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Change MS.Internal.Span (ItemSpan.h) to value struct to reduce text related internal allocations #11747

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Change MS.Internal.Span (ItemSpan.h) to value struct to reduce text related internal allocations #11747

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54634e0
Change MS.Internal.Span (ItemSpan.h) to value struct to reduce text r…
nietras Jul 2, 2026
9602a05
Potential fix for pull request finding
nietras Jul 2, 2026
3634cea
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nietras Jul 2, 2026
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6 changes: 3 additions & 3 deletions src/Microsoft.DotNet.Wpf/src/DirectWriteForwarder/CPP/DWriteWrapper/ItemSpan.h
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@
#include "Common.h"
namespace MS { namespace Internal
{
private ref struct Span sealed
private value struct Span
{
/// <summary>
/// Constructor
Expand All @@ -20,12 +20,12 @@ namespace MS { namespace Internal
/// <summary>
/// Span element
/// </summary>
Object^ element;
initonly Object^ element;

/// <summary>
/// Span length
/// </summary>
int length;
initonly int length;
};
}}//MS::Internal
#endif //_ITEM_SPAN_H
12 changes: 6 additions & 6 deletions src/Microsoft.DotNet.Wpf/src/DirectWriteForwarder/CPP/DWriteWrapper/TextAnalyzer.cpp
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Expand Up @@ -16,7 +16,7 @@ namespace MS { namespace Internal { namespace Text { namespace TextInterface
_textAnalyzer = gcnew NativeIUnknownWrapper<IDWriteTextAnalyzer>(textAnalyzer);
}

IList<Span^>^ TextAnalyzer::Itemize(
IList<Span>^ TextAnalyzer::Itemize(
__in_ecount(length) const WCHAR* text,
UINT32 length,
CultureInfo^ culture,
Expand Down Expand Up @@ -46,7 +46,7 @@ namespace MS { namespace Internal { namespace Text { namespace TextInterface
try
{
hr = pDWriteFactory->CreateTextAnalyzer(&pTextAnalyzer);
ConvertHresultToException(hr, "List<Span^>^ TextAnalyzer::Itemize");
ConvertHresultToException(hr, "List<Span>^ TextAnalyzer::Itemize");

pin_ptr<const WCHAR> pNumberSubstitutionLocaleNamePinned;

Expand All @@ -73,7 +73,7 @@ namespace MS { namespace Internal { namespace Text { namespace TextInterface
ignoreUserOverride,
numberSubstitutionMethod,
(void**)&pTextAnalysisSource));
ConvertHresultToException(hr, "List<Span^>^ TextAnalyzer::Itemize");
ConvertHresultToException(hr, "List<Span>^ TextAnalyzer::Itemize");


pTextAnalysisSink = (IDWriteTextAnalysisSink*)pfnCreateTextAnalysisSink();
Expand All @@ -83,14 +83,14 @@ namespace MS { namespace Internal { namespace Text { namespace TextInterface
0,
length,
pTextAnalysisSink);
ConvertHresultToException(hr, "List<Span^>^ TextAnalyzer::Itemize");
ConvertHresultToException(hr, "List<Span>^ TextAnalyzer::Itemize");

// Analyze the number substitution ranges.
hr = pTextAnalyzer->AnalyzeNumberSubstitution(pTextAnalysisSource,
0,
length,
pTextAnalysisSink);
ConvertHresultToException(hr, "List<Span^>^ TextAnalyzer::Itemize");
ConvertHresultToException(hr, "List<Span>^ TextAnalyzer::Itemize");

DWriteTextAnalysisNode<DWRITE_SCRIPT_ANALYSIS>* dwriteScriptAnalysisNode = (DWriteTextAnalysisNode<DWRITE_SCRIPT_ANALYSIS>*)pfnGetScriptAnalysisList((void*)pTextAnalysisSink);
DWriteTextAnalysisNode<IDWriteNumberSubstitution*>* dwriteNumberSubstitutionNode = (DWriteTextAnalysisNode<IDWriteNumberSubstitution*>*)pfnGetNumberSubstitutionList((void*)pTextAnalysisSink);
Expand All @@ -114,7 +114,7 @@ namespace MS { namespace Internal { namespace Text { namespace TextInterface

