diff --git a/base b/base
index 89a3711b6..ffdcfc5e5 160000
--- a/base
+++ b/base
@@ -1 +1 @@
-Subproject commit 89a3711b68cbe5abffc91529d009e1e27c3a1c73
+Subproject commit ffdcfc5e5d91f427002bbd0e51ece7e86cbf8ea1
diff --git a/frontend/apps/filemanager/filemanager.lua b/frontend/apps/filemanager/filemanager.lua
index 8d14ca2bc..63f097fb7 100644
--- a/frontend/apps/filemanager/filemanager.lua
+++ b/frontend/apps/filemanager/filemanager.lua
@@ -36,7 +36,7 @@ function FileManager:init()
             face = Font:getFace("tfont", 24),
             text = self.title,
         },
-        VerticalSpan:new{ width = Screen:scaleByDPI(10) }
+        VerticalSpan:new{ width = Screen:scaleBySize(10) }
     }
 
     local g_show_hidden = G_reader_settings:readSetting("show_hidden")
diff --git a/frontend/apps/reader/modules/readercropping.lua b/frontend/apps/reader/modules/readercropping.lua
index fe5fc7f19..55404dc9f 100644
--- a/frontend/apps/reader/modules/readercropping.lua
+++ b/frontend/apps/reader/modules/readercropping.lua
@@ -20,7 +20,7 @@ local PageCropDialog = VerticalGroup:new{
     cancel_text = "Cancel",
     ok_callback = function() end,
     cancel_callback = function() end,
-    button_width = math.floor(Screen:scaleByDPI(70)),
+    button_width = math.floor(Screen:scaleBySize(70)),
 }
 
 function PageCropDialog:init()
diff --git a/frontend/apps/reader/modules/readerdictionary.lua b/frontend/apps/reader/modules/readerdictionary.lua
index e9660f5db..b35e876ac 100644
--- a/frontend/apps/reader/modules/readerdictionary.lua
+++ b/frontend/apps/reader/modules/readerdictionary.lua
@@ -96,7 +96,7 @@ function ReaderDictionary:showDict(word, results, box)
             word = word,
             results = results,
             dictionary = self.default_dictionary,
-            width = Screen:getWidth() - Screen:scaleByDPI(80),
+            width = Screen:getWidth() - Screen:scaleBySize(80),
             word_box = box,
             -- differentiate between dict and wiki
             wiki = self.wiki,
diff --git a/frontend/apps/reader/modules/readerfont.lua b/frontend/apps/reader/modules/readerfont.lua
index b87f031e6..f4d1d16c0 100644
--- a/frontend/apps/reader/modules/readerfont.lua
+++ b/frontend/apps/reader/modules/readerfont.lua
@@ -81,7 +81,7 @@ function ReaderFont:onReadSettings(config)
 
     self.font_size = config:readSetting("font_size")
             or DCREREADER_CONFIG_DEFAULT_FONT_SIZE or 22
-    self.ui.document:setFontSize(Screen:scaleByDPI(self.font_size))
+    self.ui.document:setFontSize(Screen:scaleBySize(self.font_size))
 
     self.font_embolden = config:readSetting("font_embolden")
             or G_reader_settings:readSetting("copt_font_weight") or 0
@@ -149,7 +149,7 @@ function ReaderFont:onSetFontSize(new_size)
         text = _("Set font size to ")..self.font_size,
         timeout = 1,
     })
-    self.ui.document:setFontSize(Screen:scaleByDPI(new_size))
+    self.ui.document:setFontSize(Screen:scaleBySize(new_size))
     self.ui:handleEvent(Event:new("UpdatePos"))
 
     return true
diff --git a/frontend/apps/reader/modules/readerfooter.lua b/frontend/apps/reader/modules/readerfooter.lua
index bcce9fdbc..574baf19d 100644
--- a/frontend/apps/reader/modules/readerfooter.lua
+++ b/frontend/apps/reader/modules/readerfooter.lua
@@ -27,9 +27,9 @@ local ReaderFooter = InputContainer:new{
     progress_text = nil,
     text_font_face = "ffont",
     text_font_size = DMINIBAR_FONT_SIZE,
-    bar_height = Screen:scaleByDPI(DMINIBAR_HEIGHT),
-    height = Screen:scaleByDPI(DMINIBAR_CONTAINER_HEIGHT),
-    padding = Screen:scaleByDPI(10),
+    bar_height = Screen:scaleBySize(DMINIBAR_HEIGHT),
+    height = Screen:scaleBySize(DMINIBAR_CONTAINER_HEIGHT),
+    padding = Screen:scaleBySize(10),
 }
 
 function ReaderFooter:init()
diff --git a/frontend/apps/reader/modules/readerpaging.lua b/frontend/apps/reader/modules/readerpaging.lua
index d2343648c..6b43d8662 100644
--- a/frontend/apps/reader/modules/readerpaging.lua
+++ b/frontend/apps/reader/modules/readerpaging.lua
@@ -17,7 +17,7 @@ local ReaderPaging = InputContainer:new{
     visible_area = nil,
     page_area = nil,
     show_overlap_enable = nil,
-    overlap = Screen:scaleByDPI(DOVERLAPPIXELS),
+    overlap = Screen:scaleBySize(DOVERLAPPIXELS),
 
     page_flipping_mode = false,
     bookmark_flipping_mode = false,
diff --git a/frontend/apps/reader/modules/readerscreenshot.lua b/frontend/apps/reader/modules/readerscreenshot.lua
index f1871eb87..5a045d345 100644
--- a/frontend/apps/reader/modules/readerscreenshot.lua
+++ b/frontend/apps/reader/modules/readerscreenshot.lua
@@ -20,14 +20,14 @@ function ReaderScreenshot:init()
         TapDiagonal = {
             GestureRange:new{
                 ges = "two_finger_tap",
-                scale = {diagonal - Screen:scaleByDPI(200), diagonal},
+                scale = {diagonal - Screen:scaleBySize(200), diagonal},
                 rate = 1.0,
             }
         },
         SwipeDiagonal = {
             GestureRange:new{
                 ges = "swipe",
-                scale = {diagonal - Screen:scaleByDPI(200), diagonal},
+                scale = {diagonal - Screen:scaleBySize(200), diagonal},
                 rate = 1.0,
             }
         },
diff --git a/frontend/apps/reader/modules/readertoc.lua b/frontend/apps/reader/modules/readertoc.lua
index c69b6ddd0..f5f35edc9 100644
--- a/frontend/apps/reader/modules/readertoc.lua
+++ b/frontend/apps/reader/modules/readertoc.lua
@@ -244,14 +244,14 @@ function ReaderToc:onShowToc()
     -- update collapsible state
     self.expand_button = Button:new{
         icon = "resources/icons/appbar.control.expand.png",
-        width = Screen:scaleByDPI(30),
+        width = Screen:scaleBySize(30),
         bordersize = 0,
         show_parent = self,
     }
 
