// This idea was borrowed from Google Chrome's uniscribe handler:
// https://code.google.com/p/chromium/codesearch#chromium/src/ui/gfx/font_fallback_win.cc&q=uniscribe&sq=package:chromium&l=283&dr=CSs
// also as discussed here:
// http://stackoverflow.com/questions/16828868/how-to-automatically-choose-most-suitable-font-for-different-language
private static bool GetUniscribeFallbackFont(
Font font,
IntPtr text,
int textLength,
out GDI.LOGFONT fallbackFont)
{
fallbackFont = new GDI.LOGFONT();
// Figure out what font Uniscribe chooses for fallback by making it write to a
// metafile and then cracking it open.
using (GDIDC hdc = GDIDC.CreateCompatibleDC(IntPtr.Zero))
{
IntPtr hdcMF_ = GDI.CreateEnhMetaFile(hdc, null, IntPtr.Zero, null);
if (hdcMF_ == IntPtr.Zero)
{
Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error());
}
using (GDIDC hdcMF = new GDIDC(hdcMF_))
{
using (GDIFont gdiFont = new GDIFont(font))
{
GDI.SelectObject(hdcMF, gdiFont);
IntPtr sa = IntPtr.Zero;
try
{
int hr;
hr = ScriptStringAnalyse(
hdcMF,
text,
textLength,
0, // cGlyphs
-1, // iCharSet
SSA_METAFILE | SSA_FALLBACK | SSA_GLYPHS | SSA_LINK,
0, // required width
IntPtr.Zero, // SCRIPT_CONTROL
IntPtr.Zero, // SCRIPT_STATE
null, // piDx
IntPtr.Zero, // SCRIPT_TABDEF
null, // legacy
out sa);
if (hr < 0)
{
return false;
}
hr = ScriptStringOut(
sa,
0, // iX
0, // iY
0, // ExtTextOut options
IntPtr.Zero, // rect
0, // iMinSel
0, // iMaxSel
false); // fDisabled
if (hr < 0)
{
return false;
}
}
finally
{
ScriptStringFree(ref sa);
}
IntPtr hMF = GDI.CloseEnhMetaFile(hdcMF);
if (hMF == IntPtr.Zero)
{
Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error());
}
try
{
GDI.LOGFONT lf = new GDI.LOGFONT();
bool r = GDI.EnumEnhMetaFile(
IntPtr.Zero, // hdc
hMF,
delegate (
IntPtr hdc_,
IntPtr[] lpht,// capacity is nHandles
IntPtr lpmr, // ENHMETARECORD
int nHandles,
int data) // LPARAM
{
// read lpmr->iType
int iType = Marshal.ReadInt32(lpmr);
if (iType == GDI.EMR_EXTCREATEFONTINDIRECTW)
{
object cfio = Marshal.PtrToStructure(lpmr, typeof(GDI.EMREXTCREATEFONTINDIRECT));
GDI.EMREXTCREATEFONTINDIRECT cfi = (GDI.EMREXTCREATEFONTINDIRECT)cfio;
// Last one wins!
lf = cfi.elfw.elfLogFont;
}
return 1;
},
IntPtr.Zero, // LPARAM
IntPtr.Zero); // &RECT
if (!r)
{
Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error());
}
if (!String.IsNullOrEmpty(lf.lfFaceName))
{
fallbackFont = lf;
return true;
}
}
finally
{
GDI.DeleteEnhMetaFile(hMF);
}
return false;
}
}
}
}
// This article provides a real-world tutorial of how to actually use the API, including
// a discussion of many gotchas not identified in the MSDN documentation.
// http://www.catch22.net/tuts/uniscribe-mysteries
// http://www.catch22.net/tuts/more-uniscribe-mysteries
// http://www.catch22.net/tuts/drawing-styled-text-uniscribe
// From the developer of Google Chrome's uniscribe client:
// https://maxradi.us/documents/uniscribe/
// Arabic embedded (RTL) example:
// http://blogs.msdn.com/b/vsarabic/archive/2011/08/21/text-rendering.aspx
// Devanagari example:
// http://www.omniglot.com/language/articles/devanagari.htm
// UTF16 non-zero plane exahere:
// https://en.wikipedia.org/wiki/UTF-16#Examples
// http://www.i18nguy.com/unicode-example-plane1.html
// "Displaying Text with Uniscribe"
// https://msdn.microsoft.com/en-us/library/windows/desktop/dd317792%28v=vs.85%29.aspx
internal static TextItems AnalyzeText(
TextServiceUniscribe service,
IntPtr hdc,
IntPtr hText,
FontRunInfo[] fontRuns)
{
TextItems o = new TextItems(service);
try
{
o.fontRuns = fontRuns;
for (int i = 0; i < fontRuns.Length; i++)
{
o.count += fontRuns[i].count;
o.lineHeight = Math.Max(o.lineHeight, fontRuns[i].fontHeight);
}
if (o.count == 0)
{
return o;
}
int hr;
// Lay Out Text Using Uniscribe
// 1. Call ScriptRecordDigitSubstitution only when starting or when receiving a WM_SETTINGCHANGE message.
