Switched text layout attributes to grapheme-based indices on Windows, just like on OS X.

windows/GNUfiles.mk

@@ -28,6 +28,7 @@ CXXFILES += \
 	windows/events.cpp \
 	windows/fontbutton.cpp \
 	windows/fontdialog.cpp \
+	windows/grapheme.cpp \
 	windows/group.cpp \
 	windows/init.cpp \
 	windows/label.cpp \
@@ -66,9 +67,10 @@ RCFILES += \
 # LONGTERM split into a separate file or put in GNUmakefile.libui somehow?
 
 # flags for the Windows API
+# notice that usp10.lib comes before gdi32.lib
 # TODO prune this list
 LDFLAGS += \
-	user32.lib kernel32.lib gdi32.lib comctl32.lib uxtheme.lib msimg32.lib comdlg32.lib d2d1.lib dwrite.lib ole32.lib oleaut32.lib oleacc.lib uuid.lib
+	user32.lib kernel32.lib usp10.lib gdi32.lib comctl32.lib uxtheme.lib msimg32.lib comdlg32.lib d2d1.lib dwrite.lib ole32.lib oleaut32.lib oleacc.lib uuid.lib
 
 # flags for building a shared library
 LDFLAGS += \

windows/drawtext.cpp

@@ -337,6 +337,7 @@ struct layoutAttr {
 struct uiDrawTextLayout {
 	WCHAR *text;
 	size_t textlen;
+	size_t *graphemes;
 	double width;
 	IDWriteTextFormat *format;
 	std::vector<struct layoutAttr> *attrs;
@@ -366,6 +367,7 @@ uiDrawTextLayout *uiDrawNewTextLayout(const char *text, uiDrawTextFont *defaultF
 
 	layout->text = toUTF16(text);
 	layout->textlen = wcslen(layout->text);
+	layout->graphemes = graphemes(layout->text);
 
 	uiDrawTextLayoutSetWidth(layout, width);
 
@@ -425,8 +427,8 @@ IDWriteTextLayout *prepareLayout(uiDrawTextLayout *layout, ID2D1RenderTarget *rt
 		logHRESULT(L"error creating IDWriteTextLayout", hr);
 
 	for (const struct layoutAttr &attr : *(layout->attrs)) {
-		range.startPosition = attr.start;
+		range.startPosition = layout->graphemes[attr.start];
-		range.length = attr.end - attr.start;
+		range.length = layout->graphemes[attr.end] - layout->graphemes[attr.start];
 		switch (attr.type) {
 		case layoutAttrColor:
 			if (rt == NULL)		// determining extents, not drawing

windows/grapheme.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;
+}

windows/uipriv_windows.hpp

@@ -140,6 +140,10 @@ extern BOOL showColorDialog(HWND parent, struct colorDialogRGBA *c);
 // sizing.cpp
 extern void getSizing(HWND hwnd, uiWindowsSizing *sizing, HFONT font);
 
+// grapheme.cpp
+extern size_t *graphemes(WCHAR *msg);
+
+
 
 
 

windows/winapi.hpp

@@ -32,6 +32,7 @@
 #include <d2d1.h>
 #include <d2d1helper.h>
 #include <dwrite.h>
+#include <usp10.h>
 
 #include <stdint.h>
 #include <string.h>