1 files changed, 80 insertions, 0 deletions
diff --git a/src/libui_sdl/libui/windows/graphemes.cpp b/src/libui_sdl/libui/windows/graphemes.cpp
new file mode 100644
index 0000000..355e403
--- /dev/null
+++ b/src/libui_sdl/libui/windows/graphemes.cpp
@@ -0,0 +1,80 @@
+// 25 may 2016
+#include "uipriv_windows.hpp"
+
+// We could use CharNext() 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).
+// So let's use Uniscribe (see http://archives.miloush.net/michkap/archive/2005/01/14/352802.html)
+// See also http://www.catch22.net/tuts/uniscribe-mysteries and http://www.catch22.net/tuts/keyboard-navigation for more details.
+
+static HRESULT itemize(WCHAR *msg, size_t len, SCRIPT_ITEM **out, int *outn)
+{
+	SCRIPT_CONTROL sc;
+	SCRIPT_STATE ss;
+	SCRIPT_ITEM *items;
+	size_t maxItems;
+	int n;
+	HRESULT hr;
+
+	// make sure these are zero-initialized to avoid mangling the text
+	ZeroMemory(&sc, sizeof (SCRIPT_CONTROL));
+	ZeroMemory(&ss, sizeof (SCRIPT_STATE));
+
+	maxItems = len + 2;
+	for (;;) {
+		items = new SCRIPT_ITEM[maxItems];
+		hr = ScriptItemize(msg, len,
+			maxItems,
+			&sc, &ss,
+			items, &n);
+		if (hr == S_OK)
+			break;
+		// otherwise either an error or not enough room
+		delete[] items;
+		if (hr != E_OUTOFMEMORY)
+			return hr;
+		maxItems *= 2;		// add some more and try again
+	}
+
+	*out = items;
+	*outn = n;
+	return S_OK;
+}
+
+size_t *graphemes(WCHAR *msg)
+{
+	size_t len;
+	SCRIPT_ITEM *items;
+	int i, n;
+	size_t *out;
+	size_t *op;
+	SCRIPT_LOGATTR *logattr;
+	int j, nn;
+	HRESULT hr;
+
+	len = wcslen(msg);
+	hr = itemize(msg, len, &items, &n);
+	if (hr != S_OK)
+		logHRESULT(L"error itemizing string for finding grapheme cluster boundaries", hr);
+
+	// should be enough; 2 more just to be safe
+	out = (size_t *) uiAlloc((len + 2) * sizeof (size_t), "size_t[]");
+	op = out;
+
+	// note that there are actually n + 1 elements in items
+	for (i = 0; i < n; i++) {
+		nn = items[i + 1].iCharPos - items[i].iCharPos;
+		logattr = new SCRIPT_LOGATTR[nn];
+		hr = ScriptBreak(msg + items[i].iCharPos, nn,
+			&(items[i].a), logattr);
+		if (hr != S_OK)
+			logHRESULT(L"error breaking string for finding grapheme cluster boundaries", hr);
+		for (j = 0; j < nn; j++)
+			if (logattr[j].fCharStop != 0)
+				*op++ = items[i].iCharPos + j;
+		delete[] logattr;
+	}
+	// and handle the last item for the end of the string
+	*op++ = items[i].iCharPos;
+
+	delete[] items;
+	return out;
+}