//+------------------------------------------------------------------+
//|                   Article-22742-EquiVolume-Indicator-In-MQL5.mq5 |
//|                                             Abioye Israel Pelumi |
//|                                              https://Algoyin.com |
//+------------------------------------------------------------------+
#property indicator_separate_window
#property indicator_plots 0

//--- Input parameters
input int    InpLookback       = 100;            // number of bars for EquiVolume
input color  InpBullColor      = clrDodgerBlue;  // bullish bar color (close >= open)
input color  InpBearColor      = clrTomato;      // bearish bar color (close < open)
input color  InpOutlineColor   = clrGray;        // rectangle outline color
input double InpMaxWidthPct    = 10;             // maximum box width scaling factor

//--- Global variables
int indicator_window;                           // indicator subwindow index
datetime lastTradeBarTime = 0;                  // ensures logic runs once per new candle

//+------------------------------------------------------------------+
//| Returns unique empty box object name                             |
//+------------------------------------------------------------------+
string BoxEmptyName(datetime t)
  {
   return StringFormat("Box%d", (int)t);
  }

//+------------------------------------------------------------------+
//| Returns unique filled box object name                            |
//+------------------------------------------------------------------+
string BoxFillName(datetime t)
  {
   return StringFormat("Box Fill%d", (int)t);
  }

//+------------------------------------------------------------------+
//| Create or update volume box                                      |
//+------------------------------------------------------------------+
bool DrawBox(const string name,
             datetime x1, double yTop,
             datetime x2, double yBot, bool is_fill,
             color Col, int in_window)
  {
   bool created = false;

//--- create rectangle object only if it does not exist
   if(ObjectFind(0, name) < 0)
     {
      ObjectCreate(0, name, OBJ_RECTANGLE, in_window, x1, yTop, x2, yBot);

      //--- configure rectangle properties
      ObjectSetInteger(0, name, OBJPROP_FILL, is_fill);
      ObjectSetInteger(0, name, OBJPROP_COLOR, Col);

      created = true;
     }

//--- continuously update rectangle coordinates
   ObjectMove(0, name, 0, x1, yTop);
   ObjectMove(0, name, 1, x2, yBot);

   return created;
  }

//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int OnInit()
  {
//--- set indicator short name
   IndicatorSetString(INDICATOR_SHORTNAME, "EquiVolume");

//--- locate indicator subwindow
   indicator_window = ChartWindowFind(ChartID(), "EquiVolume");

//--- remove old box objects during initialization
   ObjectsDeleteAll(0, "Box", indicator_window);

//---
   return(INIT_SUCCEEDED);
  }

//+------------------------------------------------------------------+
//| Deinitialization                                                 |
//+------------------------------------------------------------------+
void OnDeinit(const int reason)
  {
//--- delete all indicator objects during cleanup
   ObjectsDeleteAll(0, "Box", indicator_window);
  }

//+------------------------------------------------------------------+
//| Custom indicator iteration function                              |
//+------------------------------------------------------------------+
int OnCalculate(const int32_t rates_total,
                const int32_t 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 int32_t &spread[])
  {
//--- limit processing to selected lookback range
   int bars = MathMin(rates_total, InpLookback);

//--- ensure enough bars are available
   if(bars < 2)
      return rates_total;

   bool need_redraw = false;

   datetime currentBarTime = iTime(_Symbol, PERIOD_CURRENT, 0);

//--- execute logic only once per new candle
   if(currentBarTime != lastTradeBarTime)
     {
      //--- check whether broker provides real volume
      bool useRealVol = (volume[rates_total - 1] > 0);
      int startIdx = rates_total - bars;

      long maxVol  = 0;                         // highest volume in range
      double maxHigh = 0;                       // highest price in range
      double minLow = low[startIdx];            // lowest price in range

      //--- scan candles to determine volume and price boundaries
      for(int i = startIdx; i < rates_total; i++)
        {

         long vol = useRealVol ? volume[i] : tick_volume[i];

         //--- track maximum volume
         if(vol > maxVol)
            maxVol = vol;

         //--- track highest price
         double h = high[i];
         if(h > maxHigh)
            maxHigh = high[i];

         //--- track lowest price
         double l = low[i];
         if(l < minLow)
            minLow = low[i];
        }

      //--- adjust indicator scale dynamically
      IndicatorSetDouble(INDICATOR_MAXIMUM, maxHigh);
      IndicatorSetDouble(INDICATOR_MINIMUM, minLow);

      //--- prevent division by zero
      if(maxVol == 0)
         return rates_total;

      //--- retrieve timeframe duration in seconds
      datetime periodSec = (datetime)PeriodSeconds();

      datetime start_time = time[rates_total - 1]; // starting point of current box
      datetime end_time = 0;

      //--- process candles backward
      for(int i = rates_total - 2; i >= startIdx; i--)
        {
         long vol = useRealVol ? volume[i] : tick_volume[i];

         //--- skip candles with zero volume
         if(vol == 0)
            continue;

         //--- normalize width relative to highest volume
         int val = (int)((double)vol / maxVol * InpMaxWidthPct);

         //--- calculate horizontal width endpoint
         end_time = start_time - (periodSec * val);

         //--- draw candle outline rectangle
         if(DrawBox(BoxEmptyName(time[i]), start_time, high[i], end_time, low[i], false, InpOutlineColor, indicator_window))
           {
            need_redraw = true;
           }

         //--- determine candle direction
         bool bullish = (close[i] >= open[i]);

         //--- select fill color based on candle direction
         color fillCol = bullish ? InpBullColor : InpBearColor;

         //--- draw candle body rectangle
         if(DrawBox(BoxFillName(time[i]), start_time, open[i], end_time, close[i], true, fillCol, indicator_window))
           {
            need_redraw = true;
           }

         //--- shift next rectangle starting point
         start_time = end_time;

         //--- remove outdated objects outside visible range
         for(int i = ObjectsTotal(0, indicator_window)-1; i >= 0; i--)
           {
            string obj_name = ObjectName(0, i);

            if((datetime)ObjectGetInteger(0, obj_name, OBJPROP_TIME, 0) < end_time)
              {
               ObjectDelete(0, obj_name);

               need_redraw = true;
              }
           }
        }

      //--- update last processed candle time
      lastTradeBarTime = currentBarTime;
     }
//--- redraw chart only when changes occur
   if(need_redraw)
      ChartRedraw(0);

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