api/ui: win_viewport event for visible range and cursor position in window

11 files changed, 305 insertions, 21 deletions

diff --git a/runtime/doc/ui.txt b/runtime/doc/ui.txt
index de54ce59b6..b243d9ba50 100644
--- a/runtime/doc/ui.txt
+++ b/runtime/doc/ui.txt
@@ -592,6 +592,12 @@ tabs.
 	When |ext_messages| is active, no message grid is used, and this event
 	will not be sent.
 
+["win_viewport", grid, win, topline, botline, curline, curcol]
+	Indicates the range of buffer text displayed in the window, as well
+	as the cursor position in the buffer. All positions are zero-based.
+	`botline` is set to one more than the line count of the buffer, if
+	there are filler lines past the end.
+
 ==============================================================================
 Popupmenu Events						 *ui-popupmenu*
 
diff --git a/src/nvim/api/ui_events.in.h b/src/nvim/api/ui_events.in.h
index 6677e248cf..ab31db39e9 100644
--- a/src/nvim/api/ui_events.in.h
+++ b/src/nvim/api/ui_events.in.h
@@ -115,6 +115,10 @@ void win_close(Integer grid)
 void msg_set_pos(Integer grid, Integer row, Boolean scrolled, String sep_char)
   FUNC_API_SINCE(6) FUNC_API_BRIDGE_IMPL FUNC_API_COMPOSITOR_IMPL;
 
+void win_viewport(Integer grid, Window win, Integer topline,
+                  Integer botline, Integer curline, Integer curcol)
+  FUNC_API_SINCE(7) FUNC_API_REMOTE_ONLY;
+
 void popupmenu_show(Array items, Integer selected,
                     Integer row, Integer col, Integer grid)
   FUNC_API_SINCE(3) FUNC_API_REMOTE_ONLY;
diff --git a/src/nvim/buffer_defs.h b/src/nvim/buffer_defs.h
index 3993f61a3d..366766c292 100644
--- a/src/nvim/buffer_defs.h
+++ b/src/nvim/buffer_defs.h
@@ -1190,6 +1190,8 @@ struct window_S {
                                        to adjust w_valid */
   colnr_T w_valid_leftcol;          /* last known w_leftcol */
 
+  bool w_viewport_invalid;
+
   /*
    * w_cline_height is the number of physical lines taken by the buffer line
    * that the cursor is on.  We use this to avoid extra calls to plines().
diff --git a/src/nvim/move.c b/src/nvim/move.c
index e7ed98d4f0..d4f82bc601 100644
--- a/src/nvim/move.c
+++ b/src/nvim/move.c
@@ -86,6 +86,7 @@ static void comp_botline(win_T *wp)
   /* wp->w_botline is the line that is just below the window */
   wp->w_botline = lnum;
   wp->w_valid |= VALID_BOTLINE|VALID_BOTLINE_AP;
+  wp->w_viewport_invalid = true;
 
   set_empty_rows(wp, done);
 
@@ -151,6 +152,7 @@ void update_topline(void)
     curwin->w_topline = curwin->w_cursor.lnum;
     curwin->w_botline = curwin->w_topline;
     curwin->w_valid |= VALID_BOTLINE|VALID_BOTLINE_AP;
+    curwin->w_viewport_invalid = true;
     curwin->w_scbind_pos = 1;
     return;
   }
@@ -175,6 +177,7 @@ void update_topline(void)
     curwin->w_topline = 1;
     curwin->w_botline = 2;
     curwin->w_valid |= VALID_BOTLINE|VALID_BOTLINE_AP;
+    curwin->w_viewport_invalid = true;
     curwin->w_scbind_pos = 1;
   }
   /*
@@ -311,6 +314,7 @@ void update_topline(void)
     }
   }
   curwin->w_valid |= VALID_TOPLINE;
+  curwin->w_viewport_invalid = true;
   win_check_anchored_floats(curwin);
 
