Add support for surrogate pairs to TQChar API.

This relates to issue #162.
The new code is partially taken from Qt4 but with some local rework.

Signed-off-by: Michele Calgaro <michele.calgaro@yahoo.it>
(cherry picked from commit c5cda03125a6d34c179d968011083bceb87976bd)

2 files changed, 21 insertions, 32 deletions

diff --git a/src/codecs/qgb18030codec.cpp b/src/codecs/qgb18030codec.cpp
index f2c84dab7..8630cf32e 100644
--- a/src/codecs/qgb18030codec.cpp
+++ b/src/codecs/qgb18030codec.cpp
@@ -188,18 +188,16 @@ TQCString TQGb18030Codec::fromUnicode(const TQString& uc, int& lenInOut) const
 	if ( ch.row() == 0x00 && ch.cell() < 0x80 ) {
 	    // ASCII
 	    *cursor++ = ch.cell();
-	} else if ((ch.unicode() & 0xf800) == 0xd800) {
-	    unsigned short high = ch.unicode();
+	} else if (ch.isHighSurrogate()) {
 	    // surrogates area. check for correct encoding
 	    // we need at least one more character, first the high surrogate, then the low one
-	    if (i == l-1 || high >= 0xdc00)
+	    if (i == l-1)
 		*cursor++ = '?';
 	    else {
-		unsigned short low = uc[i+1].unicode();
-		if (low >= 0xdc00 && low <= 0xdfff) {
+		if (uc[i+1].isLowSurrogate()) {
 		    // valid surrogate pair
+		    uint u = TQChar::surrogateToUcs4(uc[i], uc[i + 1]);
 		    ++i;
-		    uint u = (high-0xd800)*0x400+(low-0xdc00)+0x10000;
 		    len = qt_UnicodeToGb18030(u, buf);
 		    if (len >= 2) {
 			for (int j=0; j<len; j++)
@@ -245,15 +243,13 @@ TQString TQGb18030Codec::toUnicode(const char* chars, int len) const
 	    uint u = qt_Gb18030ToUnicode( (const uchar*)(chars + i), clen );
 
 	    if (clen == 2 || clen == 4) {
-		if (u < 0x10000)
+		if (!TQChar::requiresSurrogates(u)) {
 		    result += TQValidChar(u);
+		}
 		else {
 		    // encode into surrogate pair
-		    u -= 0x10000;
-		    unsigned short high = u/0x400 + 0xd800;
-		    unsigned short low = u%0x400 + 0xdc00;
-		    result += TQChar(high);
-		    result += TQChar(low);
+		    result += TQChar(TQChar::highSurrogate(u));
+		    result += TQChar(TQChar::lowSurrogate(u));
 		}
 		i += clen;
 	    } else if (i < len) {
@@ -406,15 +402,13 @@ public:
 		    int clen = 4;
 		    uint u = qt_Gb18030ToUnicode(buf, clen);
 		    if (clen == 4) {
-			if (u < 0x10000)
+			if (!TQChar::requiresSurrogates(u)) {
 			    result += TQValidChar(u);
+			}
 			else {
 			    // encode into surrogate pair
-			    u -= 0x10000;
-			    unsigned short high = u/0x400 + 0xd800;
-			    unsigned short low = u%0x400 + 0xdc00;
-			    result += TQChar(high);
-			    result += TQChar(low);
+			    result += TQChar(TQChar::highSurrogate(u));
+			    result += TQChar(TQChar::lowSurrogate(u));
 			}
 		    } else {
 			result += TQChar::replacement;
diff --git a/src/codecs/qutfcodec.cpp b/src/codecs/qutfcodec.cpp
index 0a47f1523..0f88b8260 100644
--- a/src/codecs/qutfcodec.cpp
+++ b/src/codecs/qutfcodec.cpp
@@ -64,13 +64,10 @@ TQCString TQUtf8Codec::fromUnicode(const TQString& uc, int& lenInOut) const
  	    if ( u < 0x0800 ) {
 		*cursor++ = 0xc0 | ((uchar) (u >> 6));
  	    } else {
-		if (u >= 0xd800 && u < 0xdc00 && i < l-1) {
-		    unsigned short low = ch[1].unicode();
-		    if (low >= 0xdc00 && low < 0xe000) {
-			++ch;
-			++i;
-			u = (u - 0xd800)*0x400 + (low - 0xdc00) + 0x10000;
-		    }
+		if (ch[0].isHighSurrogate() && i < (l - 1) && ch[1].isLowSurrogate()) {
+		    u = TQChar::surrogateToUcs4(ch[0], ch[1]);
+		    ++ch;
+		    ++i;
 		}
 		if (u > 0xffff) {
 		    // see TQString::fromUtf8() and TQString::utf8() for explanations
@@ -179,16 +176,14 @@ public:
 		    uc = (uc << 6) | (ch & 0x3f);
 		    need--;
 		    if ( !need ) {
-			if (uc > 0xffff) {
+			if (TQChar::requiresSurrogates(uc)) {
 			    // surrogate pair
-			    uc -= 0x10000;
-			    unsigned short high = uc/0x400 + 0xd800;
-			    unsigned short low = uc%0x400 + 0xdc00;
-			    *qch++ = TQChar(high);
-			    *qch++ = TQChar(low);
+			    *qch++ = TQChar(TQChar::highSurrogate(uc));
+			    *qch++ = TQChar(TQChar::lowSurrogate(uc));
 			    headerDone = TRUE;
 			} else if ((uc < min_uc) || (uc >= 0xd800 && uc <= 0xdfff) || (uc >= 0xfffe)) {
-                            *qch++ = TQChar::replacement;
+			    // overlong sequence, UTF16 surrogate or BOM
+			    *qch++ = TQChar::replacement;
 			} else {
 			    if (headerDone || TQChar(uc) != TQChar::byteOrderMark)
 				*qch++ = uc;