NinjaScript > Language Reference > Common > Drawing

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.

Notes:

•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
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 } }

Finding the draw object of a specific tag

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
}
}

Get the number of draw objects on a chart
protected override void OnBarUpdate() { if (DrawObjects.Count == 3) { // Do something } }

Looping through the collection to find specific draw objects
protected override void OnBarUpdate() { // Loops through the DrawObjects collection via a threadsafe list copy foreach (DrawingTool draw in DrawObjects.ToList()) { // Finds line objects that are attached globally to all charts of the same instrument if (draw.IsGlobalDrawingTool && draw is DrawingTools.Line) { DrawingTools.Line globalLine = draw as DrawingTools.Line; // Changes the line color and prints its starting and end points globalLine.Stroke.Brush = Brushes.Black; Print("Start: " + globalLine.StartAnchor.SlotIndex + " End: " + globalLine.EndAnchor.SlotIndex); } // Finds non-global line objects else if (draw is DrawingTools.Line) { // Indicates if this is a manually drawn or script generated line Print("Line Object: " + draw.Tag + " Manually Drawn: " + draw.IsUserDrawn); } } }

Looping through the collection to find specific draw objects

protected override void OnBarUpdate()
{
// Loops through the DrawObjects collection via a threadsafe list copy
foreach (DrawingTool draw in DrawObjects.ToList())
{
// Finds line objects that are attached globally to all charts of the same instrument
if (draw.IsGlobalDrawingTool && draw is DrawingTools.Line)
{
DrawingTools.Line globalLine = draw as DrawingTools.Line;

// Changes the line color and prints its starting and end points
globalLine.Stroke.Brush = Brushes.Black;

Print("Start: " + globalLine.StartAnchor.SlotIndex + " End: " + globalLine.EndAnchor.SlotIndex);
}

// Finds non-global line objects
else if (draw is DrawingTools.Line)
{
// Indicates if this is a manually drawn or script generated line
Print("Line Object: " + draw.Tag + " Manually Drawn: " + draw.IsUserDrawn);
}
}
}

Note: 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.