2.0.0 rc5.4 source code?

[dgkorenje]

Can I have 2.0.0 rc5.4 source code?
I tried rc6.1 and canvas area is blank. I see only axes. Also I believe points are added, just not showing. Including gridlines, as if some white surface was on top of it (cartesianchart). And when I dynamically pan the chart, it's really slow (with disabled animations). A lot slower than rc5.4 where I can get smooth performance with the same amount of points.

[beto-rodriguez]

@dgkorenje you can use git for that, fork the repo and checkout to the rc5.4 tag.

Also, performance indeed should be improved in the latest releases, can I please get more feedback on that?

[dgkorenje]

That's why I am asking. Cuz there is no rc5.4 tag.

Regarding performance I don't know what's causing it sicne I didn't dig into the source code. All I can say it's noticable. But since I don't see the points in 6.1, I can't say what's wrong. Maybe you added some checking or dispatching for each point to be dumbproof. I can't say. But all that clutter should be removed.

What I did in my program was usage of selectors, typed methods and caching typed methods. That improved my program a lot. Also for point searching for hit testing you should have option to disable it. When chart is displayed cpu usage should be 0%. Right now when there are 10000 candle points and you do nothing on the chart the cpu usage goes up for some reason. Use 3 methods of searches, prediction based on time if time axis (O1), then fallback for binary search (Ologn), then lastly scan all points (On). This are my suggestions.
I can go on... for min-max scans (for fitting) cache ranges. Should make use of multiwidth caching. This then makes fitting super fast even on very large datasets. But make that disablable.

[dgkorenje]

@beto-rodriguez

ok what I did was modify CoreMotionCanvas.cs. I added:
public Action? BeforeDraw;
public Action? AfterDraw;
And then I added them to public void DrawFrame(TDrawingContext context)

    // custom overlay layer
    AfterDraw?.Invoke(context);
    context.OnEndDraw();

This allows me to use my own drawing directly. (and yes you should add this to the source code).

In order to increase performance you need to use draw once per multiple equal entities and use only canvas.SetMatrix on them for transformation.
I first tried using SKPath, but this has some internal problems if there are 100k+ lines, so you need to split them into chunks of 10k lines. After that I decided to use SKVertices. Now this is game changer. I can draw 50 million lines at 60+ fps.

So what about hit testing. All entities should be spatial objects. Create intelligent spatial engine.

What about highlighting? Here it gets complicated. But it's doable.

Now you'll get professional charting library - but won't be "live" any more. ;)

[beto-rodriguez]

That sounds great!

In order to increase performance you need to use draw once per multiple equal entities

in theory the library only draws a frame when something in chart changed or is being animated.

I mean your results seem amazing, feel free to create a PR with your changes.

[dgkorenje]

Yeah the problem is draw and spatial indexing for my case.
I am experimenting with drawings at the moment. Note that once drawings are in gpu, transform costs nothing. 1 million lines (100 million vertices) get drawn in 0 sec.
I noticed that canvas.drawpath gives a lot better looking lines than canvas.drawvertices because of antialiasing. The best would be if we could write our own GL code so we can upload to GPU whatever we want and let gpu take care of it. Because if line is transformed, so is the thickness and rebuild is required at certain treshholds... while with GL access we could avoid all that.

[dgkorenje]

Also there is no rc5.4 tag. Can you check if the files are actually on the github.

[beto-rodriguez]

I missed the 5.4 tag, but this should be the commit: 1af9df5