BookMap: add option Alternative theme

When enabled in BookMap, both BookMap and PageBrowser get:
- alternating gray background on chapter spans
- hatched background instead of uni-gray on hidden flows.
Also, with both normal look and this alternative theme,
show some hatched overlay on thumbnails part of hidden flows.

ReaderToc: for each TOC item, have it carry its sequence/number
in that level (we do this in validateAndFixToc() where we are
already iterating all the items).

frontend/apps/reader/modules/readertoc.lua

@@ -180,8 +180,10 @@ function ReaderToc:validateAndFixToc()
     local has_bogus
     local cur_page = 0
     local max_depth = 0
+    local cur_seq_by_level = {}
     for i = first, last do
-        local page = toc[i].page
+        local item = toc[i]
+        local page = item.page
         if page < cur_page then
             has_bogus = true
             break
@@ -189,9 +191,15 @@ function ReaderToc:validateAndFixToc()
         cur_page = page
         -- Use this loop to compute max_depth here (if has_bogus,
         -- we will recompute it in the loop below)
-        if toc[i].depth > max_depth then
-            max_depth = toc[i].depth
+        local depth = item.depth
+        if depth > max_depth then
+            max_depth = depth
         end
+        -- Also use this loop to compute seq_in_level for each
+        -- item, needed by BookMap with alternative theme
+        local seq = (cur_seq_by_level[depth] or 0) + 1
+        item.seq_in_level = seq
+        cur_seq_by_level[depth] = seq
     end
     if not has_bogus then -- no TOC items, or all are valid
         logger.dbg("validateAndFixToc(): TOC is fine")
@@ -203,6 +211,7 @@ function ReaderToc:validateAndFixToc()
     -- Bad ordering previously noticed: try to fix the wrong items' page
     -- by setting it to the previous or next good item page.
     max_depth = 0 -- recompute this
+    cur_seq_by_level = {}
     local nb_bogus = 0
     local nb_fixed_pages = 0
     -- We fix only one bogus item per loop, taking the option that
@@ -215,10 +224,17 @@ function ReaderToc:validateAndFixToc()
     -- (These cases are met in the following code with cur_page=57 and page=6)
     cur_page = 0
     for i = first, last do
-        if toc[i].depth > max_depth then
-            max_depth = toc[i].depth
+        local item = toc[i]
+        -- Recompute max_depth and item's seq_in_level
+        local depth = item.depth
+        if depth > max_depth then
+            max_depth = depth
         end
-        local page = toc[i].fixed_page or toc[i].page
+        local seq = (cur_seq_by_level[depth] or 0) + 1
+        item.seq_in_level = seq
+        cur_seq_by_level[depth] = seq
+        -- Look for bogus page
+        local page = item.fixed_page or item.page
         if page >= cur_page then
             cur_page = page
         else
@@ -272,7 +288,7 @@ function ReaderToc:validateAndFixToc()
                     logger.dbg("  fix next", j, toc[j].page, "=>", fixed_page)
                 end
             end
-            cur_page = toc[i].fixed_page or toc[i].page
+            cur_page = item.fixed_page or item.page
         end
     end
     if nb_bogus > 0 then

frontend/ui/widget/bookmapwidget.lua

@@ -232,12 +232,21 @@ function BookMapRow:init()
                         text_widget = nil
                     end
                 end
+                -- Different style depending on alt_theme
+                local bgcolor = Blitbuffer.COLOR_WHITE
+                if self.alt_theme then
+                    if item.seq_in_level % 2 == 0 then -- alternate background color
+                        bgcolor = Blitbuffer.COLOR_GRAY_E
+                    else
+                        bgcolor = Blitbuffer.COLOR_GRAY_B
+                    end
+                end
                 local span_w = FrameContainer:new{
                     overlap_offset = {offset_x, offset_y},
                     margin = 0,
                     padding = 0,
                     bordersize = self.toc_span_border,
-                    background = Blitbuffer.COLOR_WHITE,
+                    background = bgcolor,
                     CenterContainer:new{
                         dimen = Geom:new{
                             w = width - 2 * self.toc_span_border,
@@ -312,7 +321,9 @@ function BookMapRow:init()
                 table.insert(self.background_fillers, {
                     x = x, y = 0,
                     w = w, h = self.pages_frame_height,
-                    color = Blitbuffer.COLOR_LIGHT_GRAY,
+                    -- Different style depending on alt_theme
+                    color = self.alt_theme and Blitbuffer.COLOR_GRAY or Blitbuffer.COLOR_LIGHT_GRAY,
+                    stripe_width = self.alt_theme and math.ceil(self.span_height / 10) or nil,
                 })
             end
         end
@@ -526,7 +537,11 @@ end
 function BookMapRow:paintTo(bb, x, y)
     -- Paint background fillers (which are not subwidgets) first
     for _, filler in ipairs(self.background_fillers) do
-        bb:paintRect(x + self.pages_frame_offset_x + filler.x, y + filler.y, filler.w, filler.h, filler.color)
+        if filler.stripe_width then
+            bb:hatchRect(x + self.pages_frame_offset_x + filler.x, y + filler.y, filler.w, filler.h, filler.stripe_width, filler.color)
+        else
+            bb:paintRect(x + self.pages_frame_offset_x + filler.x, y + filler.y, filler.w, filler.h, filler.color)
+        end
     end
     -- Paint regular sub widgets the classic way
     InputContainer.paintTo(self, bb, x, y)
@@ -828,6 +843,8 @@ function BookMapWidget:update()
     self.vgroup:clear()
     self.cropping_widget:reset()
 
