.Net Core unable to use Bitmap

Question

I am working on a Web Service using .Net Core 2.1.

I have a byte array containing all pixels values (in grey scale), a width, a height. I want to create a bitmap from theses parameters.

There is my code (from a working .Net Framework 4 project) :

public FileResult PostSealCryptItem(Byte[] matrix, int width, int height)
{
    Bitmap bmp = new Bitmap(width, height, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
    for (int y = 0; y < height; y++)
        for (int x = 0; x < width; x++)
            bmp.SetPixel(x, y, Color.FromArgb(ToArgb(matrix, x, y)));

    Byte[] data = BitmapToByteArray(bmp);
    FileContentResult result = new FileContentResult(data , "image/png");

    return result;
}

But in .NET Core, I've the error :

The type or namespace name 'Bitmap' could not be found (are you missing a using directive or an assembly reference?)

I've try to add reference to System.Drawing but it did not work.

Nebraska

There is no built in image manipulation in .NET Core, you need to use a third party tool, but there are some good ones. For example I'm currently using SkiaSharp. – Graybeard

Possible duplicate of How to use bitmap resources in ASP.NET Core app? – Palatalized

There's System.Drawing.Common – Equivalence

@Equivalence Downside of that is that you are limited to running on Windows I believe? – Graybeard

@Graybeard looks like it, now I see it has Microsoft.Win32.SystemEvents as a dependency – Equivalence

you could use the windows compatibility pack. Guess you have to stick with windows then... blogs.msdn.microsoft.com/dotnet/2017/11/16/… – Shaneka

hanselman.com/blog/HowDoYouUseSystemDrawingInNETCore.aspx – Shaneka

@Equivalence Yeah, that's why I wouldn't recommend using it. Especially considering SkiaSharp and ImageSharp both do everything (and more). Skia also supports webp which can be useful. – Graybeard

Do read learn.microsoft.com/en-us/dotnet/api/system.drawing#remarks – Cythiacyto

Answer 1

Bitmap is part of System.Drawing which was included in .Net Framework.

It is no longer included with .net core and must be added manually.

Install the Nuget package System.Drawing.Common by right-clicking on your project in visual studio and choosing Manage Nuget Packages

In the Nuget Package manager, click on the Browse Tab, search for System.Drawing.Common in the top and it should be the first Package, official by Microsoft. It will work just as in .Net Framework:

Ramsdell

Just a note for those who will come here later - as for net 6 the System.Drawing.Common package considered to be Windows-only and can not be used on Mac or Linux anymore (learn.microsoft.com/en-us/dotnet/core/compatibility/…) – Boarding

How to make it supported for linux as well? – Maccarone

Answer 2

You can use ImageSharp instead of System.Drawing

https://github.com/SixLabors/ImageSharp

Nuget console

Install-Package SixLabors.ImageSharp -Version 1.0.0-beta0005

Shaneka

Answer 3

There is a NuGet package instead of System.Drawing, you can use it

Install-Package System.Drawing.Common

Volsci

Answer 4

Aspose.Drawing is a drop-in cross-platform replacement for System.Drawing. The library is fully managed and supports Web Services using .Net Core 2.1. (I'm one of the developers.)

Take

Is that a commercial product ? – Purify

@Purify Yes. – Take

For most requirements, there is no advantage in using commercial and closed-source components. – Dogeatdog

Answer 5

This one worked for me dotnet add package System.Drawing.Common --version 5.0.3

Weywadt