canvas.drawBitmap on bitmap base on specific location in jetpack compose

Question

I have an image and i want to add a signature image on it in the position that the user place it on the screen and press "save".

I have tried in this way:

fun generateComposedImage(originalImage: Bitmap, signatureImage:Bitmap,location: Offset,signatureScreen:SizeF,imageScreenSize:Size,  zstackScreenSize: Size): ImageBitmap {
    val composedBitmap = Bitmap.createBitmap(originalImage.width, originalImage.height, originalImage.config)
    val canvas = Canvas(composedBitmap)
    val paint = Paint().apply {
        isAntiAlias = true
    }
    canvas.drawBitmap(originalImage, 0f, 0f, paint)
    // Calculate the position to draw the signature image
    val signatureX = ((location.x * originalImage.width) / imageScreenSize.width)
    -(signatureScreen.width*originalImage.width/imageScreenSize.width)/2-
            ((zstackScreenSize.width-imageScreenSize.width)*originalImage.width/imageScreenSize.width)/2
    val signatureY = ((location.y* originalImage.height) / imageScreenSize.height)-
            (signatureScreen.height*originalImage.height/imageScreenSize.height)/2-
            ((zstackScreenSize.height-imageScreenSize.height)*originalImage.height/imageScreenSize.height)/2
    val signatureWidth = (signatureScreen.width * originalImage.width / imageScreenSize.width)
    val signatureHeight = (signatureScreen.height * originalImage.height / imageScreenSize.height)
    canvas.drawBitmap(
        signatureImage,
        Rect(0, 0, signatureImage.width, signatureImage.height),
        RectF(signatureX, signatureY,
            ((signatureX + signatureWidth + signatureImage.width/2f )),
            ((signatureY + signatureHeight +signatureImage.height/2f ))),
        paint
    )

    return composedBitmap.asImageBitmap()
}

this code genereate me the image with the signature on it but the signature is little bit far from where i place it. in addition , in some images its increase me the size of the signature Any suggestion to fix it?