Best way to dispose of a SharpDX brush used in a list

[cre8able]

I have a list that contains objects and I wanted to store the SharpDX brush color in the list so that instead of doing a ternary in OnRender to figure out the color, I can just call the correct color from the list

        public class FVG
        {
            public SharpDX.Direct2D1.Brush         DxBrushGap;    
            public SharpDX.Direct2D1.Brush         DxBrushGapBorder;    
            public SharpDX.Direct2D1.Brush         DxBrushIconBorder;    

            public int                    period;                        //        period for multi FVGs
            public int                    type;                        //        BULL        BEAR
            public bool                    showGap;                    //        YES            NO
            public int                    status;                        //        OPEN        InTRADE        EXPIRED        CLOSED
​

it works for coloring my objects, but what is the best way to dispose of the brush.

This is what I use for other brushes, but wasn't sure how to dispose the one that is in the list

        if (DxBrushWhite != null)            DxBrushWhite.Dispose();            
        DxBrushWhite            = new SharpDX.Direct2D1.SolidColorBrush(RenderTarget, SharpDX.Color.White);
​

here is the ternary code i was using, but i know I'm not supposed to do too much math inside OnRender.

      RenderTarget.FillRectangle(DxRectangle, bull ?     setupQuality == GOOD ? DxBrushCyan      : DxBrushTeal25  :
                                                         setupQuality == GOOD ? DxBrushMagenta     : DxBrushCrimson25);    
​

Help please....

[NinjaTrader_ChelseaB]

Hello cre8able,

The Brush should be disposed of in OnRenderTargetChanged.

Below is a link to an example.

https://forum.ninjatrader.com/forum/ninjatrader-8/indicator-development/98639-performance-optimization?p=789606#post789606

[cre8able]

hey Chelsea

I tried to follow the example, but am still confused on how to dispose of the dxBrush that is a part of my list. Here is a simplified version of what I am trying to do.

I create a list of rectangles with 3 properties. 1 property is the fill color which is a dxBrush


First I instantiate the brushes... by the way, I'm not a C# programmer so if I get syntax wrong, I appologize

        SharpDX.Direct2D1.Brush DxBrushWhite;    
        SharpDX.Direct2D1.Brush DxBrushGreen;    
​

then I create my class list where I create rectangleFillBrush but it's a part of the list, not a global brush.

        public class rect
        {
            public SharpDX.Direct2D1.Brush        rectangleFillBrush;
            public int                            rectangleWidth;
            public int                            rectangleHeight;
        }            
        private List<rect> rectOpen                     = new List<rect>();
​

In OnBarUpdate, I "decide" what color the fill is for each rectangle. Lets pretend I have other code that has created 20 rectangles in my list.

I cycle through each rectangle and assign is fill color

        protected override void OnBarUpdate()
        {            
            for (index = rectOpen.Count - 1; index >= 0 ; index--)
                    rectOpen[index].rectangleFillBrush = rectOpen[index].rectangleHeight > 10 ? DxBrushWhite : DxBrushGreen;
​

Then I would use OnRender to draw and fill in my rectangles.

I know !'m supposed to create and dispose of the brushes in OnRenderTargetChanged. I know how to do that with a "stand alone" brush like DxBrushWhite.

        public override void OnRenderTargetChanged()
        {
            
            if (DxBrushWhite != null)            
                DxBrushWhite.Dispose();            
            DxBrushWhite = new SharpDX.Direct2D1.SolidColorBrush(RenderTarget, SharpDX.Color.White);
            
            if (DxBrushGreen != null)            
                DxBrushGreen.Dispose();            
            DxBrushGreen = new SharpDX.Direct2D1.SolidColorBrush(RenderTarget, SharpDX.Color.Green);
            
            if (rectangleFillBrush != null)
                rectangleFillBrush.Dispose();        
​

But I can't dispose of "rectangleFillBrush" because it's a list field, not a general variable like DxBrushWhite.

I guess the first question is do I have to dispose of and recreate the rectangleFillBrush in the list? If not, then I'm fine


If I do have to dispose and re-create in OnRenderTargetChanged, how can I do that if its a part of a list... and how can I do it without losing the current color of the rectangleFillBrush for each of my different rectangles?

