fix: update gesturedector constant for custom screen dpi

frontend/device/generic/device.lua

@@ -143,6 +143,11 @@ function Device:init()
     end
 end
 
+function Device:setScreenDPI(dpi_override)
+    self.screen:setDPI(dpi_override)
+    self.input.gesture_detector:init()
+end
+
 function Device:getPowerDevice()
     return self.powerd
 end

frontend/device/gesturedetector.lua

@@ -91,11 +91,12 @@ function GestureDetector:new(o)
 end
 
 function GestureDetector:init()
+    local scaler = self.screen:getDPI() / 167
     -- distance parameters
-    self.DOUBLE_TAP_DISTANCE = 50 * self.screen:getDPI() / 167
-    self.TWO_FINGER_TAP_REGION = 20 * self.screen:getDPI() / 167
-    self.PAN_THRESHOLD = 50 * self.screen:getDPI() / 167
-    self.MULTISWIPE_THRESHOLD = 50 * self.screen:getDPI() / 167
+    self.TWO_FINGER_TAP_REGION = 20 * scaler
+    self.DOUBLE_TAP_DISTANCE = 50 * scaler
+    self.PAN_THRESHOLD = self.DOUBLE_TAP_DISTANCE
+    self.MULTISWIPE_THRESHOLD = self.DOUBLE_TAP_DISTANCE
 end
 
 --[[--

reader.lua

@@ -37,7 +37,7 @@ end
 local Device = require("device")
 local dpi_override = G_reader_settings:readSetting("screen_dpi")
 if dpi_override ~= nil then
-    Device.screen:setDPI(dpi_override)
+    Device:setScreenDPI(dpi_override)
 end
 
 local CanvasContext = require("document/canvascontext")