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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
//
//
//
// Contents: base shaping engine buffers
//
//
namespace MS.Internal.Shaping
{
/// <summary>
/// ShaperBuffers encapsulates the shapers non-volatile, non-shareabld buffers
/// </summary>
/// <remarks>
/// This class owns several buffers that need to live as long as there's a
/// shaping engine that uses them. Each shaping engine "owns" one of these, but
/// the actual mapping/number of ShaperBuffers instances depends
/// on the THREAD_SAFE_SHAPERS constant in BaseShape.cs. If THREAD_SAFE_SHAPERS
/// is defined, there's one ShaperBuffers for each thread created in the
/// WCP process space. If not defined, each shaping engine has its own
/// ShaperBuffers object. In this latter case, the owner of the ShapeManager
/// that owns the shaping engine is responsible for guaranteeing thread safety (everything
/// else in the shape engines is reentrant, but each ShaperBuffers is not.
///
/// A ShaperBuffers is created whenever a IShaper interface method of a
/// shaper is called and its member ShaperBuffers is null (ie, the first time
/// a shaper's IShaper interface is invoked). It exists till the shaper is destroyed.
/// </remarks>
internal class ShaperBuffers
{
/// <summary>
/// ShaperBuffers - constructor
/// </summary>
public ShaperBuffers(ushort charCount, ushort glyphCount)
{
// the charCount is used to provide an initial size for the
// various buffers used by the shaper(s). These may
// grow over the shaper's life
_glyphInfoList = new GlyphInfoList((glyphCount > charCount ? glyphCount : charCount), 16, false);
_charMap = new UshortList(charCount, 16);
_layoutWorkspace = new OpenTypeLayoutWorkspace();
_charMap.SetRange(0,charCount);
if (glyphCount > 0)
{
_glyphInfoList.SetRange(0,glyphCount);
}
}
~ShaperBuffers()
{
_glyphInfoList = null;
_charMap = null;
_layoutWorkspace = null;
_textFeatures = null;
}
// I have laid these out alphabetically. If a particular variable has
// an accessor with a different name than the variable, I've added a
// comment in the position of the variable...
public UshortList CharMap
{
get { return _charMap; }
}
public GlyphInfoList GlyphInfoList
{
get { return _glyphInfoList; }
set { _glyphInfoList = value; }
}
/// <summary>
/// ShaperBuffers.Initialize - initializer for GetGlyphs.
/// </summary>
/// <remarks>
/// Called by every shaper's GetGlyph method (indirectly -
/// this function is actually called by the ShapingWorkspace.Initialize
/// method (which is called from IShaper.GetGlyphs)).
/// </remarks>
public bool Initialize(ushort charCount, ushort glyphCount)
{
if (charCount <= 0)
{
return false;
}
// clear charmap and resize it
if (_charMap.Length > 0)
{
_charMap.Remove(0, _charMap.Length);
}
_charMap.Insert(0, charCount);
Debug.Assert(_charMap.Length == charCount);
// clear glyphinfolist
if (_glyphInfoList.Length > 0)
{
_glyphInfoList.Remove(0, _glyphInfoList.Length);
}
if (glyphCount > 0)
{
_glyphInfoList.Insert(0, glyphCount);
}
Debug.Assert(_glyphInfoList.Length == glyphCount);
return true;
}
/// <summary>
/// ShaperBuffers.InitializeFeatureList - initializer for GetGlyphs.
/// </summary>
/// <param name="size">Requested new array size</param>
/// <param name="keep">number of features to copy into new array</param>
/// <remarks>
/// Called by pertinent shaper's GetGlyph method; ie, those shapers
/// that need to create a text dependent list of features
/// (e.g. Arabic, Mongolian).
/// The "keep" count takes priority over "size" if there's already an
/// array, so if size size is less than keep, the resized array has at
/// least keep elements. It is possible to create a 0 sized array.
/// </remarks>
public bool InitializeFeatureList(ushort size, ushort keep)
{
if (_textFeatures == null)
{
_textFeatures = new ShaperFeaturesList();
if (_textFeatures == null)
{
return false;
}
_textFeatures.Initialize(size);
}
else
{
_textFeatures.Resize(size, keep);
}
return true;
}
public OpenTypeLayoutWorkspace LayoutWorkspace
{
get { return _layoutWorkspace; }
}
// NextIx; see CurrentCharIx
public ShaperFeaturesList TextFeatures
{
get { return _textFeatures; }
}
// these are one per shaping engine (or per thread) and are kept around
// between calls (ie, we allocate these once for the lifetime of this
// ShapingWorkspace instance)
private UshortList _charMap;
private GlyphInfoList _glyphInfoList;
private OpenTypeLayoutWorkspace _layoutWorkspace;
private ShaperFeaturesList _textFeatures;
}
internal class ShaperFeaturesList
{
public int FeaturesCount
{
get { return _featuresCount; }
}
public Feature[] Features
{
get { return _features; }
}
public int NextIx
{
get { return _featuresCount; }
}
public uint CurrentTag
{
get { return _featuresCount == 0 ? 0 : _features[_featuresCount - 1].Tag;}
}
public int Length
{
get { return _featuresCount; }
}
public void SetFeatureParameter (ushort featureIx, uint paramValue)
{
Invariant.Assert ( _featuresCount > featureIx );
_features[featureIx].Parameter = paramValue;
}
/// <summary>
/// ShaperFeateruList.Initialize - initializer for GetGlyphs.
/// </summary>
/// <remarks>
/// Called by pertinent shaper's GetGlyph method (indirectly -
/// this function is actually called by the
/// ShaperBuffers.InitializeFeatureList method which is
/// called by those shapers that need to create a text dependent
/// list of features (e.g. Arabic, Mongolian).
