Started adding a hide_on_text_intersect option

Author: dstein64

autoload/scrollview.vim

@@ -44,6 +44,8 @@ if has_key(g:, 'scrollview_hide_on_intersect')
 endif
 let g:scrollview_hide_on_float_intersect =
       \ get(g:, 'scrollview_hide_on_float_intersect', v:false)
+let g:scrollview_hide_on_text_intersect =
+      \ get(g:, 'scrollview_hide_on_text_intersect', v:false)
 let g:scrollview_hover = get(g:, 'scrollview_hover', v:true)
 let g:scrollview_include_end_region =
       \ get(g:, 'scrollview_include_end_region', v:false)

lua/scrollview.lua

@@ -122,6 +122,7 @@ local VIRTUAL_LINE_COUNT_KEY_PREFIX = 0
 local PROPER_LINE_COUNT_KEY_PREFIX = 1
 local TOPLINE_LOOKUP_KEY_PREFIX = 2
 local GET_WINDOW_EDGES_KEY_PREFIX = 3
+local ROW_LENGTH_LOOKUP_KEY_PREFIX = 4
 
 -- Maps window ID and highlight group to a temporary highlight group with the
 -- corresponding definition. This is reset on each refresh cycle.
@@ -437,7 +438,7 @@ local with_win_workspace = function(winid, fun)
           -- winbar-omitted height where applicable.
           height = math.max(1, get_window_height(winid)),
           row = 0,
-          col = 0
+          col = 0,
         })
       end)
       win_workspace_lookup[winid] = workspace_winid
@@ -1379,6 +1380,52 @@ local get_scrollbar_character = function()
   return character
 end
 
+-- Returns a table that maps window rows to the length of text on that row.
+-- WARN: When a multi-cell character is the last character on a row, the length
+-- returned by this function represents the first cell of that character.
+local get_row_length_lookup = function(winid)
+  local memoize_key =
+    table.concat({ROW_LENGTH_LOOKUP_KEY_PREFIX, winid}, ':')
+  if memoize and cache[memoize_key] then return cache[memoize_key] end
+  local result = {}
+  with_win_workspace(winid, function()
+    local scrolloff = api.nvim_win_get_option(0, 'scrolloff')
+    local virtualedit = api.nvim_win_get_option(0, 'virtualedit')
+    set_window_option(0, 'scrolloff', 0)
+    set_window_option(0, 'virtualedit', 'none')
+    fn.winrestview(api.nvim_win_call(winid, fn.winsaveview))
+    vim.cmd('keepjumps normal! H')
+    local prior
+    -- Limit the number of steps as a precaution. The doubling of window height
+    -- is to be safe.
+    local max_steps = fn.winheight(0) * 2
+    local steps = 0
+    while fn.winline() > 1
+        and prior ~= fn.winline()
+        and steps < max_steps do
+      steps = steps + 1
+      prior = fn.winline()
+      vim.cmd('keepjumps normal! g0gk')
+    end
+    prior = nil
+    steps = 0
+    local winheight = get_window_height(0)
+    while fn.winline() <= winheight
+        and prior ~= fn.winline()
+        and steps < max_steps do
+      steps = steps + 1
+      prior = fn.winline()
+      vim.cmd('keepjumps normal! g$')
+      result[fn.winline()] = fn.wincol()
+      vim.cmd('keepjumps normal! g0gj')
+    end
+    set_window_option(0, 'scrolloff', scrolloff)
+    set_window_option(0, 'virtualedit', virtualedit)
+  end)
+  if memoize then cache[memoize_key] = result end
+  return result
+end
+
 -- Show a scrollbar for the specified 'winid' window ID, using the specified
 -- 'bar_winid' floating window ID (a new floating window will be created if
 -- this is -1). Returns -1 if the bar is not shown, and the floating window ID
@@ -1444,6 +1491,15 @@ local show_scrollbar = function(winid, bar_winid)
       return -1
     end
   end
+  if to_bool(vim.g.scrollview_hide_on_text_intersect) then
+    local row_length_lookup = get_row_length_lookup(winid)
+    for row = bar_position.row, bar_position.row + bar_position.height - 1 do
+      if row_length_lookup[row] ~= nil
+          and row_length_lookup[row] >= bar_position.col then
+        return -1
+      end
+    end
+  end
   if bar_bufnr == -1 or not to_bool(fn.bufloaded(bar_bufnr)) then
     if bar_bufnr == -1 then
       bar_bufnr = api.nvim_create_buf(false, true)
@@ -1800,6 +1856,16 @@ local show_signs = function(winid, sign_winids, bar_winid)
           show = false
         end
       end
+      if to_bool(vim.g.scrollview_hide_on_text_intersect) then
+        local row_length_lookup = get_row_length_lookup(winid)
+        for c = col, col + sign_width - 1 do
+          if row_length_lookup[row] ~= nil
+              and row_length_lookup[row] >= c then
+            show = false
+            break
+          end
+        end
+      end
       if show then
         if sign_bufnr == -1 or not to_bool(fn.bufloaded(sign_bufnr)) then
           if sign_bufnr == -1 then
@@ -2584,6 +2650,13 @@ local enable = function()
             \ |   execute "lua require('scrollview').refresh_bars_async()"
             \ | endif
 
+      " Refresh scrollview when text is changed in insert mode. This way,
+      " scrollbars and signs will appear/hide accordingly when modifying text.
+      autocmd TextChangedI *
+            \   if g:scrollview_hide_on_text_intersect
+            \ |   execute "lua require('scrollview').refresh_bars_async()"
+            \ | endif
+
       " The following handles when :e is used to load a file. The asynchronous
       " version handles a case where :e is used to reload an existing file, that
       " is already scrolled. This avoids a scenario where the scrollbar is