     self.collapse_button = Button:new{
         icon = "resources/icons/appbar.control.collapse.png",
-        width = Screen:scaleByDPI(30),
+        width = Screen:scaleBySize(30),
         bordersize = 0,
         show_parent = self,
     }
diff --git a/frontend/apps/reader/modules/readertypeset.lua b/frontend/apps/reader/modules/readertypeset.lua
index 92327e054..3a735edba 100644
--- a/frontend/apps/reader/modules/readertypeset.lua
+++ b/frontend/apps/reader/modules/readertypeset.lua
@@ -157,10 +157,10 @@ function ReaderTypeset:makeDefaultFloatingPunctuation()
 end
 
 function ReaderTypeset:onSetPageMargins(margins)
-    local left = Screen:scaleByDPI(margins[1])
-    local top = Screen:scaleByDPI(margins[2])
-    local right = Screen:scaleByDPI(margins[3])
-    local bottom = Screen:scaleByDPI(margins[4])
+    local left = Screen:scaleBySize(margins[1])
+    local top = Screen:scaleBySize(margins[2])
+    local right = Screen:scaleBySize(margins[3])
+    local bottom = Screen:scaleBySize(margins[4])
     self.ui.document:setPageMargins(left, top, right, bottom)
     self.ui:handleEvent(Event:new("UpdatePos"))
     return true
diff --git a/frontend/apps/reader/modules/readerview.lua b/frontend/apps/reader/modules/readerview.lua
index 94ce574a8..9d9250655 100644
--- a/frontend/apps/reader/modules/readerview.lua
+++ b/frontend/apps/reader/modules/readerview.lua
@@ -41,8 +41,8 @@ local ReaderView = OverlapGroup:new{
     page_states = {},
     scroll_mode = "vertical",
     page_gap = {
-        width = Screen:scaleByDPI(8),
-        height = Screen:scaleByDPI(8),
+        width = Screen:scaleBySize(8),
+        height = Screen:scaleBySize(8),
         color = Blitbuffer.gray(0.5),
     },
     -- DjVu page rendering mode (used in djvu.c:drawPage())
diff --git a/frontend/device/android/device.lua b/frontend/device/android/device.lua
index a75a40f49..0a52fc11b 100644
--- a/frontend/device/android/device.lua
+++ b/frontend/device/android/device.lua
@@ -1,6 +1,7 @@
 local Generic = require("device/generic/device")
 local isAndroid, android = pcall(require, "android")
 local ffi = require("ffi")
+local DEBUG = require("dbg")
 
 local function yes() return true end
 
@@ -12,14 +13,19 @@ local Device = Generic:new{
 }
 
 function Device:init()
-    self.screen = require("device/screen"):new{device = self}
+    self.screen = require("ffi/framebuffer_android"):new{device = self}
     self.powerd = require("device/android/powerd"):new{device = self}
     self.input = require("device/input"):new{
         device = self,
         event_map = require("device/android/event_map"),
         handleMiscEv = function(self, ev)
+            DEBUG("Android application event", ev.code)
             if ev.code == ffi.C.APP_CMD_SAVE_STATE then
                 return "SaveState"
+            elseif ev.code == ffi.C.APP_CMD_GAINED_FOCUS then
+                self.device.screen:refreshFull()
+            elseif ev.code == ffi.C.APP_CMD_WINDOW_REDRAW_NEEDED then
+                self.device.screen:refreshFull()
             end
         end,
     }
@@ -37,7 +43,7 @@ function Device:init()
         self.isTouchDevice = yes
     end
 
-    Generic:init()
+    Generic.init(self)
 end
 
 return Device
diff --git a/frontend/device/emulator/device.lua b/frontend/device/emulator/device.lua
index 5c536a7b7..7001fa357 100644
--- a/frontend/device/emulator/device.lua
+++ b/frontend/device/emulator/device.lua
@@ -13,13 +13,19 @@ local Device = Generic:new{
 }
 
 function Device:init()
-    self.screen = require("device/screen"):new{device = self}
-    self.input = require("device/input"):new{
-        device = self,
-        event_map = util.haveSDL2()
-            and require("device/emulator/event_map_sdl2")
-            or require("device/emulator/event_map_sdl"),
-    }
+    if util.haveSDL2() then
+        self.screen = require("ffi/framebuffer_SDL2_0"):new{device = self}
+        self.input = require("device/input"):new{
+            device = self,
+            event_map = require("device/emulator/event_map_sdl2"),
+        }
+    else
+        self.screen = require("ffi/framebuffer_SDL1_2"):new{device = self}
+        self.input = require("device/input"):new{
+            device = self,
+            event_map = require("device/emulator/event_map_sdl"),
+        }
+    end
 
     Generic.init(self)
 end
diff --git a/frontend/device/generic/device.lua b/frontend/device/generic/device.lua
index aef2bc734..0b6bf9a80 100644
--- a/frontend/device/generic/device.lua
+++ b/frontend/device/generic/device.lua
@@ -40,8 +40,10 @@ end
 
 function Device:init()
     if not self.screen then
-        self.screen = require("device/screen"):new{device = self}
+        error("screen/framebuffer must be implemented")
     end
+    self.screen.debug = DEBUG
+
     if not self.input then
         self.input = require("device/input"):new{device = self}
     end
diff --git a/frontend/device/kindle/device.lua b/frontend/device/kindle/device.lua
index 7758c5f50..fcb933065 100644
--- a/frontend/device/kindle/device.lua
+++ b/frontend/device/kindle/device.lua
@@ -69,7 +69,7 @@ local KindleVoyage = Kindle:new{
 }
 
 function Kindle2:init()
-    self.screen = require("device/screen"):new{device = self}
+    self.screen = require("ffi/framebuffer_einkfb"):new{device = self}
     self.input = require("device/input"):new{
         device = self,
         event_map = require("device/kindle/event_map_keyboard"),
@@ -79,7 +79,7 @@ function Kindle2:init()
 end
 
 function KindleDXG:init()
-    self.screen = require("device/screen"):new{device = self}
+    self.screen = require("ffi/framebuffer_einkfb"):new{device = self}
     self.input = require("device/input"):new{
         device = self,
         event_map = require("device/kindle/event_map_keyboard"),
@@ -90,7 +90,7 @@ function KindleDXG:init()
 end
 
 function Kindle3:init()
-    self.screen = require("device/screen"):new{device = self}
+    self.screen = require("ffi/framebuffer_einkfb"):new{device = self}
     self.input = require("device/input"):new{
         device = self,
         event_map = require("device/kindle/event_map_keyboard"),
@@ -101,7 +101,7 @@ function Kindle3:init()
 end
 
 function Kindle4:init()
-    self.screen = require("device/screen"):new{device = self}
+    self.screen = require("ffi/framebuffer_einkfb"):new{device = self}
     self.input = require("device/input"):new{
         device = self,
         event_map = require("device/kindle/event_map_kindle4"),
@@ -114,7 +114,7 @@ end
 local ABS_MT_POSITION_X = 53
 local ABS_MT_POSITION_Y = 54
 function KindleTouch:init()
-    self.screen = require("device/screen"):new{device = self}
+    self.screen = require("ffi/framebuffer_mxcfb"):new{device = self}
     self.powerd = require("device/kindle/powerd"):new{
         device = self,
         batt_capacity_file = "/sys/devices/system/yoshi_battery/yoshi_battery0/battery_capacity",
@@ -138,7 +138,7 @@ function KindleTouch:init()
 end
 
