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//+------------------------------------------------------------------+
//|                                     keystroke_symbol_changer.mq5 |
//|                                  Copyright 2023, MetaQuotes Ltd. |
//|                                             https://www.mql5.com |
//+------------------------------------------------------------------+
#property copyright "Copyright 2023, MetaQuotes Ltd."
#property link      "https://www.mql5.com"
#property version   "1.00"
#property indicator_chart_window
//--- input parameters
input string   NextSymbolKey="KEY_RIGHT";
input string   PrevSymbolKey="KEY_LEFT";
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
#define KEY_LEFT           37
#define KEY_RIGHT          39

int symbolIndex = 0;

int OnInit()
  {
 
    ChartSetInteger(ChartID(), CHART_EVENT_OBJECT_CREATE, true);
    ChartSetInteger(ChartID(), CHART_EVENT_OBJECT_DELETE, true);
    int total = SymbolsTotal(false); // Get the total number of symbols
    ArrayResize(symbols, total); // Resize the array to fit all symbols
    for(int i = 0; i < total; i++)
    {
        symbols[i] = SymbolName(i, false); // Get the name of the symbol and store it in the array
    }

    ChartRedraw();
    return(INIT_SUCCEEDED);
  }
int OnCalculate(const int rates_total,
                const int prev_calculated,
                const datetime& time[],
                const double& open[],
                const double& high[],
                const double& low[],
                const double& close[],
                const long& tick_volume[],
                const long& volume[],
                const int& spread[])
  {
   
   return(rates_total);
}

void OnChartEvent(const int id,
                  const long &lparam,
                  const double &dparam,
                  const string &sparam)
  {
   if(id==CHARTEVENT_KEYDOWN){
    switch(lparam)
        {
            case KEY_RIGHT:
               {
                symbolIndex++; 
                string nextSymbol = symbols[symbolIndex]; 
                ChartSetSymbolPeriod(0, nextSymbol, PERIOD_D1); 
                break;
                }
            case KEY_LEFT:
                {
                symbolIndex--; 
                string prevSymbol = symbols[symbolIndex]; // Get the previous symbol
                ChartSetSymbolPeriod(0, prevSymbol, PERIOD_D1); // Change the symbol of the chart
                break;
                }
            default:
                Print("Some not listed key has been pressed");
        }
    ChartRedraw();
   }
  }