linearGradient
fun linearGradient(from: PdfColor, to: PdfColor, startX: Float = 0.0f, startY: Float = 0.0f, endX: Float, endY: Float): PdfPaint.LinearGradient
Two-stop linear gradient running from (startX, startY) to (endX, endY). Convenience for the common "fade between two colours" case.