 function KindlePaperWhite:init()
-    self.screen = require("device/screen"):new{device = self}
+    self.screen = require("ffi/framebuffer_mxcfb"):new{device = self}
     self.powerd = require("device/kindle/powerd"):new{
         device = self,
         fl_intensity_file = "/sys/devices/system/fl_tps6116x/fl_tps6116x0/fl_intensity",
@@ -153,7 +153,7 @@ function KindlePaperWhite:init()
 end
 
 function KindlePaperWhite2:init()
-    self.screen = require("device/screen"):new{device = self}
+    self.screen = require("ffi/framebuffer_mxcfb"):new{device = self}
     self.powerd = require("device/kindle/powerd"):new{
         device = self,
         fl_intensity_file = "/sys/class/backlight/max77696-bl/brightness",
@@ -168,7 +168,7 @@ function KindlePaperWhite2:init()
 end
 
 function KindleBasic:init()
-    self.screen = require("device/screen"):new{device = self}
+    self.screen = require("ffi/framebuffer_mxcfb"):new{device = self}
     self.powerd = require("device/kindle/powerd"):new{
         device = self,
         batt_capacity_file = "/sys/devices/system/wario_battery/wario_battery0/battery_capacity",
@@ -183,7 +183,7 @@ function KindleBasic:init()
 end
 
 function KindleVoyage:init()
-    self.screen = require("device/screen"):new{device = self}
+    self.screen = require("ffi/framebuffer_mxcfb"):new{device = self}
     self.powerd = require("device/kindle/powerd"):new{
         device = self,
         fl_intensity_file = "/sys/class/backlight/max77696-bl/brightness",
diff --git a/frontend/device/kobo/device.lua b/frontend/device/kobo/device.lua
index cd54e6ed5..452b2c9c1 100644
--- a/frontend/device/kobo/device.lua
+++ b/frontend/device/kobo/device.lua
@@ -58,7 +58,7 @@ local KoboPhoenix = Kobo:new{
 }
 
 function Kobo:init()
-    self.screen = require("device/screen"):new{device = self}
+    self.screen = require("ffi/framebuffer_mxcfb"):new{device = self}
     self.powerd = require("device/kobo/powerd"):new{device = self}
     self.input = require("device/input"):new{
         device = self,
diff --git a/frontend/device/screen.lua b/frontend/device/screen.lua
deleted file mode 100644
index ce09557b7..000000000
--- a/frontend/device/screen.lua
+++ /dev/null
@@ -1,246 +0,0 @@
-local Blitbuffer = require("ffi/blitbuffer")
-local einkfb = require("ffi/framebuffer")
-local Geom = require("ui/geometry")
-local util = require("ffi/util")
-local DEBUG = require("dbg")
-
---[[
-Codes for rotation modes:
-
-1 for no rotation,
-2 for landscape with bottom on the right side of screen, etc.
-
-           2
-   +--------------+
-   | +----------+ |
-   | |          | |
-   | | Freedom! | |
-   | |          | |
-   | |          | |
- 3 | |          | | 1
-   | |          | |
-   | |          | |
-   | +----------+ |
-   |              |
-   |              |
-   +--------------+
-          0
---]]
-
-
-local Screen = {
-    cur_rotation_mode = 0,
-    native_rotation_mode = nil,
-    blitbuffer_rotation_mode = 0,
-
-    bb = nil,
-    saved_bb = nil,
-
-    screen_size = Geom:new(),
-    viewport = nil,
-
-    fb = einkfb.open("/dev/fb0"),
-    -- will be set upon loading by Device class:
-    device = nil,
-}
-
-function Screen:new(o)
-    local o = o or {}
-    setmetatable(o, self)
-    self.__index = self
-    if o.init then o:init() end
-    return o
-end
-
-function Screen:init()
-    self.bb = self.fb.bb
-    self.blitbuffer_rotation_mode = self.bb:getRotation()
-    -- asking the framebuffer for orientation is error prone,
-    -- so we do this simple heuristic (for now)
-    self.screen_size.w = self.bb:getWidth()
-    self.screen_size.h = self.bb:getHeight()
-    if self.screen_size.w > self.screen_size.h then
-        self.native_rotation_mode = 1
-        self.screen_size.w, self.screen_size.h = self.screen_size.h, self.screen_size.w
-    else
-        self.native_rotation_mode = 0
-    end
-    self.cur_rotation_mode = self.native_rotation_mode
-end
-
---[[
-set a rectangle that represents the area of the screen we are working on
---]]
-function Screen:setViewport(viewport)
-    self.viewport = self.screen_size:intersect(viewport)
-    self.bb = self.fb.bb:viewport(
-        self.viewport.x, self.viewport.y,
-        self.viewport.w, self.viewport.h)
-end
-
-function Screen:refresh(refresh_type, waveform_mode, wait_for_marker, x, y, w, h)
-    if self.viewport and x and y then
-        --[[
-            we need to adapt the coordinates when we have a viewport.
-            this adaptation depends on the rotation:
-
-          0,0               fb.w
-            +---+---------------------------+---+
-            |   |v.y                     v.y|   |
-            |v.x|                           |vx2|
-            +---+---------------------------+---+
-            |   |           v.w             |   |
-            |   |                           |   |
-            |   |                           |   |
-            |   |v.h     (viewport)         |   |
-            |   |                           |   | fb.h
-            |   |                           |   |
-            |   |                           |   |
-            |   |                           |   |
-            +---+---------------------------+---+
-            |v.x|                           |vx2|
