refactor(screen): simplify grid_clear() and win_draw_end()

grid_put_linebuf() used grid_clear() internally to handle clearing the
left part of a rightleft line. By reimplementing that internally, we
can instead use grid_put_linebuf() as the implementation of
grid_clear(), which in the end is a net reduction of code as grid_fill()
is used for nothing else.

win_draw_end: Implement "draw_margin" on a per-row basis which closer reflects how
terminals work. Also use the magic mirror for 'rightleft'

1 files changed, 3 insertions, 4 deletions

diff --git a/src/nvim/ui.c b/src/nvim/ui.c
index 9116bb22a2..5303a25acc 100644
--- a/src/nvim/ui.c
+++ b/src/nvim/ui.c
@@ -448,13 +448,12 @@ void ui_set_ext_option(UI *ui, UIExtension ext, bool active)
   }
 }
 
-void ui_line(ScreenGrid *grid, int row, int startcol, int endcol, int clearcol, int clearattr,
-             bool wrap)
+void ui_line(ScreenGrid *grid, int row, bool invalid_row, int startcol, int endcol, int clearcol,
+             int clearattr, bool wrap)
 {
   assert(0 <= row && row < grid->rows);
   LineFlags flags = wrap ? kLineFlagWrap : 0;
-  if (startcol == -1) {
-    startcol = 0;
+  if (startcol == 0 && invalid_row) {
     flags |= kLineFlagInvalid;
   }