Events for objects drawn on the chart

[Waxavi]

Hello,

I have looked on the forums and references for this feature, it seems it's not available by default.

I wonder if there's any third-party library I could use, or maybe there has been an update for it that I'm not aware of.

I would like events for:

DrawingTool Created
DrawingTool Deleted
DrawingTool Properties Changed

If this isn't available, can it be made a feature request?

Regards,

[NinjaTrader_Kate]

Hello Waxavi,

Thank you for your post.

The ChartScales has a ChartObjects object which is an observable collection and therefore has a CollectionChanged NotifyCollectionChangedEvent. One example of utilizing this may be found on this forum post:

https://ninjatrader.com/support/forum/forum/historical-beta-archive/version-8-beta/76389-insertcomplete?p=677423#post677423

I'm also including another example that uses this below. It can detect if a drawing tool is created, removed, or changed.

Please let us know if we may be of further assistance to you.

[Waxavi]

Hello Kate,

Edit
Thanks for replying, and excuse my ignorance, what should I replace "PropertyChangedDrawingToolExample" with? there's a missing reference.
If I replace it with Line, there's no "PropertyChanged" inside this object (Line 63), implementing this INotifyPropertyChanged to all tools is quite something

Would appreciate it if you could give me the complete sample.

Edit2: So it seems this adds "Spy" properties which I suppose wraps the properties I need inside a DrawingTool?

Regards,

[NinjaTrader_Kate]

Hello Waxavi,

Thank you for your reply.

The example script works for me without error - what is the error you are receiving?

Thanks in advance; I look forward to assisting you further.

[Waxavi]

Hello Kate,

I don't have "PropertyChangedDrawingToolExample", it's missing from the files, I guess it's a modified drawing tool.

[NinjaTrader_Kate]

Hello Waxavi,

Thank you for your reply.

Ah, I forgot there's an associated drawing tool script it needs. Here's an importable version with both the above example and that drawing tool script.

Please let us know if we may be of further assistance to you.

[Waxavi]

Thank you, Kate,
I think I can work with this

But I would like that these events would be available by default inside the API in the future.

Regards,

[Waxavi]

// I opted to use ChartObjects.CollectionChanged here to detect new drawing objects
// + subscribe to them in the HandleChartObjectsChanged method
// rather than do this in the performance killer i.e., OnRender()
if (ChartControl != null)
{
  foreach (ChartScale cs in ChartControl.ChartPanels.Where(x => x != null).SelectMany(cp => cp.Scales))
  {
     Print("Subscribing to HandleChartsObjectAdded");
     cs.ChartObjects.CollectionChanged += HandleChartObjectsChanged;
  }
  needsUnsubscribed = true;
}

Inside State.Configure, I would like to ask why does it need to subscribe to all ChartScales? I think it triggers the same event 3 times or more

[NinjaTrader_Kate]

Hello Waxavi,

Thank you for your reply.

That line is checking to see if an object was added to the ChartObjects for each price scale. It is necessary as a chart can have objects attached to the left, right or overlay scales.

Please let us know if we may be of further assistance to you.

[Waxavi]

Okay, I think all is good now, thanks for your help Kate

[Unsuitable]

Hello Waxavi/Kate,

Is there a way to know code an event so it knows when an object is done drawing?

The code on post #2 triggers the event when an object is initially created. The calculations require all anchors to be drawn. From my understanding the DrawObject.PropertyChanged can be used to make another event listener.

Below is the part where I get confused. Is the e.PropertyName actually IsSelectedSpy or DrawingStateSpy?

// this should be called anytime one of our "spy" properties from the drawing tool changes
        private void PropertyChangedInIndicator(object sender, PropertyChangedEventArgs e)
        {
            // we can filter through the property name to call various methods
            // Note: we set this property name during the DrawingTools "DoPropertyChanged()" method
            // if you want to add/change properties, please make sure to update its string
            switch (e.PropertyName)
            {
                case "IsSelectedSpy":
                {
                    DoWorkOnSelectionChanged(myLine.IsSelectedSpy);
                    break;
                }
                case "DrawingStateSpy":
                {
                    DoWorkOnDrawingStateChanged(myLine.DrawingStateSpy);
                    break;
                }
                
            }
        }​

Then the next part (down below) makes sense. Do stuff based on the state. This is the part where the calculations would be made

// do something when drawing state changes
        private void DoWorkOnDrawingStateChanged(DrawingState drawingState)
        {
            if (drawingState == DrawingState.Building)
            {
                Print("Do Building State work");
            }
            if (drawingState == DrawingState.Editing)
            {
                Print("Do Editing State work");
                myLine.Stroke.Brush = Brushes.Red;
            }
            if (drawingState == DrawingState.Moving)
            {
                Print("Do Moving State work");
                myLine.Stroke.Brush = Brushes.Purple;
            }
            if (drawingState == DrawingState.Normal)
            {
                Print("Do Normal State work");
                myLine.Stroke.Brush = Brushes.Yellow;
            }
        }​

So does e.PropertyName actually return IsSelectedSpy or DrawingStateSpy or are these custom drawing tool properties? My goal is to call a method once the new Risk Reward tool is done drawing (or in DrawingState.Normal)

Best regards,
Unsuitable

[NinjaTrader_ChelseaB]

Hello Unsuitable,

DrawingStateSpy is an added public variable that when set from OnMouseDown on line 90 calls DoPropertyChanged() on line 44 which triggers the PropertyChangedEvent on line 69.
This event is what the indicator is subscribed to on line 63.

The e.PropertyName would be referring to the DrawingStateSpy property which is updating with the PropertyChangedEvent.

[Unsuitable]

Hello ChelseaB,

I see where the confusion is. The example above uses a custom drawing tool. In my case I would like to capture the properties of the a Risk Reward tool once it's done drawing.

Best regards,

Unsuitable

[NinjaTrader_ChelseaB]

Hello Unsuitable,

You would need to make a copy of the RiskReward drawing tool and modify this to add the property changed handling demonstrated in this example.

[Unsuitable]

Hello Chelsea_B,

Right, that's not ideal.

Here's a sudo solution. Have the code use the event listener for changes in DrawObjects. Filter for states. If its building then store the object. Then in OnBarUpdate, check to see if the stored object is null. If it it's not, keep checking the drawing state until its normal. At which point run the appropriate code and set the stored object pointer back to null.

I figured if OnBarUpdate gets called regardless if the there's code in there or not (assumption), do one more check and see if the code should compute the relevant data.

The only other solution I could think pf would be to launch an event listener for the next mouse click on the chart. However, that's not as explicit as it assumes the next click will complete the Risk Reward drawing. Plus it may be over engineering the problem.

Best regards,

Unsuitable