qfontmetrics.3qt

Linux下的基于X11的图形开发环境。

.TP
\fCExpandTabs\fR expands tabs (see below)
.TP
\fCShowPrefix\fR interprets "&x" as "<u>x</u>", i.e. underlined.
.TP
\fCWordBreak\fR breaks the text to fit the rectangle.
.PP
Horizontal alignment defaults to \fCAlignAuto\fR and vertical alignment defaults to \fCAlignTop\fR.
.PP
If several of the horizontal or several of the vertical alignment flags are set, the resulting alignment is undefined.
.PP
These flags are defined in qnamespace.h.
.PP
If \fCExpandTabs\fR is set in \fIflgs\fR, then: if \fItabarray\fR is non-null, it specifies a 0-terminated sequence of pixel-positions for tabs; otherwise if \fItabstops\fR is non-zero, it is used as the tab spacing (in pixels).
.PP
Note that the bounding rectangle may extend to the left of (0, 0), e.g. for italicized fonts, and that the text output may cover \fIall\fR pixels in the bounding rectangle.
.PP
Newline characters are processed as linebreaks.
.PP
Despite the different actual character heights, the heights of the bounding rectangles of "Yes" and "yes" are the same.
.PP
The bounding rectangle given by this function is somewhat larger than that calculated by the simpler boundingRect() function. This function uses the maximum left and right font bearings as is necessary for multi-line text to align correctly. Also, fontHeight() and lineSpacing() are used to calculate the height, rather than individual character heights.
.PP
The \fIintern\fR argument should not be used.
.PP
See also width(), QPainter::boundingRect(), and Qt::AlignmentFlags.
.SH "int QFontMetrics::charWidth ( const QString & str, int pos ) const"
Returns the width of the character at position \fIpos\fR in the string \fIstr\fR.
.PP
The whole string is needed, as the glyph drawn may change depending on the context (the letter before and after the current one) for some languages (e.g. Arabic).
.PP
This function also takes non spacing marks and ligatures into account.
.SH "int QFontMetrics::descent () const"
Returns the descent of the font.
.PP
The descent is the distance from the base line to the lowest point characters extend to. (Note that this is different from X, which adds 1 pixel.) In practice, some font designers break this rule, e.g. to accommodate an unusual character in an exotic language, so it is possible (though rare) that this value will be too small.
.PP
See also ascent().
.PP
Examples:
.)l drawdemo/drawdemo.cpp and hello/hello.cpp.
.SH "int QFontMetrics::height () const"
Returns the height of the font.
.PP
This is always equal to ascent()+descent()+1 (the 1 is for the base line).
.PP
See also leading() and lineSpacing().
.PP
Examples:
.)l hello/hello.cpp and qfd/fontdisplayer.cpp.
.SH "bool QFontMetrics::inFont ( QChar ch ) const"
Returns TRUE if character \fIch\fR is a valid character in the font; otherwise returns FALSE.
.PP
Example: qfd/fontdisplayer.cpp.
.SH "int QFontMetrics::leading () const"
Returns the leading of the font.
.PP
This is the natural inter-line spacing.
.PP
See also height() and lineSpacing().
.SH "int QFontMetrics::leftBearing ( QChar ch ) const"
Returns the left bearing of character \fIch\fR in the font.
.PP
The left bearing is the right-ward distance of the left-most pixel of the character from the logical origin of the character. This value is negative if the pixels of the character extend to the left of the logical origin.
.PP
See width(QChar) for a graphical description of this metric.
.PP
See also rightBearing(), minLeftBearing(), and width().
.PP
Example: qfd/fontdisplayer.cpp.
.SH "int QFontMetrics::lineSpacing () const"
Returns the distance from one base line to the next.
.PP
This value is always equal to leading()+height().
.PP
See also height() and leading().
.PP
Examples:
.)l action/application.cpp, application/application.cpp, mdi/application.cpp, qfd/fontdisplayer.cpp, qwerty/qwerty.cpp, and scrollview/scrollview.cpp.
.SH "int QFontMetrics::lineWidth () const"
Returns the width of the underline and strikeout lines, adjusted for the point size of the font.
.PP
See also underlinePos() and strikeOutPos().
.SH "int QFontMetrics::maxWidth () const"
Returns the width of the widest character in the font.
.PP
Example: qfd/fontdisplayer.cpp.
.SH "int QFontMetrics::minLeftBearing () const"
Returns the minimum left bearing of the font.
.PP
This is the smallest leftBearing(char) of all characters in the font.
.PP
Note that this function can be very slow if the font is large.
.PP
See also minRightBearing() and leftBearing().
.PP
Example: qfd/fontdisplayer.cpp.
.SH "int QFontMetrics::minRightBearing () const"
Returns the minimum right bearing of the font.
.PP
This is the smallest rightBearing(char) of all characters in the font.
.PP
Note that this function can be very slow if the font is large.
.PP
See also minLeftBearing() and rightBearing().
.PP
Example: qfd/fontdisplayer.cpp.
