fix: auto dpi menu checkbox display (#4771)

frontend/device/generic/device.lua

@@ -13,6 +13,7 @@ local Device = {
     model = nil,
     powerd = nil,
     screen = nil,
+    screen_dpi_override = nil,
     input = nil,
     -- For Kobo, wait at least 15 seconds before calling suspend script. Otherwise, suspend might
     -- fail and the battery will be drained while we are in screensaver mode
@@ -146,6 +147,7 @@ end
 function Device:setScreenDPI(dpi_override)
     self.screen:setDPI(dpi_override)
     self.input.gesture_detector:init()
+    self.screen_dpi_override = dpi_override
 end
 
 function Device:getPowerDevice()

frontend/ui/elements/screen_dpi_menu_table.lua

@@ -1,7 +1,10 @@
 local _ = require("gettext")
-local Screen = require("device").screen
+local Device = require("device")
+local Screen = Device.screen
 local T = require("ffi/util").template
 
+local function isAutoDPI() return Device.screen_dpi_override == nil end
+
 local function dpi() return Screen:getDPI() end
 
 local function custom() return G_reader_settings:readSetting("custom_screen_dpi") end
@@ -14,7 +17,7 @@ local function setDPI(_dpi)
                or _("DPI set to auto. This will take effect after restarting."),
     })
     G_reader_settings:saveSetting("screen_dpi", _dpi)
-    Screen:setDPI(_dpi)
+    Device:setScreenDPI(_dpi)
 end
 
 local dpi_auto = Screen.device.screen_dpi
@@ -31,14 +34,13 @@ return {
         {
             text = dpi_auto and T(_("Auto DPI (%1)"), dpi_auto) or _("Auto DPI"),
             help_text = _("The DPI of your screen is automatically detected so items can be drawn with the right amount of pixels. This will usually display at (roughly) the same size on different devices, while remaining sharp. Increasing the DPI setting will result in larger text and icons, while a lower DPI setting will look smaller on the screen."),
-            checked_func = function()
+            checked_func = isAutoDPI,
-                return dpi() == nil
-            end,
             callback = function() setDPI() end
         },
         {
             text = T(_("Small (%1)"), dpi_small),
             checked_func = function()
+                if isAutoDPI() then return false end
                 local _dpi, _custom = dpi(), custom()
                 return _dpi and _dpi <= 140 and _dpi ~= _custom
             end,
@@ -47,6 +49,7 @@ return {
         {
             text = T(_("Medium (%1)"), dpi_medium),
             checked_func = function()
+                if isAutoDPI() then return false end
                 local _dpi, _custom = dpi(), custom()
                 return _dpi and _dpi > 140 and _dpi <= 200 and _dpi ~= _custom
             end,
@@ -55,6 +58,7 @@ return {
         {
             text = T(_("Large (%1)"), dpi_large),
             checked_func = function()
+                if isAutoDPI() then return false end
                 local _dpi, _custom = dpi(), custom()
                 return _dpi and _dpi > 200 and _dpi <= 280 and _dpi ~= _custom
             end,
@@ -63,6 +67,7 @@ return {
         {
             text = T(_("Extra large (%1)"), dpi_xlarge),
             checked_func = function()
+                if isAutoDPI() then return false end
                 local _dpi, _custom = dpi(), custom()
                 return _dpi and _dpi > 280 and _dpi <= 400 and _dpi ~= _custom
             end,
@@ -71,6 +76,7 @@ return {
         {
             text = T(_("Extra-Extra Large (%1)"), dpi_xxlarge),
             checked_func = function()
+                if isAutoDPI() then return false end
                 local _dpi, _custom = dpi(), custom()
                 return _dpi and _dpi > 400 and _dpi <= 560 and _dpi ~= _custom
             end,
@@ -79,6 +85,7 @@ return {
         {
             text = T(_("Extra-Extra-Extra Large (%1)"), dpi_xxxlarge),
             checked_func = function()
+                if isAutoDPI() then return false end
                 local _dpi, _custom = dpi(), custom()
                 return _dpi and _dpi > 560 and _dpi ~= _custom
             end,
@@ -89,6 +96,7 @@ return {
                 return T(_("Custom DPI: %1 (hold to set)"), custom() or dpi_auto)
             end,
             checked_func = function()
+                if isAutoDPI() then return false end
                 local _dpi, _custom = dpi(), custom()
                 return _custom and _dpi == _custom
             end,