Improve cursor rendering, ensure display not affected if cursor does not move. Repurpose unused "selected" attribute for marking the cursor.

protocols/ssh/include/terminal.h

@@ -112,6 +112,16 @@ struct guac_terminal {
      */
     int cursor_col;
 
+    /**
+     * The row of the rendered cursor.
+     */
+    int visible_cursor_row;
+
+    /**
+     * The column of the rendered cursor.
+     */
+    int visible_cursor_col;
+
     /**
      * The attributes which will be applied to future characters.
      */
@@ -219,9 +229,10 @@ int guac_terminal_scroll_down(guac_terminal* term,
         int start_row, int end_row, int amount);
 
 /**
- * Toggles the reverse attribute of the character at the given location.
+ * Commits the current cursor location, updating the visible cursor
+ * on the screen.
  */
-int guac_terminal_toggle_reverse(guac_terminal* term, int row, int col);
+void guac_terminal_commit_cursor(guac_terminal* term);
 
 /**
  * Scroll down the display by the given amount, replacing the new space with

protocols/ssh/include/types.h

@@ -79,9 +79,9 @@ typedef struct guac_terminal_attributes {
     bool reverse;
 
     /**
-     * Whether the associated character is selected.
+     * Whether the associated character is highlighted by the cursor.
      */
-    bool selected;
+    bool cursor;
 
     /**
      * Whether to render the character with underscore.

protocols/ssh/src/display.c

@@ -250,7 +250,7 @@ int __guac_terminal_set_colors(guac_terminal_display* display,
     int background, foreground;
 
     /* Handle reverse video */
-    if (attributes->reverse != attributes->selected) {
+    if (attributes->reverse != attributes->cursor) {
         background = attributes->foreground;
         foreground = attributes->background;
     }
@@ -758,7 +758,7 @@ void __guac_terminal_display_flush_clear(guac_terminal_display* display) {
 
                 /* Color of the rectangle to draw */
                 int color;
-                if (current->character.attributes.reverse != current->character.attributes.selected)
+                if (current->character.attributes.reverse != current->character.attributes.cursor)
                    color = current->character.attributes.foreground;
                 else
                    color = current->character.attributes.background;
@@ -824,7 +824,7 @@ void __guac_terminal_display_flush_clear(guac_terminal_display* display) {
                     for (rect_col=0; rect_col<rect_width; rect_col++) {
 
                         int joining_color;
-                        if (rect_current->character.attributes.reverse)
+                        if (rect_current->character.attributes.reverse != rect_current->character.attributes.cursor)
                            joining_color = current->character.attributes.foreground;
                         else
                            joining_color = current->character.attributes.background;

protocols/ssh/src/ssh_handlers.c

@@ -90,11 +90,6 @@ int ssh_guac_client_handle_messages(guac_client* client) {
         /* Lock terminal access */
         pthread_mutex_lock(&(client_data->term->lock));
 
-        /* Clear cursor */
-        guac_terminal_toggle_reverse(client_data->term,
-                client_data->term->cursor_row,
-                client_data->term->cursor_col);
-
         /* While data available, write to terminal */
         while (channel_is_open(client_data->term_channel)
                 && !channel_is_eof(client_data->term_channel)
@@ -113,10 +108,8 @@ int ssh_guac_client_handle_messages(guac_client* client) {
             return 1;
         }
 
-        /* Draw cursor */
+        /* Update cursor */
-        guac_terminal_toggle_reverse(client_data->term,
+        guac_terminal_commit_cursor(client_data->term);
-                client_data->term->cursor_row,
-                client_data->term->cursor_col);
 
         /* Flush terminal display */
         guac_terminal_display_flush(client_data->term->display);

protocols/ssh/src/terminal.c

@@ -83,8 +83,8 @@ guac_terminal* guac_terminal_create(guac_client* client,
     term->current_attributes = default_char.attributes;
     term->default_char = default_char;
 
-    term->cursor_row = 0;
+    term->cursor_row = term->visible_cursor_row = 0;
-    term->cursor_col = 0;
+    term->cursor_col = term->visible_cursor_col = 0;
 
     term->term_width   = width  / term->display->char_width;
     term->term_height  = height / term->display->char_height;
@@ -129,21 +129,37 @@ int guac_terminal_set(guac_terminal* term, int row, int col, int codepoint) {
 
 }
 
-int guac_terminal_toggle_reverse(guac_terminal* term, int row, int col) {
+void guac_terminal_commit_cursor(guac_terminal* term) {
 
     guac_terminal_char* guac_char;
 
-    /* Get character from buffer */
+    guac_terminal_buffer_row* old_row;
-    guac_terminal_buffer_row* buffer_row = guac_terminal_buffer_get_row(term->buffer, row, col+1);
+    guac_terminal_buffer_row* new_row;
 
-    /* Toggle reverse */
+    /* If no change, done */
-    guac_char = &(buffer_row->characters[col]);
+    if (term->visible_cursor_row == term->cursor_row && term->visible_cursor_col == term->cursor_col)
-    guac_char->attributes.reverse = !(guac_char->attributes.reverse);
+        return;
 
-    /* Set display */
+    /* Get old and new rows with cursor */
-    guac_terminal_display_set_columns(term->display, row + term->scroll_offset, col, col, guac_char);
+    new_row = guac_terminal_buffer_get_row(term->buffer, term->cursor_row, term->cursor_col+1);
+    old_row = guac_terminal_buffer_get_row(term->buffer, term->visible_cursor_row, term->visible_cursor_col+1);
 
-    return 0;
+    /* Clear cursor */
+    guac_char = &(old_row->characters[term->visible_cursor_col]);
+    guac_char->attributes.cursor = false;
+    guac_terminal_display_set_columns(term->display, term->visible_cursor_row + term->scroll_offset,
+            term->visible_cursor_col, term->visible_cursor_col, guac_char);
+
+    /* Set cursor */
+    guac_char = &(new_row->characters[term->cursor_col]);
+    guac_char->attributes.cursor = true;
+    guac_terminal_display_set_columns(term->display, term->cursor_row + term->scroll_offset,
+            term->cursor_col, term->cursor_col, guac_char);
+
+    term->visible_cursor_row = term->cursor_row;
+    term->visible_cursor_col = term->cursor_col;
+
+    return;
 
 }
 
@@ -506,6 +522,12 @@ void guac_terminal_copy_columns(guac_terminal* terminal, int row,
     guac_terminal_buffer_copy_columns(terminal->buffer, row,
             start_column, end_column, offset);
 
+    /* Update cursor location if within region */
+    if (row == terminal->visible_cursor_row &&
+            terminal->visible_cursor_col >= start_column &&
+            terminal->visible_cursor_col <= end_column)
+        terminal->visible_cursor_col += offset;
+
 }
 
 void guac_terminal_copy_rows(guac_terminal* terminal,
@@ -517,6 +539,11 @@ void guac_terminal_copy_rows(guac_terminal* terminal,
     guac_terminal_buffer_copy_rows(terminal->buffer,
             start_row, end_row, offset);
 
+    /* Update cursor location if within region */
+    if (terminal->visible_cursor_row >= start_row &&
+        terminal->visible_cursor_row <= end_row)
+        terminal->visible_cursor_row += offset;
+
 }
 
 void guac_terminal_set_columns(guac_terminal* terminal, int row,