-            |   |vy2                     vy2|   |
-            +---+---------------------------+---+
-
-            The viewport offset v.y/v.x only applies when rotation is 0 degrees.
-            For other rotations (0,0 is in one of the other edges), we need to
-            recalculate the offsets.
-        --]]
-
-        local vx2 = self.screen_size.w - (self.viewport.x + self.viewport.w)
-        local vy2 = self.screen_size.h - (self.viewport.y + self.viewport.h)
-
-        if self.cur_rotation_mode == 0 then
-            -- (0,0) is at top left of screen
-            x = x + self.viewport.x
-            y = y + self.viewport.y
-        elseif self.cur_rotation_mode == 1 then
-            -- (0,0) is at bottom left of screen
-            x = x + vy2
-            y = y + self.viewport.x
-        elseif self.cur_rotation_mode == 2 then
-            -- (0,0) is at bottom right of screen
-            x = x + vx2
-            y = y + vy2
-        else
-            -- (0,0) is at top right of screen
-            x = x + self.viewport.y
-            y = y + vx2
-        end
-    end
-    self.fb:refresh(refresh_type, waveform_mode, wait_for_marker, x, y, w, h)
-end
-
-function Screen:getSize()
-    return Geom:new{w = self.bb:getWidth(), h = self.bb:getHeight()}
-end
-
-function Screen:getWidth()
-    return self.bb:getWidth()
-end
-
-function Screen:getScreenWidth()
-    return self.screen_size.w
-end
-
-function Screen:getScreenHeight()
-    return self.screen_size.h
-end
-
-function Screen:getHeight()
-    return self.bb:getHeight()
-end
-
-function Screen:getDPI()
-    if self.dpi == nil then
-        self.dpi = G_reader_settings:readSetting("screen_dpi")
-    end
-    if self.dpi == nil then
-        self.dpi = self.device.display_dpi
-    end
-    if self.dpi == nil then
-        self.dpi = 160
-    end
-    return self.dpi
-end
-
-function Screen:setDPI(dpi)
-    G_reader_settings:saveSetting("screen_dpi", dpi)
-end
-
-function Screen:scaleByDPI(px)
-    local dpi = self:getDPI()
-    -- larger screen needs larger scale
-    local size_scale = math.min(self:getWidth(), self:getHeight())/dpi/3.6
-    -- scaled positive px should also be positive
-    return math.ceil(px * size_scale * dpi/167)
-end
-
-function Screen:getRotationMode()
-    return self.cur_rotation_mode
-end
-
-function Screen:getScreenMode()
-    if self:getWidth() > self:getHeight() then
-        return "landscape"
-    else
-        return "portrait"
-    end
-end
-
-function Screen:setRotationMode(mode)
-    self.bb:rotateAbsolute(-90 * (mode - self.native_rotation_mode - self.blitbuffer_rotation_mode))
-    if self.viewport then
-        self.fb.bb:setRotation(self.bb:getRotation())
-    end
-    self.cur_rotation_mode = mode
-end
-
-function Screen:setScreenMode(mode)
-    if mode == "portrait" then
-        if self.cur_rotation_mode ~= 0 then
-            self:setRotationMode(0)
-        end
-    elseif mode == "landscape" then
-        if self.cur_rotation_mode == 0 or self.cur_rotation_mode == 2 then
-            self:setRotationMode(DLANDSCAPE_CLOCKWISE_ROTATION and 1 or 3)
-        elseif self.cur_rotation_mode == 1 or self.cur_rotation_mode == 3 then
-            self:setRotationMode((self.cur_rotation_mode + 2) % 4)
-        end
-    end
-end
-
-function Screen:toggleNightMode()
-    self.bb:invert()
-    if self.viewport then
-        -- invert and blank out the full framebuffer when we are working on a viewport
-        self.fb.bb:invert()
-        self.fb.bb:fill(Blitbuffer.COLOR_WHITE)
-    end
-end
-
-function Screen:saveCurrentBB()
-    if self.saved_bb then self.saved_bb:free() end
-    self.saved_bb = self.bb:copy()
-end
-
-function Screen:restoreFromSavedBB()
-    if self.saved_bb then
-        self.bb:blitFullFrom(self.saved_bb)
-        -- free data
-        self.saved_bb:free()
-        self.saved_bb = nil
-    end
-end
-
-function Screen:shot(filename)
-    DEBUG("write PNG file", filename)
-    self.bb:writePNG(filename)
-end
-
-function Screen:close()
-    DEBUG("close screen framebuffer")
-    self.fb:close()
-end
-
-return Screen
diff --git a/frontend/document/koptinterface.lua b/frontend/document/koptinterface.lua
index cbece893c..64897f899 100644
--- a/frontend/document/koptinterface.lua
+++ b/frontend/document/koptinterface.lua
@@ -919,10 +919,10 @@ function KoptInterface:getLinkFromPosition(doc, pageno, pos)
             local link = page_links[i]
             -- enlarge tappable link box
             local lbox = Geom:new{
-                x = link.x0 - Screen:scaleByDPI(5),
-                y = link.y0 - Screen:scaleByDPI(5),
-                w = link.x1 - link.x0 + Screen:scaleByDPI(10),
-                h = link.y1 - link.y0 + Screen:scaleByDPI(10)
+                x = link.x0 - Screen:scaleBySize(5),
+                y = link.y0 - Screen:scaleBySize(5),
+                w = link.x1 - link.x0 + Screen:scaleBySize(10),
+                h = link.y1 - link.y0 + Screen:scaleBySize(10)
             }
             if inside_box(pos, lbox) and link.page then
                 return link, lbox
diff --git a/frontend/ui/font.lua b/frontend/ui/font.lua
index 249b3a34d..69835e275 100644
--- a/frontend/ui/font.lua
+++ b/frontend/ui/font.lua
@@ -56,7 +56,7 @@ function Font:getFace(font, size)
 
