【MQL4】証拠金維持率の推移をサブウィンドウにグラフ表示するインジケーターの作り方について解説してみた(含み損の心理的キツさを可視化)

//+------------------------------------------------------------------+
//|                                   MarginLevelHistoryChart.mq4    |
//|                     Copyright 2026, FX-EA System Project Creator |
//|                        https://creator.fx-ea-system-project.com/ |
//+------------------------------------------------------------------+
#property copyright "Copyright 2026, FX-EA System Project Creator"
#property link      "https://creator.fx-ea-system-project.com/"
#property version   "1.00"
#property strict
#property indicator_separate_window
#property indicator_buffers 1
#property indicator_minimum 0
#property indicator_level1 200
#property indicator_level2 100
#property indicator_levelcolor clrGray

input double DangerLevel  = 100.0; // この値を下回ったら危険水域とみなす
input double WarningLevel = 200.0; // この値を下回ったら警戒水域とみなす

double MarginLevelBuffer[];
bool   Recording = false;

int OnInit()
  {
   SetIndexBuffer(0, MarginLevelBuffer);
   SetIndexStyle(0, DRAW_LINE, STYLE_SOLID, 2, clrDodgerBlue);
   SetIndexLabel(0, "証拠金維持率(%)");

   ObjectCreate(0, "MarginLevelHistoryLabel", OBJ_LABEL, 0, 0, 0);
   ObjectSetInteger(0, "MarginLevelHistoryLabel", OBJPROP_CORNER, CORNER_LEFT_UPPER);
   ObjectSetInteger(0, "MarginLevelHistoryLabel", OBJPROP_XDISTANCE, 10);
   ObjectSetInteger(0, "MarginLevelHistoryLabel", OBJPROP_YDISTANCE, 10);

   return(INIT_SUCCEEDED);
  }

void OnDeinit(const int reason)
  {
   ObjectDelete(0, "MarginLevelHistoryLabel");
  }

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[])
  {
   int start = (prev_calculated > 0) ? prev_calculated - 1 : 0;

   if(!Recording)
     {
      for(int i = start; i < rates_total; i++)
         MarginLevelBuffer[i] = EMPTY_VALUE;
      Recording = true;
     }

   double equity = AccountInfoDouble(ACCOUNT_EQUITY);
   double margin = AccountInfoDouble(ACCOUNT_MARGIN);
   double level;

   if(margin <= 0)
      level = EMPTY_VALUE; // ポジション無し。0を危険水域と誤判定しない
   else
      level = AccountInfoDouble(ACCOUNT_MARGIN_LEVEL);

   MarginLevelBuffer[rates_total - 1] = level;

   string status = "ポジション無し";
   if(level != EMPTY_VALUE)
     {
      if(level < DangerLevel)
         status = "危険水域";
      else if(level < WarningLevel)
         status = "警戒水域";
      else
         status = "安全水域";
     }

   ObjectSetString(0, "MarginLevelHistoryLabel", OBJPROP_TEXT,
                    "証拠金維持率: " + (level == EMPTY_VALUE ? "---" : DoubleToString(level, 1)) +
                    "%  [" + status + "]");

   return(rates_total);
  }