In my actual application, I have 100's of rectangles and some are "closed" so I can't re-run the OnBarUpdate code to find the color again.


I have been using a variable in the list that I then use to "pick" the color during OnRender, like this:

                    RenderTarget.DrawRectangle(DxRectangle, gapBorder == RED ? DxBrushRed : gapBorder == GREEN ? DxBrushGreen : DxBrushTransparent, 1);                    
​

But I since I'm supposed to minimize OnRender calcs, and the color doesn't change very often, I wanted to make the color a property in the list.

what's the best way to solve my problem?

thanks

[NinjaTrader_ChelseaB]

Hello cre8able,

foreach (rect thisRect in rectOpen)
{
if (rect.rectangleFillBrush != null)
{
rect.rectangleFillBrush.Dispose();
}
}

Note, the ReuseDxBrushesLoopDictionaryExample example I provided you uses a dictionary and loops through the dictionary in OnRenderTargetChanged().
You might decide to use this same structure and logic.

[cre8able]

thanks Chelsea. I will try that

[cre8able]

Hey Chelsea

I tried what you said. I put the foreach loop into OnRenderTargetChanged(). When the chart first renders, it works great. But as soon as I scroll, the brushes get disposed and the rectangles no longer render.

I don't know ho to re-render each "rect.rectangleFillBrush" with the value it originally contained after I dispose of it.




help again... please

[NinjaTrader_ChelseaB]

Hello cre8able,

Are you creating new brushes for the new RenderTarget.

Have a look at the example I have provided you on lines 162 to 158.

[cre8able]

hey Chelsea

I wasn't recreating the brushes so it makes sense that they disappeared.

But I'm stuck on how to recreate the brush for my list instead of a dictionary

the dictionary version had ".Value" that i can't figure out how to do in the list

Dictionary version:

                foreach (KeyValuePair<string, DXMediaMap> item in dxmBrushes)
                {
                    if (item.Value.DxBrush != null)
                        item.Value.DxBrush.Dispose();

                    if (RenderTarget != null)
                        item.Value.DxBrush = item.Value.MediaBrush.ToDxBrush(RenderTarget);                    
                }
​

List version:

     foreach (rect thisRect in rectOpen)
     {
          if (rect.rectangleFillBrush != null)
          {
               rect.rectangleFillBrush.Dispose();
          }
     }​

how do I recreate this part for a list?

               if (RenderTarget != null)
                        item.Value.DxBrush = item.Value.MediaBrush.ToDxBrush(RenderTarget);      ​

[NinjaTrader_ChelseaB]

Hello cre8able,

A dictionary was used in the example to group one System.Windows.Media.Brush with it's SharpDX.Direct2D1.Brush equivalent.

foreach (rect thisRect in rectOpen)
{
if (thisRect.rectangleFillBrush != null)
{
thisRect.rectangleFillBrush.Dispose();
thisRect.rectangleFillBrush = thisRect.rectangleHeight > 10 ? DxBrushWhite : DxBrushGreen;
}
}

[cre8able]

thanks Chelsea

In my actual indicator the logic for the color is more complex than in my example of:

thisRect.rectangleFillBrush = thisRect.rectangleHeight > 10 ? DxBrushWhite : DxBrushGreen;

It doesn't change very often so I think I'm better off calculating the color in OnBarUpdate() and storing it in the list as non dxBrush variable. Then I can do a simple calculation to convert it to the dxBrush when I render.

That way all my dxBrushes are created and disposed of in OnRenderTargetChanged(), but all the calcs are in OnBarUpdate()

Does that sound like a better idea than having more complex calcs in OnRenderTargetChanged(),?

[NinjaTrader_ChelseaB]

Hello cre8able,

I think if the brushes are already being created and stored and recreated in OnRenderTargetChanged(), you should just point to the existing brush instead of duplicating them (which is redundant).

An easy way to do that would be to keep the brushes in a dictionary, and then select them by the key.

The rect object could just save the key string for the color it should use.

[cre8able]

got it

thanks ChelseaB