ReaderView: Recompute page layout when toggling ReaderFooter in

non-reflowable documents.

The code only handled setups with "reclaim bar height" enabled (because
that's my usual workflow, har har), but would have broken in various
more or less obvious ways without it, depending on the exact layout/zoom
settings.
The previous attempts at handling the no-reclaim case were focused
on scroll mode, which is a bit of a nightmare. This approach should
deal as well/badly as the previous one in scroll mode, but actually
handle page mode properly ;).

Re #9979

frontend/apps/reader/modules/readerfooter.lua

@@ -2199,8 +2199,8 @@ function ReaderFooter:_updateFooterText(force_repaint, force_recompute)
     if force_repaint then
         -- If there was a visibility change, notify ReaderView
         if self.visibility_change then
-            self.ui:handleEvent(Event:new("ReaderFooterVisibilityChange"))
             self.visibility_change = nil
+            self.ui:handleEvent(Event:new("ReaderFooterVisibilityChange"))
         end
 
         -- NOTE: Getting the dimensions of the widget is impossible without having drawn it first,

frontend/apps/reader/modules/readerview.lua

@@ -968,19 +968,15 @@ end
 function ReaderView:onReaderFooterVisibilityChange()
     -- Don't bother ReaderRolling with this nonsense, the footer's height is NOT handled via visible_area there ;)
     if self.ui.paging and self.state.page then
-        -- NOTE: Simply relying on recalculate would be a wee bit too much: it'd reset the in-page offsets,
-        --       which would be wrong, and is also not necessary, since the footer is at the bottom of the screen ;).
-        --       So, simply mangle visible_area's height ourselves...
+        -- We don't need to do anything if reclaim is enabled ;).
         if not self.footer.settings.reclaim_height then
-            -- NOTE: Yes, this means that toggling reclaim_height requires a page switch (for a proper recalculate).
-            --       Thankfully, most of the time, the quirks are barely noticeable ;).
-            if self.footer_visible then
-                self.visible_area.h = self.visible_area.h - self.footer:getHeight()
-            else
-                self.visible_area.h = self.visible_area.h + self.footer:getHeight()
-            end
+            -- NOTE: Mimic what onSetFullScreen does, since, without reclaim, toggling the footer affects the available area,
+            --       so we need to recompute the full layout.
+            self.ui:handleEvent(Event:new("SetDimensions", Screen:getSize()))
+            -- NOTE: Scroll mode's behavior after this might be suboptimal (until next page),
+            --       but I'm not familiar enough with it to make it behave...
+            --       (e.g., RedrawCurrentPage & co will snap to the top of the "current" page).
         end
-        self.ui:handleEvent(Event:new("ViewRecalculate", self.visible_area, self.page_area))
     end
 end