Revert "Only compute row lengths for lines with signs or a scrollbar"

This reverts commit 4ea6023.

Author: dstein64

lua/scrollview.lua

@@ -122,7 +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_KEY_PREFIX = 4
+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.
@@ -1403,34 +1403,41 @@ 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 = function(winid, row)
+local get_row_length_lookup = function(winid)
   local memoize_key =
-    table.concat({ROW_LENGTH_KEY_PREFIX, winid, row}, ':')
+    table.concat({ROW_LENGTH_LOOKUP_KEY_PREFIX, winid}, ':')
   if memoize and cache[memoize_key] then return cache[memoize_key] end
-  local result = nil
+  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))
-    local init_topline = fn.line('w0')
-    vim.cmd('keepjumps normal! g0')
-    if row >= 1 and row <= get_window_height(0) then
-      local diff = row - fn.winline()
-      if diff < 0 then
-        vim.cmd('keepjumps normal! ' .. -diff .. 'gk')
-      elseif diff > 0 then
-        vim.cmd('keepjumps normal! ' .. diff .. 'gj')
-      end
+    vim.cmd('keepjumps normal! Hg0')
+    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$')
-      -- It may not be possible to get to the desired row (e.g., virtual lines).
-      local success = fn.winline() == row
-      -- Make sure the view didn't change, as a precaution.
-      success = success and init_topline == fn.line('w0')
-      if success then
-        result = fn.wincol()
-      end
+      result[fn.winline()] = fn.wincol()
+      vim.cmd('keepjumps normal! g0gj')
     end
     set_window_option(0, 'scrolloff', scrolloff)
     set_window_option(0, 'virtualedit', virtualedit)
@@ -1505,9 +1512,10 @@ local show_scrollbar = function(winid, bar_winid)
     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
-      local row_length = get_row_length(winid, row)
-      if row_length ~= nil and row_length >= bar_position.col then
+      if row_length_lookup[row] ~= nil
+          and row_length_lookup[row] >= bar_position.col then
         return -1
       end
     end
@@ -1869,9 +1877,13 @@ local show_signs = function(winid, sign_winids, bar_winid)
         end
       end
       if to_bool(vim.g.scrollview_hide_on_text_intersect) then
-        local row_length = get_row_length(winid, row)
-        if row_length ~= nil and row_length >= col then
-          show = false
+        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