B4J Question .drawpath auto invalidates?

Star-Dust

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• Jun 23, 2018

• #2

sorex said:

Regarding the posted slowdown...



The culprit seems to be drawpath that updates the canvas/image at every usage.

@Erel, can you confirm (by looking at your sources) that drawpath auto invalidates?

is this a feature or a bug?

Click to expand...

Anyway BitmapCreator on B4J is much faster then Canvas, the procedures of DrawPath that I put in code snippet (here) ere very fast. I'll probably make a version of my B4J library that only uses BitmapCreator, if I have time

 

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sorex

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• Jun 23, 2018

• #3

I used your snippet for testing and it was dreadfull slow due to the invalidate.

you don't notice it on your rubiks cube but you will when drawing a few hundreds of polygons.

I don't think there's a real bitmapcreator fillpath or I looked over it.

 

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Star-Dust

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• Jun 23, 2018

• #4

Invalidate needed only in b4jh, while release It is only necessary in b4i.
It is explained in the documentation of the Xui library

 

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sorex

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• Jun 23, 2018

• #5

well, that's the point of the problem. it's invalidating on each drawpath that's what causing the slow down.

it should be done once and 'manually' after all polys have been drawn.

 

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Star-Dust

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• Jun 23, 2018

• #6

I did it at the end of rendering after drawing all the polygons

 

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sorex

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• Jun 23, 2018

• #7

I wrote a few times already that it is done automatically when using drawpath so you just did an extra invalidate.

here's an example that it does update the red line without the invalidate

B4X:

    Dim p As Pane
    p.Initialize("")
    MainForm.RootPane.AddNode(p,0,0,640,400)

    Dim can As B4XCanvas
    can.Initialize(p)

    Dim pp As B4XPath
    pp.Initialize(0,0)
    pp.LineTo(100,100)
    pp.LineTo(0,100)
    can.DrawPath(pp,0xffff0000,False,1)
    
'    can.Invalidate

 

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Erel

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• Jun 24, 2018

• #8

It is not related to DrawPath. JavaFX Canvas object "auto invalidates". There is no invalidate method in jFX. B4XCanvas.Invalidate doesn't do anything in B4J.

 

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sorex

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• Jun 24, 2018

• #9

ok, that's a shame then.

my initial 3D model drawing example used the extended canvas lib (from Klaus?) .drawPolygon and it's way faster and there's no need to invalidate either.

I think it's 60fps vs 0.5fps so the difference is huge.

 

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Star-Dust

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• Jun 24, 2018

• #10

Klaus uses the native android library, I use XUI.
I'll try a test using the native library

 

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Erel

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• Jun 24, 2018

• #11

It has nothing to do with invalidation.

It is possible that DrawPath is slow as it requires clipping the canvas. DrawPolygon is not the same as DrawPath.

B4XCanvas and Canvas have the exact same performance characteristics.

 

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sorex

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• Jun 24, 2018

• #12

ok, that makes sense.

I did tests before with clipping due to the lack of some function and indeed it's slow as hell.

drawPolygon exists in java fx but it's not exposed in B4J (yet)

 

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Erel

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• Jun 24, 2018

• #13

You can call it with JavaObject. Start a new thread if you like to do it.

 

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