使用ToArgb（）后跟FromArgb（）不会产生原始颜色

Question

This does not work

        int blueInt = Color.Blue.ToArgb();
        Color fred = Color.FromArgb(blueInt);
        Assert.AreEqual(Color.Blue,fred);

Any suggestions?

[Edit]

I'm using NUnit and the output is

failed:

Expected: Color [Blue]

But was: Color [A=255, R=0, G=0, B=255]

[Edit]

This works!

        int blueInt = Color.Blue.ToArgb();
        Color fred = Color.FromArgb(blueInt);
        Assert.AreEqual(Color.Blue.ToArgb(),fred.ToArgb());

Answer 1

From the MSDN documentation on Color.operator == :

This method compares more than the ARGB values of the Color structures. It also does a comparison of some state flags. If you want to compare just the ARGB values of two Color structures, compare them using the ToArgb method.

I'm guessing the state flags are different.

Answer 2

They won't equal the same, as Color.Blue doesn't equal your colour object, it equals something stored internally, a "new Color(KnownColor.Blue);" to be exact.

Answer 3

Alternatively, this also works, and I think it's more intuitive

    [Test]
    public void ColorTransform()
    {
        var argbInt = Color.LightCyan.ToArgb();
        Color backColor = Color.FromArgb(argbInt);
        Assert.AreEqual(Color.LightCyan.A, backColor.A);
        Assert.AreEqual(Color.LightCyan.B, backColor.B);
        Assert.AreEqual(Color.LightCyan.G, backColor.G);
        Assert.AreEqual(Color.LightCyan.R, backColor.R);
    }

Answer 4

I would have expected this with Assert.AreSame because of the boxing with the value types, but AreEqual should not have this problem.

Could you add which language (I'm assuming C#) your using and which testing framework?

What does Assert.AreEqual(true, Color.Blue == fred); result in?