flutter swipe images cause white screen

Question

I wrote a flutter application where the end customer doesn't want to scroll but wants to change the image simply by gestures.

So far so good I can handle this request, but the only problem is that when the image changes so I move from one to 'another, before seeing the next I get a white screen, immediately after the image. How can I remove this problem?

this is the sample code List elenco = []; //this variabile was loading in initstate

 @override
  Widget build(BuildContext context) {
   return Scaffold(
    appBar: AppBar(
    title: Text("${widget.nome}(${lstDoc.length})"),
    backgroundColor: MyColors.navy,
  ),
  resizeToAvoidBottomInset: false,
  body: myView(),
  );
 }
 void incrementaImmagine(String direzione, BuildContext context){
  if (direzione == "avanti") {
  
  if (pagina < lstDoc.length - 1) {
    if (pagina + 2 <= lstDoc.length - 1) {
      setState(() {
        current = elenco[pagina];
      });
    }
  }
  } else if (direzione == "centro") {
   setState(() {
    current = elenco[pagina];
   });
  } else if (direzione == "indietro") {
   setState(() {
    current = elenco[pagina];
   });
  }
}

 
 Widget myView() {
   return Listener(
          onPointerDown: (p) {
            startx1 = p.localPosition.dx;
            debugPrint("down: ${p.localPosition.dx}");
          },
          onPointerUp: (p) {
            startx2 = p.localPosition.dx;

            debugPrint("up: ${p.localPosition.dx}");
            if (startx > 0) {
              if (startx2 - startx1 > margSwipe) {
                debugPrint("indietro_$pagina");
                if (pagina >= 0) {
                  if (pagina >= 1) {
                    pagina -= 1;
                  } else {
                    pagina = 0;
                  }
                  incrementaImmagine("indietro", context);
                } else {
                  pagina = 0;
                  incrementaImmagine("indietro", context);
                }
              }
            }
            if (startx < 0) {
              if (startx1 - startx2 > margSwipe) {
                debugPrint("avanti$pagina");
                if (pagina + 1 < lstDoc.length - 1) {
                  pagina += 1;
                  incrementaImmagine("avanti", context);
                }
              }
            }
          },
          onPointerMove: (moveEvent) {
            startx = moveEvent.delta.dx;
          },
          child: current;
    }
  }