Getting the Accessibility Display Size Programmatically Android

Question

I need to record certain metrics for the usage of my app based on font and display size. How can I retrieve the display size under Settings -> Accessibility section programmatically? Font Scale is straight-forward, but there seems to be no way of retrieving the display size.

float fontScale = getResources().getConfiguration().fontScale;

Answer 1

The Android API does not expose this scale factor chosen by the user. However, a similar scale can be obtained by dividing the density DPI (which is scaled based on the user's setting) and DENSITY_DEVICE_STABLE, which gives the required result.

final DisplayMetrics metrics = getResources().getDisplayMetrics();
final int currentDeviceDensity = metrics.densityDpi;
float displayDensityScaleFactor = (float) currentDeviceDensity / DENSITY_DEVICE_STABLE;

Answer 2

So in my case I actually needed to check fontScale and density combined and for that it seems that using val deviceDensity = LocalDensity.current.density - (DENSITY_DEVICE_STABLE / DENSITY_DEFAULT) is better since it provides more range than densityDpi / DENSITY_DEVICE_STABLE.

Display size	DPI approach	Density approach (mine)
1st	0.85	-0.025
2nd	1.0	0.5
3rd	1.09	0.83
4th	1.19	1.16
5th	1.29	1.5

Density approach numbers can be easily combined with fontScale. For example in my case I had to check if fontScale per density is higher than 200%. For which I made a function (Compose) to get the scale:

/**
 * Gets font scale combined with screen density to check how large is the text compared to default device settings.
 * Default device density is divided by default density and by this number current density of the screen is reduced to
 *
 * Note: Preview cannot load proper [DENSITY_DEVICE_STABLE] value since it is loaded from HW configuration but density
 * from LocalDensity is loaded properly thus they cannot be combined. That is why for previous only fontScale is
 * returned.
 *
 * @return font scale for the screen density
 */
@Composable
fun getScreenDensityFontScale(): Float {
    val fontScale = LocalDensity.current.fontScale
    val isComposePreview = LocalInspectionMode.current
    return if (isComposePreview) {
        fontScale
    } else {
        val deviceDensity = LocalDensity.current.density - (DENSITY_DEVICE_STABLE / DENSITY_DEFAULT)
        fontScale + deviceDensity
    }
}

And I'm checking getScreenDensityFontScale() > 2.0f. For Pixel 7 Pro (emulator) 200% or more font scale can be reached when:

1. Font size 4/4 + Display size 3/5.
2. And Font Size + Display size 4/5.