     -- original size before scaling by screen DPI
     local orig_size = size
-    local size = Screen:scaleByDPI(size)
+    local size = Screen:scaleBySize(size)
 
     local face = self.faces[font..size]
     -- build face if not found
diff --git a/frontend/ui/uimanager.lua b/frontend/ui/uimanager.lua
index 24f8670d2..929e51254 100644
--- a/frontend/ui/uimanager.lua
+++ b/frontend/ui/uimanager.lua
@@ -6,52 +6,8 @@ local util = require("ffi/util")
 local DEBUG = require("dbg")
 local _ = require("gettext")
 
--- cf. koreader-base/ffi-cdecl/include/mxcfb-kindle.h (UPDATE_MODE_* applies to Kobo, too)
-local UPDATE_MODE_PARTIAL       = 0x0
-local UPDATE_MODE_FULL          = 0x1
-
--- Kindle waveform update modes
-local WAVEFORM_MODE_INIT        = 0x0    -- Screen goes to white (clears)
-local WAVEFORM_MODE_DU          = 0x1    -- Grey->white/grey->black
-local WAVEFORM_MODE_GC16        = 0x2    -- High fidelity (flashing)
-local WAVEFORM_MODE_GC4         = WAVEFORM_MODE_GC16 -- For compatibility
-local WAVEFORM_MODE_GC16_FAST   = 0x3    -- Medium fidelity
-local WAVEFORM_MODE_A2          = 0x4    -- Faster but even lower fidelity
-local WAVEFORM_MODE_GL16        = 0x5    -- High fidelity from white transition
-local WAVEFORM_MODE_GL16_FAST   = 0x6    -- Medium fidelity from white transition
--- Kindle FW >= 5.3
-local WAVEFORM_MODE_DU4         = 0x7    -- Medium fidelity 4 level of gray direct update
--- Kindle PW2
-local WAVEFORM_MODE_REAGL       = 0x8    -- Ghost compensation waveform
-local WAVEFORM_MODE_REAGLD      = 0x9    -- Ghost compensation waveform with dithering
--- Kindle Basic/Kindle Voyage
-local WAVEFORM_MODE_GL4         = 0xA    -- 2-bit from white transition
--- TODO: Use me in night mode on those devices?
-local WAVEFORM_MODE_GL16_INV    = 0xB    -- High fidelity for black transition
-
--- Kobo waveform update modes
-local NTX_WFM_MODE_INIT         = 0x0    -- WAVEFORM_MODE_INIT
-local NTX_WFM_MODE_DU           = 0x1    -- WAVEFORM_MODE_DU
-local NTX_WFM_MODE_GC16         = 0x2    -- WAVEFORM_MODE_GC16
-local NTX_WFM_MODE_GC4          = 0x3    -- WAVEFORM_MODE_GC4
-local NTX_WFM_MODE_A2           = 0x4    -- WAVEFORM_MODE_A2
-local NTX_WFM_MODE_GL16         = 0x5    -- WAVEFORM_MODE_GL16
-local NTX_WFM_MODE_GLR16        = 0x6    -- WAVEFORM_MODE_REAGL
-local NTX_WFM_MODE_GLD16        = 0x7    -- WAVEFORM_MODE_REAGLD
-
--- Common
-local WAVEFORM_MODE_AUTO        = 0x101
-
-
 -- there is only one instance of this
 local UIManager = {
-    default_refresh_type = UPDATE_MODE_PARTIAL,
-    default_waveform_mode = WAVEFORM_MODE_GC16, -- high fidelity waveform
-    fast_waveform_mode = WAVEFORM_MODE_A2,
-    full_refresh_waveform_mode = WAVEFORM_MODE_GC16,
-    partial_refresh_waveform_mode = WAVEFORM_MODE_GC16,
-    wait_for_every_marker = false,
-    wait_for_ui_markers = false,
     -- force to repaint all the widget is stack, will be reset to false
     -- after each ui loop
     repaint_all = false,
@@ -114,29 +70,6 @@ function UIManager:init()
         if KOBO_LIGHT_ON_START and tonumber(KOBO_LIGHT_ON_START) > -1 then
             Device:getPowerDevice():setIntensity( math.max( math.min(KOBO_LIGHT_ON_START,100) ,0) )
         end
-        -- Emulate the stock reader's refresh behavior...
-        self.full_refresh_waveform_mode = NTX_WFM_MODE_GC16
-        -- Request REAGLD waveform mode on devices that support it (Aura & H2O)
-        if Device.model == "Kobo_phoenix" or Device.model == "Kobo_dahlia" then
-            self.partial_refresh_waveform_mode = NTX_WFM_MODE_GLD16
-            -- Since Kobo doesn't have MXCFB_WAIT_FOR_UPDATE_SUBMISSION, enabling this currently has no effect :).
-            self.wait_for_every_marker = true
-            -- NOTE: The H2O appears to be the odd duck out... Nickel uses AUTO for PARTIAL updates instead of asking for REAGLD specifically...
-            -- If we try to ask for FULL REAGLD updates, like on the Aura and the PW2, we get a black flash!
-            -- The driver appears to be using some custom Kobo logic (that they only enable in their producttion build?) altering the behavior of AUTO to favor REAGL modes...
-            -- Long story short: do the same as nickel: use AUTO, and hope for the best...
-            if Device.model == "Kobo_dahlia" then
-                self.partial_refresh_waveform_mode = WAVEFORM_MODE_AUTO
-            end
-        else
-            -- Let the driver handle it on those models (asking for NTX_WFM_MODE_GL16 appears to be a very bad idea, #1146)
-            self.partial_refresh_waveform_mode = WAVEFORM_MODE_AUTO
-            self.wait_for_every_marker = false
-            -- NOTE: Let's see if a bit of waiting works around potential timing issues on Kobos when doing *UI* refreshes in fast succession. (Not a concern on Kindle, where we have MXCFB_WAIT_FOR_UPDATE_SUBMISSION).
-            self.wait_for_ui_markers = true
-        end
-        -- Let the driver decide what to do with PARTIAL UI updates...
-        self.default_waveform_mode = WAVEFORM_MODE_AUTO
     elseif Device:isKindle() then
         self.event_handlers["IntoSS"] = function()
             self:sendEvent(Event:new("FlushSettings"))
@@ -153,35 +86,6 @@ function UIManager:init()
             Device:usbPlugOut()
             self:sendEvent(Event:new("NotCharging"))
         end
-        -- Emulate the stock reader's refresh behavior...
-        --[[
-            NOTE: For ref, on a Touch (debugPaint & a patched strace are your friend!):
-                UI: flash: GC16_FAST, non-flash: AUTO (prefers GC16_FAST)
-                Reader: When flash: if to/from img: GC16, else GC16_FAST; when non-flash: AUTO (seems to prefer GL16_FAST); Waiting for marker only on flash
-            On a PW2:
-                UI: flash: GC16_FAST, non-flash: AUTO (prefers GC16_FAST)
-                Reader: When flash: if to/from img: GC16, else GC16_FAST; when non-flash: REAGL (w/ UPDATE_MODE_FULL!); Always waits for marker
-                    Note that the bottom status bar region is refreshed separately, right after the screen, as a PARTIAL, AUTO (GC16_FAST) update, and it's this marker that's waited after...
-                    Non flash lasts longer (dual timeout: 14pgs / 7mins).
-        --]]
-        -- We don't really have an easy way to know if we're refreshing the UI, or a page, or if said page contains an image, so go with the highest fidelity option
-        -- We spend much more time in the reader than the UI, and our UI isn't very graphic anyway, so we'll follow the reader's behaviour above all
-        self.full_refresh_waveform_mode = WAVEFORM_MODE_GC16
-        -- Request REAGL waveform mode on devices that support it (PW2, KT2, KV) [FIXME: Is that actually true of the KT2?]
-        if Device.model == "KindlePaperWhite2" or Device.model == "KindleBasic" or Device.model == "KindleVoyage" then
-            self.partial_refresh_waveform_mode = WAVEFORM_MODE_REAGL
-            -- We need to wait for every update marker when using REAGL waveform modes. That mostly means we always use MXCFB_WAIT_FOR_UPDATE_SUBMISSION.
-            self.wait_for_every_marker = true
-        else
-            self.partial_refresh_waveform_mode = WAVEFORM_MODE_GL16_FAST
-            -- NOTE: Or we could go back to what KOReader did before fa55acc in koreader-base, which was also to use AUTO ;).
-            -- That said, we *should* be making more or less the same decisions as AUTO on our own, if I followed things correctly...
-            --self.partial_refresh_waveform_mode = WAVEFORM_MODE_AUTO
-            -- Only wait for update markers on FULL updates
-            self.wait_for_every_marker = false
-        end
-        -- Default to GC16_FAST (will be used for PARTIAL UI updates)
-        self.default_waveform_mode = WAVEFORM_MODE_GC16_FAST
     end
 end
 
@@ -217,6 +121,7 @@ function UIManager:close(widget)
         return
     end
     DEBUG("close widget", widget.id)
+    -- TODO: Why do we the following?
     Input.disable_double_tap = DGESDETECT_DISABLE_DOUBLE_TAP
     local dirty = false
     for i = #self._window_stack, 1, -1 do
@@ -383,105 +288,78 @@ end
 
 -- repaint dirty widgets
 function UIManager:repaint()
+    -- flag in which we will record if we did any repaints at all
+    -- will trigger a refresh if set.
     local dirty = false
-    local request_full_refresh = false
-    local force_full_refresh = false
-    local force_partial_refresh = false
+
+    -- we use this to record requests for certain refresh types
+    -- TODO: fix this, see below
+    local force_full_refresh = self.full_refresh
+    self.full_refresh = false
+
+    local force_partial_refresh = self.partial_refresh
+    self.partial_refresh = false
+
     local force_fast_refresh = false
+
     for _, widget in ipairs(self._window_stack) do
         -- paint if repaint_all is request
         -- paint also if current widget or any widget underneath is dirty
         if self.repaint_all or dirty or self._dirty[widget.widget] then
             widget.widget:paintTo(Screen.bb, widget.x, widget.y)
 