}

IList<Span^>^ TextAnalyzer::AnalyzeExtendedAndItemize(
IList<Span>^ TextAnalyzer::AnalyzeExtendedAndItemize(
TextItemizer^ textItemizer,
__in_ecount(length) const WCHAR *text,
UINT32 length,
Expand Down
4 changes: 2 additions & 2 deletions src/Microsoft.DotNet.Wpf/src/DirectWriteForwarder/CPP/DWriteWrapper/TextAnalyzer.h
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Expand Up @@ -120,7 +120,7 @@ namespace MS { namespace Internal { namespace Text { namespace TextInterface
}
}

static IList<Span^>^ AnalyzeExtendedAndItemize(
static IList<Span>^ AnalyzeExtendedAndItemize(
TextItemizer^ textItemizer,
__in_ecount(length) const WCHAR *text,
UINT32 length,
Expand All @@ -147,7 +147,7 @@ namespace MS { namespace Internal { namespace Text { namespace TextInterface
IDWriteTextAnalyzer* textAnalyzer
);

static IList<Span^>^ Itemize(
static IList<Span>^ Itemize(
__in_ecount(length) const WCHAR* text,
UINT32 length,
CultureInfo^ culture,
Expand Down
6 changes: 3 additions & 3 deletions src/Microsoft.DotNet.Wpf/src/DirectWriteForwarder/CPP/DWriteWrapper/TextItemizer.cpp
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Expand Up @@ -58,7 +58,7 @@ namespace MS { namespace Internal { namespace Text { namespace TextInterface

}

__declspec(noinline) IList<Span^>^ TextItemizer::Itemize(CultureInfo^ numberCulture, __in_ecount(textLength) CharAttributeType* pCharAttribute, UINT32 textLength)
__declspec(noinline) IList<Span>^ TextItemizer::Itemize(CultureInfo^ numberCulture, __in_ecount(textLength) CharAttributeType* pCharAttribute, UINT32 textLength)
{
DWriteTextAnalysisNode<DWRITE_SCRIPT_ANALYSIS>* pScriptAnalysisListPrevious = _pScriptAnalysisListHead;
DWriteTextAnalysisNode<DWRITE_SCRIPT_ANALYSIS>* pScriptAnalysisListCurrent = _pScriptAnalysisListHead;
Expand All @@ -79,7 +79,7 @@ namespace MS { namespace Internal { namespace Text { namespace TextInterface
&pNumberSubstitutionListCurrent, numberSubstitutionRangeIndex,
isDigitIndex, isDigitRangeIndex);

List<Span^>^ spanVector = gcnew List<Span^>();
List<Span>^ spanVector = gcnew List<Span>();
while (
rangeEnd != textLength
&& (pScriptAnalysisListCurrent != NULL
Expand Down Expand Up @@ -193,7 +193,7 @@ namespace MS { namespace Internal { namespace Text { namespace TextInterface
isLatin
);

spanVector->Add(gcnew Span(itemProps, (int)(rangeEnd - rangeStart)));
spanVector->Add(Span(itemProps, (int)(rangeEnd - rangeStart)));
}

return spanVector;
Expand Down
2 changes: 1 addition & 1 deletion src/Microsoft.DotNet.Wpf/src/DirectWriteForwarder/CPP/DWriteWrapper/TextItemizer.h
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Expand Up @@ -66,7 +66,7 @@ namespace MS { namespace Internal { namespace Text { namespace TextInterface
TextItemizer(DWriteTextAnalysisNode<DWRITE_SCRIPT_ANALYSIS>* pScriptAnalysisListHead,
DWriteTextAnalysisNode<IDWriteNumberSubstitution*>* pNumberSubstitutionListHead);

