//+------------------------------------------------------------------+
//|                                                 zoom-hotkeys.mq4 |
//|                                                        binarytek |
//|                                    https://github.com/binarytek/ |
//+------------------------------------------------------------------+
#property copyright "binarytek"
#property link      "https://github.com/binarytek/"
#property version   "1.00"
#property strict
#property indicator_chart_window

#import "user32.dll"
//void keybd_event(int bVk,int bScan,int dwFlags,int dwExtraInfo);
void keybd_event(int bVirtualKey, int bScanCode, int dwFlags, int dwExtraInfo);
#import

input string note = ""; // Enter only one character to customize the keys for zooming
input string zoomInKey = "q";
input string zoomOutKey = "e";

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 value of prev_calculated for next call
   return(rates_total);
  }

void OnChartEvent(const int id,
                  const long &lparam,
                  const double &dparam,
                  const string &sparam) 
{
  if (id == CHARTEVENT_KEYDOWN) 
  {
    if (lparam == getKeyCode(zoomInKey)) 
    {
      keybd_event(189,0,0,0); //+ button out
    }

    if (lparam == getKeyCode(zoomOutKey)) 
    {
      //keybd_event(187,0,0,0); //- button in
         
      keybd_event(0x10, 0, 0, 0); 
      keybd_event(0xBB, 0, 0, 0); 
      keybd_event(0xBB, 0, 0x0002 , 0);
      keybd_event(0x10, 0, 0x0002 , 0); 
    }
  }
}

// Keycodes: http://help.adobe.com/en_US/AS2LCR/Flash_10.0/help.html?content=00000520.html
int getKeyCode(string val) {
   StringToUpper(val);
   return StringGetChar(val, 0);
}