How to Draw a Line with Six Labors ImageSharp?

Question

Using Six Labors ImageSharp 1.0.4 for .Net core, how can I draw a line between two points? My code below combines three images into the GridImage and then I want to draw a line on the new image.

When I call imageContext.DrawLines(linePen, points) I am getting the error:

The type IImageProcessingContext<> is defined in a reference that is not referenced to assembly Sixlabors.ImageSharp.

However, I am referencing SixLabors in the using statement.

using SixLabors.ImageSharp;
using SixLabors.ImageSharp.PixelFormats;
using SixLabors.ImageSharp.Processing;
using System;
using System.IO;

public void CombineImagesDrawLine() {
    using (Image<Rgba32> img1 = Image.Load<Rgba32>("gridTemplate.png"))
    using (Image<Rgba32> img2 = Image.Load<Rgba32>("circleOne.png"))
    using (Image<Rgba32> img3 = Image.Load<Rgba32>("circleTwo.png"))

    using (Image<Rgba32> GridImage = new Image<Rgba32>(1024, 576)) // create output image of the correct dimensions
    {
        // take img1 and img2 and draw them onto the image
        GridImage.Mutate(o => o
            .DrawImage(img1, new Point(0, 0), 1f)
            .DrawImage(img2, new Point(100, 100), 1f) 
        );

        // Add img3
        GridImage.Mutate(o => o
            .DrawImage(img3, new Point(200, 250), 1f)
        );

        GridImage.Mutate(imageContext =>
        {
            var points = new SixLabors.Primitives.PointF[2];
            points[0] = new SixLabors.Primitives.PointF(
                x: (float)(89),
                y: (float)(118));
            points[1] = new SixLabors.Primitives.PointF(
                x: (float)(901),
                y: (float)(379));

            var lineColor = SixLabors.ImageSharp.Color.FromRgb(
                r: (byte)124,
                g: (byte)190,
                b: (byte)75);
            float lineWidth = 5;

            var linePen = new Pen(lineColor, lineWidth);                     

            imageContext.DrawLines(linePen, points); // !!This is where my code fails
     }
}

Answer 1

The error is stating Sixlabors.ImageSharp is referencing another assembly that your project is missing.

The Github samples for Sixlabors shows these references in the .csproj:

<ItemGroup>
  <PackageReference Include="SixLabors.Fonts" Version="1.0.0-beta15" />
  <PackageReference Include="SixLabors.ImageSharp" Version="1.0.3" />
</ItemGroup>

And looking at the dependencies in Nuget for SixLabors.ImageSharp.Drawing:

.NETCoreApp 2.1
SixLabors.Fonts (>= 1.0.0-beta15)
SixLabors.ImageSharp (>= 1.0.3)

.NETCoreApp 3.1
SixLabors.Fonts (>= 1.0.0-beta15)
SixLabors.ImageSharp (>= 1.0.3)

.NETFramework 4.7.2
SixLabors.Fonts (>= 1.0.0-beta15)
SixLabors.ImageSharp (>= 1.0.3)

.NETStandard 1.3
NETStandard.Library (>= 1.6.1)
SixLabors.Fonts (>= 1.0.0-beta15)
SixLabors.ImageSharp (>= 1.0.3)

.NETStandard 2.0
SixLabors.Fonts (>= 1.0.0-beta15)
SixLabors.ImageSharp (>= 1.0.3)

.NETStandard 2.1
SixLabors.Fonts (>= 1.0.0-beta15)
SixLabors.ImageSharp (>= 1.0.3)

If you're not using Nuget to pull the package down, then try removing the current reference and then re-referencing with the Nuget package.

Otherwise, remove the current SixLabors reference and then grab the latest Release from SixLabors, and add to your project.

Finally, be sure to read the SixLabors installation documentation.