ReaderToc: add option to show chapter lengths (#11546)

frontend/apps/reader/modules/readertoc.lua

@@ -104,6 +104,7 @@ end
 
 function ReaderToc:resetToc()
     self.toc = nil
+    self.toc_menu_items_built = false
     self.toc_depth = nil
     self.ticks = nil
     self.ticks_flattened = nil
@@ -314,6 +315,37 @@ function ReaderToc:validateAndFixToc()
     self.toc_depth = max_depth
 end
 
+function ReaderToc:completeTocWithChapterLengths()
+    local toc = self.toc
+    local first = 1
+    local last = #toc
+    if last == 0 then
+        return
+    end
+    local prev_item_by_level = {}
+    for i = first, last do
+        local item = toc[i]
+        local page = item.page
+        local depth = item.depth
+        for j=#prev_item_by_level, depth, -1 do
+            local prev_item = prev_item_by_level[j]
+            if prev_item then
+                prev_item.chapter_length = page - prev_item.page
+            end
+            prev_item_by_level[j] = nil
+        end
+        prev_item_by_level[depth] = item
+    end
+    -- Set the length of the last ones
+    local page = self.ui.document:getPageCount()
+    for j=#prev_item_by_level, 0, -1 do
+        local prev_item = prev_item_by_level[j]
+        if prev_item then
+            prev_item.chapter_length = page - prev_item.page
+        end
+    end
+end
+
 function ReaderToc:getTocIndexByPage(pn_or_xp, skip_ignored_ticks)
     self:fillToc()
     if #self.toc == 0 then return end
@@ -661,11 +693,16 @@ function ReaderToc:onShowToc()
 
     local items_per_page = G_reader_settings:readSetting("toc_items_per_page") or self.toc_items_per_page_default
     local items_font_size = G_reader_settings:readSetting("toc_items_font_size") or Menu.getItemFontSize(items_per_page)
+    local items_show_chapter_length = G_reader_settings:isTrue("toc_items_show_chapter_length")
     local items_with_dots = G_reader_settings:nilOrTrue("toc_items_with_dots")
 
     self:fillToc()
     -- build menu items
-    if #self.toc > 0 and not self.toc[1].text then
+    if #self.toc > 0 and not self.toc_menu_items_built then
+        self.toc_menu_items_built = true
+        if items_show_chapter_length then
+            self:completeTocWithChapterLengths()
+        end
         -- Have the width of 4 spaces be the unit of indentation
         local tmp = TextWidget:new{
             text = "    ",
@@ -679,6 +716,11 @@ function ReaderToc:onShowToc()
             v.index = k
             v.indent = toc_indent * (v.depth-1)
             v.text = self:cleanUpTocTitle(v.title, true)
+            if items_show_chapter_length then
+                v.post_text = T("(%1)", v.chapter_length)
+            else
+                v.post_text = nil
+            end
             v.bidi_wrap_func = BD.auto
             v.mandatory = v.page
             if has_hidden_flows then
@@ -1147,6 +1189,17 @@ Enabling this option will restrict display to the chapter titles of progress bar
             UIManager:show(items_font)
         end,
     }
+    menu_items.toc_items_show_chapter_length = {
+        text = _("Show chapter length"),
+        keep_menu_open = true,
+        checked_func = function()
+            return not G_reader_settings:nilOrFalse("toc_items_show_chapter_length")
+        end,
+        callback = function()
+            G_reader_settings:flipNilOrFalse("toc_items_show_chapter_length")
+            self.toc_menu_items_built = false
+        end
+    }
     menu_items.toc_items_with_dots = {
         text = _("With dots"),
         keep_menu_open = true,

frontend/ui/elements/reader_menu_order.lua

@@ -35,6 +35,7 @@ local order = {
         "----------------------------",
         "toc_items_per_page",
         "toc_items_font_size",
+        "toc_items_show_chapter_length",
         "toc_items_with_dots",
         "----------------------------",
         "toc_alt_toc",

frontend/ui/widget/menu.lua

@@ -184,6 +184,12 @@ function MenuItem:init()
     self.face = Font:getFace(self.font, self.font_size)
     -- Font for "mandatory" on the right
     self.info_face = Font:getFace(self.infont, self.infont_size)
+    -- Font for post_text if any: for now, this is only used with TOC, showing
+    -- the chapter length: if feels best to use the face of the main text, but
+    -- with the size of the mandatory font (which shows some number too).
+    if self.post_text then
+        self.post_text_face = Font:getFace(self.font, self.infont_size)
+    end
 
     -- "mandatory" is the text on the right: file size, page number...
     -- Padding before mandatory
@@ -219,10 +225,23 @@ function MenuItem:init()
         text = self.bidi_wrap_func(text)
     end
 
+    -- Note: support for post_text is currently implemented only when single_line=true
+    local post_text_widget
+    local post_text_left_padding = Size.padding.large
+    local post_text_right_padding = self.with_dots and 0 or Size.padding.large
     local dots_widget
     local dots_left_padding = Size.padding.small
     local dots_right_padding = Size.padding.small
     if self.single_line then  -- items only in single line
+        if self.post_text then
+            post_text_widget = TextWidget:new{
+                text = self.post_text,
+                face = self.post_text_face,
+                bold = self.bold,
+                fgcolor = self.dim and Blitbuffer.COLOR_DARK_GRAY or nil,
+            }
+            available_width = available_width - post_text_widget:getWidth() - post_text_left_padding - post_text_right_padding
+        end
         -- No font size change: text will be truncated if it overflows
         item_name = TextWidget:new{
             text = text,
@@ -271,6 +290,9 @@ function MenuItem:init()
             if dots_widget then
                 dots_widget.forced_height = self.dimen.h
             end
+            if post_text_widget then
+                post_text_widget.forced_height = self.dimen.h
+            end
             -- And adjust their baselines for proper centering and alignment
             -- (We made sure the font sizes wouldn't exceed self.dimen.h, so we
             -- get only non-negative pad_top here, and we're moving them down.)
@@ -289,6 +311,9 @@ function MenuItem:init()
             if dots_widget then
                 dots_widget.forced_baseline = mdtr_baseline
             end
+            if post_text_widget then
+                post_text_widget.forced_baseline = mdtr_baseline
+            end
         end
 
     elseif self.multilines_show_more_text then
@@ -374,6 +399,8 @@ function MenuItem:init()
                 width = state_width,
             },
             item_name,
+            post_text_widget and HorizontalSpan:new{ width = post_text_left_padding },
+            post_text_widget,
         }
     }
 
@@ -1083,6 +1110,7 @@ function Menu:updateItems(select_number)
                 state_w = self.state_w or 0,
                 text = Menu.getMenuText(self.item_table[i]),
                 bidi_wrap_func = self.item_table[i].bidi_wrap_func,
+                post_text = self.item_table[i].post_text,
                 mandatory = self.item_table[i].mandatory,
                 mandatory_func = self.item_table[i].mandatory_func,
                 mandatory_dim = self.item_table[i].mandatory_dim or self.item_table[i].dim,