Rewrite Line Breaker.

[JimBobSquarePants]

Prerequisites

• I have written a descriptive pull-request title
• I have verified that there are no overlapping pull-requests open
• I have verified that I am following matches the existing coding patterns and practice as demonstrated in the repository. These follow strict Stylecop rules 👮.
• I have provided test coverage for my change (where applicable)

Description

A complete rewrite of the line breaker to fix a series of issues including #434 I've not benchmarked this but in addition to fixing bugs the code is now doing far less work per code point so should be faster.

I've also added testing that will generate output using ImageSharp.Drawing which allows us to better visualize the layout. Adding this helped identify multiple issues. The generation code is togglable via a compiler condition introduced via the csproj file. This allows us to turn them off should we introduce breaking changes.

All output has been sense checked and compared to browser output to ensure correctness.

Copilot reviewed 46 out of 66 changed files in this pull request and generated no comments.

Files not reviewed (20)

• tests/Images/ReferenceOutput/CountLinesWrappingLength_100-4.png: Language not supported
• tests/Images/ReferenceOutput/CountLinesWrappingLength_200-3.png: Language not supported
• tests/Images/ReferenceOutput/CountLinesWrappingLength_25-6.png: Language not supported
• tests/Images/ReferenceOutput/CountLinesWrappingLength_50-5.png: Language not supported
• tests/Images/ReferenceOutput/MeasureTextWordBreakMatchesMDN_238-layoutMode_HorizontalBottomTop-wordBreaking_BreakAll.png: Language not supported
• tests/Images/ReferenceOutput/MeasureTextWordBreakMatchesMDN_238-layoutMode_HorizontalBottomTop-wordBreaking_BreakWord.png: Language not supported
• tests/Images/ReferenceOutput/MeasureTextWordBreakMatchesMDN_238-layoutMode_HorizontalBottomTop-wordBreaking_KeepAll.png: Language not supported
• tests/Images/ReferenceOutput/MeasureTextWordBreakMatchesMDN_238-layoutMode_HorizontalBottomTop-wordBreaking_Standard.png: Language not supported
• tests/Images/ReferenceOutput/MeasureTextWordBreakMatchesMDN_238-layoutMode_HorizontalTopBottom-wordBreaking_BreakAll.png: Language not supported
• tests/Images/ReferenceOutput/MeasureTextWordBreakMatchesMDN_238-layoutMode_HorizontalTopBottom-wordBreaking_BreakWord.png: Language not supported
• tests/Images/ReferenceOutput/MeasureTextWordBreakMatchesMDN_238-layoutMode_HorizontalTopBottom-wordBreaking_KeepAll.png: Language not supported
• tests/Images/ReferenceOutput/MeasureTextWordBreakMatchesMDN_238-layoutMode_HorizontalTopBottom-wordBreaking_Standard.png: Language not supported
• tests/Images/ReferenceOutput/MeasureTextWordBreak_500-layoutMode_HorizontalBottomTop-wordBreaking_BreakAll.png: Language not supported
• tests/Images/ReferenceOutput/MeasureTextWordBreak_500-layoutMode_HorizontalBottomTop-wordBreaking_BreakWord.png: Language not supported
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• tests/Images/ReferenceOutput/MeasureTextWordBreak_500-layoutMode_HorizontalTopBottom-wordBreaking_BreakAll.png: Language not supported
• tests/Images/ReferenceOutput/MeasureTextWordBreak_500-layoutMode_HorizontalTopBottom-wordBreaking_BreakWord.png: Language not supported
• tests/Images/ReferenceOutput/MeasureTextWordBreak_500-layoutMode_HorizontalTopBottom-wordBreaking_KeepAll.png: Language not supported
• tests/Images/ReferenceOutput/MeasureTextWordBreak_500-layoutMode_HorizontalTopBottom-wordBreaking_Standard.png: Language not supported

[tocsoft]

lgtm 👍

[jez9999]

I've tried 2.0.8 against my bugs #431 and #434 and it seems to have fixed both issues. 👍

I would note however that it appears to have changed what ImageSharp considers to be the bounding box of the rendered text, based on WrappingLength. The first imgTest1 output from #431 now wraps after "Lorem ipsullll" unless I slightly increase the WrappingLength. Maybe the original behaviour was a bug that's also been fixed.

[JimBobSquarePants]

I've tried 2.0.8 against my bugs #431 and #434 and it seems to have fixed both issues. 👍

I would note however that it appears to have changed what ImageSharp considers to be the bounding box of the rendered text, based on WrappingLength. The first imgTest1 output from #431 now wraps after "Lorem ipsullll" unless I slightly increase the WrappingLength. Maybe the original behaviour was a bug that's also been fixed.

I'm not sure I understand what you are saying. In your original issue the text wrapped following "Lorem ipsullll"

[jez9999]

With 2.0.6 I got:

With 2.0.8 I get:

[JimBobSquarePants]

I see this in my tests.

[Fact]
public void ShouldNotInsertExtraLineBreaks()
{
    if (SystemFonts.TryGet("Arial", out FontFamily family))
    {
        Font font = family.CreateFont(60);
        const string text = "- Lorem ipsullll\ndolor sit amet\n-consectetur elit";

        TextOptions options = new(font)
        {
            Origin = new Vector2(50, 20),
            WrappingLength = 400,
        };

        int lineCount = TextMeasurer.CountLines(text, options);
        Assert.Equal(4, lineCount);

        IReadOnlyList<GlyphLayout> layout = TextLayout.GenerateLayout(text, options);
        Assert.Equal(46, layout.Count);

        TextLayoutTestUtilities.TestLayout(text, options);
    }
}

[jez9999]

Hmm, well I can't easily use TextLayoutTestUtilities because it's internal. Can't it just be made public?

[jez9999]

Also I noticed your test string is - Lorem ipsullll\ndolor sit amet\n-consectetur elit, instead try - Lorem ipsullll dolor sit amet\n-consectetur elit without the explicit newline and it wraps. I think it's not considering a space at the end of a line to be a zero-width character, which it should be.

[JimBobSquarePants]

Hmm, well I can't easily use TextLayoutTestUtilities because it's internal. Can't it just be made public?

Why would I make a test utility that doesn’t get published with any code public? You know the code is right here yeah? You can simply clone the repo and run it?

Please stop changing the goal posts and drip feeding me examples. I’m testing the strings provided in your issues and each test takes a lot of my time of which I have a limited capacity.

This is not only not helpful but incredibly frustrating.

[jez9999]

OK well I'm sorry, I didn't intend that.

I tested it with the string - Lorem ipsullll dolor sit amet\n-consectetur elit and it appears to incorrectly line wrap the "ipsullll" in 2.0.8: