Question

I’m creating (yet another) ruler app for wp7.

I know the res. is always 480×800, but devices have different screen sizes.

I tried searching around, but i couldn’t find out how to get the ppi, so i can map the pixels to the physical dimension.

so how do i get the ppi of the current device, or the physical screen size ?

Answer 1

There is no way to retrieve the PPI on the device, you best shot would be to maintain a list of devices and their respective PPI. You can use this helper method to access device properties:

Using Microsoft.Phone.Info;
...
private static string GetDeviceProperty(string propertyName)
    {
        object propertyValue;

        if (!DeviceExtendedProperties.TryGetValue(propertyName, out propertyValue))
            return String.Empty;

        return propertyValue as string ?? String.Empty;
    }

Now the relevant properties would be:

string manufacturer = GetDeviceProperty("DeviceManufacturer");
string devicename = GetDeviceProperty("DeviceName");

Hope this helps! More information about DeviceExtendedProperties can be found on MSDN