   /*
@@ -407,6 +411,7 @@ void check_cursor_moved(win_T *wp)
                      |VALID_CHEIGHT|VALID_CROW|VALID_TOPLINE);
     wp->w_valid_cursor = wp->w_cursor;
     wp->w_valid_leftcol = wp->w_leftcol;
+    wp->w_viewport_invalid = true;
   } else if (wp->w_cursor.col != wp->w_valid_cursor.col
              || wp->w_leftcol != wp->w_valid_leftcol
              || wp->w_cursor.coladd != wp->w_valid_cursor.coladd
@@ -415,6 +420,7 @@ void check_cursor_moved(win_T *wp)
     wp->w_valid_cursor.col = wp->w_cursor.col;
     wp->w_valid_leftcol = wp->w_leftcol;
     wp->w_valid_cursor.coladd = wp->w_cursor.coladd;
+    wp->w_viewport_invalid = true;
   }
 }
 
@@ -1458,6 +1464,7 @@ void scroll_cursor_top(int min_scroll, int always)
       curwin->w_valid &=
         ~(VALID_WROW|VALID_CROW|VALID_BOTLINE|VALID_BOTLINE_AP);
     curwin->w_valid |= VALID_TOPLINE;
+    curwin->w_viewport_invalid = true;
   }
 }
 
@@ -1662,6 +1669,7 @@ void scroll_cursor_bot(int min_scroll, int set_topbot)
     curwin->w_valid = old_valid;
   }
   curwin->w_valid |= VALID_TOPLINE;
+  curwin->w_viewport_invalid = true;
 }
 
 /// Recompute topline to put the cursor halfway across the window
@@ -1818,6 +1826,7 @@ void cursor_correct(void)
     }
   }
   curwin->w_valid |= VALID_TOPLINE;
+  curwin->w_viewport_invalid = true;
 }
 
 
diff --git a/src/nvim/normal.c b/src/nvim/normal.c
index 6c92b136da..be131f7e00 100644
--- a/src/nvim/normal.c
+++ b/src/nvim/normal.c
@@ -4121,6 +4121,7 @@ void scroll_redraw(int up, long count)
   }
   if (curwin->w_cursor.lnum != prev_lnum)
     coladvance(curwin->w_curswant);
+  curwin->w_viewport_invalid = true;
   redraw_later(VALID);
 }
 
diff --git a/src/nvim/screen.c b/src/nvim/screen.c
index 2e2c6ca737..6e1273ed0c 100644
--- a/src/nvim/screen.c
+++ b/src/nvim/screen.c
@@ -417,7 +417,7 @@ int update_screen(int type)
     need_wait_return = false;
   }
 
-  win_ui_flush_positions();
+  win_ui_flush();
   msg_ext_check_clear();
 
   /* reset cmdline_row now (may have been changed temporarily) */
@@ -1629,6 +1629,7 @@ static void win_update(win_T *wp)
      * changes are relevant).
      */
     wp->w_valid |= VALID_BOTLINE;
+    wp->w_viewport_invalid = true;
     if (wp == curwin && wp->w_botline != old_botline && !recursive) {
       recursive = TRUE;
       curwin->w_valid &= ~VALID_TOPLINE;
@@ -1648,7 +1649,7 @@ static void win_update(win_T *wp)
   /* restore got_int, unless CTRL-C was hit while redrawing */
   if (!got_int)
     got_int = save_got_int;
-}
+}  // NOLINT(readability/fn_size)
 
 /// Returns width of the signcolumn that should be used for the whole window
 ///
diff --git a/src/nvim/ui.c b/src/nvim/ui.c
index 0f841760d6..3a5aa95ad3 100644
--- a/src/nvim/ui.c
+++ b/src/nvim/ui.c
@@ -424,7 +424,7 @@ int ui_current_col(void)
 void ui_flush(void)
 {
   cmdline_ui_flush();
-  win_ui_flush_positions();
+  win_ui_flush();
   msg_ext_ui_flush();
   msg_scroll_flush();
 
diff --git a/src/nvim/window.c b/src/nvim/window.c
index fb3f1e0c9f..9ec47f8e89 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -773,6 +773,21 @@ static void ui_ext_win_position(win_T *wp)
 
