static bool CompositeHasInstructions(BigEndianReader reader, ushort compositeGlyphIndex)
{
//To find if a composite has instruction or not.
//This method is similar to ReadCompositeGlyph() (below)
//but this dose not create actual composite glyph.
CompositeGlyphFlags flags;
do
{
flags = (CompositeGlyphFlags)reader.ReadUInt16();
ushort glyphIndex = reader.ReadUInt16();
short arg1 = 0;
short arg2 = 0;
ushort arg1and2 = 0;
if (HasCompositeFlag(flags, CompositeGlyphFlags.ARG_1_AND_2_ARE_WORDS))
{
arg1 = reader.ReadInt16();
arg2 = reader.ReadInt16();
}
else
{
arg1and2 = reader.ReadUInt16();
}
//-----------------------------------------
float xscale = 1;
float scale01 = 0;
float scale10 = 0;
float yscale = 1;
bool useMatrix = false;
bool hasScale = false;
//-----------------------------------------
if (HasCompositeFlag(flags, CompositeGlyphFlags.WE_HAVE_A_SCALE))
{
//If the bit WE_HAVE_A_SCALE is set,
//the scale value is read in 2.14 format-the value can be between -2 to almost +2.
//The glyph will be scaled by this value before grid-fitting.
xscale = yscale = reader.ReadF2Dot14(); /* Format 2.14 */
hasScale = true;
}
else if (HasCompositeFlag(flags, CompositeGlyphFlags.WE_HAVE_AN_X_AND_Y_SCALE))
{
xscale = reader.ReadF2Dot14(); /* Format 2.14 */
yscale = reader.ReadF2Dot14(); /* Format 2.14 */
hasScale = true;
}
else if (HasCompositeFlag(flags, CompositeGlyphFlags.WE_HAVE_A_TWO_BY_TWO))
{
//The bit WE_HAVE_A_TWO_BY_TWO allows for linear transformation of the X and Y coordinates by specifying a 2 × 2 matrix.
//This could be used for scaling and 90-degree*** rotations of the glyph components, for example.
//2x2 matrix
//The purpose of USE_MY_METRICS is to force the lsb and rsb to take on a desired value.
//For example, an i-circumflex (U+00EF) is often composed of the circumflex and a dotless-i.
//In order to force the composite to have the same metrics as the dotless-i,
//set USE_MY_METRICS for the dotless-i component of the composite.
//Without this bit, the rsb and lsb would be calculated from the hmtx entry for the composite
//(or would need to be explicitly set with TrueType instructions).
//Note that the behavior of the USE_MY_METRICS operation is undefined for rotated composite components.
useMatrix = true;
hasScale = true;
xscale = reader.ReadF2Dot14(); /* Format 2.14 */
scale01 = reader.ReadF2Dot14(); /* Format 2.14 */
scale10 = reader.ReadF2Dot14(); /* Format 2.14 */
yscale = reader.ReadF2Dot14(); /* Format 2.14 */
}
if (useMatrix || hasScale)
{
//This is to be implemented in WOFF2
}
} while (HasCompositeFlag(flags, CompositeGlyphFlags.MORE_COMPONENTS));
//
return(HasCompositeFlag(flags, CompositeGlyphFlags.WE_HAVE_INSTRUCTIONS));
}
