First Commit

libui-ng/windows/graphemes.cpp

@@ -0,0 +1,60 @@
+// 25 may 2016
+#include "uipriv_windows.hpp"
+#include "attrstr.hpp"
+
+// We could use CharNextW() to generate grapheme cluster boundaries, but it doesn't handle surrogate pairs properly (see http://archives.miloush.net/michkap/archive/2008/12/16/9223301.html).
+// We could also use Uniscribe (see http://archives.miloush.net/michkap/archive/2005/01/14/352802.html, http://www.catch22.net/tuts/uniscribe-mysteries, http://www.catch22.net/tuts/keyboard-navigation, and https://maxradi.us/documents/uniscribe/), but its rules for buffer sizes is convoluted.
+// Let's just deal with the CharNextW() bug.
+
+int uiprivGraphemesTakesUTF16(void)
+{
+	return 1;
+}
+
+uiprivGraphemes *uiprivNewGraphemes(void *s, size_t len)
+{
+	uiprivGraphemes *g;
+	WCHAR *str;
+	size_t *pPTG, *pGTP;
+
+	g = uiprivNew(uiprivGraphemes);
+
+	g->len = 0;
+	str = (WCHAR *) s;
+	while (*str != L'\0') {
+		g->len++;
+		str = CharNextW(str);
+		// no need to worry about surrogates if we're just counting
+	}
+
+	g->pointsToGraphemes = (size_t *) uiprivAlloc((len + 1) * sizeof (size_t), "size_t[] (graphemes)");
+	g->graphemesToPoints = (size_t *) uiprivAlloc((g->len + 1) * sizeof (size_t), "size_t[] (graphemes)");
+
+	pPTG = g->pointsToGraphemes;
+	pGTP = g->graphemesToPoints;
+	str = (WCHAR *) s;
+	while (*str != L'\0') {
+		WCHAR *next, *p;
+		ptrdiff_t nextoff;
+
+		// as part of the bug, we need to make sure we only call CharNextW() on low halves, otherwise it'll return the same low half forever
+		nextoff = 0;
+		if (IS_HIGH_SURROGATE(*str))
+			nextoff = 1;
+		next = CharNextW(str + nextoff);
+		if (IS_LOW_SURROGATE(*next))
+			next--;
+
+		*pGTP = pPTG - g->pointsToGraphemes;
+		for (p = str; p < next; p++)
+			*pPTG++ = pGTP - g->graphemesToPoints;
+		pGTP++;
+
+		str = next;
+	}
+	// and handle the last item for the end of the string
+	*pGTP = pPTG - g->pointsToGraphemes;
+	*pPTG = pGTP - g->graphemesToPoints;
+
+	return g;
+}