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Reduce Allocations in Text Rendering #20175

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Merged
MrJul merged 5 commits into from
Dec 15, 2025
Merged

Reduce Allocations in Text Rendering #20175

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a802849
Reduce allocations for FontFamily.Parse
Washi1337 Nov 28, 2025
d11689f
Turn Trie data into static data
Washi1337 Nov 28, 2025
33b7b9d
Use static lambda in s_cachedLanguage.GetOrAdd
Washi1337 Nov 28, 2025
cc3f7c1
Make LineBreakEnumerator+LineBreakState a ref struct to avoid allocat…
Washi1337 Nov 28, 2025
430f7a7
Use backing field for storing trie data in debug builds
Washi1337 Dec 14, 2025
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72 changes: 37 additions & 35 deletions src/Avalonia.Base/Media/FontFamily.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -131,53 +131,55 @@ private static FrugalStructList<FontSourceIdentifier> GetFontSourceIdentifier(st
{
var result = new FrugalStructList<FontSourceIdentifier>(1);

var segments = name.Split(',');

for (int i = 0; i < segments.Length; i++)
int commaIndex = -1;
do
{
var segment = segments[i];
var innerSegments = segment.Split('#');
// Look for a comma separator to carve out a single segment.
int segmentStart = commaIndex + 1;
commaIndex = name.IndexOf(',', segmentStart);
int segmentEnd = commaIndex == -1
? name.Length
: commaIndex;

var segment = name.AsSpan(segmentStart..segmentEnd).Trim();

FontSourceIdentifier identifier = new FontSourceIdentifier(name, null);
FontSourceIdentifier? identifier = null;

switch (innerSegments.Length)
// Check if there is exactly one '#' (i.e., segment is in the format "path#innerName").
int separatorIndex = segment.IndexOf('#');
if (separatorIndex != -1 && segment[(separatorIndex + 1)..].IndexOf('#') == -1)
{
case 1:
var pathSpan = segment[..separatorIndex].Trim();
var innerName = segment[(separatorIndex + 1)..].Trim();

if (pathSpan.IsEmpty)
{
identifier = new FontSourceIdentifier(innerName.ToString(), null);
}
else
{
string path = pathSpan.ToString();
if (pathSpan.Contains('/') && Uri.TryCreate(path, UriKind.Relative, out var source))
{
identifier = new FontSourceIdentifier(innerSegments[0].Trim(), null);
break;
identifier = new FontSourceIdentifier(innerName.ToString(), source);
}

case 2:
else
{
var path = innerSegments[0].Trim();
var innerName = innerSegments[1].Trim();

if (string.IsNullOrEmpty(path))
{
identifier = new FontSourceIdentifier(innerName, null);
}
else
if (Uri.TryCreate(path, UriKind.Absolute, out source))
{
if (path.Contains('/') && Uri.TryCreate(path, UriKind.Relative, out var source))
{
identifier = new FontSourceIdentifier(innerName, source);
}
else
{
if (Uri.TryCreate(path, UriKind.Absolute, out source))
{
identifier = new FontSourceIdentifier(innerName, source);
}
}
identifier = new FontSourceIdentifier(innerName.ToString(), source);
}

break;
}
}
}

result.Add(identifier);
}
// If we didn't manage to match it to any known format, treat the entire segment as the font name.
identifier ??= new FontSourceIdentifier(
segment.Length == name.Length ? name : segment.ToString(),
null);

result.Add(identifier.Value);
} while (commaIndex != -1);

return result;
}
Expand Down
16 changes: 12 additions & 4 deletions src/Avalonia.Base/Media/TextFormatting/Unicode/BiDi.trie.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -16,10 +16,18 @@ public static UnicodeTrie Trie
{
[MethodImpl(MethodImplOptions.AggressiveInlining)]
get => new(Data, 0x00100000, 0x00000000);
}
}

private static ReadOnlySpan<uint> Data => new uint[]
{
// For Debug builds, we store the data in a separate uint[] field to avoid RuntimeFieldInfoStub allocations.
// See also: https://github.com/AvaloniaUI/Avalonia/pull/20175

#if DEBUG
public static ReadOnlySpan<uint> Data => s_data;
private static uint[] s_data =
#else
public static ReadOnlySpan<uint> Data =>
#endif
[
0x0000038D, 0x00000395, 0x0000039D, 0x000003A5, 0x000003BD, 0x000003C5, 0x000003CD, 0x000003D5, 0x000003AD, 0x000003B5, 0x000003AD, 0x000003B5,
0x000003AD, 0x000003B5, 0x000003AD, 0x000003B5, 0x000003AD, 0x000003B5, 0x000003AD, 0x000003B5, 0x000003DB, 0x000003E3, 0x000003EB, 0x000003F3,
0x000003FB, 0x00000403, 0x000003FF, 0x00000407, 0x0000040F, 0x00000417, 0x00000412, 0x0000041A, 0x000003AD, 0x000003B5, 0x000003AD, 0x000003B5,
Expand Down Expand Up @@ -1104,5 +1112,5 @@ public static UnicodeTrie Trie
0x00000000, 0x00040000, 0x00040000, 0x00040000, 0x00040000, 0x00040000, 0x00000000, 0x00040000, 0x00040000, 0x00040000, 0x00040000, 0x00040000,
0x00040000, 0x00040000, 0x00040000, 0x00040000, 0x00040000, 0x00040000, 0x00040000, 0x00040000, 0x00040000, 0x00040000, 0x00040000, 0x00040000,
0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000
};
];
}
2 changes: 1 addition & 1 deletion src/Avalonia.Base/Media/TextFormatting/Unicode/EastAsianWidth.trie.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,7 @@ public static UnicodeTrie Trie
get => new(Data, 0x00110000, 0x00000000);
}

private static ReadOnlySpan<uint> Data => new uint[]
private static readonly uint[] Data = new uint[]
{
0x000003E7, 0x000003EF, 0x000003F7, 0x000003FF, 0x0000041F, 0x00000427, 0x0000042F, 0x00000437, 0x0000043F, 0x00000447, 0x0000044F, 0x00000457,
0x00000417, 0x0000041F, 0x0000045C, 0x00000464, 0x00000417, 0x0000041F, 0x00000468, 0x00000470, 0x00000417, 0x0000041F, 0x00000477, 0x0000047F,
Expand Down
2 changes: 1 addition & 1 deletion src/Avalonia.Base/Media/TextFormatting/Unicode/GraphemeBreak.trie.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,7 @@ public static UnicodeTrie Trie
get => new(Data, 0x000E1000, 0x00000000);
}

private static ReadOnlySpan<uint> Data => new uint[]
private static readonly uint[] Data = new uint[]
{
0x0000035A, 0x00000362, 0x0000036A, 0x00000372, 0x0000038A, 0x00000392, 0x00000362, 0x0000036A, 0x00000362, 0x0000036A, 0x00000362, 0x0000036A,
0x00000362, 0x0000036A, 0x00000362, 0x0000036A, 0x00000362, 0x0000036A, 0x00000362, 0x0000036A, 0x00000362, 0x0000036A, 0x00000362, 0x0000036A,
Expand Down
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