How can i get exposure time by rational from photo properties in android?

Question

I'm writing gallery.But I got double when i use exifInterface.getAttribute(ExifInterface.TAG_EXPOSURE_TIME), it should be rational(fraction). If I open system gallery, it is rational.Please help me.Thanks.

Answer 1

To get precise/correct values use the new ExifInterface support library instead of the old ExifInterface.

You must add to your gradle:

compile "com.android.support:exifinterface:25.1.0"

And then ensure you use the new android.support.media.ExifInterface library instead of the old android.media.ExifInterface.

import android.support.media.ExifInterface;

String getExposureTime(final ExifInterface exif)
{
    String exposureTime = exif.getAttribute(ExifInterface.TAG_EXPOSURE_TIME);

    if (exposureTime != null)
    {
        exposureTime = formatExposureTime(Double.valudeOf(exposureTime));
    }

    return exposureTime;
}

public static String formatExposureTime(final double value)
{
    String output;

    if (value < 1.0f)
    {
        output = String.format(Locale.getDefault(), "%d/%d", 1, (int)(0.5f + 1 / value));
    }
    else
    {
        final int    integer = (int)value;
        final double time    = value - integer;
        output = String.format(Locale.getDefault(), "%d''", integer);

        if (time > 0.0001f)
        {
            output += String.format(Locale.getDefault(), " %d/%d", 1, (int)(0.5f + 1 / time));
        }
    }

    return output;
}