Question

I am trying to detect 7″ tablets in my code (i.e. Kindle Fire & Nook Color). However, simply testing for minimum dimensions 1024×600 is not good, because then the Galaxy Nexus would pass this test as well. Anybody has experience with detecting this kind of information?

Thanks,
Igor

EDIT:
I have found one way to detect Kindle Fire & Nook Color devices with the following code:

Activity activity = (Activity) activityContext;
activity.getWindowManager().getDefaultDisplay().getMetrics(metrics);
int width = activity.getWindowManager().getDefaultDisplay().getWidth();
int height = activity.getWindowManager().getDefaultDisplay().getHeight();
if ((width == 1024 && height == 600) || (width == 600 && height == 1024)) {    
        //Detects 7" tablets: i.e. Kindle Fire & Nook Color
        isTablet = true;
    }

Answer 1

To calculate the height and width of the device (in inches) you can use the following code.

DisplayMetrics metrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics);

float widthInInches = metrics.widthPixels / metrics.xdpi;
float heightInInches = metrics.heightPixels / metrics.ydpi;

Then the size can be calculated

double sizeInInches = Math.sqrt(Math.pow(widthInInches, 2) + Math.pow(heightInInches, 2));
//0.5" buffer for 7" devices
boolean is7inchTablet = sizeInInches >= 6.5 && sizeInInches <= 7.5; 

As per Commonsware suggestion above, a potentially faster, but less obvious implementation.

double sizeInInchesSquared = (widthInInches * widthInInches) + (heightInInches * heightInInches);
//0.5" buffer for 7" devices (6.5^2 = 42.25) (7.5^2 = 56.25)
boolean is7inchTablet = sizeInInchesSquared >= 42.25 && sizeInInchesSquared <= 56.25;