Fix computation of string width when using a QTextLayout

It was not a good idea to rely on QTextLine::naturalTextWidth() to
compute a string width. The correct method is horizontalAdvance().

Also round the value to the nearest pixel, since this is what
QFontMetrics::width() does.

Fixes bug #10700 (and maybe others).
This commit is contained in:
Jean-Marc Lasgouttes 2017-08-28 12:05:35 +02:00
parent f4511485da
commit c874641e95

View File

@ -19,6 +19,7 @@
#include "support/convert.h" #include "support/convert.h"
#include "support/lassert.h" #include "support/lassert.h"
#include "support/lyxlib.h"
#define DISABLE_PMPROF #define DISABLE_PMPROF
#include "support/pmprof.h" #include "support/pmprof.h"
@ -199,7 +200,7 @@ int GuiFontMetrics::width(docstring const & s) const
tl.beginLayout(); tl.beginLayout();
QTextLine line = tl.createLine(); QTextLine line = tl.createLine();
tl.endLayout(); tl.endLayout();
w = int(line.naturalTextWidth()); w = iround(line.horizontalAdvance());
} }
strwidth_cache_.insert(s, w, s.size() * sizeof(char_type)); strwidth_cache_.insert(s, w, s.size() * sizeof(char_type));
return w; return w;
@ -386,7 +387,8 @@ GuiFontMetrics::breakAt_helper(docstring const & s, int const x,
line.setLineWidth(x); line.setLineWidth(x);
tl.createLine(); tl.createLine();
tl.endLayout(); tl.endLayout();
if ((force && line.textLength() == offset) || int(line.naturalTextWidth()) > x) int const line_wid = iround(line.horizontalAdvance());
if ((force && line.textLength() == offset) || line_wid > x)
return {-1, -1}; return {-1, -1};
/* Since QString is UTF-16 and docstring is UCS-4, the offsets may /* Since QString is UTF-16 and docstring is UCS-4, the offsets may
* not be the same when there are high-plan unicode characters * not be the same when there are high-plan unicode characters
@ -411,8 +413,7 @@ GuiFontMetrics::breakAt_helper(docstring const & s, int const x,
--len; --len;
LASSERT(len > 0 || qlen == 0, /**/); LASSERT(len > 0 || qlen == 0, /**/);
#endif #endif
// The -1 is here to account for the leading zerow_nbsp. return {len, line_wid};
return {len, int(line.naturalTextWidth())};
} }