Creating invisible digital signatures in Android

// Create an empty rect.
val rectFSignatureFormConfiguration = RectF(
    30f, // left
    190f, // top
    30f, // right
    190f // bottom
)

val signatureFormConfiguration = SignatureFormConfiguration.Builder(0, rectFSignatureFormConfiguration)
    .build()

// `addFormElementToPage()` is a suspend function, so call it from a coroutine.
lifecycleScope.launch {
    val signatureFormField = document.formProvider.addFormElementToPage("signaturefield-1", signatureFormConfiguration) as SignatureFormField

    // Now perform the digital signing with the newly created form field.
    performSigning(signatureFormField)
}

// Create an empty rect.
RectF rectFSignatureFormConfiguration = new RectF(
    30, // left
    190, // top
    30, // right
    190 // bottom
);

SignatureFormConfiguration signatureFormConfiguration = new SignatureFormConfiguration.Builder(0, rectFSignatureFormConfiguration)
    .build();
// `addFormElementToPage()` is a suspend function. `runBlocking()` waits for it to finish,
// so only call this on a worker thread.
try {
    SignatureFormField signatureFormField = (SignatureFormField) BuildersKt.runBlocking(
        EmptyCoroutineContext.INSTANCE,
        (scope, continuation) -> document.getFormProvider()
            .addFormElementToPage("signaturefield-1", signatureFormConfiguration, continuation));

    // Now perform the digital signing with the newly created form field.
    performSigning(signatureFormField);
} catch (InterruptedException e) {
    Thread.currentThread().interrupt();
}