Reusing DX brushes in OnRender()

[Zeos6]

Hi,

I have an efficiency/performance question regarding reusing DX brushes during calls to OnRender().

I understand that it is not efficient to recreate brushes during each call to OnRender(). This leaves me with two options:

Option A:
Inside OnRender() I can set

SharpDX.Direct2D1.Brush areaBrushDX = areaBrush.ToDxBrush(RenderTarget);
SharpDX.Direct2D1.Brush textBrushDX  = textBrush.ToDxBrush(RenderTarget);

and dispose of the brushes at the end of OnRender().

Alternatively, I can have

Option B:
Inside OnRenderTargetChanged() I can set

        public override void OnRenderTargetChanged()
        {
            if (areaBrushDx != null)
                areaBrushDx.Dispose();

            if (textBrushDx != null)
                textBrushDx.Dispose();

            if (RenderTarget != null)
            {
                try
                {
                    areaBrushDx            = areaBrush.ToDxBrush(RenderTarget);
                    textBrushDx            = textBrush.ToDxBrush(RenderTarget);
                }
                catch (Exception e) { }
            }
        }

I have two questions:
1. Which option is most efficient in terms of resources and performance?
2. Which option should be used if you have a lot of brushes you need to use?

Thank you.

[NinjaTrader_ChelseaB]

Hello Zeos6,

It is most efficient to create the brushes when the render target changes in OnRenderTargetChanged() when it is necessary to.

[Harry]

You may easily test the case by inserting print instructions in both OnRender and OnRenderTargetChanged.

Have a look at the output window, and you will exactly know when OnRenderTargetChanged() and OnRender() are being called.

As OnRender() is being called many more times than OnRenderTargetChanged(), it is best practice to create and dispose of DX brushes in OnRenderTargetChanged(). This is particularly true, as conversion of System.Media.Brushes to DX brushes is an "expensive" process.

Thank you for posting this question, as I am sure that other users will appreciate this question as well.

[Zeos6]

Thank you ChelseaB and Harry. Harry, I appreciate the information and your insight on this matter. I already handle strokes via OnRenderTargetChanged() so I will simply add handling brushes here as well. Thank you once again.

[Harry]

NT 8.0.14 breaks all our indicators with custom OnRender() sections

It seems that NT 8.0.14 has broken all our indicators that use OnRenderTargetChanged() to set and dispose of DX brushes.

All indicators that follow the approach of declaring DX brushes in the variables section, then set DX brushes in OnRenderTargetChanged() and access those brushes in OnRender() are throwing exceptions most of the time.

We are also seeing issue with synchronization between State.Configure() and OnRenderTargetChanged(), as OnRenderTargetChanged() is called prior to the completion of State.Configure.

The behavior is specific to the release NT 8.0.14.1 and did not occur with prior releases.

Beware of release NT 8.0.14.1!

This is a huge desaster, as nothing works anymore.

NT 8.0.13.1 was just fine and did not show this behavior.