MQL5 ReferenceConstants, Enumerations and StructuresChart ConstantsTypes of Chart Events

Types of Chart Events

There are 11 types of events that can be processed using the predefined function OnChartEvent(). For custom events 65535 identifiers are provided in the range of CHARTEVENT_CUSTOM to CHARTEVENT_CUSTOM_LAST inclusive. To generate a custom event, the EventChartCustom() function should be used.

ENUM_CHART_EVENT

ID	Description
CHARTEVENT_KEYDOWN	Keystrokes
CHARTEVENT_MOUSE_MOVE	Mouse move, mouse clicks (if CHART_EVENT_MOUSE_MOVE=true is set for the chart)
CHARTEVENT_MOUSE_WHEEL	Pressing or scrolling the mouse wheel (if CHART_EVENT_MOUSE_WHEEL=True for the chart)
CHARTEVENT_OBJECT_CREATE	Graphical object created (if CHART_EVENT_OBJECT_CREATE=true is set for the chart)
CHARTEVENT_OBJECT_CHANGE	Graphical object property changed via the properties dialog
CHARTEVENT_OBJECT_DELETE	Graphical object deleted (if CHART_EVENT_OBJECT_DELETE=true is set for the chart)
CHARTEVENT_CLICK	Clicking on a chart
CHARTEVENT_OBJECT_CLICK	Clicking on a graphical object
CHARTEVENT_OBJECT_DRAG	Drag and drop of a graphical object
CHARTEVENT_OBJECT_ENDEDIT	End of text editing in the graphical object Edit
CHARTEVENT_CHART_CHANGE	Change of the chart size or modification of chart properties through the Properties dialog
CHARTEVENT_CUSTOM	Initial number of an event from a range of custom events
CHARTEVENT_CUSTOM_LAST	The final number of an event from a range of custom events

For each type of event, the input parameters of the OnChartEvent() function have definite values that are required for the processing of this event. The events and values passed through this parameters are listed in the below table.

Event	Value of the id parameter	Value of the lparam parameter	Value of the dparam parameter	Value of the sparam parameter
Event of a keystroke	CHARTEVENT_KEYDOWN	code of a pressed key	Repeat count (the number of times the keystroke is repeated as a result of the user holding down the key)	The string value of a bit mask describing the status of keyboard buttons
Mouse events (if CHART_EVENT_MOUSE_MOVE=true is set for the chart)	CHARTEVENT_MOUSE_MOVE	the X coordinate	the Y coordinate	The string value of a bit mask describing the status of mouse buttons
Mouse wheel event (if CHART_EVENT_MOUSE_WHEEL=true for the chart)	CHARTEVENT_MOUSE_WHEEL	Flags of states of keys and mouse buttons, the X and Y coordinates of the mouse pointer. See description in the example below	The Delta value of the mouse wheel scroll	—
event of graphical object creation (if CHART_EVENT_OBJECT_CREATE=true is set for the chart)	CHARTEVENT_OBJECT_CREATE	—	—	Name of the created graphical object
Event of change of an object property via the properties dialog	CHARTEVENT_OBJECT_CHANGE	—	—	Name of the modified graphical object
Event of graphical object deletion (if CHART_EVENT_OBJECT_DELETE=true is set for the chart)	CHARTEVENT_OBJECT_DELETE	—	—	Name of the deleted graphical object
Event of a mouse click on the chart	CHARTEVENT_CLICK	the X coordinate	the Y coordinate	—
Event of a mouse click in a graphical object belonging to the chart	CHARTEVENT_OBJECT_CLICK	the X coordinate	the Y coordinate	Name of the graphical object, on which the event occurred
Event of a graphical object dragging using the mouse	CHARTEVENT_OBJECT_DRAG	—	—	Name of the moved graphical object
Event of the finished text editing in the entry box of the LabelEdit graphical object	CHARTEVENT_OBJECT_ENDEDIT	—	—	Name of the LabelEdit graphical object, in which text editing has completed
Event of change of the chart size or modification of chart properties through the Properties dialog	CHARTEVENT_CHART_CHANGE	—	—	—
ID of the user event under the N number	CHARTEVENT_CUSTOM+N	Value set by the EventChartCustom() function	Value set by the EventChartCustom() function	Value set by the EventChartCustom() function

Example:

