XTextExtents(3X11) X Version 11 (Release 4) XTextExtents(3X11)
NAME
XTextExtents, XTextExtents16, XQueryTextExtents,
XQueryTextExtents16 - compute or query text extents
SYNTAX
XTextExtents(font_struct, string, nchars, direction_return,
font_ascent_return,
font_descent_return, overall_return)
XFontStruct *font_struct;
char *string;
int nchars;
int *direction_return;
int *font_ascent_return, *font_descent_return;
XCharStruct *overall_return;
XTextExtents16(font_struct, string, nchars,
direction_return, font_ascent_return,
font_descent_return, overall_return)
XFontStruct *font_struct;
XChar2b *string;
int nchars;
int *direction_return;
int *font_ascent_return, *font_descent_return;
XCharStruct *overall_return;
XQueryTextExtents(display, font_ID, string, nchars,
direction_return, font_ascent_return,
font_descent_return, overall_return)
Display *display;
XID font_ID;
char *string;
int nchars;
int *direction_return;
int *font_ascent_return, *font_descent_return;
XCharStruct *overall_return;
XQueryTextExtents16(display, font_ID, string, nchars,
direction_return, font_ascent_return,
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font_descent_return, overall_return)
Display *display;
XID font_ID;
XChar2b *string;
int nchars;
int *direction_return;
int *font_ascent_return, *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 a pointer to 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
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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
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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(3X11), XTextWidth(3X11)
Xlib - C Language X Interface
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