In the attached zip file are the FontData and GlyphDataTable classes that I modified. I admit these changes are more than what is absolutely necessary to resolve the threading problem. So if you want the absolute minimum changes required and are willing to sacrifice a small sliver of performance, I suggest modifying the GlyphDataTable class as follows:
Code:
public void CompleteGlyphClosure(Dictionary<int, object> glyphs)
{
int count = glyphs.Count;
int[] glyphArray = new int[glyphs.Count];
glyphs.Keys.CopyTo(glyphArray, 0);
if (!glyphs.ContainsKey(0))
{
glyphs.Add(0, null);
}
// ensure no other threads can alter the Position property of this FontData instance
lock (this.fontData)
{
for (int idx = 0; idx < count; idx++)
{
AddCompositeGlyphs(glyphs, glyphArray[idx]);
}
}
}
{
int count = glyphs.Count;
int[] glyphArray = new int[glyphs.Count];
glyphs.Keys.CopyTo(glyphArray, 0);
if (!glyphs.ContainsKey(0))
{
glyphs.Add(0, null);
}
// ensure no other threads can alter the Position property of this FontData instance
lock (this.fontData)
{
for (int idx = 0; idx < count; idx++)
{
AddCompositeGlyphs(glyphs, glyphArray[idx]);
}
}
}
Regarding the attached source, the centerpiece of what I did involves abstracting all of the Read and Seek methods and the Position property into an interface IFontDataReader. I created a class named FontData.Reader that implements the interface. FontData has a default instance of the FontData.Reader class that it uses internally plus a public method to obtain a new instance of the FontData.Reader class. For the sake of code compatibility the rest of the project, FontData also implements IFontDataReader (dispatching the calls to its internal default instance of the FontData.Reader class). With this approach, the modifications to GlyphDataTable are as follows:
Code:
public void CompleteGlyphClosure(Dictionary<int, object> glyphs)
{
int count = glyphs.Count;
int[] glyphArray = new int[glyphs.Count];
glyphs.Keys.CopyTo(glyphArray, 0);
if (!glyphs.ContainsKey(0))
{
glyphs.Add(0, null);
}
IFontDataReader fontDataReader = this.fontData.NewReader();
for (int idx = 0; idx < count; idx++)
{
AddCompositeGlyphs(fontDataReader, glyphs, glyphArray[idx]);
}
}
void AddCompositeGlyphs(IFontDataReader fontDataReader, Dictionary<int, object> glyphs, int glyph)
{
//int start = this.fontData.loca.GetOffset(glyph);
int start = GetOffset(glyph);
// Has no contour?
if (start == GetOffset(glyph + 1))
return;
fontDataReader.Position = start;
int numContours = fontDataReader.ReadShort();
// Is not a composite glyph?
if (numContours >= 0)
return;
fontDataReader.SeekOffset(8);
for (; ; )
{
int flags = fontDataReader.ReadUFWord();
int cGlyph = fontDataReader.ReadUFWord();
if (!glyphs.ContainsKey(cGlyph))
glyphs.Add(cGlyph, null);
if ((flags & MORE_COMPONENTS) == 0)
return;
int offset = (flags & ARG_1_AND_2_ARE_WORDS) == 0 ? 2 : 4;
if ((flags & WE_HAVE_A_SCALE) != 0)
offset += 2;
else if ((flags & WE_HAVE_AN_X_AND_Y_SCALE) != 0)
offset += 4;
if ((flags & WE_HAVE_A_TWO_BY_TWO) != 0)
offset += 8;
fontDataReader.SeekOffset(offset);
}
}
{
int count = glyphs.Count;
int[] glyphArray = new int[glyphs.Count];
glyphs.Keys.CopyTo(glyphArray, 0);
if (!glyphs.ContainsKey(0))
{
glyphs.Add(0, null);
}
IFontDataReader fontDataReader = this.fontData.NewReader();
for (int idx = 0; idx < count; idx++)
{
AddCompositeGlyphs(fontDataReader, glyphs, glyphArray[idx]);
}
}
void AddCompositeGlyphs(IFontDataReader fontDataReader, Dictionary<int, object> glyphs, int glyph)
{
//int start = this.fontData.loca.GetOffset(glyph);
int start = GetOffset(glyph);
// Has no contour?
if (start == GetOffset(glyph + 1))
return;
fontDataReader.Position = start;
int numContours = fontDataReader.ReadShort();
// Is not a composite glyph?
if (numContours >= 0)
return;
fontDataReader.SeekOffset(8);
for (; ; )
{
int flags = fontDataReader.ReadUFWord();
int cGlyph = fontDataReader.ReadUFWord();
if (!glyphs.ContainsKey(cGlyph))
glyphs.Add(cGlyph, null);
if ((flags & MORE_COMPONENTS) == 0)
return;
int offset = (flags & ARG_1_AND_2_ARE_WORDS) == 0 ? 2 : 4;
if ((flags & WE_HAVE_A_SCALE) != 0)
offset += 2;
else if ((flags & WE_HAVE_AN_X_AND_Y_SCALE) != 0)
offset += 4;
if ((flags & WE_HAVE_A_TWO_BY_TWO) != 0)
offset += 8;
fontDataReader.SeekOffset(offset);
}
}
| Attachments: |
File comment: Modifications for thread safety.
PDFSharp-fontdata-glyphdatatable.zip [10.93 KiB]
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