transparent
@@ -1628,6 +1698,7 @@ void FVTerm::updateVTerm (term_area* area)
                   || ch.code == fc::FullBlock )
                 ch.code = ' ';
 
+              ch.no_changes = bool(! tc->restored && *tc == ch);
               std::memcpy (tc, &ch, sizeof(char_data));
             }
             else if ( ac->inherit_bg )
@@ -1637,16 +1708,30 @@ void FVTerm::updateVTerm (term_area* area)
               std::memcpy (&ch, ac, sizeof(char_data));
               cc = getCoveredCharacter (gx+1 - ol, gy+1, area->widget);
               ch.bg_color = cc.bg_color;
+              ch.no_changes = bool(*tc == ch);
               std::memcpy (tc, &ch, sizeof(char_data));
             }
             else  // default
+            {
+              if ( ! tc->restored && *tc == *ac )
+              {
                 std::memcpy (tc, ac, sizeof(char_data));
+                tc->no_changes = true;
+              }
+              else
+              {
+                std::memcpy (tc, ac, sizeof(char_data));
+                tc->no_changes = false;
+              }
+            }
           }
 
           modified = true;
         }
         else if ( ! modified )
           line_xmin++;  // don't update covered character
+
+        tc->restored = false;
       }
 
       _xmin = ax + line_xmin - ol;
@@ -1745,7 +1830,6 @@ void FVTerm::setAreaCursor ( int x, int y
   area->input_cursor_x = x - 1;
   area->input_cursor_y = y - 1;
   area->input_cursor_visible = visible;
-  updateVTerm (area);
 }
 
 //----------------------------------------------------------------------
@@ -2014,6 +2098,24 @@ void FVTerm::scrollAreaForward (term_area* area)
   std::fill_n (dc, area->width, nc);
   area->changes[y_max].xmin = 0;
   area->changes[y_max].xmax = uInt(area->width - 1);
+  area->has_changes = true;
+
+  if ( area == vdesktop )
+  {
+    if ( tcap[fc::t_scroll_forward].string  )
+    {
+      setTermXY (0, vdesktop->height);
+      scrollTermForward();
+      putArea (1, 1, vdesktop);
+
+      // avoid update lines from 0 to (y_max-1)
+      for (int y=0; y < y_max; y++)
+      {
+        area->changes[y].xmin = uInt(area->width - 1);
+        area->changes[y].xmax = 0;
+      }
+    }
+  }
 }
 
 //----------------------------------------------------------------------
@@ -2022,6 +2124,7 @@ void FVTerm::scrollAreaReverse (term_area* area)
   // Scrolls the entire area one line down
   int total_width;
   int length;
+  int y_max;
   char_data  nc; // next character
   char_data* lc; // last character
   char_data* sc; // source character
@@ -2035,8 +2138,9 @@ void FVTerm::scrollAreaReverse (term_area* area)
 
   length = area->width;
   total_width = area->width + area->right_shadow;
+  y_max = area->height - 1;
 
-  for (int y=area->height-1; y > 0; y--)
+  for (int y=y_max; y > 0; y--)
   {
     int pos1 = (y-1) * total_width;
     int pos2 = y * total_width;
@@ -2055,6 +2159,24 @@ void FVTerm::scrollAreaReverse (term_area* area)
   std::fill_n (dc, area->width, nc);
   area->changes[0].xmin = 0;
   area->changes[0].xmax = uInt(area->width - 1);
+  area->has_changes = true;
+
+  if ( area == vdesktop )
+  {
+    if ( tcap[fc::t_scroll_reverse].string  )
+    {
+      setTermXY (0, 0);
+      scrollTermReverse();
+      putArea (1, 1, vdesktop);
+
+      // avoid update lines from 1 to y_max
+      for (int y=1; y <= y_max; y++)
+      {
+        area->changes[y].xmin = uInt(area->width - 1);
+        area->changes[y].xmax = 0;
+      }
+    }
+  }
 }
 
 //----------------------------------------------------------------------
@@ -2130,7 +2252,7 @@ void FVTerm::clearArea (term_area* area, int fillchar)
     area->changes[y].trans_count = w;
   }
 
-  updateVTerm (area);
+  area->has_changes = true;
 }
 
 //----------------------------------------------------------------------
@@ -2334,7 +2456,6 @@ void FVTerm::init()
   init_object   = this;
   vterm         =  0;
   vdesktop      =  0;
-  last_area     =  0;
   term_pos      = new FPoint(-1,-1);
   output_buffer = new std::queue<int>;
 
@@ -2363,7 +2484,9 @@ void FVTerm::init()
   term_attribute.pc_charset    = \
   term_attribute.transparent   = \
   term_attribute.trans_shadow  = \
-  term_attribute.inherit_bg    = false;
+  term_attribute.inherit_bg    = \
+  term_attribute.no_changes    = \
+  term_attribute.restored      = false;
 
   // next_attribute contains the state of the next printed character
   std::memcpy (&next_attribute, &term_attribute, sizeof(char_data));

src/fvterm.h

@@ -68,6 +68,7 @@ class FVTerm : public FObject, public FTerm
      FWidget* widget;
      line_changes* changes;
      char_data* text;
+     bool has_changes;
      bool visible;
    } term_area;
 
