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]