-            if self._dirty[widget.widget] == "auto" then
-                -- Most likely a 'reader' refresh. 'request' in the sense once we hit our FULL_REFRESH_COUNT ;).
-                request_full_refresh = true
-            end
+            -- self._dirty[widget.widget] may also be "auto"
             if self._dirty[widget.widget] == "full" then
                 force_full_refresh = true
-            end
-            if self._dirty[widget.widget] == "partial" then
+            elseif self._dirty[widget.widget] == "partial" then
                 force_partial_refresh = true
-            end
-            if self._dirty[widget.widget] == "fast" then
+            elseif self._dirty[widget.widget] == "fast" then
                 force_fast_refresh = true
             end
+
             -- and remove from list after painting
             self._dirty[widget.widget] = nil
+
             -- trigger repaint
             dirty = true
         end
     end
-
-    if self.full_refresh then
-        dirty = true
-        force_full_refresh = true
-    end
-
-    if self.partial_refresh then
-        dirty = true
-        force_partial_refresh = true
-    end
-
     self.repaint_all = false
-    self.full_refresh = false
-    self.partial_refresh = false
 
-    local refresh_type = self.default_refresh_type
-    local waveform_mode = self.default_waveform_mode
-    local wait_for_marker = self.wait_for_every_marker
     if dirty then
-        if force_partial_refresh or force_fast_refresh or self.update_regions_func then
-            refresh_type = UPDATE_MODE_PARTIAL
-            -- Override wait_for_marker if we need to enable the Kobo timing workaround on UI refreshes
-            if self.wait_for_ui_markers then
-                wait_for_marker = true
-            end
+        -- select proper refresh mode
+        -- TODO: fix this. We should probably do separate refreshes
+        -- by regional refreshes (e.g. fast refresh, some partial refreshes)
+        -- and full-screen full refresh
+        local refresh
+
+        if force_fast_refresh then
+            refresh = Screen.refreshFast
+        elseif force_partial_refresh then
+            refresh = Screen.refreshPartial
         elseif force_full_refresh or self.refresh_count == self.FULL_REFRESH_COUNT - 1 then
-            refresh_type = UPDATE_MODE_FULL
-        end
-        -- Handle the waveform mode selection...
-        if refresh_type == UPDATE_MODE_FULL then
-            waveform_mode = self.full_refresh_waveform_mode
+            refresh = Screen.refreshFull
+            -- a full refresh will reset the counter which leads to an automatic full refresh
+            self.refresh_count = 0
         else
-            waveform_mode = self.partial_refresh_waveform_mode
-        end
-        if force_fast_refresh then
-            waveform_mode = self.fast_waveform_mode
-            -- FIXME: Should we also avoid doing an MXCFB_WAIT_FOR_UPDATE_SUBMISSION for this update?
-            --wait_for_marker = false
-        end
-        -- If the device is REAGL-aware, we're specifically asking for a REAGL update, and we're doing a PARTIAL *reader* refresh, apply some trickery to match the stock reader's behavior
-        -- (On most device, REAGL updates are always FULL, but there's no black flash. On devices where this isn't the case [H2O], we're letting the driver do the job by using AUTO).
-        if not force_partial_refresh and not force_fast_refresh and refresh_type == UPDATE_MODE_PARTIAL and (waveform_mode == WAVEFORM_MODE_REAGL or waveform_mode == NTX_WFM_MODE_GLD16) then
-            refresh_type = UPDATE_MODE_FULL
-        end
-        -- On the other hand, if we asked for a PARTIAL *UI* refresh, fall back to the default waveform mode, which is tailored per-device to hopefully be more appropriate in this instance than the one we use in the reader.
-        if force_partial_refresh then
-            -- NOTE: Using default_waveform_mode might seem counter-intuitive when we have partial_refresh_waveform_mode, but partial_refresh_waveform_mode is mostly there as a means to flag REAGL-aware devices ;).
-            -- Here, we're actually interested in handling PARTIAL, regional (be it properly flagged or not) updates, and not the PARTIAL updates from the reader that actually refresh the whole screen (i.e., those between black flashes).
-            waveform_mode = self.default_waveform_mode
+            -- default
+            refresh = Screen.refreshPartial
+            -- increment refresh counter in this case
+            self.refresh_count = (self.refresh_count + 1) % self.FULL_REFRESH_COUNT
         end
+
         if self.update_regions_func then
             local update_regions = self.update_regions_func()
             for _, update_region in ipairs(update_regions) do
                 -- in some rare cases update region has 1 pixel offset
-                Screen:refresh(refresh_type, waveform_mode, wait_for_marker,
-                               update_region.x-1, update_region.y-1,
+                refresh(Screen, update_region.x-1, update_region.y-1,
                                update_region.w+2, update_region.h+2)
             end
+            self.update_regions_func = nil
         else
-            Screen:refresh(refresh_type, waveform_mode, wait_for_marker)
-        end
-        -- REAGL refreshes are always FULL (but without a black flash), but we want to keep our black flash timeout working, so don't reset the counter on FULL REAGL refreshes...
-        if refresh_type == UPDATE_MODE_FULL and waveform_mode ~= WAVEFORM_MODE_REAGL and waveform_mode ~= NTX_WFM_MODE_GLD16 then
-            self.refresh_count = 0
-        elseif not force_partial_refresh and not force_full_refresh and not self.update_regions_func then
-            self.refresh_count = (self.refresh_count + 1)%self.FULL_REFRESH_COUNT
+            refresh(Screen)
         end
     end
-    self.update_regions_func = nil
 end
 
 -- this is the main loop of the UI controller
diff --git a/frontend/ui/widget/buttontable.lua b/frontend/ui/widget/buttontable.lua
index fcdfadc73..45a74a13f 100644
--- a/frontend/ui/widget/buttontable.lua
+++ b/frontend/ui/widget/buttontable.lua
@@ -15,8 +15,8 @@ local ButtonTable = VerticalGroup:new{
             {text="Cancel", enabled=false, callback=nil},
         },
     },
-    sep_width = Screen:scaleByDPI(1),
-    padding = Screen:scaleByDPI(2),
+    sep_width = Screen:scaleBySize(1),
+    padding = Screen:scaleBySize(2),
 
     zero_sep = false,
     button_font_face = "cfont",
@@ -66,7 +66,7 @@ function ButtonTable:init()
 end
 
 function ButtonTable:addHorizontalSep()
-    table.insert(self, VerticalSpan:new{ width = Screen:scaleByDPI(2) })
+    table.insert(self, VerticalSpan:new{ width = Screen:scaleBySize(2) })
     table.insert(self, LineWidget:new{
         background = Blitbuffer.gray(0.5),
         dimen = Geom:new{
@@ -74,7 +74,7 @@ function ButtonTable:addHorizontalSep()
             h = self.sep_width,
         }
     })
-    table.insert(self, VerticalSpan:new{ width = Screen:scaleByDPI(2) })
+    table.insert(self, VerticalSpan:new{ width = Screen:scaleBySize(2) })
 end
 
