key-binding: add bind to clear scrollback but keep current line

commands.c

@@ -113,3 +113,17 @@ cmd_scrollback_down(struct terminal *term, int rows)
     render_refresh_urls(term);
     render_refresh(term);
 }
+
+void
+cmd_scrollback_clear_keepcur(struct terminal *term) {
+    const struct coord cursor = term->grid->cursor.point;
+    int real_row = grid_row_absolute(term->grid, cursor.row - 1);
+    struct row *row;
+    while (row = term->grid->rows[real_row], row && !row->linebreak)
+        real_row = (real_row - 1) & (term->grid->num_rows - 1);
+    int screen_row = (real_row + 1 - term->grid->offset) & (term->grid->num_rows - 1);
+    term_scroll_partial(term, (struct scroll_region){0, term->rows}, screen_row);
+    term_cursor_to(term, cursor.row - screen_row, cursor.col);
+    term_erase_scrollback(term);
+    render_refresh(term);
+}

commands.h

@@ -4,3 +4,4 @@
 
 void cmd_scrollback_up(struct terminal *term, int rows);
 void cmd_scrollback_down(struct terminal *term, int rows);
+void cmd_scrollback_clear_keepcur(struct terminal *term);

config.c

@@ -117,6 +117,7 @@ static const char *const binding_action_map[] = {
     [BIND_ACTION_SCROLLBACK_DOWN_LINE] = "scrollback-down-line",
     [BIND_ACTION_SCROLLBACK_HOME] = "scrollback-home",
     [BIND_ACTION_SCROLLBACK_END] = "scrollback-end",
+    [BIND_ACTION_SCROLLBACK_CLEAR_KEEPCUR] = "scrollback-clear-keepcur",
     [BIND_ACTION_CLIPBOARD_COPY] = "clipboard-copy",
     [BIND_ACTION_CLIPBOARD_PASTE] = "clipboard-paste",
     [BIND_ACTION_PRIMARY_PASTE] = "primary-paste",

doc/foot.ini.5.scd

@@ -1193,6 +1193,10 @@ e.g. *search-start=none*.
 *scrollback-end*
 	Scroll to the end (bottom) of the scrollback. Default: _none_.
 
+*scrollback-clear-keepcur*
+	Clear scrollback, keeping only the line currently being edited. Might break
+	applications that do not expect it. Default: _not bound_.
+
 *clipboard-copy*
 	Copies the current selection into the _clipboard_. Default: _Control+Shift+c_
 	_XF86Copy_.

foot.ini

@@ -186,6 +186,7 @@
 # scrollback-down-line=none
 # scrollback-home=none
 # scrollback-end=none
+# scrollback-clear-keepcur=none
 # clipboard-copy=Control+Shift+c XF86Copy
 # clipboard-paste=Control+Shift+v XF86Paste
 # primary-paste=Shift+Insert

input.c

@@ -168,6 +168,13 @@ execute_binding(struct seat *seat, struct terminal *term,
         }
         break;
 
+    case BIND_ACTION_SCROLLBACK_CLEAR_KEEPCUR:
+        if (term->grid == &term->normal) {
+            cmd_scrollback_clear_keepcur(term);
+            return true;
+        }
+        break;
+
     case BIND_ACTION_CLIPBOARD_COPY:
         selection_to_clipboard(seat, term, serial);
         return true;

key-binding.h

@@ -18,6 +18,7 @@ enum bind_action_normal {
     BIND_ACTION_SCROLLBACK_DOWN_LINE,
     BIND_ACTION_SCROLLBACK_HOME,
     BIND_ACTION_SCROLLBACK_END,
+    BIND_ACTION_SCROLLBACK_CLEAR_KEEPCUR,
     BIND_ACTION_CLIPBOARD_COPY,
     BIND_ACTION_CLIPBOARD_PASTE,
     BIND_ACTION_PRIMARY_PASTE,