Scrolling Text Matrix with Bluetooth app control

#include <Adafruit_GFX.h>
#include <Adafruit_NeoMatrix.h>
#include <Adafruit_NeoPixel.h>
#include <BluetoothSerial.h> // Available here : https://github.com/espressif/arduino-esp32/tree/master/libraries/BluetoothSerial

BluetoothSerial BT_Text;

#define PIN 25 // This is the led signal pin

Adafruit_NeoMatrix matrix = Adafruit_NeoMatrix(32, 8, PIN,
  NEO_MATRIX_TOP    + NEO_MATRIX_LEFT +
  NEO_MATRIX_COLUMNS + NEO_MATRIX_ZIGZAG,
  NEO_GRB            + NEO_KHZ800);

int i; 
String Text;
int x = matrix.width();
int Size;

const uint16_t colors[] = {
  matrix.Color(204, 0, 204), matrix.Color(204, 204, 0), matrix.Color(0, 255, 255),
  matrix.Color(255, 10, 127), matrix.Color(127, 0, 255), matrix.Color(0, 255, 0),
  matrix.Color(255, 99, 255), matrix.Color(204,177,0), matrix.Color(0,0,244) };  // Colour presets

void PrintOut() {
  while (!BT_Text.available()) {
    }
    while (BT_Text.available()) {
      i = BT_Text.read();
      Text = Text + char (i);
    }
}


  

void setup() {
 // Serial.begin(115200);
  BT_Text.begin("BT_Text");  //Name of the Bluetooth interface (On your phone)
  matrix.begin();
  matrix.setTextWrap(false);
  matrix.setBrightness(40);
  matrix.setTextColor(colors[0]);
  Text = "*MERRY CHRISTMAS*";
  Size = Text.length()*6;
}



void loop() {
  if (BT_Text.available()) {
    i = BT_Text.read();
      if (i < 9) {
      matrix.setTextColor(colors[i]);
      }
      else {
        Text = "";
        PrintOut();
        Size = Text.length()*6;
      }
      }
  matrix.fillScreen(0);    //Turn off all the LEDs
  matrix.setCursor(x, 0);
  matrix.print(Text);
  if ( --x < -Size) {
    x = matrix.width();
  }
  matrix.show();
  delay(50);
}