perf(menu): make preview smoother; reduce unnecessary cursor jumps

Bekaboo · Dec 14, 2023 · 4f22910 · 4f22910
1 parent 9405df5
commit 4f22910
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Showing 4 changed files with 18 additions and 16 deletions.
diff --git a/README.md b/README.md
@@ -1914,7 +1914,7 @@ basic element of [`dropbar_t`](#dropbar_t) and [`dropbar_menu_entry_t`](#dropbar
 | `dropbar_symbol_t:displaywidth(): integer`                        | returns the display width of the symbol                                                                                                                                                       |
 | `dropbar_symbol_t:bytewidth(): integer`                           | returns the byte width of the symbol                                                                                                                                                          |
 | `dropbar_symbol_t:jump()`                                         | jump to the start of the range of the dropbar symbol                                                                                                                                          |
-| `dropbar_symbol_t:preview()`                                      | preview the symbol in the source window                                                                                                                                                       |
+| `dropbar_symbol_t:preview(orig_view: table?)`                     | preview the symbol in the source window, use `orig_table` as the original view of the source window (to restore win view after preview ends)                                                  |
 | `dropbar_symbol_t:preview_restore_hl()`                           | clear the preview highlights in the source window                                                                                                                                             |
 | `dropbar_symbol_t:preview_restore_view()`                         | restore the view in the source window after previewing the symbol                                                                                                                             |
 | `dropbar_symbol_t:swap_field(field: string, new_val: any)`        | temporarily change the content of a dropbar symbol                                                                                                                                            |

diff --git a/doc/dropbar.txt b/doc/dropbar.txt
@@ -1681,7 +1681,13 @@ dropbar_symbol_t:jump()                              *dropbar_symbol_t:jump()*
 
  	Jump to the start of the symbol associated with the winbar symbol
 
-dropbar_symbol_t:preview()                        *dropbar_symbol_t:preview()*
+dropbar_symbol_t:preview([{orig_view}])           *dropbar_symbol_t:preview()*
+
+	Parameters ~
+	    • {orig_view} (table?): Use this win view as the original view of
+				    the source window, see |winsaveview()| and
+				    |winrestview()|. Default to the current
+				    view of the source window
 
  	Preview the symbol in the source window
 

diff --git a/lua/dropbar/bar.lua b/lua/dropbar/bar.lua
@@ -293,15 +293,13 @@ function dropbar_symbol_t:jump()
 end
 
 ---Preview the symbol in the source window
+---@param orig_view table? use this view as original view
 ---@return nil
-function dropbar_symbol_t:preview()
-  if not self.range then
+function dropbar_symbol_t:preview(orig_view)
+  if not self.range or not self.win or not self.buf then
     return
   end
-  if not self.win or not self.buf then
-    return
-  end
-  self.view = vim.api.nvim_win_call(self.win, vim.fn.winsaveview)
+  self.view = orig_view or vim.api.nvim_win_call(self.win, vim.fn.winsaveview)
   utils.hl.range_single(self.buf, 'DropBarPreview', self.range)
   vim.api.nvim_win_set_cursor(self.win, {
     self.range.start.line + 1,

diff --git a/lua/dropbar/menu.lua b/lua/dropbar/menu.lua
@@ -726,17 +726,15 @@ end
 ---@param look_ahead boolean? whether to look ahead for a component
 ---@return nil
 function dropbar_menu_t:preview_symbol_at(pos, look_ahead)
-  if self.prev_cursor then
-    local prev_component = self:get_component_at(self.prev_cursor, look_ahead)
-    if prev_component then
-      prev_component:preview_restore_view()
-    end
+  if not pos then
+    return
   end
   local component = self:get_component_at(pos, look_ahead)
-  if component then
-    self.symbol_previewed = component
-    component:preview()
+  if not component or component == self.symbol_previewed then
+    return
   end
+  component:preview(self.symbol_previewed and self.symbol_previewed.view)
+  self.symbol_previewed = component
 end
 
 ---Finish the preview in current menu