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_re-
turn, 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_re-
turn, 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 struc-
ture.
DESCRIPTION
The XTextExtents and XTextExtents16 functions perform the size computa-
tion locally and, thereby, avoid the round-trip overhead of XQueryTex-
tExtents 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 charac-
ter-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 index-
ing, each XChar2b structure is interpreted as a 16-bit number with byte1
as the most significant byte. If the font has no defined default char-
acter, 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 func-
tions query the X server and, therefore, suffer the round-trip overhead
that is avoided by XTextExtents and XTextExtents16. Both functions re-
turn 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 charac-
ter-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 index-
ing, each XChar2b structure is interpreted as a 16-bit number with byte1
as the most significant byte. If the font has no defined default char-
acter, undefined characters in the string are taken to have all zero
metrics.
Characters with all zero metrics are ignored. If the font has no de-
fined default_char, the undefined characters in the string are also ig-
nored.
XQueryTextExtents and XQueryTextExtents16 can generate BadFont and BadGC
errors.
DIAGNOSTICS
BadFont A value for a Font or GContext argument does not name a de-
fined Font.
BadGC A value for a GContext argument does not name a defined GCon-
text.
SEE ALSO
XLoadFont(3), XTextWidth(3)
Xlib - C Language X Interface
X Version 11 libX11 1.8.12 XTextExtents(3)
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