QDialogButtonBox for the remaining dialogs.

[lyx.git] / src / frontends / qt4 / GuiFontMetrics.cpp

diff --git a/src/frontends/qt4/GuiFontMetrics.cpp b/src/frontends/qt4/GuiFontMetrics.cpp
index b9eab8531fec62276a33fccdd04ab3437733fb1a..c2d4b884e4eddc8018c8824c593f77969fdbb980 100644 (file)
--- a/src/frontends/qt4/GuiFontMetrics.cpp
+++ b/src/frontends/qt4/GuiFontMetrics.cpp
@@ -181,26 +181,38 @@ int GuiFontMetrics::width(docstring const & s) const
        if (strwidth_cache_.contains(s))
                return strwidth_cache_[s];
        PROFILE_CACHE_MISS(width);
-       /* For some reason QMetrics::width returns a wrong value with Qt5
-        * with some arabic text. OTOH, QTextLayout is broken for single
-        * characters with null width (like \not in mathed). Also, as a
-        * safety measure, always use QMetrics::width with our math fonts.
+       /* Several problems have to be taken into account:
+        * * QFontMetrics::width does not returns a wrong value with Qt5 with
+        *   some arabic text, since the glyph-shaping operations are not
+        *   done (documented in Qt5).
+        * * QTextLayout is broken for single characters with null width
+        *   (like \not in mathed).
+        * * While QTextLine::horizontalAdvance is the right thing to use
+     *   for text strings, it does not give a good result with some
+     *   characters like the \int (gyph 4) of esint.
+
+        * Also, as a safety measure, always use QFontMetrics::width with
+        * our math fonts.
        */
        int w = 0;
-       if (s.length() == 1
+       // is the string a single character from a math font ?
 #if QT_VERSION >= 0x040800
-           || font_.styleName() == "LyX"
+       bool const math_char = s.length() == 1 || font_.styleName() == "LyX";
+#else
+       bool const math_char = s.length() == 1;
 #endif
-           )
-               w = metrics_.width(toqstr(s));
-       else {
+       // keep value 0 for math chars with width 0
+       if (!math_char || metrics_.width(toqstr(s)) != 0) {
                QTextLayout tl;
                tl.setText(toqstr(s));
                tl.setFont(font_);
                tl.beginLayout();
                QTextLine line = tl.createLine();
                tl.endLayout();
-               w = iround(line.horizontalAdvance());
+               if (math_char)
+                       w = iround(line.naturalTextWidth());
+               else
+                       w = iround(line.horizontalAdvance());
        }
        strwidth_cache_.insert(s, w, s.size() * sizeof(char_type));
        return w;