refuel.mixedup.dev/docs/ReFuel.StbImage.md

ReFuel.StbImage

StbImage is a very common library that has been developed mainly by Sean Barett. It is one of the easiest to use image loading libraries on the planet especially for C and C++ users. It is relatively simple to load up and use in C#, however the C# build system makes it a bit difficult to manage native dependencies. Therefore this package makes it easy for you and everyone else who needs a cross platform way to load images.

Intended OS targets are:

• Windows (x86 and x64)
• Linux (arm32, arm64, x86 and x64)
• MacOS (arm64, x64)

Usage

using ReFuel.Stb;

// Simply load an image from a Stream or Span<T> (T: unmanaged) source.
using StbImage image = StbImage.Load(source);

Console.WriteLine("{0}x{1}", image.Width, image.Height);
// StbImage.ImagePointer is a pointer to the image data.
// Pass the image to an unsafe library as is (e.g. OpenGL), or cast it to a span. Currently there is no "safe" way to do this.

// OpenGL example
GL.TexImage2D(TextureTarget.Texture2D, 0, PixelInternalFormat.Rgba, image.Width, image.Height, 0, StbiFormatToGLFormat(image.Format, image.IsFloat ? PixelFormat.Float : PixelFormat.UnsignedByte), image.ImagePointer);

// C# example
struct Pixel
{
    int R, G, B, A;
}

Span<Pixel> pixels;
unsafe
{
    pixels = new Span<Pixel>(image.ImagePointer, image.Width * image.Height);
}

Global Options

Option	Description
bool StbImage.FlipVerticallyOnLoad	Flips the image vertically after loading. Practical for uses where a right handed coordinate system is used (e.g. OpenGL)
bool UnpremultiplyOnLoad	Applies to Apple iPhone PNG images, where the image is sometimes encoded with premultiplied alpha. Reverses this premultiplication.

Calling Stbi directly.

If you wish to call the native Stbi library, call functions in the static class Stbi. See stb_image.h documentation online.