Fix UITest screenshot taking on MacCatalyst

[albyrock87]

Description of Change

MacCatalyst VerifyScreenshot now extracts the window's content instead of the entire screen.

I've added an option to include titlebar (for testing purposes).

In the future, we may want to replace constants with the actual title bar height.
In the past the title bar height changed on MacOS (11) so we should be aware of that.

The trick on MacOS may be to look at the Y coordinate of the first maroon-like pixel.
ImageMagick provides access to pixels colors, but pay attention that night "Night Shift" or "True Tone" may affect the output color, so we may need to verify a given color range.

On Windows this is not working and we need to find a better strategy.
So for now we rolled back to constants.

This is the code we used as tentative.

protected override void FixtureSetup()
{
    base.FixtureSetup();
#if MACUITEST || WINTEST
    _titleBarHeight = GetTitleBarHeight();
#endif
}

int GetTitleBarHeight()
{
#if MACUITEST
    var bytes = TakeScreenshot();
#else
    var bytes = App.Screenshot();
#endif
    using var image = new MagickImage(bytes);
    var pixels = image.GetPixels();
    var y = 0;

    const int minR = 0x73;
    const int maxR = 0x83;
    const int maxG = 0x20;
    const int maxB = 0x20;

    while (true)
    {
        if (y >= image.Height)
        {
            Assert.Fail("Failed to find the title bar color");
        }

        var pixelColor = pixels[3, y]!.ToColor()!;
        var r = pixelColor.R;
        var g = pixelColor.G;
        var b = pixelColor.B;

        ++y;

        if (r is >= minR and <= maxR && g <= maxG && b <= maxB)
        {
            break;
        }
    }

    return y;
}

Issues Fixed

Taking screenshot on MacCatalyst in CI and on developer machine is a nightmare:

• Unreliable due to maximize/minimize actions
• Developers may have different screen sizes compared to CI

[jsuarezruiz]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[jsuarezruiz]

New macOS snapshots available. I am going to commit the changes.

[jsuarezruiz]

Include a condition for macOS to crop off the TitleBar:

maui/src/Controls/tests/TestCases.Shared.Tests/UITest.cs

Line 212 in aa3f986

_ => 0,

[PureWeen]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[PureWeen]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[PureWeen]

/rebase

[jsuarezruiz]

/azp run

[PureWeen]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[jsuarezruiz]