Add function to SkiaSharp.Harfbuzz for getting shaped text paths

[ScrubN]

Description of Change

Add a class and set of new methods to SkiaSharp.Harfbuzz for shaping a text input and returning an SKPath of said text input

Features Resolved

• Resolves [FEATURE] Add function to SkiaSharp.Harfbuzz for getting shaped text paths #2512

API Changes

Added:

• SKPath FontExtensions.GetShapedTextPath(this SKFont paint, string text, SKPoint p, SKTextAlign textAlign)
• SKPath FontExtensions.GetShapedTextPath(this SKFont paint, string text, float x, float y, SKTextAlign textAlign)
• SKPath FontExtensions.GetShapedTextPath(this SKFont paint, SKShaper shaper, string text, float x, float y, SKTextAlign textAlign)

Behavioral Changes

None.

Required skia PR

None.

PR Checklist

• Has tests (if omitted, state reason in description)
• Rebased on top of main at time of PR
• Merged related skia PRs
• Changes adhere to coding standard
• Updated documentation

Additional Notes

If this PR is wanted, I can create a documentation PR as well.

[ScrubN]

@dotnet-policy-service agree

[ScrubN]

I should also mention that the choice to use SKFont.GetGlyphPath() over SKFont.GetGlyphPaths() was deliberate. In my testing, GetGlyphPaths() tended to be 2-5% slower and allocated up to 50% more memory (.NET 7).

BenchmarkDotNet=v0.13.5, OS=Windows 10 (10.0.19045.3086/22H2/2022Update)
AMD Ryzen 7 5800X, 1 CPU, 16 logical and 8 physical cores
.NET SDK=7.0.304
  [Host]     : .NET 7.0.7 (7.0.723.27404), X64 RyuJIT AVX2
  DefaultJob : .NET 7.0.7 (7.0.723.27404), X64 RyuJIT AVX2

Method	StringLength	Mean	Error	StdDev	Gen0	Gen1	Gen2	Allocated
GetShapedTextPath_GetGlyphPath	41	297.2 μs	5.72 μs	4.78 μs	-	-	-	6.33 KB
GetShapedTextPath_GetGlyphPaths	41	304.0 μs	5.98 μs	9.65 μs	0.4883	-	-	9.16 KB
GetShapedTextPath_GetGlyphPath	410	627.2 μs	8.06 μs	6.30 μs	2.9297	-	-	55.99 KB
GetShapedTextPath_GetGlyphPaths	410	648.6 μs	12.84 μs	12.01 μs	4.8828	3.9063	-	83.43 KB
GetShapedTextPath_GetGlyphPath	4,100	5,035.4 μs	97.87 μs	133.96 μs	31.2500	-	-	552.75 KB
GetShapedTextPath_GetGlyphPaths	4,100	4,603.0 μs	90.81 μs	114.84 μs	46.8750	39.0625	-	826.29 KB
GetShapedTextPath_GetGlyphPath	41,000	49,409.5 μs	973.14 μs	1,543.50 μs	636.3636	454.5455	454.5455	5520.5 KB
GetShapedTextPath_GetGlyphPaths	41,000	51,697.9 μs	979.89 μs	1,663.93 μs	750.0000	750.0000	500.0000	8255.01 KB

Notes

• These results are from the final benchmark run (3 runs total). This was the only run where GetGlyphPaths() was faster with a string length of 4,100.
• The string used was الثعلب البني السريع يقفز فوق الكلب الكسول. The length was increased by appending the string to itself multiple times within the benchmark global setup.