 }
 
+void ui_ext_win_viewport(win_T *wp)
+{
+  if ((wp == curwin || ui_has(kUIMultigrid)) && wp->w_viewport_invalid) {
+    int botline = wp->w_botline;
+    if (botline == wp->w_buffer->b_ml.ml_line_count+1
+        && wp->w_empty_rows == 0) {
+      // TODO(bfredl): The might be more cases to consider, like how does this
+      // interact with incomplete final line? Diff filler lines?
+      botline = wp->w_buffer->b_ml.ml_line_count;
+    }
+    ui_call_win_viewport(wp->w_grid.handle, wp->handle, wp->w_topline-1,
+                         botline, wp->w_cursor.lnum-1, wp->w_cursor.col);
+    wp->w_viewport_invalid = false;
+  }
+}
 
 static bool parse_float_anchor(String anchor, FloatAnchor *out)
 {
@@ -4688,6 +4703,7 @@ static win_T *win_alloc(win_T *after, int hidden)
   new_wp->w_scbind_pos = 1;
   new_wp->w_floating = 0;
   new_wp->w_float_config = FLOAT_CONFIG_INIT;
+  new_wp->w_viewport_invalid = true;
 
   // use global option for global-local options
   new_wp->w_p_so = -1;
@@ -6992,7 +7008,7 @@ void get_framelayout(const frame_T *fr, list_T *l, bool outer)
   }
 }
 
-void win_ui_flush_positions(void)
+void win_ui_flush(void)
 {
   FOR_ALL_TAB_WINDOWS(tp, wp) {
     if (wp->w_pos_changed && wp->w_grid.chars != NULL) {
@@ -7003,6 +7019,9 @@ void win_ui_flush_positions(void)
       }
       wp->w_pos_changed = false;
     }
+    if (tp == curtab) {
+      ui_ext_win_viewport(wp);
+    }
   }
 }
 
diff --git a/test/functional/ui/float_spec.lua b/test/functional/ui/float_spec.lua
index 7a5569c14b..639e311ae6 100644
--- a/test/functional/ui/float_spec.lua
+++ b/test/functional/ui/float_spec.lua
@@ -976,6 +976,28 @@ describe('floatwin', function()
           {2:~                   }|
         ]], float_pos={
           [5] = {{id = 1002}, "NE", 4, 0, 50, true}
+        }, win_viewport = {
+          [2] = {
+              topline = 0,
+              botline = 3,
+              curline = 0,
+              curcol = 3,
+              win = { id = 1000 }
+          },
+          [4] = {
+              topline = 0,
+              botline = 3,
+              curline = 0,
+              curcol = 3,
+              win = { id = 1001 }
+          },
+          [5] = {
+            topline = 0,
+            botline = 2,
+            curline = 0,
+            curcol = 0,
+            win = { id = 1002 }
+          }
         }}
       else
         screen:expect([[
diff --git a/test/functional/ui/multigrid_spec.lua b/test/functional/ui/multigrid_spec.lua
index 01ffe80be3..e4d1187dea 100644
--- a/test/functional/ui/multigrid_spec.lua
+++ b/test/functional/ui/multigrid_spec.lua
@@ -1962,4 +1962,191 @@ describe('ext_multigrid', function()
       {1:~                             }|
     ]]}
   end)
+
+  it('has viewport information', function()
+    screen:try_resize(48, 8)
+    screen:expect{grid=[[
+    ## grid 1
+      [2:------------------------------------------------]|
+      [2:------------------------------------------------]|
+      [2:------------------------------------------------]|
+      [2:------------------------------------------------]|
+      [2:------------------------------------------------]|
+      [2:------------------------------------------------]|
+      {11:[No Name]                                       }|
+      [3:------------------------------------------------]|
+    ## grid 2
+      ^                                                |
+      {1:~                                               }|
+      {1:~                                               }|
+      {1:~                                               }|
+      {1:~                                               }|
+      {1:~                                               }|
+    ## grid 3
+                                                      |
+    ]], win_viewport={
+      [2] = {win = { id = 1000 }, topline = 0, botline = 2, curline = 0, curcol = 0}
+    }}
+    insert([[
+      Lorem ipsum dolor sit amet, consectetur
+      adipisicing elit, sed do eiusmod tempor
+      incididunt ut labore et dolore magna aliqua.
+      Ut enim ad minim veniam, quis nostrud
+      exercitation ullamco laboris nisi ut aliquip ex
+      ea commodo consequat. Duis aute irure dolor in
+      reprehenderit in voluptate velit esse cillum
+      dolore eu fugiat nulla pariatur. Excepteur sint
+      occaecat cupidatat non proident, sunt in culpa
+      qui officia deserunt mollit anim id est
+      laborum.]])
+
+    screen:expect{grid=[[
+    ## grid 1
+      [2:------------------------------------------------]|
+      [2:------------------------------------------------]|
+      [2:------------------------------------------------]|
+      [2:------------------------------------------------]|
+      [2:------------------------------------------------]|
+      [2:------------------------------------------------]|
+      {11:[No Name] [+]                                   }|
+      [3:------------------------------------------------]|
+    ## grid 2
+      ea commodo consequat. Duis aute irure dolor in  |
+      reprehenderit in voluptate velit esse cillum    |
+      dolore eu fugiat nulla pariatur. Excepteur sint |
+      occaecat cupidatat non proident, sunt in culpa  |
+      qui officia deserunt mollit anim id est         |
+      laborum^.                                        |
+    ## grid 3
+                                                      |
+    ]], win_viewport={
+      [2] = {win = {id = 1000}, topline = 5, botline = 11, curline = 10, curcol = 7},
+    }}
+
+
+    feed('<c-u>')
+    screen:expect{grid=[[
+    ## grid 1
+      [2:------------------------------------------------]|
+      [2:------------------------------------------------]|
+      [2:------------------------------------------------]|
+      [2:------------------------------------------------]|
+      [2:------------------------------------------------]|
+      [2:------------------------------------------------]|
+      {11:[No Name] [+]                                   }|
+      [3:------------------------------------------------]|
+    ## grid 2
+      incididunt ut labore et dolore magna aliqua.    |
+      Ut enim ad minim veniam, quis nostrud           |
+      exercitation ullamco laboris nisi ut aliquip ex |
+      ea commodo consequat. Duis aute irure dolor in  |
+      reprehenderit in voluptate velit esse cillum    |
+      ^dolore eu fugiat nulla pariatur. Excepteur sint |
+    ## grid 3
+                                                      |
+    ]], win_viewport={
+      [2] = {win = {id = 1000}, topline = 2, botline = 9, curline = 7, curcol = 0},
+    }}
+
+    command("split")
+    screen:expect{grid=[[
+    ## grid 1
+      [4:------------------------------------------------]|
+      [4:------------------------------------------------]|
+      [4:------------------------------------------------]|
+      {11:[No Name] [+]                                   }|
+      [2:------------------------------------------------]|
+      [2:------------------------------------------------]|
+      {12:[No Name] [+]                                   }|
+      [3:------------------------------------------------]|
+    ## grid 2
+      reprehenderit in voluptate velit esse cillum    |
+      dolore eu fugiat nulla pariatur. Excepteur sint |
+    ## grid 3
+                                                      |
+    ## grid 4
+      ea commodo consequat. Duis aute irure dolor in  |
+      reprehenderit in voluptate velit esse cillum    |
+      ^dolore eu fugiat nulla pariatur. Excepteur sint |
+    ]], win_viewport={
+      [2] = {win = {id = 1000}, topline = 6, botline = 9, curline = 7, curcol = 0},
+      [4] = {win = {id = 1001}, topline = 5, botline = 9, curline = 7, curcol = 0},
+    }}
+
+    feed("b")
+    screen:expect{grid=[[
+    ## grid 1
+      [4:------------------------------------------------]|
+      [4:------------------------------------------------]|
+      [4:------------------------------------------------]|
+      {11:[No Name] [+]                                   }|
+      [2:------------------------------------------------]|
+      [2:------------------------------------------------]|
+      {12:[No Name] [+]                                   }|
+      [3:------------------------------------------------]|
+    ## grid 2
+      reprehenderit in voluptate velit esse cillum    |
+      dolore eu fugiat nulla pariatur. Excepteur sint |
+    ## grid 3
+                                                      |
+    ## grid 4
+      ea commodo consequat. Duis aute irure dolor in  |
+      reprehenderit in voluptate velit esse ^cillum    |
+      dolore eu fugiat nulla pariatur. Excepteur sint |
+    ]], win_viewport={
+      [2] = {win = {id = 1000}, topline = 6, botline = 9, curline = 7, curcol = 0},
+      [4] = {win = {id = 1001}, topline = 5, botline = 9, curline = 6, curcol = 38},
+    }}
+
+    feed("2k")
+    screen:expect{grid=[[
+    ## grid 1
+      [4:------------------------------------------------]|
+      [4:------------------------------------------------]|
+      [4:------------------------------------------------]|
+      {11:[No Name] [+]                                   }|
+      [2:------------------------------------------------]|
+      [2:------------------------------------------------]|
+      {12:[No Name] [+]                                   }|
+      [3:------------------------------------------------]|
+    ## grid 2
+      reprehenderit in voluptate velit esse cillum    |
+      dolore eu fugiat nulla pariatur. Excepteur sint |
+    ## grid 3
+                                                      |
+    ## grid 4
+      exercitation ullamco laboris nisi ut a^liquip ex |
+      ea commodo consequat. Duis aute irure dolor in  |
+      reprehenderit in voluptate velit esse cillum    |
+    ]], win_viewport={
+      [2] = {win = {id = 1000}, topline = 6, botline = 9, curline = 7, curcol = 0},
+      [4] = {win = {id = 1001}, topline = 4, botline = 8, curline = 4, curcol = 38},
+    }}
+
+    -- handles non-current window
+    meths.win_set_cursor(1000, {1, 10})
+    screen:expect{grid=[[
+    ## grid 1
+      [4:------------------------------------------------]|
+      [4:------------------------------------------------]|
+      [4:------------------------------------------------]|
+      {11:[No Name] [+]                                   }|
+      [2:------------------------------------------------]|
+      [2:------------------------------------------------]|
+      {12:[No Name] [+]                                   }|
+      [3:------------------------------------------------]|
+    ## grid 2
+      Lorem ipsum dolor sit amet, consectetur         |
+      adipisicing elit, sed do eiusmod tempor         |
+    ## grid 3
+                                                      |
+    ## grid 4
+      exercitation ullamco laboris nisi ut a^liquip ex |
+      ea commodo consequat. Duis aute irure dolor in  |
+      reprehenderit in voluptate velit esse cillum    |
+    ]], win_viewport={
+      [2] = {win = {id = 1000}, topline = 0, botline = 3, curline = 0, curcol = 10},
+      [4] = {win = {id = 1001}, topline = 4, botline = 8, curline = 4, curcol = 38},
+    }}
+  end)
 end)
diff --git a/test/functional/ui/screen.lua b/test/functional/ui/screen.lua
index 64f784afe3..bf979e89f4 100644
--- a/test/functional/ui/screen.lua
+++ b/test/functional/ui/screen.lua
@@ -158,6 +158,7 @@ function Screen.new(width, height)
     wildmenu_items = nil,
     wildmenu_selected = nil,
     win_position = {},
+    win_viewport = {},
     float_pos = {},
     msg_grid = nil,
     msg_grid_pos = nil,
@@ -254,7 +255,7 @@ end
 -- canonical order of ext keys, used  to generate asserts
 local ext_keys = {
   'popupmenu', 'cmdline', 'cmdline_block', 'wildmenu_items', 'wildmenu_pos',
-  'messages', 'showmode', 'showcmd', 'ruler', 'float_pos',
+  'messages', 'showmode', 'showcmd', 'ruler', 'float_pos', 'win_viewport'
 }
 