#define KEY_NUMPAD_5       12
#define KEY_LEFT           37
#define KEY_UP             38
#define KEY_RIGHT          39
#define KEY_DOWN           40
#define KEY_NUMLOCK_DOWN   98
#define KEY_NUMLOCK_LEFT  100
#define KEY_NUMLOCK_5     101
#define KEY_NUMLOCK_RIGHT 102
#define KEY_NUMLOCK_UP    104
//+------------------------------------------------------------------+
//| Expert initialization function                                   |
//+------------------------------------------------------------------+
int OnInit()
  {
//---
   Print("The expert with name ",MQL5InfoString(MQL5_PROGRAM_NAME)," is running");
//--- enable object create events
   ChartSetInteger(ChartID(),CHART_EVENT_OBJECT_CREATE,true);
//--- enable object delete events
   ChartSetInteger(ChartID(),CHART_EVENT_OBJECT_DELETE,true);
//--- forced updating of chart properties ensures readiness for event processing
   ChartRedraw();
//---
   return(INIT_SUCCEEDED);
  }
//+------------------------------------------------------------------+
//| ChartEvent function                                              |
//+------------------------------------------------------------------+
void OnChartEvent(const int id,         // Event identifier
                  const long& lparam,   // Event parameter of long type
                  const double& dparam, // Event parameter of double type
                  const string& sparam  // Event parameter of string type
                  )
  {
//--- the left mouse button has been pressed on the chart
   if(id==CHARTEVENT_CLICK)
     {
      Print("The coordinates of the mouse click on the chart are: x = ",lparam,"  y = ",dparam);
     }
//--- the mouse has been clicked on the graphic object
   if(id==CHARTEVENT_OBJECT_CLICK)
     {
      Print("The mouse has been clicked on the object with name '"+sparam+"'");
     }
//--- the key has been pressed
   if(id==CHARTEVENT_KEYDOWN)
     {
      switch(lparam)
        {
         case KEY_NUMLOCK_LEFT:  Print("The KEY_NUMLOCK_LEFT has been pressed");   break;
         case KEY_LEFT:          Print("The KEY_LEFT has been pressed");           break;
         case KEY_NUMLOCK_UP:    Print("The KEY_NUMLOCK_UP has been pressed");     break;
         case KEY_UP:            Print("The KEY_UP has been pressed");             break;
         case KEY_NUMLOCK_RIGHT: Print("The KEY_NUMLOCK_RIGHT has been pressed");  break;
         case KEY_RIGHT:         Print("The KEY_RIGHT has been pressed");          break;
         case KEY_NUMLOCK_DOWN:  Print("The KEY_NUMLOCK_DOWN has been pressed");   break;
         case KEY_DOWN:          Print("The KEY_DOWN has been pressed");           break;
         case KEY_NUMPAD_5:      Print("The KEY_NUMPAD_5 has been pressed");       break;
         case KEY_NUMLOCK_5:     Print("The KEY_NUMLOCK_5 has been pressed");      break;
         default:                Print("Some not listed key has been pressed");
        }
      ChartRedraw();
     }
//--- the object has been deleted
   if(id==CHARTEVENT_OBJECT_DELETE)
     {
      Print("The object with name ",sparam," has been deleted");
     }
//--- the object has been created
   if(id==CHARTEVENT_OBJECT_CREATE)
     {
      Print("The object with name ",sparam," has been created");
     }
//--- the object has been moved or its anchor point coordinates has been changed
   if(id==CHARTEVENT_OBJECT_DRAG)
     {
      Print("The anchor point coordinates of the object with name ",sparam," has been changed");
     }
//--- the text in the Edit of object has been changed
   if(id==CHARTEVENT_OBJECT_ENDEDIT)
     {
      Print("The text in the Edit field of the object with name ",sparam," has been changed");
     }
  }

For CHARTEVENT_MOUSE_MOVE event the sparam string parameter contains information about state of the keyboard and mouse buttons:

Bit	Description
1	State of the left mouse button
2	State of the right mouse button
3	State of the SHIFT button
4	State of the CTRL button
5	State of the middle mouse button
6	State of the first extra mouse button
7	State of the second extra mouse button

Example:

