How to detect hand-drawn lines

[turbofib]

hi,,

if i hand draw line , in OnBarUpdate i dont see it..(if price is not working )

I want to have the Drawing Object loader in every situation

i must to use OnRender method?

It true, how to use it? ...

Examples:

On render protected override void OnRender(ChartControl chartControl, ChartScale chartScale)
{

  foreach (DrawingTool draw in DrawObjects)
.......

}

i know this examples is not correct but i would to use this method correctly


(I practically i want to detect it at any time when i drawing )

[NinjaTrader_Jim]

Hello turbofib,

Thanks for opening the thread.

It would not be necessarily recommended to loop through collections in OnRender() as OnRender() can be called often in a short period of time. For example, when clicking and dragging on a chart.

I would suggest to check for the number of DrawObjects that are on the chart before looping through the collection. Another approach would be to use a custom event where you can check if the drawing objects have changed over a certain period of time.

Various ways to reference the DrawObjects collection in addition to checking the count can be found here: https://ninjatrader.com/support/help...rawobjects.htm

For information on using OnRender(), please see here: https://ninjatrader.com/support/help...e_onrender.htm

The bundled SampleCustomRender indicator provides a good example of using OnRender() for custom rendering.

An example NinjaScript for creating a custom event that triggers on a timer can be found here: http://ninjatrader.com/support/forum...ead.php?t=5965

Please let me know if I may be of further assistance.

[turbofib]

A question:

DrawObject is a list?

if i draw line,this is in the last list Position ?

DrawingTool draw1 = DrawObjects[DrawObject.count-1] ...is not correct ...it need String Not Int..


Can you help, thanks

[NinjaTrader_Jim]

Hello turbofib,

The DrawObjects collection should not be handled the same way as a list:

Note: When reloading NinjaScript, all objects (including manual drawing tools) are reloaded at the same time. There is no guarantee a manually drawn object will be added to the DrawObjects collection before an indicator starts processing data.

Considering this implication, it would not be advised to try and reference the last item in the collection.

There is an example in the help guide that demonstrates how to reference a DrawObject by the DrawObject's tag. This is the string that is expected in your syntax.

protected override void OnBarUpdate()
{
  if (DrawObjects["someTag"] != null && DrawObjects["someTag"] is DrawingTools.Line)
  {
    // Do something with the drawing tool line
  }       
 
  // An alternative approach to find the draw object by a tag
  if (DrawObjects["someTag"] as DrawingTools.Line != null)
  {
    // Do something drawing tool line
  }   
 
  // Yet another way to find a drawing tool by a tag
  if (DrawObjects["someTag"].GetType().Name == "Line")
  {
    // Do something drawing tool line 
  }
}

You could check if the Count property changes, and if it does you can update a list that you manage that keeps track of the tags added so you can identify a newly added DrawObject.

[turbofib]

ah ok...i need to create a list...in this list i store all tag of draw...
Is correct?


can you give me information how i can to read last element of DrawObjects ? thanks

[NinjaTrader_Jim]

Hello turbofib,

Yes, I would suggest to keep track of the tags for each drawing object in a list so when you see the count change, you can see which tag in the collection doesn't match a tag saved in your list. That will be the most recently added DrawObject.

I would recommend to compare tags to identify DrawObjects that have been recently added because of the stipulation noted in the help guide. Referencing a "last" drawing object in another way would not be guaranteed after reloading the NinjaScript with F5.

Here is a rough example outlining how you can loop through a collection of DrawObjects and the list you manage to see which DrawObject is added. This code is only meant to convey an idea and is is not intended to be used directly in a script.

List<string> myList = new List<string>();
if (DrawObjects.Count > lastCount)
{
	foreach (DrawingTool draw in DrawObjects)
	{
	    foreach( string ListedTag in myList)
	    {
	        if (ListedTag != draw.Tag)
			myList.Add(draw.Tag);
	    }
	}
}

[turbofib]

ok ....i understand it...
but i ask you another question :

can you give me information how i can to read last element of DrawObjects ? (i want find it but without loop it)

(i don't use it in a code..ok.....)

[NinjaTrader_Jim]

Hello turbofib,

I did not want to provide instruction because using the Last() method of the collection would not always guarantee the last item. If you press F5, the order of the DrawObjects could come out of order. It may not be an adequate solution.

You may try getting the last IDrawingTool in the collection by referencing the Last() method to see if you it will work for you:

IDrawingTool myDrawingTool = DrawObjects.Last();

[turbofib]

last question :

When I press the first point to draw the line, the drawobject counter is incremented ......
I just want to find out when the line is over at 2 points

how i do it?

[NinjaTrader_Jim]

Hello turbofib,

Thanks of the additional question.

Since DrawObjects is a collection of IDrawingTools, you can use additional logic to check if the IDrawingTool is a certain type, and you can use the properties of the IDrawingTool to limit certain actions as well.

For example, you could check if the DrawingState of the draw object is in a Normal state, or you could check the Anchors of the IDrawingTool to see if any Anchors are editing.

Here are a couple examples:

foreach (DrawingTool draw in DrawObjects)
{
	if (draw is DrawingTools.Line)
	{
		DrawingTools.Line myLine = draw as DrawingTools.Line;
		if (myLine.DrawingState == DrawingState.Normal)
			Print("myLine complete.");		
	}
}

foreach (DrawingTool draw in DrawObjects)
{
	if (draw is DrawingTools.Line)
	{
		bool lineComplete = true; 
		DrawingTools.Line myLine = draw as DrawingTools.Line;
		        
		if(myLine.Anchors.Count() == 2)
			foreach (ChartAnchor anchor in myLine.Anchors)
				if(anchor.IsEditing)
					lineComplete = false;
		if (lineComplete)
			Print("myLine complete.");
	}
}

These properties are listed and documented here:

IDrawingTool - http://ninjatrader.com/support/helpG...rawingtool.htm

DrawingState - http://ninjatrader.com/support/helpG...awingstate.htm

ChartAnchor - http://ninjatrader.com/support/helpG...hartanchor.htm