/// <summary>
/// Scan through specified character string checking for valid character
/// nominal glyph.
/// </summary>
/// <param name="charBufferRange">character buffer range</param>
/// <param name="emSize">height of Em</param>
/// <param name="scalingFactor">This is the factor by which we will scale up
/// the metrics. Typically this value to used to convert metrics from the real
/// space to the ideal space</param>
/// <param name="widthMax">maximum width allowed</param>
/// <param name="keepAWord">do not stop arbitrarily in the middle of a word</param>
/// <param name="numberSubstitution">digits require complex shaping</param>
/// <param name="cultureInfo">CultureInfo of the text</param>
/// <param name="textFormattingMode">The TextFormattingMode used (Ideal vs. Display)</param>
/// <param name="isSideways">Indicates whether to rotate glyphs.</param>
/// <param name="breakOnTabs">Determines whether to stop checking at a tab and
/// break the run there</param>
/// <param name="stringLengthFit">number of character fit in given width</param>
/// <returns>whether the specified string can be optimized by nominal glyph lookup</returns>
internal bool CheckFastPathNominalGlyphs(
CharacterBufferRange charBufferRange,
double emSize,
double scalingFactor,
double widthMax,
bool keepAWord,
bool numberSubstitution,
CultureInfo cultureInfo,
TextFormattingMode textFormattingMode,
bool isSideways,
bool breakOnTabs,
out int stringLengthFit
)
{
stringLengthFit = 0;
if (CachedTypeface.NullFont)
{
return(false);
}
GlyphTypeface glyphTypeface = TryGetGlyphTypeface();
if (glyphTypeface == null)
{
return(false);
}
double totalWidth = 0;
int i = 0;
ushort blankGlyph = glyphTypeface.BlankGlyphIndex;
ushort glyph = blankGlyph;
ushort charFlagsMask = numberSubstitution ?
(ushort)(CharacterAttributeFlags.CharacterComplex | CharacterAttributeFlags.CharacterDigit) :
(ushort)CharacterAttributeFlags.CharacterComplex;
ushort charFlags = 0;
ushort charFastTextCheck = (ushort)(CharacterAttributeFlags.CharacterFastText | CharacterAttributeFlags.CharacterIdeo);
bool symbolTypeface = glyphTypeface.Symbol;
if (symbolTypeface)
{
// we don't care what code points are present if it's a non-Unicode font such as Symbol or Wingdings;
// the code points don't have any standardized meanings, and we always want to bypass shaping
charFlagsMask = 0;
}
bool ignoreWidths = widthMax == double.MaxValue;
ushort[] glyphIndices = BufferCache.GetUShorts(charBufferRange.Length);
MS.Internal.Text.TextInterface.GlyphMetrics[] glyphMetrics = ignoreWidths ? null : BufferCache.GetGlyphMetrics(charBufferRange.Length);
glyphTypeface.GetGlyphMetricsOptimized(charBufferRange,
emSize,
glyphIndices,
glyphMetrics,
textFormattingMode,
isSideways
);
double designToEm = emSize / glyphTypeface.DesignEmHeight;
//
// This block will advance until one of:
// 1. The end of the charBufferRange is reached
// 2. The charFlags have some of the charFlagsMask values
// 3. The glyph is BlankGlyph (space)
// 4. Glyph index is 0 (unless symbol font)
//
// At this point totalWidth includes all of the widths including the stop character (which fits above)
// i indexes the next character (not included in the width)
//
if (keepAWord)
{
do
{
char ch = charBufferRange[i++];
if (ch == TextStore.CharLineFeed || ch == TextStore.CharCarriageReturn || (breakOnTabs && ch == TextStore.CharTab))
{
--i;
break;
}
else
{
int charClass = (int)Classification.GetUnicodeClassUTF16(ch);
charFlags = Classification.CharAttributeOf(charClass).Flags;
charFastTextCheck &= charFlags;
glyph = glyphIndices[i - 1];
if (!ignoreWidths)
{
totalWidth += TextFormatterImp.RoundDip(glyphMetrics[i - 1].AdvanceWidth * designToEm, textFormattingMode) * scalingFactor;
}
}
} while(
i < charBufferRange.Length &&
((charFlags & charFlagsMask) == 0) &&
(glyph != 0 || symbolTypeface) &&
glyph != blankGlyph
);
// i is now at a character immediately following a leading blank
}
//
// This block will advance until one of:
// 1. The end of the charBufferRange is reached
// 2. The charFlags have some of the charFlagsMask values
// 3. Glyph index is 0 (unless symbol font)
// 4. totalWidth > widthMax
//
while (
i < charBufferRange.Length &&
(ignoreWidths || totalWidth <= widthMax) &&
((charFlags & charFlagsMask) == 0) &&
(glyph != 0 || symbolTypeface)
)
{
char ch = charBufferRange[i++];
if (ch == TextStore.CharLineFeed || ch == TextStore.CharCarriageReturn || (breakOnTabs && ch == TextStore.CharTab))
{
--i;
break;
}
else
{
int charClass = (int)Classification.GetUnicodeClassUTF16(ch);
charFlags = Classification.CharAttributeOf(charClass).Flags;
charFastTextCheck &= charFlags;
glyph = glyphIndices[i - 1];
if (!ignoreWidths)
{
totalWidth += TextFormatterImp.RoundDip(glyphMetrics[i - 1].AdvanceWidth * designToEm, textFormattingMode) * scalingFactor;
}
}
}
BufferCache.ReleaseUShorts(glyphIndices);
glyphIndices = null;
BufferCache.ReleaseGlyphMetrics(glyphMetrics);
glyphMetrics = null;
if (symbolTypeface)
{
// always optimize for non-Unicode font as we don't support shaping or typographic features;
// we also don't fall back from non-Unicode fonts so we don't care if there are missing glyphs
stringLengthFit = i;
return(true);
}
if (glyph == 0)
{
// character is not supported by the font
return(false);
}
if ((charFlags & charFlagsMask) != 0)
{
// complex character encountered, exclude it
Debug.Assert(i > 0);
if (--i <= 0)
{
// first char is complex, fail the call
return(false);
}
}
stringLengthFit = i;
TypographyAvailabilities typography = glyphTypeface.FontFaceLayoutInfo.TypographyAvailabilities;
if ((charFastTextCheck & (byte)CharacterAttributeFlags.CharacterFastText) != 0)
{
// all input code points are Fast Text
if ((typography &
(TypographyAvailabilities.FastTextTypographyAvailable
| TypographyAvailabilities.FastTextMajorLanguageLocalizedFormAvailable
)
) != 0
)
{
// Considered too risky to optimize. It is either because the font
// has required features or the font has 'locl' lookup for major languages.
return(false);
}
else if ((typography & TypographyAvailabilities.FastTextExtraLanguageLocalizedFormAvailable) != 0)
{
// The font has 'locl' lookup for FastText code points for non major languages.
// Check whether the input is major langauge. If it is, we are still good to optimize.
return(MajorLanguages.Contains(cultureInfo));
}
else
{
// No FastText flags are present, safe to optimize
return(true);
}
}
else if ((charFastTextCheck & (byte)CharacterAttributeFlags.CharacterIdeo) != 0)
{
// The input are all ideographs, check the IdeoTypographyAvailable bit. It is safe if
// the bit is not set.
return((typography & TypographyAvailabilities.IdeoTypographyAvailable) == 0);
}
else
{
// for all the rest of the cases, just check whether there is any required typography
// present at all. If none exists, it is optimizable. We might under-optimize here but
// it will be non-major languages.
return((typography & TypographyAvailabilities.Available) == 0);
}
}