 return ButtonTable
diff --git a/frontend/ui/widget/configdialog.lua b/frontend/ui/widget/configdialog.lua
index 7243d8e04..a5a5d09f0 100644
--- a/frontend/ui/widget/configdialog.lua
+++ b/frontend/ui/widget/configdialog.lua
@@ -161,7 +161,7 @@ function ConfigOption:init()
     -- fill vertical group of config tab
     local vertical_group = VerticalGroup:new{}
     table.insert(vertical_group, VerticalSpan:new{
-        width = Screen:scaleByDPI(default_option_padding),
+        width = Screen:scaleBySize(default_option_padding),
     })
     local show_advanced = G_reader_settings:readSetting("show_advanced") or false
     for c = 1, #self.options do
@@ -173,10 +173,10 @@ function ConfigOption:init()
             local name_font_size = self.options[c].name_font_size and self.options[c].name_font_size or default_name_font_size
             local item_font_face = self.options[c].item_font_face and self.options[c].item_font_face or "cfont"
             local item_font_size = self.options[c].item_font_size and self.options[c].item_font_size or default_item_font_size
-            local option_height = Screen:scaleByDPI(self.options[c].height and self.options[c].height or default_option_height)
+            local option_height = Screen:scaleBySize(self.options[c].height and self.options[c].height or default_option_height)
             local item_spacing_with = self.options[c].spacing and self.options[c].spacing or default_items_spacing
             local items_spacing = HorizontalSpan:new{
-                width = Screen:scaleByDPI(item_spacing_with)
+                width = Screen:scaleBySize(item_spacing_with)
             }
             local horizontal_group = HorizontalGroup:new{}
             if self.options[c].name_text then
@@ -284,7 +284,7 @@ function ConfigOption:init()
                 local max_item_spacing = (Screen:getWidth() * item_align -
                         middle_item:getSize().w * items_count) / items_count
                 local items_spacing = HorizontalSpan:new{
-                    width = math.min(max_item_spacing, Screen:scaleByDPI(item_spacing_with))
+                    width = math.min(max_item_spacing, Screen:scaleBySize(item_spacing_with))
                 }
                 for d = 1, #self.options[c].item_text do
                     local option_item = nil
@@ -334,7 +334,7 @@ function ConfigOption:init()
                 local max_item_spacing = (Screen:getWidth() * item_align -
                         first_item:getSize().w * items_count) / items_count
                 local items_spacing = HorizontalSpan:new{
-                    width = math.min(max_item_spacing, Screen:scaleByDPI(item_spacing_with))
+                    width = math.min(max_item_spacing, Screen:scaleBySize(item_spacing_with))
                 }
                 for d = 1, #self.options[c].item_icons do
                     local option_item = OptionIconItem:new{
@@ -362,7 +362,7 @@ function ConfigOption:init()
 
             if self.options[c].toggle then
                 local max_toggle_width = Screen:getWidth() / 2
-                local toggle_width = Screen:scaleByDPI(self.options[c].width or 216)
+                local toggle_width = Screen:scaleBySize(self.options[c].width or 216)
                 local switch = ToggleSwitch:new{
                     width = math.min(max_toggle_width, toggle_width),
                     font_face = item_font_face,
diff --git a/frontend/ui/widget/dictquicklookup.lua b/frontend/ui/widget/dictquicklookup.lua
index e3997e641..000f4d292 100644
--- a/frontend/ui/widget/dictquicklookup.lua
+++ b/frontend/ui/widget/dictquicklookup.lua
@@ -41,13 +41,13 @@ local DictQuickLookup = InputContainer:new{
     -- box of highlighted word, quick lookup window tries to not hide the word
     word_box = nil,
 
-    title_padding = Screen:scaleByDPI(5),
-    title_margin = Screen:scaleByDPI(2),
-    word_padding = Screen:scaleByDPI(5),
-    word_margin = Screen:scaleByDPI(2),
-    definition_padding = Screen:scaleByDPI(2),
-    definition_margin = Screen:scaleByDPI(2),
-    button_padding = Screen:scaleByDPI(14),
+    title_padding = Screen:scaleBySize(5),
+    title_margin = Screen:scaleBySize(2),
+    word_padding = Screen:scaleBySize(5),
+    word_margin = Screen:scaleBySize(2),
+    definition_padding = Screen:scaleBySize(2),
+    definition_margin = Screen:scaleBySize(2),
+    button_padding = Screen:scaleBySize(14),
 }
 
 function DictQuickLookup:init()
@@ -202,7 +202,7 @@ function DictQuickLookup:update()
         --background = Blitbuffer.gray(0.5),
         dimen = Geom:new{
             w = button_table:getSize().w + self.button_padding,
-            h = Screen:scaleByDPI(2),
+            h = Screen:scaleBySize(2),
         }
     }
 
@@ -252,7 +252,7 @@ function DictQuickLookup:update()
         dimen = self.region,
         FrameContainer:new{
             bordersize = 0,
-            padding = Screen:scaleByDPI(5),
+            padding = Screen:scaleBySize(5),
             self.dict_frame,
         }
     }
diff --git a/frontend/ui/widget/inputdialog.lua b/frontend/ui/widget/inputdialog.lua
index 4eef63062..9b10e6517 100644
--- a/frontend/ui/widget/inputdialog.lua
+++ b/frontend/ui/widget/inputdialog.lua
@@ -27,11 +27,11 @@ local InputDialog = InputContainer:new{
     title_face = Font:getFace("tfont", 22),
     input_face = Font:getFace("cfont", 20),
 
-    title_padding = Screen:scaleByDPI(5),
-    title_margin = Screen:scaleByDPI(2),
-    input_padding = Screen:scaleByDPI(10),
-    input_margin = Screen:scaleByDPI(10),
-    button_padding = Screen:scaleByDPI(14),
+    title_padding = Screen:scaleBySize(5),
+    title_margin = Screen:scaleBySize(2),
+    input_padding = Screen:scaleBySize(10),
+    input_margin = Screen:scaleBySize(10),
+    button_padding = Screen:scaleBySize(14),
 }
 
 function InputDialog:init()
@@ -76,7 +76,7 @@ function InputDialog:init()
         --background = Blitbuffer.gray(0.5),
         dimen = Geom:new{
             w = self.button_table:getSize().w + self.button_padding,
-            h = Screen:scaleByDPI(2),
+            h = Screen:scaleBySize(2),
         }
     }
 
