svn commit: r1596218 - /openoffice/trunk/main/vcl/aqua/source/gdi/ctlayout.cxx

[hd...@apache.org]

Author: hdu
Date: Tue May 20 12:00:50 2014
New Revision: 1596218

URL: http://svn.apache.org/r1596218
Log:
#i124935# fix expanded/condensed text breaking in the CoreText engine

the concept of an extra-width per code-unit was obsolete at least since apps
supported unicode with its different normalization forms, diacritical marks,
surrogate-pairs, non-printing characters such as ZWJ/ZWNJ/RLM, etc.  so of
course modern engines like CoreText don't aid this typographical crime.

The fix here extends the CTLayout::GetTextBreak() method to handle the obsolete
semantic of per code-unit extra-widths by successively approximating the number
of involved code-units.

Modified:
    openoffice/trunk/main/vcl/aqua/source/gdi/ctlayout.cxx

Modified: openoffice/trunk/main/vcl/aqua/source/gdi/ctlayout.cxx
URL: http://svn.apache.org/viewvc/openoffice/trunk/main/vcl/aqua/source/gdi/ctlayout.cxx?rev=1596218&r1=1596217&r2=1596218&view=diff
==============================================================================
--- openoffice/trunk/main/vcl/aqua/source/gdi/ctlayout.cxx (original)
+++ openoffice/trunk/main/vcl/aqua/source/gdi/ctlayout.cxx Tue May 20 12:00:50 2014
@@ -451,13 +451,35 @@ int CTLayout::GetTextBreak( long nMaxWid
 		return STRING_LEN;
 
 	CTTypesetterRef aCTTypeSetter = CTTypesetterCreateWithAttributedString( mpAttrString );
-	const double fCTMaxWidth = (double)nMaxWidth / (nFactor * mfFontScale);
-	CFIndex nIndex = CTTypesetterSuggestClusterBreak( aCTTypeSetter, 0, fCTMaxWidth );
-	if( nIndex >= mnCharCount )
-		return STRING_LEN;
 
-	nIndex += mnMinCharPos;
-	return (int)nIndex;
+	CFIndex nBestGuess = (nCharExtra >= 0) ? 0 : mnCharCount;
+	for( int i = 1; i <= mnCharCount; i *= 2 )
+	{
+		// guess the target width considering char-extra expansion/condensation
+		const long nTargetWidth = nMaxWidth - nBestGuess * nCharExtra;
+		const double fCTMaxWidth = nTargetWidth / (nFactor * mfFontScale);
+		// calculate the breaking index for the guessed target width
+		const CFIndex nNewIndex = CTTypesetterSuggestClusterBreak( aCTTypeSetter, 0, fCTMaxWidth );
+		if( nNewIndex >= mnCharCount ) {
+			CFRelease( aCTTypeSetter );
+			return STRING_LEN;
+		}
+		// check if the original extra-width guess was good
+		if( !nCharExtra )
+			nBestGuess = nNewIndex;
+		if( nBestGuess == nNewIndex )
+			break;
+		// prepare another round for a different number of characters
+		CFIndex nNewGuess = (nNewIndex + nBestGuess + 1) / 2;
+		if( nNewGuess == nBestGuess )
+			nNewGuess += (nNewIndex > nBestGuess) ? +1 : -1;
+		nBestGuess = nNewGuess;
+	}
+
+	// suggest the best fitting cluster break as breaking position
+	CFRelease( aCTTypeSetter );
+	const int nIndex = nBestGuess + mnMinCharPos;
+	return nIndex;
 }
 
 // -----------------------------------------------------------------------