@@ -263,7 +264,7 @@ class FVTerm : public FObject, public FTerm
    static covered_state isCovered ( int, int
                                   , term_area* );
 
-   static void          updateVTerm (bool);
+   static void          updateVTerm();
    static void          updateVTerm (term_area*);
    static bool          updateVTermCursor (term_area*);
    static bool          isInsideArea (int, int, term_area*);
@@ -302,7 +303,6 @@ class FVTerm : public FObject, public FTerm
    // Data Members
    static        term_area* vterm;        // virtual terminal
    static        term_area* vdesktop;     // virtual desktop
-   static        term_area* last_area;    // last used area
    static        term_area* active_area;  // active area
    term_area*    print_area;              // print area for this object
    term_area*    vwin;                    // virtual window
@@ -342,7 +342,6 @@ class FVTerm : public FObject, public FTerm
    static bool             terminal_update_pending;
    static bool             force_terminal_update;
    static bool             stop_terminal_updates;
-   static bool             vterm_updates;
    static int              skipped_terminal_update;
 };
 
@@ -404,7 +403,8 @@ inline void FVTerm::setNormal()
   next_attribute.pc_charset    = \
   next_attribute.transparent   = \
   next_attribute.trans_shadow  = \
-  next_attribute.inherit_bg    = false;
+  next_attribute.inherit_bg    = \
+  next_attribute.no_changes    = false;
 
   next_attribute.fg_color      = fc::Default;
   next_attribute.bg_color      = fc::Default;

test/calculator.cpp

@@ -302,7 +302,6 @@ Calc::~Calc()
 void Calc::drawDispay()
 {
   FString display = input;
-  updateVTerm(false);
 
   if ( display.isNull() || display.isEmpty()  )
     display = L'0';
@@ -364,8 +363,6 @@ void Calc::drawDispay()
     setPrintPos (1,4);
     print(separator);
   }
-
-  updateVTerm(true);
 }
 
 //----------------------------------------------------------------------

test/keyboard.cpp

@@ -41,15 +41,9 @@ void keyboard::onKeyPress (FKeyEvent* ev)
 
   printf ("Key %s (id %d)\n", getKeyName(key_id).c_str(), key_id);
 
-
   if ( is_last_line )
-  {
     scrollAreaForward (vdesktop);
 
-    if ( ! scrollTermForward() )
-      putArea (getTermPos(), vdesktop);
-  }
-
   setAreaCursor (1, getPrintPos().getY(), true, vdesktop);
 }
 

test/mandelbrot.cpp

@@ -94,8 +94,6 @@ void Mandelbrot::draw()
       print(' ');
     }
   }
-
-  updateVTerm(true);
 }
 
 //----------------------------------------------------------------------

test/term-attributes.cpp

@@ -261,8 +261,6 @@ void AttribDemo::printAltCharset()
 //----------------------------------------------------------------------
 void AttribDemo::draw()
 {
-  updateVTerm(false);
-
   // test alternate character set
   printAltCharset();
 
@@ -383,7 +381,6 @@ void AttribDemo::draw()
 
   setPrintPos (16, 17);
   print ("Change background color ->");
-  updateVTerm(true);
 }
 
 

test/timer.cpp

@@ -60,13 +60,8 @@ void timer::onTimer (FTimerEvent* ev)
   printf ("timer event, id %d\n", timer_id );
 
   if ( is_last_line )
-  {
     scrollAreaForward (vdesktop);
 
-    if ( ! scrollTermForward() )
-      putArea (getTermPos(), vdesktop);
-  }
-
   setAreaCursor (1, getPrintPos().getY(), true, vdesktop);
 }
 

test/transparent.cpp

@@ -67,7 +67,6 @@ Transparent::~Transparent()
 void Transparent::draw()
 {
   FDialog::draw();
-  updateVTerm(false);
 
   if ( isMonochron() )
     setReverse(true);
@@ -106,8 +105,6 @@ void Transparent::draw()
 
   if ( isMonochron() )
     setReverse(false);
-
-  updateVTerm(true);
 }
 
 //----------------------------------------------------------------------
@@ -188,19 +185,16 @@ MainWindow::MainWindow (FWidget* parent)
   transpwin->setText("transparent");
   transpwin->setGeometry (6, 3, 29, 12);
   transpwin->unsetTransparentShadow();
-  transpwin->show();
 
   Transparent* shadowwin = new Transparent(this, Transparent::shadow);
   shadowwin->setText("shadow");
   shadowwin->setGeometry (46, 11, 29, 12);
   shadowwin->unsetTransparentShadow();
-  shadowwin->show();
 
   Transparent* ibg = new Transparent(this, Transparent::inherit_background);
   ibg->setText("inherit background");
   ibg->setGeometry (42, 3, 29, 7);
   ibg->unsetTransparentShadow();
-  ibg->show();
 
   // Statusbar at the bottom
   FStatusBar* statusbar = new FStatusBar (this);
@@ -219,7 +213,6 @@ MainWindow::~MainWindow()
 void MainWindow::draw()
 {
   FDialog::draw();
-  updateVTerm(false);
 
   if ( isMonochron() )
     setReverse(true);
@@ -233,7 +226,7 @@ void MainWindow::draw()
   if ( isMonochron() )
     setReverse(false);
 
-  updateVTerm(true);
+  updateTerminal();
 }
 
 //----------------------------------------------------------------------