api/ui: externalize tabline

runtime/doc/msgpack_rpc.txt

@@ -266,7 +266,11 @@ a dictionary with these (optional) keys:
 				most 256 different colors).
 	`popupmenu_external`	Instead of drawing the completion popupmenu on
 				the grid, Nvim will send higher-level events to
-				the ui and let it draw the popupmenu.
+				the UI and let it draw the popupmenu.
+				Defaults to false.
+	`tabline_external`	Instead of drawing the tabline on the grid,
+			        Nvim will send higher-level events to
+				the UI and let it draw the tabline.
 				Defaults to false.
 
 Nvim will then send msgpack-rpc notifications, with the method name "redraw"
@@ -436,5 +440,10 @@ states might be represented as separate modes.
 ["popupmenu_hide"]
 	The popupmenu is hidden.
 
+["tabline_update", curtab, tabs]
+	Nvim will send this event when drawing tabline. curtab is the tab id
+	of the current tab. tabs is an arrays of the form:
+	[tabid, { "name": name }]
+
 ==============================================================================
  vim:tw=78:ts=8:noet:ft=help:norl:

src/nvim/api/ui.c

@@ -69,6 +69,7 @@ void nvim_ui_attach(uint64_t channel_id, Integer width, Integer height,
   ui->height = (int)height;
   ui->rgb = true;
   ui->pum_external = false;
+  ui->tabline_external = false;
   ui->resize = remote_ui_resize;
   ui->clear = remote_ui_clear;
   ui->eol_clear = remote_ui_eol_clear;
@@ -171,19 +172,26 @@ void nvim_ui_set_option(uint64_t channel_id, String name,
 }
 
 static void ui_set_option(UI *ui, String name, Object value, Error *error) {
-  if (strcmp(name.data, "rgb") == 0) {
+  if (strequal(name.data, "rgb")) {
     if (value.type != kObjectTypeBoolean) {
       api_set_error(error, kErrorTypeValidation, "rgb must be a Boolean");
       return;
     }
     ui->rgb = value.data.boolean;
-  } else if (strcmp(name.data, "popupmenu_external") == 0) {
+  } else if (strequal(name.data, "popupmenu_external")) {
     if (value.type != kObjectTypeBoolean) {
       api_set_error(error, kErrorTypeValidation,
                     "popupmenu_external must be a Boolean");
       return;
     }
     ui->pum_external = value.data.boolean;
+  } else if (strequal(name.data, "tabline_external")) {
+    if (value.type != kObjectTypeBoolean) {
+      api_set_error(error, kErrorTypeValidation,
+                    "tabline_external must be a Boolean");
+      return;
+    }
+    ui->tabline_external = value.data.boolean;
   } else {
     api_set_error(error, kErrorTypeValidation, "No such ui option");
   }

src/nvim/screen.c

@@ -132,6 +132,7 @@
 #include "nvim/version.h"
 #include "nvim/window.h"
 #include "nvim/os/time.h"
+#include "nvim/api/private/helpers.h"
 
 #define MB_FILLER_CHAR '<'  /* character used when a double-width character
                              * doesn't fit. */
@@ -6885,8 +6886,13 @@ static void draw_tabline(void)
   if (ScreenLines == NULL) {
     return;
   }
-  redraw_tabline = false;
 
+  if (ui_is_widget_external(kUITabline)) {
+    draw_tabline_ext();
+    return;
+  }
+
+  redraw_tabline = false;
 
   if (tabline_height() < 1)
     return;
@@ -7027,6 +7033,34 @@ static void draw_tabline(void)
   redraw_tabline = FALSE;
 }
 
+// send tabline update to external ui
+void draw_tabline_ext(void)
+{
+  win_T       *cwp;
+
+  Array args = ARRAY_DICT_INIT;
+  ADD(args, INTEGER_OBJ(curtab->handle));
+  Array tabs = ARRAY_DICT_INIT;
+  FOR_ALL_TABS(tp) {
+    if (tp == curtab) {
+      cwp = curwin;
+    } else {
+      cwp = tp->tp_curwin;
+    }
+    get_trans_bufname(cwp->w_buffer);
+    Array tab = ARRAY_DICT_INIT;
+    ADD(tab, INTEGER_OBJ(tp->handle));
+
+    Dictionary tab_info = ARRAY_DICT_INIT;
+    PUT(tab_info, "name", STRING_OBJ(cstr_to_string((char *)NameBuff)));
+    ADD(tab, DICTIONARY_OBJ(tab_info));
+    ADD(tabs, ARRAY_OBJ(tab));
+  }
+  ADD(args, ARRAY_OBJ(tabs));
+
+  ui_event("tabline_update", args);
+}
+
 /*
  * Get buffer name for "buf" into NameBuff[].
  * Takes care of special buffer names and translates special characters.

src/nvim/tui/tui.c

@@ -110,6 +110,7 @@ UI *tui_start(void)
   ui->stop = tui_stop;
   ui->rgb = p_tgc;
   ui->pum_external = false;
+  ui->tabline_external = false;
   ui->resize = tui_resize;
   ui->clear = tui_clear;
   ui->eol_clear = tui_eol_clear;

src/nvim/ui.c

@@ -58,6 +58,10 @@ static int busy = 0;
 static int height, width;
 static int old_mode_idx = -1;
 
