Convert pixels to sp

Question

I need the current TextSize of the TextView in sp units.

But getTextSize() returns the size in pixels. So is there a way to convert pixels to sp?

Answer 1

Use this

public static float pixelsToSp(Context context, float px) {
    float scaledDensity = context.getResources().getDisplayMetrics().scaledDensity;
    return px/scaledDensity;
}

If you wanna test if this method works right use this snippet

XML

<TextView
        android:id="@+id/txtHelloWorld"
        android:text="@string/hello_world"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="20sp"/>

<TextView
        android:id="@+id/txtHelloWorld2"
        android:text="@string/hello_world"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        />

Java

View rootView = inflater.inflate(R.layout.fragment_main, container, false);
TextView helloWorldTextView = (TextView)    rootView.findViewById(R.id.txtHelloWorld);
TextView helloWorldTextView2 = (TextView) rootView.findViewById(R.id.txtHelloWorld2);
helloWorldTextView2.setTextSize(pixelsToSp(getActivity(), helloWorldTextView.getTextSize()));

Both TextView's font size should be same.

Answer 2

See the DisplayMetrics class, it has fields for densityDpi and scaledDensity.

Example usage:

float sp = px / getResources().getDisplayMetrics().scaledDensity;

Answer 3

weird to see public field that is adjusted at run time but it works. Standard Dpi is 160 so whatever your device Dpi is, say 240, both density and scaledDensity will show 240/160=1.5 This is how you convert between pixels and sp: px=1.5*sp