XQueryTextExtents
Syntax
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;
Arguments
| display
| Specifies the connection to the X server.
|
| font_ID
| Specifies either the font ID or the
GContext
ID that contains the font.
|
| string
| Specifies the character string.
|
| nchars
| Specifies the number of characters in the character string.
|
| direction_return
| Returns the value of the direction hint
(FontLeftToRight
or
FontRightToLeft).
|
| font_ascent_return
| Returns the font ascent.
|
| font_descent_return
| Returns the font descent.
|
| overall_return
| Returns the overall size in the specified
XCharStruct
structure.
|
Description
The
XQueryTextExtents()
function returns the bounding box of the specified 8-bit
character string in the specified font or the font contained in the
specified GC.
This function queries the X server and, therefore, suffer the round-trip
overhead that is avoided by
XTextExtents().
The function returns 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()
can generate
BadFont
and
BadGC
errors.
Diagnostics
| BadFont
| A value for a font argument does not name a defined font (or, in some cases,
GContext).
|
| BadGC
| A value for a GContext
argument does not name a defined
GContext.
|
See also
XLoadFont(),
XQueryTextExtents16(),
XTextExtents(),
XTextExtents16(),
XTextWidth(),
"
Computing Logical Extents".
Christophe Tronche, [email protected]