 -- Asserts that the screen state eventually matches an expected state.
@@ -421,6 +422,9 @@ screen:redraw_debug() to show all intermediate screen states.  ]])
     if expected.mode ~= nil then
       extstate.mode = self.mode
     end
+    if expected.win_viewport == nil then
+      extstate.win_viewport = nil
+    end
 
     -- Convert assertion errors into invalid screen state descriptions.
     for _, k in ipairs(concat_tables(ext_keys, {'mode'})) do
@@ -726,6 +730,7 @@ function Screen:_handle_grid_destroy(grid)
   self._grids[grid] = nil
   if self._options.ext_multigrid then
     self.win_position[grid] = nil
+    self.win_viewport[grid] = nil
   end
 end
 
@@ -746,14 +751,24 @@ function Screen:_handle_grid_cursor_goto(grid, row, col)
 end
 
 function Screen:_handle_win_pos(grid, win, startrow, startcol, width, height)
-    self.win_position[grid] = {
-        win = win,
-        startrow = startrow,
-        startcol = startcol,
-        width = width,
-        height = height
-    }
-    self.float_pos[grid] = nil
+  self.win_position[grid] = {
+    win = win,
+    startrow = startrow,
+    startcol = startcol,
+    width = width,
+    height = height
+  }
+  self.float_pos[grid] = nil
+end
+
+function Screen:_handle_win_viewport(grid, win, topline, botline, curline, curcol)
+  self.win_viewport[grid] = {
+    win = win,
+    topline = topline,
+    botline = botline,
+    curline = curline,
+    curcol = curcol
+  }
 end
 
 function Screen:_handle_win_float_pos(grid, ...)
@@ -1130,6 +1145,8 @@ function Screen:_extstate_repr(attr_state)
     messages[i] = {kind=entry[1], content=self:_chunks_repr(entry[2], attr_state)}
   end
 
+  local win_viewport = (next(self.win_viewport) and self.win_viewport) or nil
+
   return {
     popupmenu=self.popupmenu,
     cmdline=cmdline,
@@ -1141,7 +1158,8 @@ function Screen:_extstate_repr(attr_state)
     showcmd=self:_chunks_repr(self.showcmd, attr_state),
     ruler=self:_chunks_repr(self.ruler, attr_state),
     msg_history=msg_history,
-    float_pos=self.float_pos
+    float_pos=self.float_pos,
+    win_viewport=win_viewport,
   }
 end
 
@@ -1216,10 +1234,6 @@ function Screen:render(headers, attr_state, preview)
   return rv
 end
 
-local remove_all_metatables = function(item, path)
-  if path[#path] ~= inspect.METATABLE then return item end
-end
-
 -- Returns the current screen state in the form of a screen:expect()
 -- keyword-args map.
 function Screen:get_snapshot(attrs, ignore)
@@ -1269,6 +1283,26 @@ function Screen:get_snapshot(attrs, ignore)
   return kwargs, ext_state, attr_state
 end
 
+local function fmt_ext_state(name, state)
+  if name == "win_viewport" then
+    local str = "{\n"
+    for k,v in pairs(state) do
+      str = (str.."  ["..k.."] = {win = {id = "..v.win.id.."}, topline = "
+             ..v.topline..", botline = "..v.botline..", curline = "..v.curline
+             ..", curcol = "..v.curcol.."},\n")
+    end
+    return str .. "}"
+  else
+    -- TODO(bfredl): improve formatting of more states
+    local function remove_all_metatables(item, path)
+      if path[#path] ~= inspect.METATABLE then
+        return item
+      end
+    end
+    return inspect(state,{process=remove_all_metatables})
+  end
+end
+
 function Screen:print_snapshot(attrs, ignore)
   local kwargs, ext_state, attr_state = self:get_snapshot(attrs, ignore)
   local attrstr = ""
@@ -1291,9 +1325,8 @@ function Screen:print_snapshot(attrs, ignore)
   print(kwargs.grid)
   io.stdout:write( "]]"..attrstr)
   for _, k in ipairs(ext_keys) do
-    if ext_state[k] ~= nil then
-      -- TODO(bfredl): improve formatting
-      io.stdout:write(", "..k.."="..inspect(ext_state[k],{process=remove_all_metatables}))
+    if ext_state[k] ~= nil and not (k == "win_viewport" and not self.options.ext_multigrid) then
+      io.stdout:write(", "..k.."="..fmt_ext_state(k, ext_state[k]))
     end
   end
   print("}\n")