ReferencesCommonDrawing

DrawObjects

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Definition

A collection holding all of the drawn chart objects on the chart, for all series. The draw objects can be manually drawn or script generated objects.

  • 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.
  • DrawObjects.ToList() is thread safe. DrawObjects collection itself is still dynamic (meaning it updates live) and as a result you can still run the risk of the collection being modified while you try to read it (and thus would see the related C# log entry). However, DrawObjects.ToList() is a snapshot of DrawObjects collection at the time the call is made.
  • Also please keep in mind that iterating over a large DrawObjects collection could have an impact on performance.
  • Draw objects are disposed (for example on chart closing) after State.Terminated is seen for your custom NinjaScript studies potentially working with those.

Property Value

A collection of IDrawingTool objects.

Syntax

DrawObjects*

DrawObjects[string tag]

DrawObjects.Count

Examples

Finding the draw object of a specific tag

1protected override void OnBarUpdate()
2{
3   if (DrawObjects["someTag"] != null && DrawObjects["someTag"] is DrawingTools.Line)
4   {
5     // Do something with the drawing tool line
6   }
7  
8   // An alternative approach to find the draw object by a tag
9   if (DrawObjects["someTag"] as DrawingTools.Line != null)
10   {
11     // Do something drawing tool line
12   }
13  
14   // Yet another way to find a drawing tool by a tag
15   if (DrawObjects["someTag"].GetType().Name == "Line")
16   {
17     // Do something drawing tool line
18   }
19}

Get the number of draw objects on a chart

1protected override void OnBarUpdate()
2{
3   if (DrawObjects.Count == 3)
4   {
5         // Do something
6   }
7}

Looping through the collection to find specific draw objects

1protected override void OnBarUpdate()
2{
3   // Loops through the DrawObjects collection via a threadsafe list copy
4   foreach (DrawingTool draw in DrawObjects.ToList())
5   {
6     // Finds line objects that are attached globally to all charts of the same instrument
7     if (draw.IsGlobalDrawingTool && draw is DrawingTools.Line)
8     {
9         DrawingTools.Line globalLine = draw as DrawingTools.Line;
10
11         // Changes the line color and prints its starting and end points
12         globalLine.Stroke.Brush = Brushes.Black;
13
14         Print("Start: " + globalLine.StartAnchor.SlotIndex + " End: " + globalLine.EndAnchor.SlotIndex);
15     }
16
17     // Finds non-global line objects
18     else if (draw is DrawingTools.Line)
19     {
20         // Indicates if this is a manually drawn or script generated line
21         Print("Line Object: " + draw.Tag + " Manually Drawn: " + draw.IsUserDrawn);
22     }
23   }
24}

Typecasting as in the example above will not function the same way in a compiled assembly (DLL). For an alternative approach, see the Considerations For Compiled Assemblies page.