CoverBrowser: list mode fixes and tweaks (#5525)

- Use a hardcoded default value of 10 files per page.
- Save cover sizetag as "s<nb of items per page>" instead
of "s<item height>" so they are stable (and not re-fetched)
when switching between FileBrowser and History, which have
some small geometry differences.
- When showing History in landscape mode, decrease perpage
from the set value, so items don't look smaller.
- Use a step, larger with big items, when iterating and decreasing
font sizes to make text fit, to speed up the process a bit.

plugins/coverbrowser.koplugin/listmenu.lua

@@ -194,6 +194,9 @@ function ListMenuItem:update()
         local font_size = nominal * dimen.h / 64 / scale_by_size
         return math.floor(font_size)
     end
+    -- Will speed up a bit if we don't do all font sizes when
+    -- looking for one that make text fit
+    local fontsize_dec_step = math.ceil(_fontSize(100) / 100)
 
     -- We'll draw a border around cover images, it may not be
     -- needed with some covers, but it's nicer when cover is
@@ -202,7 +205,7 @@ function ListMenuItem:update()
     local max_img_w = dimen.h - 2*border_size -- width = height, squared
     local max_img_h = dimen.h - 2*border_size
     local cover_specs = {
-        sizetag = "s"..max_img_h,
+        sizetag = self.menu.cover_sizetag,
         max_cover_w = max_img_w,
         max_cover_h = max_img_h,
     }
@@ -559,12 +562,11 @@ function ListMenuItem:update()
                 end
                 if height < dimen.h then -- we fit !
                     break
-                else
-                    logger.dbg(title, "recalculate title/author with", fontsize_title - 1)
                 end
                 -- If we don't fit, decrease both font sizes
-                fontsize_title = fontsize_title - 1
-                fontsize_authors = fontsize_authors - 1
+                fontsize_title = fontsize_title - fontsize_dec_step
+                fontsize_authors = fontsize_authors - fontsize_dec_step
+                logger.dbg(title, "recalculate title/author with", fontsize_title)
                 -- Don't go too low, and get out of this loop
                 if fontsize_title < 3 or fontsize_authors < 3 then
                     break
@@ -651,7 +653,7 @@ function ListMenuItem:update()
                     fgcolor = self.file_deleted and Blitbuffer.COLOR_DARK_GRAY or nil,
                 }
                 -- reduce font size for next loop, in case text widget is too large to fit into ListMenuItem
-                fontsize_no_bookinfo = fontsize_no_bookinfo - 1
+                fontsize_no_bookinfo = fontsize_no_bookinfo - fontsize_dec_step
             until text_widget:getSize().h <= dimen.h
             widget = LeftContainer:new{
                 dimen = dimen,
@@ -786,9 +788,25 @@ function ListMenu:_recalculateDimen()
     end
     local available_height = self.dimen.h - self.others_height - Size.line.thin
 
-    -- default is 64px per ListMenuItem, gives 10 items both in filemanager
-    -- and history on kobo glo hd
-    self.perpage = BookInfoManager:getSetting("files_per_page") or math.floor(available_height / scale_by_size / 64)
+    -- (perpage used to be static and computed from a base of 64px per ListMenuItem,
+    -- which gave 10 items both in filemanager and history on kobo glo hd - now that
+    -- we can change the nb of items, let's start with a default of 10 - as it must
+    -- be known as the initial value by the menu selection widget, but there is not
+    -- enough information there to compute it as we could here).
+    -- local default_per_page = math.floor(available_height / scale_by_size / 64)
+    self.perpage = BookInfoManager:getSetting("files_per_page") or 10
+    self.cover_sizetag = "s" .. self.perpage
+    if Screen:getWidth() > Screen:getHeight() then -- landscape mode
+        -- When in landscape mode (only possible with History), adjust
+        -- perpage so items get a chance to have about the same height
+        -- as when in portrait mode.
+        -- This computation is not strictly correct, as "others_height" would
+        -- have a different value in portrait mode. But let's go with that.
+        local portrait_available_height = Screen:getWidth() - self.others_height - Size.line.thin
+        local portrait_item_height = math.floor(portrait_available_height / self.perpage) - Size.line.thin
+        self.perpage = Math.round(available_height / portrait_item_height)
+    end
+
     self.page_num = math.ceil(#self.item_table / self.perpage)
     -- fix current page if out of range
     if self.page_num > 0 and self.page > self.page_num then self.page = self.page_num end