How can I generate images of circles, of varying sizes?

Question

For the task I'm trying to accomplish, I need to generate many images, all consisting of a black circle border on a transparent background, but each a different size (going up in size from 3x3 to, say, 20x20).

Preferably they would be GIFs or PNGs, as these support transparency.

I started building a simple C# Console project for this, but I'm wondering if there's already a tool out there that does this, so I can avoid wasting time.

Answer 1

I think it would be faster to just make your 18 PNGs in GIMP or some other comparable paint program.

Answer 2

Your strategy sounds good.

Simply create a Bitmap of the correct size, create a Graphics object using Graphics.FromImage().

Clear the Graphics using Color.Transparent and draw a black circle with FillCircle().

If you need antialiasing, set smoothing mode to high quality.

Answer 3

Draw one 256x256 image of a circle, and scale it down with a batch tool like imagemagick, graphicsmagick, irfan-view, or some-such to all the sizes you need. Little code needed. This assumes you don't need a constantly sized width to the circle outline.