XTextExtents(3) XLIB FUNCTIONS XTextExtents(3)
NAME
XTextExtents, XTextExtents16, XQueryTextExtents, XQueryTextExtents16
- compute or query text extents
SYNTAX
int XTextExtents(XFontStruct *
font_struct, _Xconst char *
string, int
nchars, int *
direction_return, int *
font_ascent_return, int
*
font_descent_return, XCharStruct *
overall_return);
int XTextExtents16(XFontStruct *
font_struct, _Xconst XChar2b *
string,
int
nchars, int *
direction_return, int *
font_ascent_return,
int *
font_descent_return, XCharStruct *
overall_return);
int XQueryTextExtents(Display *
display, XID
font_ID, _Xconst char
*
string, int
nchars, int *
direction_return, int
*
font_ascent_return, int *
font_descent_return, XCharStruct
*
overall_return);
int XQueryTextExtents16(Display *
display, XID
font_ID, _Xconst
XChar2b *
string, int
nchars, int *
direction_return, int
*
font_ascent_return, int *
font_descent_return, XCharStruct
*
overall_return);
ARGUMENTS
direction_return Returns the value of the direction hint (
FontLeftToRight or
FontRightToLeft).
display Specifies the connection to the X server.
font_ID Specifies either the font ID or the
GContext ID that
contains the font.
font_ascent_return Returns the font ascent.
font_descent_return Returns the font descent.
font_struct Specifies the
XFontStruct structure.
nchars Specifies the number of characters in the character string.
string Specifies the character string.
overall_return Returns the overall size in the specified
XCharStruct structure.
DESCRIPTION
The
XTextExtents and
XTextExtents16 functions perform the size
computation locally and, thereby, avoid the round-trip overhead of
XQueryTextExtents and
XQueryTextExtents16. Both functions return an
XCharStruct structure, whose members are set to the values as
follows.
The ascent member is set to the maximum of the ascent metrics of all
characters in the string. The descent member is set to the maximum
of the descent metrics. The width member is set to the sum of the
character-width metrics of all characters in the string. For each
character in the string, let W be the sum of the character-width
metrics of all characters preceding it in the string. Let L be the
left-side-bearing metric of the character plus W. Let R be the
right-side-bearing metric of the character plus W. The lbearing
member is set to the minimum L of all characters in the string. The
rbearing member is set to the maximum R.
For fonts defined with linear indexing rather than 2-byte matrix
indexing, each
XChar2b structure is interpreted as a 16-bit number
with byte1 as the most significant byte. If the font has no defined
default character, undefined characters in the string are taken to
have all zero metrics.
The
XQueryTextExtents and
XQueryTextExtents16 functions return the
bounding box of the specified 8-bit and 16-bit character string in
the specified font or the font contained in the specified GC. These
functions query the X server and, therefore, suffer the round-trip
overhead that is avoided by
XTextExtents and
XTextExtents16. Both
functions return a
XCharStruct structure, whose members are set to
the values as follows.
The ascent member is set to the maximum of the ascent metrics of all
characters in the string. The descent member is set to the maximum
of the descent metrics. The width member is set to the sum of the
character-width metrics of all characters in the string. For each
character in the string, let W be the sum of the character-width
metrics of all characters preceding it in the string. Let L be the
left-side-bearing metric of the character plus W. Let R be the
right-side-bearing metric of the character plus W. The lbearing
member is set to the minimum L of all characters in the string. The
rbearing member is set to the maximum R.
For fonts defined with linear indexing rather than 2-byte matrix
indexing, each
XChar2b structure is interpreted as a 16-bit number
with byte1 as the most significant byte. If the font has no defined
default character, undefined characters in the string are taken to
have all zero metrics.
Characters with all zero metrics are ignored. If the font has no
defined default_char, the undefined characters in the string are also
ignored.
XQueryTextExtents and
XQueryTextExtents16 can generate
BadFont and
BadGC errors.
DIAGNOSTICS
BadFont A value for a Font or GContext argument does not name a
defined Font.
BadGC A value for a GContext argument does not name a defined
GContext.
SEE ALSO
XLoadFont(3),
XTextWidth(3) Xlib - C Language X InterfaceX Version 11 libX11 1.8.10 XTextExtents(3)
