Feature Request: Optional rounded corner in RectangularPolygon

[Spawnkid]

Though this would work on images https://github.com/SixLabors/Samples/blob/master/ImageSharp/AvatarWithRoundedCorner/Program.cs this is not possible in Shapes where you need to use Pen (all paths should be closed). See attached sample

It might be a good idea to add an optional parameter in RectangularPolygon constructor to have a radius value of the rounded corner. Thank You.

[ThaDaVos]

Also really want something like this!
Any ETA

[JackSteel97]

Any progress on this? Or is there a workaround for drawing rectangles with rounded corners someone can point me to?

[antonfirsov]

@JackSteel97 you can use this code to produce a rounded rectanle path:

https://github.com/SixLabors/Samples/blob/38faba5caf866c0168ea67a5e7c37c06d3043775/ImageSharp/AvatarWithRoundedCorner/Program.cs#L72-L91

Then use one of the overloads in DrawPathExtensions to draw it:
https://docs.sixlabors.com/api/ImageSharp.Drawing/SixLabors.ImageSharp.Drawing.Processing.DrawPathExtensions.html#SixLabors_ImageSharp_Drawing_Processing_DrawPathExtensions_Draw_IImageProcessingContext_SixLabors_ImageSharp_Drawing_Processing_IPen_SixLabors_ImageSharp_Drawing_IPath_

[JackSteel97]

@antonfirsov This provides no options for positioning the new rectangle and no option to fill the rectangle either??

[antonfirsov]

Positioning the new rectangle

You can transform IPathCollection with IPathCollection.Transform. Use it in tandem with Matrix3x.CreateTranslation

Fill the rectangle

Sorry second link was wrong in my previous comment. You can use imageProcessingContext.Draw(IPen pen, IPath path) for drawing the outline, and imageProcessingContext.Fill(IBrush brush, IPath path) to fill it.

[ggolda]

@antonfirsov could you please explain how to make those corners transparent? I need to draw one image atop of another and it should have rounded corners.

The only result that I can achieve using example above is colored corners. If Color.Transparent is provided they are not visible at all (obviously). Is there a way to use those corners as a mask and hide parts of image that they overlap?

[AndrewShepherd]

Here is method that converts a RectangularPolygon to a path with rounded corners.

Personally, I feel that implementing this as a user is straightforward enough, and this functionality needn't be baked into the core library.

private static IPath ApplyRoundCorners(RectangularPolygon rectangularPolygon, float radius)
{
	var squareSize = new SizeF(radius, radius);
	var ellipseSize = new SizeF(radius * 2, radius * 2);
	var offsets = new[]
	{
		(0, 0),
		(1, 0),
		(0, 1),
		(1, 1),
	};
	var holes = offsets.Select(
		offset =>
		{
			var squarePos = new PointF(
				offset.Item1 == 0 ? rectangularPolygon.Left : rectangularPolygon.Right - radius,
				offset.Item2 == 0 ? rectangularPolygon.Top : rectangularPolygon.Bottom - radius
			);
			var circlePos = new PointF(
				offset.Item1 == 0 ? rectangularPolygon.Left + radius : rectangularPolygon.Right - radius,
				offset.Item2 == 0 ? rectangularPolygon.Top + radius : rectangularPolygon.Bottom - radius
			);
			return new RectangularPolygon(squarePos, squareSize)
				.Clip(new EllipsePolygon(circlePos, ellipseSize));
		}
	);
	return rectangularPolygon.Clip(holes);
}