Canvas issue

[peteritv]

After reading some docs, I am sure you are not telling something.

You want to draw on something that is white, correct?
So your canvas must be a child of something that is white.

For instance:
Rectangle { color: white; Canvas { ... } }

Is that the case here?

[Tikani]

@peteritv Yes, you are correct. In my case I set Canvas as a child of a white Window, but Context2D shows me, suddenly, that the canvas is the child of the black Window. Though it is displayed as white.

[peteritv]

OK, I just run your example, and it seems to work.

I have a white background on which I can draw.
When I draw I see the traces of my mouse with a big "point" size.
Draw color is blue.

Everything seems to work.

Now, since I don't have your "Neuro" file, THAT may be your problem...

[peteritv]

We have a synchronisation issue here to :)

So when you run your program, you are drawing on a black thing?

[peteritv]

Where/How do you use Context2D?

[peteritv]

Ahhhh! I understand now! (I think)

You think that what ever background you choose, it will be part of your canvas?
That is NOT the case!

The canvas just is a container for some points being drawn!

For instance, you can take the canvas, and put it on something else like a red Rectangle.
It will still have the same points, but now on a red background.

In other words, the canvas does NOT hold any information at all about the background. It just knows about some pixels.

[peteritv]

So in your case, you need to fill your Canvas with white pixels itself.

So with ur ctx functions, draw a white rectangle first, which will be the base of your canvas for drawing on.

[peteritv]

So, instead of making your parent white:

Within your canvas, draw a white rectangle on start,
and then start drawing on that

[peteritv]

But that explaines why you see "black" instead of "white" on your Context2D

I am assuming you are just interested in the points, and not the background, for further processing.
So forget about the canvas background, ok?

[Tikani]

@peteritv Huge thanks, I finnally got what's going on! A visible background of working application is just a result of visual compositing the Canvas with it's parent and these two does not share any properties between each other. Thanks a lot again, I think it is very important to know such nuances.