+static bool tabline_external = false;
+static bool cmdline_external = false;
+static bool wildmenu_external = false;
+
 // UI_CALL invokes a function on all registered UI instances. The functions can
 // have 0-5 arguments (configurable by SELECT_NTH).
 //
@@ -167,17 +171,20 @@ void ui_refresh(void)
 
   int width = INT_MAX, height = INT_MAX;
   bool pum_external = true;
+  bool tabline_external = true;
 
   for (size_t i = 0; i < ui_count; i++) {
     UI *ui = uis[i];
     width = MIN(ui->width, width);
     height = MIN(ui->height, height);
     pum_external &= ui->pum_external;
+    tabline_external &= ui->tabline_external;
   }
 
   row = col = 0;
   screen_resize(width, height);
   pum_set_external(pum_external);
+  ui_set_widget_external(kUITabline, tabline_external);
   ui_mode_info_set();
   old_mode_idx = -1;
   ui_cursor_shape();
@@ -557,3 +564,30 @@ void ui_cursor_shape(void)
   conceal_check_cursur_line();
 }
 
+bool ui_is_widget_external(UIWidget widget)
+{
+  switch (widget) {
+    case kUITabline:
+      return tabline_external;
+    case kUICmdline:
+      return cmdline_external;
+    case kUIWildmenu:
+      return wildmenu_external;
+  }
+  return false;
+}
+
+void ui_set_widget_external(UIWidget widget, bool external)
+{
+  switch (widget) {
+    case kUITabline:
+      tabline_external = external;
+      break;
+    case kUICmdline:
+      cmdline_external = external;
+      break;
+    case kUIWildmenu:
+      wildmenu_external = external;
+      break;
+  }
+}

src/nvim/ui.h

@@ -8,6 +8,13 @@
 #include "api/private/defs.h"
 #include "nvim/buffer_defs.h"
 
+// values for externalized widgets
+typedef enum {
+  kUITabline,
+  kUICmdline,
+  kUIWildmenu
+} UIWidget;
+
 typedef struct {
   bool bold, underline, undercurl, italic, reverse;
   int foreground, background, special;
@@ -16,7 +23,7 @@ typedef struct {
 typedef struct ui_t UI;
 
 struct ui_t {
-  bool rgb, pum_external;
+  bool rgb, pum_external, tabline_external;
   int width, height;
   void *data;
   void (*resize)(UI *ui, int rows, int columns);

src/nvim/ui_bridge.c

@@ -58,6 +58,7 @@ UI *ui_bridge_attach(UI *ui, ui_main_fn ui_main, event_scheduler scheduler)
   rv->ui = ui;
   rv->bridge.rgb = ui->rgb;
   rv->bridge.pum_external = ui->pum_external;
+  rv->bridge.tabline_external = ui->tabline_external;
   rv->bridge.stop = ui_bridge_stop;
   rv->bridge.resize = ui_bridge_resize;
   rv->bridge.clear = ui_bridge_clear;

src/nvim/window.c

@@ -48,6 +48,7 @@
 #include "nvim/syntax.h"
 #include "nvim/terminal.h"
 #include "nvim/undo.h"
+#include "nvim/ui.h"
 #include "nvim/os/os.h"
 
 
@@ -5223,6 +5224,9 @@ static void last_status_rec(frame_T *fr, int statusline)
  */
 int tabline_height(void)
 {
+  if (ui_is_widget_external(kUITabline)) {
+      return 0;
+  }
   assert(first_tabpage);
   switch (p_stal) {
   case 0: return 0;

test/functional/ui/tabline_spec.lua

@@ -0,0 +1,58 @@
+local helpers = require('test.functional.helpers')(after_each)
+local Screen = require('test.functional.ui.screen')
+local clear, feed, eq = helpers.clear, helpers.feed, helpers.eq
+
+if helpers.pending_win32(pending) then return end
+
+describe('External tab line', function()
+  local screen
+  local tabs, curtab
+
+  before_each(function()
+    clear()
+    screen = Screen.new(25, 5)
+    screen:attach({rgb=true, tabline_external=true})
+    screen:set_on_event_handler(function(name, data)
+      if name == "tabline_update" then
+        curtab, tabs = unpack(data)
+      end
+    end)
+  end)
+
+  after_each(function()
+    screen:detach()
+  end)
+
+  describe("'tabline'", function()
+    it('tabline', function()
+      local expected = {
+        {1, {['name'] = '[No Name]'}},
+        {2, {['name'] = '[No Name]'}},
+      }
+      feed(":tabnew<CR>")
+      screen:expect([[
+        ^                         |
+        ~                        |
+        ~                        |
+        ~                        |
+                                 |
+      ]], nil, nil, function()
+        eq(2, curtab)
+        eq(expected, tabs)
+      end)
+
+      feed(":tabNext<CR>")
+      screen:expect([[
+        ^                         |
+        ~                        |
+        ~                        |
+        ~                        |
+                                 |
+      ]], nil, nil, function()
+        eq(1, curtab)
+        eq(expected, tabs)
+      end)
+
+    end)
+  end)
+end)