.SH "QFontMetrics & QFontMetrics::operator= ( const QFontMetrics & fm )"
Assigns the font metrics \fIfm\fR.
.SH "int QFontMetrics::rightBearing ( QChar ch ) const"
Returns the right bearing of character \fIch\fR in the font.
.PP
The right bearing is the left-ward distance of the right-most pixel of the character from the logical origin of a subsequent character. This value is negative if the pixels of the character extend to the right of the width() of the character.
.PP
See width() for a graphical description of this metric.
.PP
See also leftBearing(), minRightBearing(), and width().
.PP
Example: qfd/fontdisplayer.cpp.
.SH "QSize QFontMetrics::size ( int flgs, const QString & str, int len = -1, int tabstops = 0, int * tabarray = 0, QTextParag ** intern = 0 ) const"
Returns the size in pixels of the first \fIlen\fR characters of \fIstr\fR.
.PP
If \fIlen\fR is negative (the default), the entire string is used.
.PP
The \fIflgs\fR argument is the bitwise OR of the following flags:
.TP
\fCSingleLine\fR ignores newline characters.
.TP
\fCExpandTabs\fR expands tabs (see below)
.TP
\fCShowPrefix\fR interprets "&x" as "<u>x</u>", i.e. underlined.
.TP
\fCWordBreak\fR breaks the text to fit the rectangle.
.PP
These flags are defined in qnamespace.h.
.PP
If \fCExpandTabs\fR is set in \fIflgs\fR, then: if \fItabarray\fR is non-null, it specifies a 0-terminated sequence of pixel-positions for tabs; otherwise if \fItabstops\fR is non-zero, it is used as the tab spacing (in pixels).
.PP
Newline characters are processed as linebreaks.
.PP
Despite the different actual character heights, the heights of the bounding rectangles of "Yes" and "yes" are the same.
.PP
The \fIintern\fR argument should not be used.
.PP
See also boundingRect().
.SH "int QFontMetrics::strikeOutPos () const"
Returns the distance from the base line to where the strikeout line should be drawn.
.PP
See also underlinePos() and lineWidth().
.SH "int QFontMetrics::underlinePos () const"
Returns the distance from the base line to where an underscore should be drawn.
.PP
See also strikeOutPos() and lineWidth().
.SH "int QFontMetrics::width ( const QString & str, int len = -1 ) const"
Returns the width in pixels of the first \fIlen\fR characters of \fIstr\fR. If \fIlen\fR is negative (the default), the entire string is used.
.PP
Note that this value is \fInot\fR equal to boundingRect().width(); boundingRect() returns a rectangle describing the pixels this string will cover whereas width() returns the distance to where the next string should be drawn.
.PP
See also boundingRect().
.PP
Examples:
.)l drawdemo/drawdemo.cpp, hello/hello.cpp, movies/main.cpp, qfd/fontdisplayer.cpp, and scrollview/scrollview.cpp.
.SH "int QFontMetrics::width ( QChar ch ) const"
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
.PP
.ce 1
.B "[Image Omitted]"
.PP
Returns the logical width of character \fIch\fR in pixels. This is a distance appropriate for drawing a subsequent character after \fIch\fR.
.PP
Some of the metrics are described in the image to the right. The central dark rectangles cover the logical width() of each character. The outer pale rectangles cover the leftBearing() and rightBearing() of each character. Notice that the bearings of "f" in this particular font are both negative, while the bearings of" o" are both positive.
.PP
\fBWarning:\fR This function will produce incorrect results for Arabic characters or non spacing marks in the middle of a string, as the glyph shaping and positioning of marks that happens when processing strings cannot be taken into account. Use charWidth() instead if you aren't looking for the width of isolated characters.
.PP
See also boundingRect() and charWidth().
.SH "int QFontMetrics::width ( char c ) const"
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
.PP
\fBThis function is obsolete.\fR It is provided to keep old source working. We strongly advise against using it in new code.
.PP
Provided to aid porting from Qt 1.x.

.SH "SEE ALSO"
.BR http://doc.trolltech.com/qfontmetrics.html
.BR http://www.trolltech.com/faq/tech.html
.SH COPYRIGHT
Copyright 1992-2001 Trolltech AS, http://www.trolltech.com.  See the
license file included in the distribution for a complete license
statement.
.SH AUTHOR
Generated automatically from the source code.
.SH BUGS
If you find a bug in Qt, please report it as described in
.BR http://doc.trolltech.com/bughowto.html .
Good bug reports help us to help you. Thank you.
.P
The definitive Qt documentation is provided in HTML format; it is
located at $QTDIR/doc/html and can be read using Qt Assistant or with
a web browser. This man page is provided as a convenience for those
users who prefer man pages, although this format is not officially
supported by Trolltech. 
.P
If you find errors in this manual page, please report them to
.BR [e-mail] .
Please include the name of the manual page (qfontmetrics.3qt) and the Qt
version (3.1.1).