[fix] Scale ImageWidget by screen size as well as DPI

Fix #3204

frontend/ui/widget/button.lua

@@ -1,19 +1,20 @@
+--[[--
+A button widget that shows text or a icon and handles callback when tapped.
+--]]
+
+local Blitbuffer = require("ffi/blitbuffer")
 local CenterContainer = require("ui/widget/container/centercontainer")
-local InputContainer = require("ui/widget/container/inputcontainer")
+local Device = require("device")
+local Font = require("ui/font")
 local FrameContainer = require("ui/widget/container/framecontainer")
+local Geom = require("ui/geometry")
+local GestureRange = require("ui/gesturerange")
 local ImageWidget = require("ui/widget/imagewidget")
+local InputContainer = require("ui/widget/container/inputcontainer")
 local TextWidget = require("ui/widget/textwidget")
-local GestureRange = require("ui/gesturerange")
-local Blitbuffer = require("ffi/blitbuffer")
 local UIManager = require("ui/uimanager")
-local Geom = require("ui/geometry")
-local Device = require("device")
-local Font = require("ui/font")
 local _ = require("gettext")
 
---[[
-a button widget that shows text or a icon and handles callback when tapped
---]]
 local Button = InputContainer:new{
     text = nil, -- mandatory
     icon = nil,
@@ -45,6 +46,7 @@ function Button:init()
         self.label_widget = ImageWidget:new{
             file = self.icon,
             dim = not self.enabled,
+            scale_for_dpi = true,
         }
     end
     local widget_size = self.label_widget:getSize()

frontend/ui/widget/imagewidget.lua

@@ -177,9 +177,9 @@ function ImageWidget:_render()
 
     -- scale_for_dpi setting: update scale_factor (even if not set) with it
     if self.scale_for_dpi then
+        local size_scale = math.min(Screen:getWidth(), Screen:getHeight())/600
         local dpi_scale = Screen:getDPI() / 167
-        -- rounding off to power of 2 to avoid alias with pow(2, floor(log(x)/log(2))
-        dpi_scale = math.pow(2, math.max(0, math.floor(math.log(dpi_scale)/0.69)))
+        dpi_scale = math.pow(2, math.max(0, math.log((size_scale+dpi_scale)/2)/0.69))
         if self.scale_factor == nil then
             self.scale_factor = 1
         end