NAME
XTextExtents, XTextExtents16, XQueryTextExtents, XQueryTextExtents16 -
compute or query text extents
SYNTAX
int XTextExtents(XFontStruct *font_struct, char *string, int nchars,
int *direction_return, int *font_ascent_return, int
*font_descent_return, XCharStruct *overall_return);
int XTextExtents16(XFontStruct *font_struct, 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, 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, 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 Interface