Fix metrics of math characters with 0 width

It seems that QTextLayout does not handle properly a single character
with 0 width. This breaks drawing of things like \not.

Actually the problem had been worked around already in lib/symbol. The
work around can therefore by removed now.
[additionally, remove extra spacing from \mapsto, \Mapsto]

diff --git a/lib/symbols b/lib/symbols
index 82a6d132d54c107afdcecbc16647cce5a5c8f1a5..31ba7f0eb18dbcca076be334a35d6f5264e7ec60 100644 (file)
--- a/lib/symbols
+++ b/lib/symbols
@@ -314,7 +314,7 @@ spadesuit          cmsy        127 170 mathord  ♠
 lyxnot             cmsy         54  47 mathrel  /           hiddensymbol
 iffont cmsy
 # kerning is slightly imperfect so that one can see when \not is selected
-\def\not{\lyxnot\mathrel{\kern-11mu}}
+\def\not{\lyxnot}
 else
 \def\not{\kern4mu\lyxnot\kern-19mu}
 endif
@@ -991,11 +991,11 @@ bignplus           stmry 112   0 mathop     x  stmaryrd # caution: named hugenpl
 
 \def\varcopyright{\mathord{c\kern-11mu\varbigcirc}}         stmaryrd
 # kerning is slightly imperfect so that one sees when \[Aa]rrownot is selected
-\def\arrownot{\lyxarrownot\mathrel{\kern-11mu}}             stmaryrd
-\def\Arrownot{\lyxArrownot\mathrel{\kern-10.5mu}}           stmaryrd
+\def\arrownot{\lyxarrownot}                                 stmaryrd
+\def\Arrownot{\lyxArrownot\mathrel{\kern0.5mu}}             stmaryrd
 \def\longarrownot{\mathrel{\kern5.5mu}\arrownot\mathrel{\kern-5.5mu}} stmaryrd
 \def\Longarrownot{\mathrel{\kern5.5mu}\Arrownot\mathrel{\kern-5.5mu}} stmaryrd
-\def\Mapsto{\Mapstochar\mathrel{\kern-2mu}\Rightarrow}   mathrel ⤇ stmaryrd
+\def\Mapsto{\Mapstochar\mathrel\Rightarrow}              mathrel ⤇ stmaryrd
 \def\mapsfrom{\leftarrow\kern-9mu\mapsfromchar}          mathrel ↤ stmaryrd
 \def\Mapsfrom{\Leftarrow\kern-9mu\Mapsfromchar}          mathrel ⤆ stmaryrd
 \def\Longmapsto{\Mapstochar\Longrightarrow}              mathrel ⟾ stmaryrd
@@ -1174,7 +1174,7 @@ iffont cmsy
 \def\Longleftarrow{\Leftarrow\joinrel\Relbar}                   mathrel ⟸
 \def\implies{\Longrightarrow}                                   mathrel ⟹ amsmath
 \def\impliedby{\Longleftarrow}                                  mathrel ⟸ amsmath
-\def\mapsto{\mapstochar\mathrel{\kern-2mu}\rightarrow}          mathrel ↤
+\def\mapsto{\mapstochar\rightarrow}                             mathrel ↤
 \def\longmapsto{\mapstochar\joinrel\relbar\joinrel\rightarrow}  mathrel ⟻
 \def\models{\mathrel{\vert}\joinrel\Relbar}                     mathrel ⊨
 else

diff --git a/src/frontends/qt4/GuiFontMetrics.cpp b/src/frontends/qt4/GuiFontMetrics.cpp
index a0fa6998ab109070293ce1782ff2ebf965d42187..2f598f43dc7ec73d5d257fdb1b2401f949ab92ed 100644 (file)
--- a/src/frontends/qt4/GuiFontMetrics.cpp
+++ b/src/frontends/qt4/GuiFontMetrics.cpp
@@ -182,17 +182,28 @@ int GuiFontMetrics::width(docstring const & s) const
        int * pw = strwidth_cache_[s];
        if (pw)
                return *pw;
-       // For some reason QMetrics::width returns a wrong value with Qt5
-       // int w = metrics_.width(toqstr(s));
        PROFILE_CACHE_MISS(width)
 #endif
-       QTextLayout tl;
-       tl.setText(toqstr(s));
-       tl.setFont(font_);
-       tl.beginLayout();
-       QTextLine line = tl.createLine();
-       tl.endLayout();
-       int w = int(line.naturalTextWidth());
+       /* 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).
+       */
+       int w = 0;
+       if (s.length() == 1
+#if QT_VERSION >= 0x040800
+           || font_.styleName() == "LyX"
+#endif
+           )
+               w = metrics_.width(toqstr(s));
+       else {
+               QTextLayout tl;
+               tl.setText(toqstr(s));
+               tl.setFont(font_);
+               tl.beginLayout();
+               QTextLine line = tl.createLine();
+               tl.endLayout();
+               w = int(line.naturalTextWidth());
+       }
 #ifdef CACHE_METRICS_WIDTH
        strwidth_cache_.insert(s, new int(w), s.size() * sizeof(char_type));
 #endif