toCommand method
Implementation
Future<String> toCommand() async {
return await image.toCommand().then(
(value) =>
'-i $value -filter_complex "[1:v]${(watermarkSize ?? WatermarkSize.symmertric(100)).toCommand()}format=argb,geq=r=\'r(X,Y)\':a=\'$opacity*alpha(X,Y)\'[i];[0:v][i]overlay=${(watermarkAlignment ?? WatermarkAlignment.center).toCommand()}[o]" -map "[o]" -map "0:a?"',
);
}