Chaining DeviceContext methods together

How to do it

Aside from the extensions used for the new features, there are also extension methods that copy the already existing ones, with a small difference: They make the DeviceContext return itself, which means you can chain methods behind each other. As a result, all draw calls will no longer take an unnecassarily large amount of workspace. For example, this:

Global.Setups[0].DC.BeginDraw();
Global.Setups[0].DC.Clear(new RawColor4(1, 0, 0, 1));
Global.Setups[0].DC.FillRectangle(new RawRectangleF(0, 0, 100, 100), brush1);
Global.Setups[0].DC.DrawImage(shader1);
Global.Setups[0].DC.FillRectangle(new RawRectangleF(0, 100, 200, 400), brush2);
Global.Setups[0].DC.DrawImage(shader2, new RawVector2(100, 100));
Global.Setups[0].DC.DrawBitmap(someBitmap);
Global.Setups[0].DC.EndDraw();

can be shortened into this. Notice that the new() commands don't need to have a class name specified, which is a feature of .NET 5.

Global.Setups[0].DC.ChainBeginDraw()
	.ChainClear(new(1, 0, 0, 1))
	.ChainFillRectangle(new(0, 0, 100, 100), brush1)
	.ChainDrawImage(shader1)
	.ChainFillRectangle(new(0, 100, 200, 400), brush2)
	.ChainDrawImage(shader2, new(100, 100))
	.ChainDrawBitmap(someBitmap).EndDraw();

Same can be done when registering multiple effects at once:

Global.D2DFactory.RegisterEffect<Shader1>();
Global.D2DFactory.RegisterEffect<Shader2>();
Global.D2DFactory.RegisterEffect<Shader3>();
Global.D2DFactory.RegisterEffect<Shader4>();
Global.D2DFactory.RegisterEffect<Shader5>();

Global.D2DFactory.RegisterEffects<Shader1, Shader2, Shader3, Shader4, Shader5>();

How does it work?

Extension methods in C# are static methods in a static class that can "insert" themselves into another, non-static class and pretend they come from there. In Visual Studio they show up as an arrow next to a purple cube. See DCChaining.cs or Global.cs for all the extensions available. This is how an extension method looks like:

public static DeviceContext ChainBeginDraw(this DeviceContext d2dc)
{
	d2dc.BeginDraw(); return d2dc;
}

As you can see, the parameter has a this keyword in front of DeviceContext. On outside, the method will show up as DeviceContext.ChainBeginDraw(), but in reality, this method comes from a different class. The source class was simply replaced by the class of the first parameter.