/// </remarks>
internal bool Initialize (ushort newSize)
{
if (_features == null ||
newSize > _features.Length ||
newSize == 0)
{
Feature[] newArray = new Feature[newSize];
if (newArray != null)
{
_features = newArray;
}
}
_featuresCount = 0;
_minimumAddCount = 3; // add space for init,med,final whenever we need to actually resize array
return _features != null;
}
/// <summary>
/// ShaperFeateruList.Resize - used to change the size of the features array
/// </summary>
/// <param name="newSize">Requested new array size</param>
/// <param name="keepCount">number of features to copy into new array</param>
/// <remarks>
/// Used locally for each AddFeature, and by ShaperBuffers.InitializeFeatureList.
/// May be called from a shaping engine.
/// The "keepCount" count takes priority over "newSize" if there's already an
/// array, so if size is less than keep, the resized array has at least keep elements.
/// </remarks>
internal bool Resize (ushort newSize, ushort keepCount)
{
_featuresCount = keepCount; //
if (_features != null &&
_features.Length != 0 &&
keepCount > 0 &&
_features.Length >= keepCount)
{
// make sure keep count is no bigger than current
// array size
ushort currentLength = (ushort)_features.Length;
// make sure new size is at least as big as keep count
if (newSize < keepCount)
{
newSize = keepCount;
}
// if new size is bigger than the current array, create
// a new array
if (newSize > currentLength)
{
// always use minimum leap for adding to array
if (newSize < (currentLength + _minimumAddCount))
{
newSize = (ushort)(currentLength + _minimumAddCount);
}
Feature[] newArray = new Feature[newSize];
if (newArray == null)
{
// can't create new array, leave (at least we still
// have our current array)
return false;
}
// Our client wants us to keep the first "keepCount" entries.
// so copy them now.
for (int i = 0; i < keepCount; ++i)
{
newArray[i] = _features[i];
}
_features = newArray;
}
}
else
{
// nothing to keep, or currently no array so initialize
return Initialize(newSize);
}
return true;
}
/// <summary>
/// ShaperFeateruList.AddFeature - add a feature to the array
/// </summary>
/// <param name="feature">new feature to add</param>
/// <remarks>
/// This is aimed at allowing shaping engines to add features
/// to the array (generally used for required, all character
/// features added at the start of shaping)
/// </remarks>
internal void AddFeature (Feature feature)
{
if ( _featuresCount == _features.Length )
{
// need more space, so resize the array
if (!Resize((ushort)(_featuresCount + 1),_featuresCount))
{
return; // can't resize array, fail quietly (not going
// to apply this feature!)
}
}
_features[_featuresCount] = feature;
++_featuresCount;
}
/// <summary>
/// ShaperFeateruList.AddFeature - add a feature to the array
/// </summary>
/// <remarks>
/// An alternative to adding an already created feature.
/// </remarks>
internal void AddFeature (ushort startIndex, ushort length, uint featureTag, uint parameter)
{
if ( _featuresCount == _features.Length )
{
// need more space
if (!Resize((ushort)(_featuresCount + 1),_featuresCount))
{
return;
}
}
if (_features[_featuresCount] != null)
{
_features[_featuresCount].Tag = featureTag;
_features[_featuresCount].StartIndex = startIndex;
_features[_featuresCount].Length = length;
_features[_featuresCount].Parameter = parameter;
}
else
{
_features[_featuresCount] = new Feature(startIndex,length,featureTag,parameter);
}
++_featuresCount;
}
/// <summary>
/// ShaperFeateruList.AddFeature - add a feature to the array
/// </summary>
/// <remarks>
/// This variation of "AddFeature" is used by the shaper state
/// machines for adding each new feature.
/// </remarks>
internal void AddFeature (ushort charIx, uint featureTag )
{
if (featureTag == 1) // "NotShaped"
{
return;
}
if (_featuresCount > 0) // if previous feature exists
{
// see if this feature can just be subsumed in the latest feature
ushort latestFeatureIx = (ushort)(_featuresCount - 1);
if ((featureTag == 0 || featureTag == _features[latestFeatureIx].Tag) &&
(_features[latestFeatureIx].StartIndex +
_features[latestFeatureIx].Length) == charIx)
{
_features[latestFeatureIx].Length += 1;
}
else
{
// can't be added to previous feature, so add one.
AddFeature(charIx,
1,
(featureTag == 0 ? _features[latestFeatureIx].Tag : featureTag),
1);
}
}
else if (featureTag != 0) // cant' be "Same" (there's no feature yet)
{
AddFeature(charIx,1,featureTag,1);
}
}
/// <summary>
/// ShaperFeateruList.UpdatePreviousShapedChar - adjust previous char's tag
/// </summary>
/// <remarks>
/// This is used by the shaper state machines for modifying the
/// feature tag of the previous character.
/// </remarks>
internal void UpdatePreviousShapedChar (uint featureTag)
{
if (featureTag <= 1) // nothing to do if "NotShaped" or "Same"
{
return;
}
if (_featuresCount > 0)
{
// see if this feature can just be subsumed in the latest feature
ushort latestFeatureIx = (ushort)(_featuresCount - 1);
if (_features[latestFeatureIx].Tag != featureTag)
{
// the previous char's feature just applied to
// it, so update its tag and we're done
_features[latestFeatureIx].Tag = featureTag;
}
}
}
private ushort _minimumAddCount;
private ushort _featuresCount;
private Feature[] _features;
}
}
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