//+------------------------------------------------------------------+
//| Expert initialization function                                   |
//+------------------------------------------------------------------+
void OnInit()
  {
//--- enable CHART_EVENT_MOUSE_MOVE messages
   ChartSetInteger(0,CHART_EVENT_MOUSE_MOVE,1);
//--- disable the context menu of the chart (on the right)
   ChartSetInteger(0,CHART_CONTEXT_MENU,0);
//--- disable the crosshair (by the middle button)
   ChartSetInteger(0,CHART_CROSSHAIR_TOOL,0);
//--- forced updating of chart properties ensures readiness for event processing
   ChartRedraw();
  }
//+------------------------------------------------------------------+
//| MouseState                                                       |
//+------------------------------------------------------------------+
string MouseState(uint state)
  {
   string res;
   res+="\nML: "   +(((state& 1)== 1)?"DN":"UP");   // mouse left
   res+="\nMR: "   +(((state& 2)== 2)?"DN":"UP");   // mouse right
   res+="\nMM: "   +(((state&16)==16)?"DN":"UP");   // mouse middle
   res+="\nMX: "   +(((state&32)==32)?"DN":"UP");   // mouse first X key
   res+="\nMY: "   +(((state&64)==64)?"DN":"UP");   // mouse second X key
   res+="\nSHIFT: "+(((state& 4)== 4)?"DN":"UP");   // shift key
   res+="\nCTRL: " +(((state& 8)== 8)?"DN":"UP");   // control key
   return(res);
  }
//+------------------------------------------------------------------+
//| ChartEvent function                                              |
//+------------------------------------------------------------------+
void OnChartEvent(const int id,const long &lparam,const double &dparam,const string &sparam)
  {
   if(id==CHARTEVENT_MOUSE_MOVE)
      Comment("POINT: ",(int)lparam,",",(int)dparam,"\n",MouseState((uint)sparam));
  }

For the CHARTEVENT_MOUSE_WHEEL event, parameters lparam and dparam contain information about the states of the Ctrl and Shift keys, of mouse buttons, cursor coordinates and the mouse wheel scroll value. For a better understanding, run this Expert Advisor on a chart and scroll the mouse wheel, while pressing different buttons and holding down the keys described in the code.

Example of CHARTEVENT_MOUSE_WHEEL event processing:

//+------------------------------------------------------------------+
//| Expert initialization function                                   |
//+------------------------------------------------------------------+
init OnInit()
  {
//--- Enabling mouse wheel scrolling messages
   ChartSetInteger(0,CHART_EVENT_MOUSE_WHEEL,1);
//--- Forced updating of chart properties ensures readiness for event processing
   ChartRedraw();
//---
   return(INIT_SUCCEEDED);
  }
//+------------------------------------------------------------------+
//| ChartEvent function                                              |
//+------------------------------------------------------------------+
void OnChartEvent(const int id,const long &lparam,const double &dparam,const string &sparam)
  {
   if(id==CHARTEVENT_MOUSE_WHEEL)
     {
      //--- Consider the state of mouse buttons and wheel for this event
      int flg_keys = (int)(lparam>>32);          // The flag of states of the Ctrl and Shift keys, and mouse buttons
      int x_cursor = (int)(short)lparam;         // the X coordinate where the mousse wheel event occurred
      int y_cursor = (int)(short)(lparam>>16);   // the Y coordinate where the mousse wheel event occurred
      int delta    = (int)dparam;                // the total value of mouse scroll, triggers when +120 or -120 is reached
      //--- Processing the flag
      string str_keys="";
      if((flg_keys&0x0001)!=0) str_keys+="LMOUSE ";
      if((flg_keys&0x0002)!=0) str_keys+="RMOUSE ";
      if((flg_keys&0x0004)!=0) str_keys+="SHIFT ";
      if((flg_keys&0x0008)!=0) str_keys+="CTRL ";
      if((flg_keys&0x0010)!=0) str_keys+="MMOUSE ";
      if((flg_keys&0x0020)!=0) str_keys+="X1MOUSE ";
      if((flg_keys&0x0040)!=0) str_keys+="X2MOUSE ";

      if(str_keys!="")
         str_keys=", keys='"+StringSubstr(str_keys,0,StringLen(str_keys)-1) + "'";
      PrintFormat("%s: X=%d, Y=%d, delta=%d%s",EnumToString(CHARTEVENT_MOUSE_WHEEL),x_cursor,y_cursor,delta,str_keys);
     }
  }
//+------------------------------------------------------------------+ /*
   Example of the output
   CHARTEVENT_MOUSE_WHEEL: Ctrl pressed: X=193, Y=445, delta=-120
   CHARTEVENT_MOUSE_WHEEL: Shift pressed: X=186, Y=446, delta=120
   CHARTEVENT_MOUSE_WHEEL:  X=178, Y=447, delta=-120
   CHARTEVENT_MOUSE_WHEEL:  X=231, Y=449, delta=120
   CHARTEVENT_MOUSE_WHEEL: MiddleButton pressed: X=231, Y=449, delta=120
   CHARTEVENT_MOUSE_WHEEL: LeftButton pressed: X=279, Y=320, delta=-120
   CHARTEVENT_MOUSE_WHEEL: RightButton pressed: X=253, Y=330, delta=120  */