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(FontLeftToRightorFontRightToLeft).

display

Specifies the connection to the X server.

font_ID

Specifies either the font ID or theGContextID that contains the font.

font_ascent_return

Returns the font ascent.

font_descent_return

Returns the font descent.

font_struct

Specifies theXFontStructstructure.

nchars

Specifies the number of characters in the character string.

string

Specifies the character string.

overall_return

Returns the overall size in the specifiedXCharStructstructure.

DESCRIPTION¶

TheXTextExtentsandXTextExtents16functionsperform the size computation locally and, thereby,avoid the round-trip overhead ofXQueryTextExtentsandXQueryTextExtents16.Both functions return anXCharStructstructure, whose members are set to the values as follows.

The ascent member is set to the maximum of the ascent metrics of allcharacters 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 allcharacters in the string.For each character in the string,let W be the sum of the character-width metrics of all characters precedingit 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,eachXChar2bstructure is interpreted as a 16-bit number with byte1 as themost significant byte.If the font has no defined default character,undefined characters in the string are taken to have all zero metrics.

TheXQueryTextExtentsandXQueryTextExtents16functions return the bounding box of the specified 8-bit and 16-bitcharacter string in the specified font or the font contained in thespecified GC.These functions query the X server and, therefore, suffer the round-tripoverhead that is avoided byXTextExtentsandXTextExtents16.Both functions return aXCharStructstructure, whose members are set to the values as follows.

The ascent member is set to the maximum of the ascent metricsof 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 metricsof all characters in the string.For each character in the string,let W be the sum of the character-width metrics of all characters precedingit 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,eachXChar2bstructure is interpreted as a 16-bit number with byte1 as themost 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.

XQueryTextExtentsandXQueryTextExtents16can generateBadFontandBadGCerrors.

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