Android Question Calculate Physical Screen Size

[wonder]

Hi guys!!

Given the resolution and dpi, is it possible to calculate the screen physical size in centimeters?

I know this is simple math, but my brain refuses to work anymore today.

 

[NJDude]

With this code you get the size in inches:

GetDeviceLayoutValues.ApproximateScreenSize

Just multiply the result by 2.54

 

[wonder]

Wow, it's even easier than I thought!! Thank you very much!!!

 

[Erel]

Note that this method returns the approximate size which is based on the approximate scale.

If you want to find the exact activity size then you can use:

Sub ExactSize As Double
  Dim r As Reflector
  r.Target = r.GetContext
  r.Target = r.RunMethod("getResources")
  r.Target = r.RunMethod("getDisplayMetrics")
  Dim xdpi As Double = r.GetField("xdpi")
  Dim ydpi As Double = r.GetField("ydpi")
  Return Sqrt(Power(100%x / xdpi, 2) + Power(100%y / ydpi, 2))
End Sub

This is only useful if the exact size is really important. For example if you create a ruler app.

 

[Peter Simpson]

Note that this method returns the approximate size which is based on the approximate scale.

If you want to find the exact activity size then you can use:

Sub ExactSize As Double
  Dim r As Reflector
  r.Target = r.GetContext
  r.Target = r.RunMethod("getResources")
  r.Target = r.RunMethod("getDisplayMetrics")
  Dim xdpi As Double = r.GetField("xdpi")
  Dim ydpi As Double = r.GetField("ydpi")
  Return Sqrt(Power(100%x / xdpi, 2) + Power(100%y / ydpi, 2))
End Sub

This is only useful if the exact size is really important. For example if you create a ruler app.

This will definitely come in handy one day.

Cheers...

 

[wonder]

Thank you for the clarification, Erel.
I want to experiment with a button that remains the same physical size independently of the device.

 

[ArminKH]

As @Erel said the result for my device is about 4.58 but when i measure my device's diameter by using real ruler(From top corner to bottom corner(above navbar)) the result is 5.31 inches
my phone is huawei g610(named 5")
I set #FullScreen to true and #IncludeTitle to false
Please help me if i am on wrong way

 

[incendio]

Note that this method returns the approximate size which is based on the approximate scale.

If you want to find the exact activity size then you can use:

Sub ExactSize As Double
  Dim r As Reflector
  r.Target = r.GetContext
  r.Target = r.RunMethod("getResources")
  r.Target = r.RunMethod("getDisplayMetrics")
  Dim xdpi As Double = r.GetField("xdpi")
  Dim ydpi As Double = r.GetField("ydpi")
  Return Sqrt(Power(100%x / xdpi, 2) + Power(100%y / ydpi, 2))
End Sub

This is only useful if the exact size is really important. For example if you create a ruler app.

Tested on Nexus 7, it returns 7.668"
Shouldn't it returns 7" ?

 

[Erel]

It returns the Activity size based on the dimensions returned from the native API. The formula is correct.