// 2. (Optional) Call ScriptIsComplex to determine if the paragraph requires complex processing.
hr = ScriptIsComplex(
hText,
o.count,
ScriptIsComplexFlags.SIC_ASCIIDIGIT | ScriptIsComplexFlags.SIC_COMPLEX);
if (hr < 0)
{
Marshal.ThrowExceptionForHR(hr);
}
// Optional: if S_FALSE (1) is returned, one can fall back to TextRenderer and simplified hit testing
// 3. (Optional) If using Uniscribe to handle bidirectional text and/or digit substitution, call
// ScriptApplyDigitSubstitution to prepare the SCRIPT_CONTROL and SCRIPT_STATE structures as inputs
// to ScriptItemize. If skipping this step, but still requiring digit substitution, substitute
// national digits for Unicode U+0030 through U+0039 (European digits). For information about digit
// substitution, see Digit Shapes.
hr = ScriptApplyDigitSubstitution(
IntPtr.Zero,
out o.sControl,
out o.sState);
if (hr < 0)
{
Marshal.ThrowExceptionForHR(hr);
}
// 4. Call ScriptItemize to divide the paragraph into items. If not using Uniscribe for digit
// substitution and the bidirectional order is known, for example, because of the keyboard layout
// used to enter the character, call ScriptItemize. In the call, provide null pointers for the
// SCRIPT_CONTROL and SCRIPT_STATE structures. This technique generates items by use of the shaping
// engine only, and the items can be reordered using the engine information.
// Note: Typically, applications that work only with left-to-right scripts and without any digit
// substitution should pass null pointers for the SCRIPT_CONTROL and SCRIPT_STATE structures.
{
int cMaxItems = 8;
SCRIPT_ITEM[] sItems;
OPENTYPE_TAG[] sTags;
while (true)
{
sItems = new SCRIPT_ITEM[cMaxItems + 1]; // method adds terminator;
sTags = new OPENTYPE_TAG[cMaxItems];
hr = ScriptItemizeOpenType(
hText,
o.count,
cMaxItems,
ref o.sControl,
ref o.sState,
sItems,
sTags,
out o.cItems);
if (hr == E_OUTOFMEMORY)
{
cMaxItems *= 2;
continue;
}
if (hr < 0)
{
Marshal.ThrowExceptionForHR(hr);
}
break;
}
o.sItems = sItems;
o.sTags = sTags;
}
// 5. Merge the item information with the run information to produce ranges.
{
int fontRunOffset = 0;
int f = 0;
int i = 0;
while ((f < o.fontRuns.Length) && (i < o.cItems))
{
if (fontRunOffset + o.fontRuns[f].count > o.sItems[i + 1].iCharPos)
{
// run is longer - current item remains intact; advance to next
i++;
continue;
}
else if (fontRunOffset + o.fontRuns[f].count < o.sItems[i + 1].iCharPos)
{
// item too long - split
Array.Resize(ref o.sItems, o.cItems + 1 + 1);
Array.Copy(o.sItems, i, o.sItems, i + 1, o.sItems.Length - (i + 1));
Array.Resize(ref o.sTags, o.cItems + 1);
Array.Copy(o.sTags, i, o.sTags, i + 1, o.sTags.Length - (i + 1));
o.cItems++;
o.sItems[i + 1].iCharPos = fontRunOffset + o.fontRuns[f].count;
}
Debug.Assert(fontRunOffset + o.fontRuns[f].count == o.sItems[i + 1].iCharPos);
fontRunOffset += o.fontRuns[f].count;
f++;
i++;
}
Debug.Assert(fontRunOffset == o.count);
Debug.Assert(o.sItems[o.cItems].iCharPos == o.count);
}
// 6. Call ScriptShape to identify clusters and generate glyphs.
