About Drawing Object Classes

The EasyLanguage drawing object classes allow you to create drawing objects on a chart from your analysis technique and to programmatically manage their appearance and position. The trendline and text objects parallel the functionality of the legacy EasyLanguage TL_xxx and Text_xxx reserved words. The Ellipse, HorizontalLine, Rectangle, and Vertical line objects are equivalent to the drawing tools you were able to manually insert in a chart.

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EasyLanguage Drawing Objects


Drawing Object Classes

  • Ellipse - Draws an ellipse based on two points, the starting point at the upper left and the ending point at the lower right of a bounding rectangular area. The border line and fill pattern characteristics can be user specified.
  • HorizontalLine - Draws a horizontal line that intersects a specified price. The line style and thickness can be user specified.
  • Rectangle - Draws a rectangle based on two points, the starting point at the upper left and the ending point at the lower right corner of the rectangle. The border line and fill pattern characteristics can be user specified.
  • Text - Displays a text string at a specified point. The font style and horizontal/vertical centering can be user specified.
  • TrendLine - Draws a trendline between two points, the starting point and the ending point. The line characteristics and left/right extension properties can be user specified.
  • VerticalLine - Draws a vertical line that intersects a specified time interval. The line style and thickness can be user specified.

Point Classes

  • BNPoint - Used to define a drawing object point based on a bar number and a price value. Objects positioned with a BNPoint will move along with the bars they are anchored to.
  • DTPoint - Used to define a drawing object point based on a bar date/time stamp and a price value. Objects positioned with a DTPoint will move along with the bars they are anchored to.
  • XYPoint - Used to define a drawing object (Ellipse, Rectangle, or Text) point based on a chart X and Y location (relative to the upper left corner of the chart window). Objects positioned with an XYPoint will not move when the bars are scrolled.
Adding Drawing Objects to your EasyLanguage Code

   To use EasyLanguage drawing objects, you should have the following elements:  

  • Declare a variable for each type of object to be used. The class type of each variable must be appropriate for the object it will reference. Remember to include the namespace identifier "elsystem.drawingtools" in front of the specific class type unless you have previously added a 'using' statement for the namespace.  In this example, "myHorizLine1" and "myTrendLine1" are the names of the variables being created for each drawing object type.

using elsystem.drawingobjects;

using elsystem;

vars: HorizontalLine myHorizLine1(null), // declare myHorizLine1 as a HorizontalLine type

TrendLine myTrendLine1(null), // declare myTrendLine1 as a TrendLine type

BNPoint BNPoint1(null), BNPoint BNPoint2(null);// declare bar number points 1 & 2

  • Create an instance of each drawing object at the point locations specified.

myHorizLine1 = HorizontalLine.Create(last-.02); // create a horizontal line at .02 below the last price

myPoint1 = BNPoint.Create(barnumber-10,close[10]);// create first trendline point 10 bars to the left of the current bar

myPoint2 = BNPoint.Create(barnumber,close); // create second trendline point at current bar

myTrendLine1 = TrendLine.Create(myPoint1,myPoint2 ); // create a trend line and assign it to myTrendLine

(Note that you can also create the above trendline without needing to define BNPoint objects by directly specifying the BNPoint values when creating the trendline instance)


myTrendLine1 = TrendLine.Create(BNPoint.Create(barnumber-10,close[10]),BNPoint.Create(barnumber,close));

  • Add drawing objects (e.g. TrendLine, HorizontalLine) to a the DrawingObjects property of the AnalysisTechnique

DrawingObjects.Add(myHorizLine1);

DrawingObjects.Add(myTrendLine1);

  • Associate an event handler with the objects (to call the DOClick method when either drawing object is clicked).

myHorizLine1.Click += DOClick;

myTrendLine1.Click += DOClick;

  • Finally, write the method(s) to be called when a drawing object click event happens.

method void DOClick( Object sender,DrawingObjectEventArgs args)

begin

// Your EasyLanguage code to handle a drawing object that has been clicked

end;

Alerts with Drawing Objects

You can set alerts for TrendLine, HorizontalLine, and VerticalLine drawing objects so that they will notify you when specified alert criteria occur.

Refer to Using Alert with Drawing Objects for more information and examples.

Inheritance Hierarchy

elsystem.Object

elsystem.drawingobjects.DrawingObject

elsystem.drawingobjects.[ClassType]