Make Inverted Portrait a first-class citizen (#5783)

* Don't store stale screen/rotation modes in book's settings!

Gyro events *may* entirely bypass the local copy...
In any case, using a local copy was essentially asking for trouble...

Actually fix #5772

(because the issue was indeed that a Gyro swap from Portrait to Inverted
Portrait wasn't stored properly).

* Allow showing ScreenSavers in Inverted Portrait.

That works just fine, and won't lead to the confusing situation where a
lefty might pick up the device as a righty because the ScreenSaver
happens to be shown that way, only to have it rotate back to its lefty
orientation on wakeup...

frontend/apps/filemanager/filemanager.lua

@@ -47,9 +47,16 @@ local Screen = Device.screen
 local T = require("ffi/util").template
 
 local function restoreScreenMode()
-    local screen_mode = G_reader_settings:readSetting("fm_screen_mode")
+    --- @todo: Not Yet Implemented. Layout is currently broken in Landscape.
+    local screen_mode = G_reader_settings:readSetting("fm_screen_mode") or "portrait"
+    --- @note: Basically, if we were already in Portrait/Inverted Portrait, don't mess with it,
+    --         as the FM supports it.
+    --         See setScreenMode in base's ffi/framebuffer.lua for the gory details.
+    --         See also ReaderView:onSetScreenMode in apps/reader/modules/readerview.lua for a similar logic,
+    --         if we ever need to add Landscape to the mix.
+    --         c.f., https://github.com/koreader/koreader/issues/5772#issuecomment-577242365
     if Screen:getScreenMode() ~= screen_mode then
-        Screen:setScreenMode(screen_mode or "portrait")
+        Screen:setScreenMode(screen_mode)
     end
 end
 

frontend/apps/reader/modules/readerview.lua

@@ -693,7 +693,6 @@ function ReaderView:onSetScreenMode(new_mode, rotation, noskip)
         return true
     end
     if new_mode == "landscape" or new_mode == "portrait" then
-        self.screen_mode = new_mode
         -- NOTE: Hacky hack! If rotation is "true", that's actually an "interactive" flag for setScreenMode
         --- @fixme That's because we can't store nils in a table, which is what Event:new attempts to do ;).
         --        c.f., <https://stackoverflow.com/q/7183998/> & <http://lua-users.org/wiki/VarargTheSecondClassCitizen>
@@ -710,7 +709,6 @@ function ReaderView:onSetScreenMode(new_mode, rotation, noskip)
         self.ui:onScreenResize(new_screen_size)
         self.ui:handleEvent(Event:new("InitScrollPageStates"))
     end
-    self.cur_rotation_mode = Screen:getRotationMode()
     return true
 end
 
@@ -758,7 +756,6 @@ function ReaderView:onReadSettings(config)
         screen_mode = config:readSetting("screen_mode") or G_reader_settings:readSetting("copt_screen_mode") or "portrait"
     end
     if screen_mode then
-        Screen:setScreenMode(screen_mode)
         self:onSetScreenMode(screen_mode, config:readSetting("rotation_mode"), true)
     end
     self.state.gamma = config:readSetting("gamma") or 1.0
@@ -846,8 +843,8 @@ end
 
 function ReaderView:onSaveSettings()
     self.ui.doc_settings:saveSetting("render_mode", self.render_mode)
-    self.ui.doc_settings:saveSetting("screen_mode", self.screen_mode)
-    self.ui.doc_settings:saveSetting("rotation_mode", self.cur_rotation_mode)
+    self.ui.doc_settings:saveSetting("screen_mode", Screen:getScreenMode())
+    self.ui.doc_settings:saveSetting("rotation_mode", Screen:getRotationMode())
     self.ui.doc_settings:saveSetting("gamma", self.state.gamma)
     self.ui.doc_settings:saveSetting("highlight", self.highlight.saved)
     self.ui.doc_settings:saveSetting("page_overlap_style", self.page_overlap_style)

frontend/device/generic/device.lua

@@ -205,7 +205,7 @@ function Device:onPowerEvent(ev)
                     network_manager:scheduleConnectivityCheck()
                 end
                 self:resume()
-                -- restore to previous rotation mode, if need be.
+                -- Restore to previous rotation mode, if need be.
                 if self.orig_rotation_mode then
                     self.screen:setRotationMode(self.orig_rotation_mode)
                 end
@@ -228,11 +228,17 @@ function Device:onPowerEvent(ev)
         self.powerd:beforeSuspend()
         local UIManager = require("ui/uimanager")
         logger.dbg("Suspending...")
-        -- Mostly always suspend in portrait mode...
-        -- ... except when we just show an InfoMessage, it plays badly with landscape mode (c.f., #4098)
+        -- Mostly always suspend in Portrait/Inverted Portrait mode...
+        -- ... except when we just show an InfoMessage, it plays badly with Landscape mode (c.f., #4098)
         if G_reader_settings:readSetting("screensaver_type") ~= "message" then
             self.orig_rotation_mode = self.screen:getRotationMode()
-            self.screen:setRotationMode(0)
+            -- Leave Portrait & Inverted Portrait alone, that works just fine.
+            if bit.band(self.orig_rotation_mode, 1) == 1 then
+                -- i.e., only switch to Portrait if we're currently in *any* Landscape orientation (odd number)
+                self.screen:setRotationMode(0)
+            else
+                self.orig_rotation_mode = nil
+            end
 
             -- On eInk, if we're using a screensaver mode that shows an image,
             -- flash the screen to white first, to eliminate ghosting.