o.sItemsExtra = new ItemInfo[o.cItems];
o.logAttrs = new SCRIPT_LOGATTR[o.count];
for (int i = 0; i < o.cItems; i++)
{
int start = o.sItems[i].iCharPos;
int length = o.sItems[i + 1].iCharPos - start;
Font font = null;
for (int f = 0, pos = 0; f < o.fontRuns.Length; pos += o.fontRuns[f].count, f++)
{
font = o.fontRuns[f].font;
if (pos < start + length)
{
break;
}
}
int cMaxGlyphs = (3 * o.count / 2) + 16; // recommended starting value
short[] glyphs;
short[] logicalClusters;
SCRIPT_VISATTR[] visAttrs; // superceded by glyphProps
SCRIPT_GLYPHPROP[] glyphProps;
int cGlyphs;
int fallbackLevel = 0;
Font fallbackFont = null;
SCRIPT_CHARPROP[] charProps = new SCRIPT_CHARPROP[length];
while (true)
{
glyphs = new short[cMaxGlyphs];
logicalClusters = new short[cMaxGlyphs];
visAttrs = new SCRIPT_VISATTR[cMaxGlyphs];
glyphProps = new SCRIPT_GLYPHPROP[cMaxGlyphs];
bool needFallback = false;
int fontCacheIndex = service.FontCacheIndex(font);
GDIFont gdiFont;
if (!service.fontToHFont.TryGetValue(font, out gdiFont))
{
gdiFont = new GDIFont(font);
service.fontToHFont.Add(font, gdiFont);
}
GDI.SelectObject(hdc, gdiFont);
#if false // choose old or OpenType API
hr = ScriptShape(
hdc,
ref service.caches[fontCacheIndex].cache,
new IntPtr(hText.ToInt64() + start * 2),
length,
cMaxGlyphs,
ref o.sItems[i].a,
glyphs,
logicalClusters,
visAttrs,
out cGlyphs);
#else
hr = ScriptShapeOpenType(
hdc,
ref service.caches[fontCacheIndex].cache,
ref o.sItems[i].a,
o.sTags[i], // tagScript
o.sTags[i], // tagLangSys -- right thing to pass here?
null, // rcRangeChars
null, // rpRangeProperties
0, // cRanges
new IntPtr(hText.ToInt64() + start * 2),
length,
cMaxGlyphs,
logicalClusters,
charProps,
glyphs,
glyphProps, // supercedes visAttrs
out cGlyphs);
#endif
if (hr == E_OUTOFMEMORY)
{
cMaxGlyphs *= 2;
glyphs = new short[cMaxGlyphs];
logicalClusters = new short[cMaxGlyphs];
visAttrs = new SCRIPT_VISATTR[cMaxGlyphs];
continue;
}
if (hr == USP_E_SCRIPT_NOT_IN_FONT)
{
needFallback = true;
goto FontFallback;
}
if (hr < 0)
{
Marshal.ThrowExceptionForHR(hr);
}
// 7. If ScriptShape returns the code USP_E_SCRIPT_NOT_IN_FONT or S_OK with the output containing
// missing glyphs, select characters from a different font. Either substitute another font or disable
// shaping by setting the eScript member of the SCRIPT_ANALYSIS structure passed to ScriptShape to
// SCRIPT_UNDEFINED. For more information, see Using Font Fallback.
SCRIPT_FONTPROPERTIES sfp;
ScriptGetFontProperties(
hdc,
ref service.caches[fontCacheIndex].cache,
out sfp);
for (int j = 0; j < cGlyphs; j++)
{
if (glyphs[j] == sfp.wgDefault)
{
needFallback = true;
break;
}
}
FontFallback:
if (needFallback)
{
// What worked:
// https://code.google.com/p/chromium/codesearch#chromium/src/ui/gfx/font_fallback_win.cc&q=uniscribe&sq=package:chromium&l=283&dr=CSs
// http://stackoverflow.com/questions/16828868/how-to-automatically-choose-most-suitable-font-for-different-language
// What didn't work:
// The totally unhelpful Uniscribe font/script fallback documentation:
// https://msdn.microsoft.com/en-us/library/windows/desktop/dd374105%28v=vs.85%29.aspx
// MSDN Globalization how-to page about font fallback:
// https://msdn.microsoft.com/en-us/goglobal/bb688134.aspx
// ScriptShape page:
// https://msdn.microsoft.com/en-us/library/windows/desktop/dd368564(v=vs.85).aspx
fallbackLevel++;
switch (fallbackLevel)
{
case 1:
GDI.LOGFONT fallbackLF;
if (GetUniscribeFallbackFont(
font,
new IntPtr(hText.ToInt64() + 2 * start),
length,
out fallbackLF))
{
fallbackFont = null;
foreach (KeyValuePair<GDI.LOGFONT, Font> item in service.fallbackFonts)
{
if (String.Equals(item.Key.lfFaceName, fallbackLF.lfFaceName)
&& (item.Key.lfCharSet == fallbackLF.lfCharSet)
&& (item.Key.lfHeight == fallbackLF.lfHeight))
{
fallbackFont = item.Value;
break;
}
}
if (fallbackFont == null)
{
fallbackFont = Font.FromLogFont(fallbackLF);
service.fallbackFonts.Add(new KeyValuePair<GDI.LOGFONT, Font>(fallbackLF, fallbackFont));
}
font = fallbackFont;
continue;
}
continue;
case 2:
if (o.sItems[i].a.eScript != SCRIPT_UNDEFINED)
{
o.sItems[i].a.eScript = SCRIPT_UNDEFINED;
}
continue;
default:
// give up
break;
}
}
break;
}
// 8. Call ScriptPlace to generate advance widths and x and y positions for the glyphs in each
// successive range. This is the first step for which text size becomes a consideration.
