tui: Eliminate more extraneous control sequences.

When higher layers flush the TUI layer output buffer, but there is
nothing in the buffer to flush, no longer does the TUI layer write out
unnecessary cnorm/civis sequences surrounding that nothing.

1 files changed, 41 insertions, 19 deletions

diff --git a/src/nvim/tui/tui.c b/src/nvim/tui/tui.c
index d017db3651..931f2738ab 100644
--- a/src/nvim/tui/tui.c
+++ b/src/nvim/tui/tui.c
@@ -39,8 +39,8 @@
 #include "nvim/syntax.h"
 #include "nvim/macros.h"
 
-// Space reserved in the output buffer to restore the cursor to normal when
-// flushing. No existing terminal will require 32 bytes to do that.
+// Space reserved in two output buffers to make the cursor normal or invisible
+// when flushing. No existing terminal will require 32 bytes to do that.
 #define CNORM_COMMAND_MAX_SIZE 32
 #define OUTBUF_SIZE 0xffff
 
@@ -73,7 +73,10 @@ typedef struct {
   bool stop;
   unibi_var_t params[9];
   char buf[OUTBUF_SIZE];
-  size_t bufpos, bufsize;
+  size_t bufpos;
+  char norm[CNORM_COMMAND_MAX_SIZE];
+  char invis[CNORM_COMMAND_MAX_SIZE];
+  size_t normlen, invislen;
   TermInput input;
   uv_loop_t write_loop;
   unibi_term *ut;
@@ -155,12 +158,20 @@ UI *tui_start(void)
   return ui_bridge_attach(ui, tui_main, tui_scheduler);
 }
 
+static size_t unibi_pre_fmt_str(TUIData *data, unsigned int unibi_index, char * buf, size_t len)
+{
+  const char *str = unibi_get_str(data->ut, unibi_index);
+  if (!str) {
+    return 0U;
+  }
+  return unibi_run(str, data->params, buf, len);
+}
+
 static void terminfo_start(UI *ui)
 {
   TUIData *data = ui->data;
   data->scroll_region_is_full_screen = true;
   data->bufpos = 0;
-  data->bufsize = sizeof(data->buf) - CNORM_COMMAND_MAX_SIZE;
   data->default_attr = false;
   data->showing_mode = SHAPE_IDX_N;
   data->unibi_ext.enable_mouse = -1;
@@ -205,6 +216,8 @@ static void terminfo_start(UI *ui)
   data->immediate_wrap_after_last_column =
     terminfo_is_term_family(term, "cygwin")
     || terminfo_is_term_family(term, "interix");
+  data->normlen = unibi_pre_fmt_str(data, unibi_cursor_normal, data->norm, sizeof data->norm);
+  data->invislen = unibi_pre_fmt_str(data, unibi_cursor_invisible, data->invis, sizeof data->invis);
   // Set 't_Co' from the result of unibilium & fix_terminfo.
   t_colors = unibi_get_num(data->ut, unibi_max_colors);
   // Enter alternate screen and clear
@@ -1183,7 +1196,7 @@ static void out(void *ctx, const char *str, size_t len)
 {
   UI *ui = ctx;
   TUIData *data = ui->data;
-  size_t available = data->bufsize - data->bufpos;
+  size_t available = sizeof(data->buf) - data->bufpos;
 
   if (len > available) {
     flush_buf(ui, false);
@@ -1613,28 +1626,37 @@ static void augment_terminfo(TUIData *data, const char *term,
 static void flush_buf(UI *ui, bool toggle_cursor)
 {
   uv_write_t req;
-  uv_buf_t buf;
+  uv_buf_t bufs[3];
+  uv_buf_t *bufp = bufs;
   TUIData *data = ui->data;
 
+  if (data->bufpos <= 0) {
+    return;
+  }
+
   if (toggle_cursor && !data->busy) {
-    // not busy and the cursor is invisible(see below). Append a "cursor
-    // normal" command to the end of the buffer.
-    data->bufsize += CNORM_COMMAND_MAX_SIZE;
-    unibi_out(ui, unibi_cursor_normal);
-    data->bufsize -= CNORM_COMMAND_MAX_SIZE;
+    // not busy and cursor is visible, write a "cursor invisible" command
+    // before writing the buffer.
+    bufp->base = data->invis;
+    bufp->len = data->invislen;
+    bufp++;
   }
 
-  buf.base = data->buf;
-  buf.len = data->bufpos;
-  uv_write(&req, STRUCT_CAST(uv_stream_t, &data->output_handle), &buf, 1, NULL);
-  uv_run(&data->write_loop, UV_RUN_DEFAULT);
-  data->bufpos = 0;
+  bufp->base = data->buf;
+  bufp->len = data->bufpos;
+  bufp++;
 
   if (toggle_cursor && !data->busy) {
-    // not busy and cursor is visible(see above), append a "cursor invisible"
-    // command to the beginning of the buffer for the next flush
-    unibi_out(ui, unibi_cursor_invisible);
+    // not busy and the cursor is invisible. Write a "cursor normal" command
+    // after writing the buffer.
+    bufp->base = data->norm;
+    bufp->len = data->normlen;
+    bufp++;
   }
+
+  uv_write(&req, STRUCT_CAST(uv_stream_t, &data->output_handle), bufs, (unsigned)(bufp - bufs), NULL);
+  uv_run(&data->write_loop, UV_RUN_DEFAULT);
+  data->bufpos = 0;
 }
 
 #if TERMKEY_VERSION_MAJOR > 0 || TERMKEY_VERSION_MINOR > 18