Canvas Circle Math Help?

Thanks to the contributions of @Tomas Jakobs I have been starting to play with his Dashcontrol project which is very appealing. It has a look that we are seeing in many of the new bootstraps these days.

My issue is that I slightly changed the colors around and notices a funky edge action (for lack of a better term:) ) and I can’t seem to find out where the math is causing this. Since this already is an open project I was hoping someone could guide me to finding the issue?

On Tomas’ original version the pastel colors didn’t show this edge jumping like it does with darker colors.

This is noticed on Mac OS X 10.10.1 Retina (which I hope its not because of my retina)

Thank you in advance all and well done @Tomas Jakobs!

Original Thread by Tomas:

It’s not Retina. The is an artifact of Antialiasing (or lack of). You don’t notice it so much on the pastels because the contrast between the circle color and the background is low. The darker (or more saturated) the color you use, the higher that contrast will be come.

Unfortunately, while I understand the “why”, it will require someone with more than my boot camp level of graphics knowledge to provide a solution to antialias the circle that you draw.

I am hacking at it now as we speak also Tim :slight_smile:


The rings look antialiased to me, the problem is arc points appear to be limited to integer pixel coordinates so the rendered arcs polygon wiggles around those rounded coordinates.

Instead I used a masked picture where the ring is drawn into the mask with DrawOval which is doesn’t suffer coordinate rounding. Then a polygon wedge is built and filled to color in the percent part.

Wow Will thank you so very much! I will merge that into Tomas’ project and repost it as another option to his three.

Thank you again Will!