int[] iAdvances = new int[cGlyphs];
GOFFSET[] goffsets = new GOFFSET[cGlyphs];
ABC abc = new ABC();
{
int fontCacheIndex = service.FontCacheIndex(font);
#if false // choose old or OpenType API
hr = ScriptPlace(
hdc,
ref service.caches[fontCacheIndex].cache,
glyphs,
cGlyphs,
visAttrs,
ref o.sItems[i].a,
iAdvances,
goffsets,
out abc);
#else
hr = ScriptPlaceOpenType(
hdc,
ref service.caches[fontCacheIndex].cache,
ref o.sItems[i].a,
o.sTags[i], // tagScript
o.sTags[i], // tagLangSys -- right thing to pass here?
null, // rcRangeChars
null, // rpRangeProperties
0, // cRanges
new IntPtr(hText.ToInt64() + start * 2),
logicalClusters,
charProps,
length,
glyphs,
glyphProps,
cGlyphs,
iAdvances,
goffsets,
out abc);
#endif
if (hr < 0)
{
Marshal.ThrowExceptionForHR(hr);
}
}
o.sItemsExtra[i].glyphs = glyphs;
o.sItemsExtra[i].logicalClusters = logicalClusters;
o.sItemsExtra[i].visAttrs = visAttrs;
o.sItemsExtra[i].cGlyphs = cGlyphs;
o.sItemsExtra[i].charProps = charProps;
o.sItemsExtra[i].glyphProps = glyphProps;
o.sItemsExtra[i].iAdvances = iAdvances;
o.sItemsExtra[i].goffsets = goffsets;
o.sItemsExtra[i].abc = abc;
o.sItemsExtra[i].fallbackFont = fallbackFont;
// 9. Sum the range sizes until the line overflows.
// 10. Break the range on a word boundary by using the fSoftBreak and fWhiteSpace members in the
// logical attributes. To break a single character cluster off the run, use the information returned
// by calling ScriptBreak.
// Note: Decide if the first code point of a range should be a word break point because the last
// character of the previous range requires it. For example, if one range ends in a comma, consider
// the first character of the next range to be a word break point.
SCRIPT_LOGATTR[] logAttrs1 = new SCRIPT_LOGATTR[o.count];
hr = ScriptBreak(
new IntPtr(hText.ToInt64() + 2 * start),
length,
ref o.sItems[i].a,
logAttrs1);
if (hr < 0)
{
Marshal.ThrowExceptionForHR(hr);
}
Array.Copy(logAttrs1, 0, o.logAttrs, o.sItems[i].iCharPos, length);
// 11. Repeat steps 6 through 10 for each line in the paragraph. However, if breaking the last run
// on the line, call ScriptShape to reshape the remaining part of the run as the first run on the
// next line.
}
// Display Text Using Uniscribe
// 1. For each run, do the following:
// a. If the style has changed since the last run, update the handle to the device context by releasing
// and getting it again.
// b. Call ScriptShape to generate glyphs for the run.
// c. Call ScriptPlace to generate an advance width and an x,y offset for each glyph.
// 2. Do the following to establish the correct visual order for the runs in the line:
// a. Extract an array of bidirectional embedding levels, one per range. The embedding level is
// given by (SCRIPT_ITEM) si.(SCRIPT_ANALYSIS) a. (SCRIPT_STATE) s.uBidiLevel.
// b. Pass this array to ScriptLayout to generate a map of visual positions to logical positions.
byte[] bidiEmbeddingLevels = new byte[o.cItems];
for (int i = 0; i < o.cItems; i++)
{
bidiEmbeddingLevels[i] = (byte)o.sItems[i].a.s.uBidiLevel;
}
o.iVisualToLogical = new int[o.cItems];
o.iLogicalToVisual = new int[o.cItems];
hr = ScriptLayout(
o.cItems,
bidiEmbeddingLevels,
o.iVisualToLogical,
o.iLogicalToVisual);
if (hr < 0)
{
Marshal.ThrowExceptionForHR(hr);
}
for (int i = 0; i < o.cItems; i++)
{
for (int j = 0; j < o.sItemsExtra[i].iAdvances.Length; j++)
{
o.sItemsExtra[i].totalWidth += o.sItemsExtra[i].iAdvances[j];
}
}
}
catch (Exception)
{
o.Dispose();
throw;
}
return o;
}