Status bar: dynamic filler (#13702)

frontend/apps/reader/modules/readerfooter.lua

@@ -49,6 +49,7 @@ local MODE = {
     custom_text = 17,
     book_author = 18,
     page_turning_inverted = 19, -- includes both page-turn-button and swipe-and-tap inversion
+    dynamic_filler = 20,
 }
 
 local symbol_prefix = {
@@ -133,7 +134,8 @@ if BD.mirroredUILayout() then
 end
 
 -- functions that generates footer text for each mode
-local footerTextGeneratorMap = {
+local footerTextGeneratorMap
+footerTextGeneratorMap = {
     empty = function() return "" end,
     frontlight = function(footer)
         local symbol_type = footer.settings.item_prefix
@@ -412,6 +414,42 @@ local footerTextGeneratorMap = {
         local merge = footer.custom_text:gsub(" ", ""):len() == 0
         return footer.custom_text:rep(footer.custom_text_repetitions), merge
     end,
+    dynamic_filler = function(footer)
+        local max_width = footer[1]:getSize().w - 2 * footer.horizontal_margin
+        -- when the filler is between other items, it replaces the separator
+        local text, is_filler_inside = footer:genAllFooterText(footerTextGeneratorMap.dynamic_filler)
+        local tmp = TextWidget:new{
+            text = text,
+            face = footer.footer_text_face,
+            bold = footer.settings.text_font_bold,
+        }
+        local text_width = tmp:getSize().w
+        tmp:free()
+        if footer.separator_width == nil then
+            tmp = TextWidget:new{
+                text = footer:genSeparator(),
+                face = footer.footer_text_face,
+                bold = footer.settings.text_font_bold,
+            }
+            footer.separator_width = tmp:getSize().w
+            tmp:free()
+        end
+        local separator_width = is_filler_inside and footer.separator_width or 0
+        local filler_space = "\u{200A}" -- HAIR SPACE
+        if footer.filler_space_width == nil then
+            tmp = TextWidget:new{
+                text = filler_space,
+                face = footer.footer_text_face,
+                bold = footer.settings.text_font_bold,
+            }
+            footer.filler_space_width = tmp:getSize().w
+            tmp:free()
+        end
+        local filler_nb = math.floor((max_width - text_width + separator_width) / footer.filler_space_width)
+        if filler_nb > 0 then
+            return filler_space:rep(filler_nb), true
+        end
+    end,
 }
 
 local ReaderFooter = WidgetContainer:extend{
@@ -980,6 +1018,7 @@ function ReaderFooter:textOptionTitles(option)
         custom_text = T(_("Custom text (long-press to edit): \'%1\'%2"), self.custom_text,
             self.custom_text_repetitions > 1 and
             string.format(" × %d", self.custom_text_repetitions) or ""),
+        dynamic_filler = _("Dynamic filler"),
     }
     return option_titles[option]
 end
@@ -1372,6 +1411,7 @@ function ReaderFooter:addToMainMenu(menu_items)
     table.insert(footer_items, getMinibarOption("book_title"))
     table.insert(footer_items, getMinibarOption("book_chapter"))
     table.insert(footer_items, getMinibarOption("custom_text"))
+    table.insert(footer_items, getMinibarOption("dynamic_filler"))
 
     -- configure footer_items
     table.insert(sub_items, {
@@ -1500,6 +1540,8 @@ With this feature enabled, the current page is factored in, resulting in the cou
                                         bold = self.settings.text_font_bold,
                                     }
                                     self.text_container[1] = self.footer_text
+                                    self.separator_width = nil
+                                    self.filler_space_width = nil
                                     self:refreshFooter(true, true)
                                     if touchmenu_instance then touchmenu_instance:updateItems() end
                                 end,
@@ -1522,6 +1564,8 @@ With this feature enabled, the current page is factored in, resulting in the cou
                                 bold = self.settings.text_font_bold,
                             }
                             self.text_container[1] = self.footer_text
+                            self.separator_width = nil
+                            self.filler_space_width = nil
                             self:refreshFooter(true, true)
                         end,
                     },
@@ -1823,6 +1867,7 @@ function ReaderFooter:genItemSeparatorMenuItems(value)
         end,
         callback = function()
             self.settings.items_separator = value
+            self.separator_width = nil
             self:refreshFooter(true)
         end,
     }
@@ -1922,16 +1967,23 @@ function ReaderFooter:genSeparator()
         or (self.settings.item_prefix == "compact_items" and " " or "  ")
 end
 
-function ReaderFooter:genAllFooterText()
+function ReaderFooter:genAllFooterText(gen_to_skip)
     local info = {}
     -- We need to BD.wrap() all items and separators, so we're
     -- sure they are laid out in our order (reversed in RTL),
     -- without ordering by the RTL Bidi algorithm.
-    local prev_had_merge
+    local count = 0 -- total number of visible items
+    local skipped_idx, prev_had_merge
     for _, gen in ipairs(self.footerTextGenerators) do
+        if gen == gen_to_skip then
+            count = count + 1
+            skipped_idx = count
+            goto continue
+        end
         -- Skip empty generators, so they don't generate bogus separators
         local text, merge = gen(self)
         if text and text ~= "" then
+            count = count + 1
             if self.settings.item_prefix == "compact_items" then
                 -- remove whitespace from footer items if symbol_type is compact_items
                 -- use a hair-space to avoid issues with RTL display
@@ -1950,8 +2002,9 @@ function ReaderFooter:genAllFooterText()
                 table.insert(info, BD.wrap(text))
             end
         end
+        ::continue::
     end
-    return table.concat(info, BD.wrap(self:genSeparator()))
+    return table.concat(info, BD.wrap(self:genSeparator())), skipped_idx ~= 1 and skipped_idx ~= count
 end
 
 function ReaderFooter:setTocMarkers(reset)