+    self.alt_theme = G_reader_settings:isTrue("book_map_alt_theme")
+
     -- Flat book map has each TOC item on a new line, and pages graph underneath.
     -- Non-flat book map shows a grid with TOC items following each others.
     self.flat_map = self.ui.doc_settings:readSetting("book_map_flat", false)
@@ -987,6 +1004,7 @@ function BookMapWidget:update()
                         title = item.title,
                         p_start = item.page,
                         p_end = nil,
+                        seq_in_level = item.seq_in_level,
                     }
                 end
             end
@@ -1090,6 +1108,7 @@ function BookMapWidget:update()
             nb_toc_spans = self.nb_toc_spans,
             span_height = self.span_height,
             font_face = self.toc_span_face,
+            alt_theme = self.alt_theme,
             start_page_text = start_page_text,
             start_page = p_start,
             end_page = p_end,
@@ -1197,6 +1216,31 @@ function BookMapWidget:showMenu()
                 b:refresh()
             end,
         }},
+        {{
+            text_func = function(no_size_trick)
+                local text = _("Alternative theme")
+                if G_reader_settings:isTrue("book_map_alt_theme") then
+                    text = text .. "  \u{2713}" -- checkmark
+                else
+                    if not no_size_trick then
+                        -- Initial call, make it wide enough so the checkmark text will fit
+                        text = text .. "  \u{2003}" -- wide em space
+                    end
+                    -- Otherwise, keep it small without the checkmark, which will fit
+                end
+                return text
+            end,
+            id = "alt_theme",
+            align = "left",
+            callback = function()
+                G_reader_settings:flipTrue("book_map_alt_theme")
+                local b = button_dialog:getButtonById("alt_theme")
+                b:setText(b.text_func(true), b.width)
+                b:refresh()
+                self.editable_stuff_edited = true -- have this change reflected on any lower bookmap & pagebrowser
+                self:update()
+            end,
+        }},
         not self.overview_mode and {{
             text = _("Switch current/initial views"),
             align = "left",

frontend/ui/widget/pagebrowserwidget.lua

@@ -497,7 +497,6 @@ function PageBrowserWidget:update()
 
     -- We need to rebuilt the full set of toc spans that will be shown
     -- Similar (but simplified) to what is done in BookMapWidget.
-    self.toc_depth = self.nb_toc_spans
     local toc = self.ui.toc.toc
     local cur_toc_items = {}
     local row_toc_items = {}
@@ -508,9 +507,9 @@ function PageBrowserWidget:update()
         if item.page > p_end then
             break
         end
-        if item.depth <= self.toc_depth then -- ignore lower levels we won't show
+        if item.depth <= self.nb_toc_spans then -- ignore lower levels we won't show
             -- An item at level N closes all previous items at level >= N
-            for lvl = item.depth, self.toc_depth do
+            for lvl = item.depth, self.nb_toc_spans do
                 local done_toc_item = cur_toc_items[lvl]
                 cur_toc_items[lvl] = nil
                 if done_toc_item then
@@ -533,6 +532,7 @@ function PageBrowserWidget:update()
                 title = item.title,
                 p_start = item.page,
                 p_end = nil,
+                seq_in_level = item.seq_in_level,
             }
         end
         toc_idx = toc_idx + 1
@@ -572,6 +572,7 @@ function PageBrowserWidget:update()
         nb_toc_spans = self.nb_toc_spans,
         span_height = self.span_height,
         font_face = self.toc_span_face,
+        alt_theme = G_reader_settings:isTrue("book_map_alt_theme"),
         start_page_text = "",
         start_page = p_start,
         end_page = p_end,
@@ -748,6 +749,19 @@ function PageBrowserWidget:showTile(grid_idx, page, tile, do_refresh)
         -- thumb_frame will overflow its CenterContainer because of the added borders,
         -- but CenterContainer handles that well. We will refresh the outer dimensions.
 
+    if self.has_hidden_flows and self.ui.document:getPageFlow(page) ~= 0 then
+        -- We want to distinguish pages part of hidden flow.
+        -- Using a uniform gray background may not be enough on scanned PDF
+        -- gray pages non-dewatermarked, so we use diagonal gray stripes.
+        -- We use a gray background similar to how it appears on hidden flows
+        -- in the BookMapRow, where they are COLOR_LIGHT_GRAY (0xCC).
+        -- To achieve the same color, we can use COLOR_BLACK with alpha = 0.2.
+        thumb_frame.stripe_width = math.ceil(math.min(self.grid_item_width, self.grid_item_height) / 2)
+        thumb_frame.stripe_color = Blitbuffer.COLOR_BLACK
+        thumb_frame.stripe_over = true
+        thumb_frame.stripe_over_alpha = 0.2
+    end
+
     local page_num_widget
     if item_frame.show_pagenum and self.pagenum_page_texts[page] then
         local page_text = table.concat(util.splitToChars(self.pagenum_page_texts[page]), "\n")