Fixed calculating widths in wxCairoContext::GetPartialTextExtents (wxMSW).

Widths from the beginning of text to the corresponding character should be calculated instead of widths of individual characters.

src/generic/graphicc.cpp

@@ -2333,24 +2333,14 @@ void wxCairoContext::GetPartialTextExtents(const wxString& text, wxArrayDouble&
     while (i++ < len)
         widths.Add(PANGO_PIXELS(w));
 #else
-    const wxCharBuffer data = text.utf8_str();
-    for (size_t i = 0; i < data.length(); i++)
+    for (size_t i = 0; i < text.Length(); i++)
     {
+        const wxCharBuffer data = text.SubString(0, i).utf8_str();
+
         cairo_text_extents_t te;
-        char ch[2];
+        cairo_text_extents(m_context, (const char*)data, &te);
 
-        ch[0] = data[i];
-        ch[1] = '\0';
-        cairo_text_extents(m_context, ch, &te);
-
-        double w;
-        // Last character is interpreted in a different way.
-        if( i == data.length()-1 )
-            w = te.width;
-        else
-            w = te.x_advance;
-
-        widths.push_back(w);
+        widths.push_back(te.width);
     }
 #endif
 }