readersearch: do not show regexp checkbutton in pdf (#8450)

Minor optimization.

frontend/apps/reader/modules/readersearch.lua

@@ -79,11 +79,12 @@ end
 
 -- if reverse ~= 0 search backwards
 function ReaderSearch:searchCallback(reverse)
-    if self.input_dialog:getInputText() == "" then return end
-    self.last_search_text = self.input_dialog:getInputText()
+    local search_text = self.input_dialog:getInputText()
+    if search_text == "" then return end
+    self.last_search_text = search_text
     self.use_regex = self.check_button_regex.checked
     self.case_insensitive = not self.check_button_case.checked
-    local regex_error = self.use_regex and self.ui.document:checkRegex(self.input_dialog:getInputText())
+    local regex_error = self.use_regex and self.ui.document:checkRegex(search_text)
     if self.use_regex and regex_error ~= 0 then
         logger.dbg("ReaderSearch: regex error", regex_error, SRELL_ERROR_CODES[regex_error])
         local error_message
@@ -95,7 +96,7 @@ function ReaderSearch:searchCallback(reverse)
         UIManager:show(InfoMessage:new{ text = error_message })
     else
         UIManager:close(self.input_dialog)
-        self:onShowSearchDialog(self.input_dialog:getInputText(), reverse, self.use_regex, self.case_insensitive)
+        self:onShowSearchDialog(search_text, reverse, self.use_regex, self.case_insensitive)
     end
 end
 
@@ -159,7 +160,9 @@ function ReaderSearch:onShowFulltextSearchInput()
             })
         end,
     }
-    self.input_dialog:addWidget(self.check_button_regex)
+    if self.ui.rolling then
+        self.input_dialog:addWidget(self.check_button_regex)
+    end
 
     UIManager:show(self.input_dialog)
     self.input_dialog:onShowKeyboard()