Kobo: Boost saturation for CFA refreshes (and add a dev setting to disable it) (#11883)

Being able to disable it can be interesting, because it *is* a somewhat destructive process.

* Requires a base bump:
https://github.com/koreader/koreader-base/pull/1793
https://github.com/koreader/koreader-base/pull/1794

frontend/apps/filemanager/filemanagermenu.lua

@@ -629,6 +629,21 @@ To:
             end,
         })
     end
+    if Device:isKobo() and Device:hasColorScreen() then
+        table.insert(self.menu_items.developer_options.sub_item_table, {
+            -- We default to a flag (G2) that slightly boosts saturation,
+            -- but it *is* a destructive process, so we want to allow disabling it.
+            -- @translators CFA is a technical term for the technology behind eInk's color panels. It stands for Color Film/Filter Array, leave the abbreviation alone ;).
+            text = _("Disable CFA post-processing"),
+            checked_func = function()
+                return G_reader_settings:isTrue("no_cfa_post_processing")
+            end,
+            callback = function()
+                G_reader_settings:flipNilOrFalse("no_cfa_post_processing")
+                UIManager:askForRestart()
+            end,
+        })
+    end
     table.insert(self.menu_items.developer_options.sub_item_table, {
         text = _("Anti-alias rounded corners"),
         checked_func = function()

frontend/device/kobo/device.lua

@@ -699,6 +699,7 @@ function Kobo:init()
             debug = logger.dbg,
             is_always_portrait = self.isAlwaysPortrait(),
             mxcfb_bypass_wait_for = mxcfb_bypass_wait_for,
+            no_cfa_post_processing = G_reader_settings:isTrue("no_cfa_post_processing"),
         }
         if self.screen.fb_bpp == 32 and not self:hasColorScreen() then
             -- Ensure we decode images properly, as our framebuffer is BGRA...