IList<Span^>^ Itemize(CultureInfo^ numberCulture, __in_ecount(textLength) CharAttributeType* pCharAttribute, UINT32 textLength);
IList<Span>^ Itemize(CultureInfo^ numberCulture, __in_ecount(textLength) CharAttributeType* pCharAttribute, UINT32 textLength);

void SetIsDigit(
UINT32 textPosition,
Expand Down
39 changes: 26 additions & 13 deletions src/Microsoft.DotNet.Wpf/src/PresentationCore/MS/internal/Span.cs
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Expand Up @@ -51,7 +51,7 @@ public IEnumerator GetEnumerator()
/// <summary>
/// Add a new span to vector
/// </summary>
private void Add(Span span)
private void Add(in Span span)
{
_spans.Add(span);
}
Expand Down Expand Up @@ -87,6 +87,13 @@ private void Insert(int index, int count)
}

#region Public operation
/// <summary>
/// Place item into the store at index
/// </summary>
public void SetAt(int index, in Span span)
{
_spans.SetAt(index, span);
}

/// <summary>
/// Finds the span that contains the specified character position.
Expand Down Expand Up @@ -164,7 +171,7 @@ internal bool FindSpan(int cp, SpanPosition latestPosition, out SpanPosition spa
// Return true if the span is in range.
return spanIndex != spanCount;
}


/// <summary>
/// Set an element as a value to a character range
Expand Down Expand Up @@ -226,19 +233,23 @@ private SpanPosition Set(int first, int length, object element, Equals equals, S
Add(new Span(_defaultObject, first - fc));
}

if ( Count > 0
&& equals(_spans[Count-1].element, element))
bool addElement = true;
if (Count > 0)
{
// New Element matches end Element, just extend end Element
_spans[Count - 1].length += length;

// Make sure fs and fc still agree
if (fs == Count)
var span = _spans[Count - 1];
if (equals(span.element, element))
{
fc += length;
// New Element matches end Element, just extend end Element
_spans[Count - 1] = new(span.element, span.length + length);
addElement = false;
// Make sure fs and fc still agree
if (fs == Count)
{
fc += length;
}
}
}
else
if (addElement)
{
Add(new Span(element, length));
}
Expand Down Expand Up @@ -314,7 +325,8 @@ private SpanPosition Set(int first, int length, object element, Equals equals, S
if (!Resize(fs + 2))
throw new OutOfMemoryException();
}
_spans[fs].length = first - fc;
var oldFsSpan = _spans[fs];
_spans[fs] = new Span(oldFsSpan.element, first - fc);
_spans[fs + 1] = new Span(element, length);
}
else
Expand Down Expand Up @@ -370,7 +382,8 @@ private SpanPosition Set(int first, int length, object element, Equals equals, S

if (fc < first)
{
_spans[fs].length = first - fc;
var oldFsSpan = _spans[fs];
_spans[fs] = new Span(oldFsSpan.element, first - fc);
fs++;
fc = first;
}
Expand Down
3 changes: 2 additions & 1 deletion src/Microsoft.DotNet.Wpf/src/PresentationCore/MS/internal/TextFormatting/TextStore.cs
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Expand Up @@ -1076,7 +1076,8 @@ internal bool InsertFakeLineBreak(int cpLimit)
if (lsrun.Type == Plsrun.Text && cp + lsrun.Length > cpLimit)
{
lsrun.Truncate(cpLimit - cp);
span.length = lsrun.Length;
span = new(span.element, lsrun.Length);
_plsrunVector.SetAt(i, span);
}

_lscchUpTo = lscp + lsrun.Length;
Expand Down
11 changes: 11 additions & 0 deletions src/Microsoft.DotNet.Wpf/src/Shared/MS/Utility/FrugalList.cs
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Expand Up @@ -2221,6 +2221,17 @@ public void Insert(int index, T value)
throw new ArgumentOutOfRangeException(nameof(index));
}

public void SetAt(int index, T value)
{
if ((_listStore is not null) && ((index < _listStore.Count) && (index >= 0)))
{
_listStore.SetAt(index, value);
return;
}

throw new ArgumentOutOfRangeException(nameof(index));
}

public bool Remove(T value)
{
if ((_listStore is not null) && (_listStore.Count > 0))
Expand Down