diff --git a/frontend/ui/widget/menu.lua b/frontend/ui/widget/menu.lua
index d8db38ded..f0b03d53d 100644
--- a/frontend/ui/widget/menu.lua
+++ b/frontend/ui/widget/menu.lua
@@ -323,7 +323,7 @@ local Menu = FocusManager:new{
     width = 500,
     -- height will be calculated according to item number if not given
     height = nil,
-    header_padding = Screen:scaleByDPI(10),
+    header_padding = Screen:scaleBySize(10),
     dimen = Geom:new{},
     item_table = {},
     item_shortcuts = {
@@ -359,7 +359,7 @@ function Menu:_recalculateDimen()
     self.dimen.w = self.width
     self.item_dimen = Geom:new{
         w = self.dimen.w,
-        h = Screen:scaleByDPI(46), -- hardcoded for now
+        h = Screen:scaleBySize(46), -- hardcoded for now
     }
     -- if height not given, dynamically calculate it
     self.dimen.h = self.height or (#self.item_table + 2) * self.item_dimen.h
@@ -418,7 +418,7 @@ function Menu:init()
         show_parent = self,
     }
     self.page_info_spacer = HorizontalSpan:new{
-        width = Screen:scaleByDPI(32),
+        width = Screen:scaleBySize(32),
     }
     self.page_info_left_chev:hide()
     self.page_info_right_chev:hide()
@@ -449,7 +449,7 @@ function Menu:init()
     self.page_return_arrow:hide()
     self.return_button = HorizontalGroup:new{
         HorizontalSpan:new{
-            width = Screen:scaleByDPI(5),
+            width = Screen:scaleBySize(5),
         },
         self.page_return_arrow,
     }
diff --git a/frontend/ui/widget/scrolltextwidget.lua b/frontend/ui/widget/scrolltextwidget.lua
index 707ad1120..fdc8b90df 100644
--- a/frontend/ui/widget/scrolltextwidget.lua
+++ b/frontend/ui/widget/scrolltextwidget.lua
@@ -19,8 +19,8 @@ local ScrollTextWidget = InputContainer:new{
     fgcolor = Blitbuffer.COLOR_BLACK,
     width = 400,
     height = 20,
-    scroll_bar_width = Screen:scaleByDPI(6),
-    text_scroll_span = Screen:scaleByDPI(6),
+    scroll_bar_width = Screen:scaleBySize(6),
+    text_scroll_span = Screen:scaleBySize(6),
     dialog = nil,
 }
 
@@ -38,12 +38,12 @@ function ScrollTextWidget:init()
         enable = visible_line_count < total_line_count,
         low = 0,
         high = visible_line_count/total_line_count,
-        width = Screen:scaleByDPI(6),
+        width = Screen:scaleBySize(6),
         height = self.height,
     }
     local horizontal_group = HorizontalGroup:new{}
     table.insert(horizontal_group, self.text_widget)
-    table.insert(horizontal_group, HorizontalSpan:new{width = Screen:scaleByDPI(6)})
+    table.insert(horizontal_group, HorizontalSpan:new{width = Screen:scaleBySize(6)})
     table.insert(horizontal_group, self.v_scroll_bar)
     self[1] = horizontal_group
     self.dimen = Geom:new(self[1]:getSize())
diff --git a/frontend/ui/widget/toggleswitch.lua b/frontend/ui/widget/toggleswitch.lua
index 4d2aee713..ee6004d82 100644
--- a/frontend/ui/widget/toggleswitch.lua
+++ b/frontend/ui/widget/toggleswitch.lua
@@ -25,8 +25,8 @@ function ToggleLabel:paintTo(bb, x, y)
 end
 
 local ToggleSwitch = InputContainer:new{
-    width = Screen:scaleByDPI(216),
-    height = Screen:scaleByDPI(30),
+    width = Screen:scaleBySize(216),
+    height = Screen:scaleBySize(30),
     bgcolor = Blitbuffer.COLOR_WHITE, -- unfoused item color
     fgcolor = Blitbuffer.gray(0.5), -- focused item color
     font_face = "cfont",
diff --git a/frontend/ui/widget/touchmenu.lua b/frontend/ui/widget/touchmenu.lua
index 13aacc253..37fe8af2f 100644
--- a/frontend/ui/widget/touchmenu.lua
+++ b/frontend/ui/widget/touchmenu.lua
@@ -149,16 +149,16 @@ local TouchMenuBar = InputContainer:new{
 }
 
 function TouchMenuBar:init()
-    local icon_sep_width = Screen:scaleByDPI(2)
+    local icon_sep_width = Screen:scaleBySize(2)
     local icons_sep_width = icon_sep_width * (#self.icons + 1)
     -- we assume all icons are of the same width
     local ib = IconButton:new{icon_file = self.icons[1]}
     local content_width = ib:getSize().w * #self.icons + icons_sep_width
     local spacing_width = (self.width - content_width)/(#self.icons*2)
     local spacing = HorizontalSpan:new{
-        width = math.min(spacing_width, Screen:scaleByDPI(20))
+        width = math.min(spacing_width, Screen:scaleBySize(20))
     }
-    self.height = ib:getSize().h + Screen:scaleByDPI(10)
+    self.height = ib:getSize().h + Screen:scaleBySize(10)
     self.show_parent = self.show_parent or self
     self.bar_icon_group = HorizontalGroup:new{}
     -- build up image widget for menu icon bar
@@ -192,7 +192,7 @@ function TouchMenuBar:init()
             self.bar_sep = LineWidget:new{
                 dimen = Geom:new{
                     w = self.width,
-                    h = Screen:scaleByDPI(2),
+                    h = Screen:scaleBySize(2),
                 },
                 empty_segments = {
                     {
@@ -205,7 +205,7 @@ function TouchMenuBar:init()
         local icon_sep = LineWidget:new{
             style = k == 1 and "solid" or "none",
             dimen = Geom:new{
-                w = Screen:scaleByDPI(2),
+                w = Screen:scaleBySize(2),
                 h = self.height,
             }
         }
@@ -258,9 +258,9 @@ local TouchMenu = InputContainer:new{
     -- for returnning in multi-level menus
     item_table_stack = nil,
     item_table = nil,
-    item_height = Screen:scaleByDPI(50),
-    bordersize = Screen:scaleByDPI(2),
-    padding = Screen:scaleByDPI(5),
+    item_height = Screen:scaleBySize(50),
+    bordersize = Screen:scaleBySize(2),
+    padding = Screen:scaleBySize(5),
     fface = Font:getFace("ffont", 20),
     width = nil,
     height = nil,
@@ -353,7 +353,7 @@ function TouchMenu:init()
         end,
     }
     local footer_width = self.width - self.padding*2 - self.bordersize*2
-    local footer_height = up_button:getSize().h + Screen:scaleByDPI(2)
+    local footer_height = up_button:getSize().h + Screen:scaleBySize(2)
     self.footer = HorizontalGroup:new{
         LeftContainer:new{
             dimen = Geom:new{ w = footer_width*0.33, h = footer_height},
@@ -450,7 +450,7 @@ function TouchMenu:updateItems()
         end -- if i <= self.items
     end -- for c=1, self.perpage
 
-    table.insert(self.item_group, VerticalSpan:new{width = Screen:scaleByDPI(2)})
+    table.insert(self.item_group, VerticalSpan:new{width = Screen:scaleBySize(2)})
     table.insert(self.item_group, self.footer)
     self.page_info_text.text = util.template(_("Page %1 of %2"), self.page, self.page_num)
     self.page_info_left_chev:showHide(self.page_num > 1)
diff --git a/frontend/ui/widget/virtualkeyboard.lua b/frontend/ui/widget/virtualkeyboard.lua
index 0de815cd3..b0a8fe6b8 100644
--- a/frontend/ui/widget/virtualkeyboard.lua
+++ b/frontend/ui/widget/virtualkeyboard.lua
@@ -155,7 +155,7 @@ local VirtualKeyboard = InputContainer:new{
     height = 256,
     bordersize = 2,
     padding = 2,
-    key_padding = Screen:scaleByDPI(6),
+    key_padding = Screen:scaleBySize(6),
 }
 
 function VirtualKeyboard:init()