feat: Save and restore winopts of diff buffers.

(closes #97)

lua/diffview/ui/panel.lua

@@ -3,6 +3,7 @@ local utils = require("diffview.utils")
 local renderer = require("diffview.renderer")
 local logger = require("diffview.logger")
 local PerfTimer = require("diffview.perf").PerfTimer
+local FileEntry = require("diffview.views.file_entry").FileEntry
 local api = vim.api
 local M = {}
 local uid_counter = 0
@@ -166,6 +167,12 @@ end
 
 function Panel:close()
   if self:is_open() then
+    local num_wins = api.nvim_tabpage_list_wins(api.nvim_win_get_tabpage(self.winid))
+    if #num_wins == 1 then
+      -- Ensure that the tabpage doesn't close if the panel is the last window.
+      vim.cmd("sp")
+      FileEntry.load_null_buffer(0)
+    end
     api.nvim_win_hide(self.winid)
   end
 end

lua/diffview/views/diff/listeners.lua

@@ -3,6 +3,7 @@ local git = require("diffview.git.utils")
 local lib = require("diffview.lib")
 local RevType = require("diffview.git.rev").RevType
 local Event = require("diffview.events").Event
+local FileEntry = require("diffview.views.file_entry").FileEntry
 local api = vim.api
 
 local function prepare_goto_file(view)
@@ -42,6 +43,15 @@ return function(view)
       if file then
         file:detach_buffers()
       end
+      local cur_winid = api.nvim_get_current_win()
+      if cur_winid == view.left_winid or cur_winid == view.right_winid then
+        -- Change the current buffer such that 'restore_winopts()' will work
+        -- correctly.
+        FileEntry.load_null_buffer(cur_winid)
+      end
+      for _, f in view.panel.files:ipairs() do
+        f:restore_winopts()
+      end
     end,
     buf_write_post = function()
       if git.has_local(view.left, view.right) then

lua/diffview/views/file_entry.lua

@@ -40,11 +40,16 @@ local FileEntry = oop.create_class("FileEntry")
 ---@type integer|nil
 FileEntry._null_buffer = nil
 
+---@static
+---@type table<integer, table>
+FileEntry.winopt_store = {}
+
 ---@static
 FileEntry.winopts = {
   diff = true,
   scrollbind = true,
   cursorbind = true,
+  scrollopt = { "ver", "hor", "jump" },
   foldmethod = "diff",
   foldcolumn = "1",
   foldlevel = 0,
@@ -82,6 +87,7 @@ end
 function FileEntry:destroy()
   self.active = false
   self:detach_buffers()
+  self:restore_winopts()
   for _, bn in ipairs(self.created_bufs) do
     FileEntry.safe_delete_buf(bn)
   end
@@ -136,6 +142,9 @@ function FileEntry:load_buffers(git_root, left_winid, right_winid, callback)
           else
             api.nvim_win_set_buf(sp.winid, sp.bufid)
           end
+          if sp.rev.type == RevType.LOCAL and not FileEntry.winopt_store[sp.bufid] then
+            FileEntry._save_winopts(sp.bufid, sp.winid)
+          end
         end
         FileEntry._update_windows(left_winid, right_winid)
         perf:lap("view updated")
@@ -295,6 +304,14 @@ function FileEntry:compare(other)
   return (self.path == other.path and self.status == other.status)
 end
 
+function FileEntry:restore_winopts()
+  for _, bufid in ipairs({ self.left_bufid, self.right_bufid }) do
+    if bufid then
+      FileEntry._restore_winopts(bufid)
+    end
+  end
+end
+
 ---@static Get the bufid of the null buffer. Create it if it's not loaded.
 ---@return integer
 function FileEntry._get_null_buffer()
@@ -412,6 +429,28 @@ function FileEntry.safe_delete_buf(bufid)
   pcall(api.nvim_buf_delete, bufid, { force = true })
 end
 
+---@static
+function FileEntry._save_winopts(bufid, winid)
+  FileEntry.winopt_store[bufid] = {}
+  api.nvim_win_call(winid, function()
+    for option, _ in pairs(FileEntry.winopts) do
+      FileEntry.winopt_store[bufid][option] = vim.o[option]
+    end
+  end)
+end
+
+---@static
+function FileEntry._restore_winopts(bufid)
+  if FileEntry.winopt_store[bufid] then
+    utils.no_win_event_call(function()
+      vim.cmd("sp")
+      api.nvim_win_set_buf(0, bufid)
+      utils.set_local(0, FileEntry.winopt_store[bufid])
+      api.nvim_win_close(0, true)
+    end)
+  end
+end
+
 ---@static
 function FileEntry._update_windows(left_winid, right_winid)
   utils.set_local({ left_winid, right_winid }, FileEntry.winopts)

lua/diffview/views/file_history/listeners.lua

@@ -3,6 +3,7 @@ local git = require("diffview.git.utils")
 local lib = require("diffview.lib")
 local RevType = require("diffview.git.rev").RevType
 local DiffView = require("diffview.views.diff.diff_view").DiffView
+local FileEntry = require("diffview.views.file_entry").FileEntry
 local api = vim.api
 
 local function prepare_goto_file(view)
@@ -38,6 +39,17 @@ return function(view)
       if file then
         file:detach_buffers()
       end
+      local cur_winid = api.nvim_get_current_win()
+      if cur_winid == view.left_winid or cur_winid == view.right_winid then
+        -- Change the current buffer such that 'restore_winopts()' will work
+        -- correctly.
+        FileEntry.load_null_buffer(cur_winid)
+      end
+      for _, entry in ipairs(view.panel.entries) do
+        for _, f in ipairs(entry.files) do
+          f:restore_winopts()
+        end
+      end
     end,
     win_closed = function(winid)
       if winid and winid == view.panel.option_panel.winid then