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gdk_visual_ref ()
GdkVisual*gdk_visual_ref(GdkVisual *visual); 

　　In theory, increases the reference count of a visual. However, the set of visuals is determined statically when GTK+ is initialized, so this operation does nothing.

　　visual : a GdkVisual.

　　Returns : visual.

gdk_visual_unref ()
voidgdk_visual_unref(GdkVisual *visual); 

　　In theory, decreases the reference count of a visual. Like gdk_visual_ref(), this operation does nothing.

　　visual : a GdkVisual.

　　Fonts

　　Name

　　Fonts -- loading and manipulating fonts

　　Synopsis

#include <gdk/gdk.h>
structGdkFont;
enumGdkFontType;
GdkFont*gdk_font_load (const gchar *font_name);
GdkFont*gdk_fontset_load(gchar *fontset_name);
GdkFont*gdk_font_ref(GdkFont *font);
voidgdk_font_unref(GdkFont *font);
gintgdk_font_id (const GdkFont *font);
gintgdk_font_equal(const GdkFont *fonta,const GdkFont *fontb);
voidgdk_string_extents(GdkFont *font,
const gchar *string,gint *lbearing,gint *rbearing,
gint *width,gint *ascent,gint *descent);
voidgdk_text_extents(GdkFont *font,
const gchar *text,gint text_length,gint *lbearing,
gint *rbearing,gint *width,gint *ascent,gint *descent);
voidgdk_text_extents_wc (GdkFont *font,
const GdkWChar *text,gint text_length,gint *lbearing,gint *rbearing,
gint *width,gint *ascent,gint *descent);
gintgdk_string_width(GdkFont *font,const gchar *string);
gintgdk_text_width(GdkFont *font,const gchar *text,gint text_length);
gintgdk_text_width_wc (GdkFont *font,const GdkWChar *text,gint text_length);
gintgdk_char_width(GdkFont *font,gchar character);
gintgdk_char_width_wc (GdkFont *font,GdkWChar character);
gintgdk_string_measure(GdkFont *font,const gchar *string);
gintgdk_text_measure(GdkFont *font,const gchar *text,gint text_length);
gintgdk_char_measure(GdkFont *font,gchar character);
gintgdk_string_height (GdkFont *font,const gchar *string);
gintgdk_text_height (GdkFont *font,const gchar *text,gint text_length);
gintgdk_char_height (GdkFont *font,gchar character);
typedef GdkWChar;
gchar*gdk_wcstombs(const GdkWChar *src);
gintgdk_mbstowcs(GdkWChar *dest,const gchar *src,gint dest_max); 

　　Description

　　The GdkFont data type represents a font for drawing on the screen. These functions provide support for loading fonts, and also for determining the dimensions of characters and strings when drawn with a particular font.

　　Fonts in X are specified by a X Logical Font Description. The following description is considerably simplified. For definitive information about XLFD's see the X reference documentation. A X Logical Font Description (XLFD) consists of a sequence of fields separated (and surrounded by) '-' characters. For example, Adobe Helvetica Bold 12 pt, has the full description: "-adobe-helvetica-bold-r-normal--12-120-75-75-p-70-iso8859-1"

　　The fields in the XLFD are:

　　Foundry the company or organization where the font originated.

　　Family the font family (a group of related font designs).

　　Weight A name for the font's typographic weight For example, 'bold' or 'medium').

　　Slant The slant of the font. Common values are 'R' for Roman, 'I' for italoc, and 'O' for oblique.

　　Set Width A name for the width of the font. For example, 'normal' or 'condensed'.

　　Add Style Additional information to distinguish a font from other fonts of the same family.

　　Pixel Size The body size of the font in pixels.

　　Point Size The body size of the font in 10ths of a point. (A point is 1/72.27 inch)

　　Resolution X The horizontal resolution that the font was designed for.

　　Resolution Y The vertical resolution that the font was designed for .

　　Spacing The type of spacing for the font - can be 'p' for proportional, 'm' for monospaced or 'c' for charcell.

　　Average Width The average width of a glyph in the font. For monospaced and charcell fonts, all glyphs in the font have this width

　　Charset Registry The registration authority that owns the encoding for the font. Together with the Charset Encoding field, this defines the character set for the font.

　　Charset Encoding An identifier for the particular character set encoding.

　　When specifying a font via a X logical Font Description, '*' can be used as a wildcard to match any portion of the XLFD. For instance, the above example could also be specified as "-*-helvetica-bold-r-normal--*-120-*-*-*-*-iso8859-1"

　　It is generally a good idea to use wildcards for any portion of the XLFD that your program does not care about specifically, since that will improve the chances of finding a matching font.