XCURSOR(3) UNIX Programmer's Manual XCURSOR(3)
NAME
XCURSOR - Cursor management library
SYNOPSIS
#include <X11/Xcursor/Xcursor.h>
DESCRIPTION
Xcursor is a simple library designed to help locate and load
cursors. Cursors can be loaded from files or memory. A
library of common cursors exists which map to the standard X
cursor names. Cursors can exist in several sizes and the
library automatically picks the best size.
FUNCTIONAL OVERVIEW
Xcursor is built in a couple of layers; at the bottom layer
is code which can load cursor images from files. Above that
is a layer which locates cursor files based on the library
path and theme. At the top is a layer which builds cursors
either out of an image loaded from a file or one of the
standard X cursors. When using images loaded from files,
Xcursor prefers to use the Render extension CreateCursor
request if supported by the X server. Where not supported,
Xcursor maps the cursor image to a standard X cursor and
uses the core CreateCursor request.
CURSOR FILES
Xcursor defines a new format for cursors on disk. Each file
holds one or more cursor images. Each cursor image is
tagged with a nominal size so that the best size can be
selected automatically. Multiple cursors of the same nomi-
nal size can be loaded together; applications are expected
to use them as an animated sequence.
Cursor files are stored as a header containing a table of
contents followed by a sequence of chunks. The table of
contents indicates the type, subtype and position in the
file of each chunk. The file header looks like:
magic: CARD32 'Xcur' (0x58, 0x63, 0x75, 0x72)
header: CARD32 bytes in this header
version: CARD32 file version number
ntoc: CARD32 number of toc entries toc: LISTofTOC table of
contents
Each table of contents entry looks like:
type: CARD32 entry type subtype: CARD32 type-specific
label - size for images position: CARD32 absolute byte
position of table in file
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Each chunk in the file has set of common header fields fol-
lowed by additional type-specific fields:
header: CARD32 bytes in chunk header (including type-
specific fields)
type: CARD32 must match type in TOC for this chunk
subtype: CARD32 must match subtype in TOC for this chunk
version: CARD32 version number for this chunk type
There are currently two chunk types defined for cursor
files; comments and images. Comments look like:
header: 20 Comment headers are 20 bytes
type: 0xfffe0001 Comment type is 0xfffe0001
subtype: { 1 (COPYRIGHT), 2 (LICENSE), 3 (OTHER) }
version: 1
length: CARD32 byte length of UTF-8 string
string: LISTofCARD8 UTF-8 string
Images look like:
header: 36 Image headers are 36 bytes
type: 0xfffd0002 Image type is 0xfffd0002
subtype: CARD32 Image subtype is the nominal size
version: 1
width: CARD32 Must be less than or equal to 0x7fff
height: CARD32 Must be less than or equal to 0x7fff
xhot: CARD32 Must be less than or equal to width
yhot: CARD32 Must be less than or equal to height
delay: CARD32 Delay between animation frames in mil-
liseconds
pixels: LISTofCARD32 Packed ARGB format pixels
THEMES
Xcursor (mostly) follows the freedesktop.org spec for them-
ing icons. The default search path it uses is $HOME/.icons,
/usr/share/icons, /usr/share/pimaps,
/usr/X11R6/lib/X11/icons. Within each of these directories,
it searches for a directory using the theme name. Within
the theme directory, it looks for cursor files in the 'cur-
sors' subdirectory. It uses the first cursor file found
along the path.
If necessary, Xcursor also looks for a "index.theme" file in
each theme directory to find inherited themes and searches
along the path for those themes as well.
If no theme is set, or if no cursor is found for the speci-
fied theme, Xcursor checks the "default" theme.
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DATATYPES
XcursorImage
holds a single cursor image in memory. Each pixel in
the cursor is a 32-bit value containing ARGB with A in
the high byte.
typedef struct _XcursorImage {
XcursorDim size; /* nominal size for matching */
XcursorDim width; /* actual width */
XcursorDim height; /* actual height */
XcursorDim xhot; /* hot spot x (must be inside image) */
XcursorDim yhot; /* hot spot y (must be inside image) */
XcursorPixel *pixels; /* pointer to pixels */
} XcursorImage;
XcursorImages
holds multiple XcursorImage structures. They're all
freed when the XcursorImages is freed.
typedef struct _XcursorImages {
int nimage; /* number of images */
XcursorImage **images; /* array of XcursorImage pointers */
} XcursorImages;
XcursorCursors
Holds multiple Cursor objects. They're all freed when
the XcursorCursors is freed. These are reference
counted so that multiple XcursorAnimate structures can
use the same XcursorCursors.
typedef struct _XcursorCursors {
Display *dpy; /* Display holding cursors */
int ref; /* reference count */
int ncursor; /* number of cursors */
Cursor *cursors; /* array of cursors */
} XcursorCursors;
XcursorAnimate
References a set of cursors and a sequence within that
set. Multiple XcursorAnimate structures may reference
the same XcursorCursors; each holds a reference which
is removed when the XcursorAnimate is freed.
typedef struct _XcursorAnimate {
XcursorCursors *cursors; /* list of cursors to use */
int sequence; /* which cursor is next */
} XcursorAnimate;
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XcursorFile
Xcursor provides an abstract API for accessing the file
data. Xcursor provides a stdio implementation of this
abstract API; applications are free to create addi-
tional implementations. These functions parallel the
stdio functions in return value and expected argument
values; the read and write functions flip the arguments
around to match the POSIX versions.
typedef struct _XcursorFile {
void *closure;
int (*read) (XcursorFile *file, unsigned char *buf, int len);
int (*write) (XcursorFile *file, unsigned char *buf, int len);
int (*seek) (XcursorFile *file, long offset, int whence);
};
FUNCTIONS
Object Management
XcursorImage *XcursorImageCreate (int width, int height)
void XcursorImageDestroy (XcursorImage *image)
Allocate and free images. On allocation, the hotspot
and the pixels are left uninitialized. The size is set
to the maximum of width and height.
XcursorImages *XcursorImagesCreate (int size)
void XcursorImagesDestroy (XcursorImages *images)
Allocate and free arrays to hold multiple cursor
images. On allocation, nimage is set to zero.
XcursorCursors *XcursorCursorsCreate (Display *dpy, int size)
void XcursorCursorsDestroy (XcursorCursors *cursors)
Allocate and free arrays to hold multiple cursors. On
allocation, ncursor is set to zero, ref is set to one.
Reading and writing images.
XcursorImage *XcursorXcFileLoadImage (XcursorFile *file, int
size)
XcursorImages *XcursorXcFileLoadImages (XcursorFile *file, int
size)
XcursorImages *XcursorXcFileLoadAllImages (XcursorFile *file)
XcursorBool XcursorXcFileLoad (XcursorFile *file, XcursorComments
**commentsp, XcursorImages **imagesp)
XcursorBool XcursorXcFileSave (XcursorFile *file, const Xcursor-
Comments *comments, const XcursorImages *images)
These read and write cursors from an XcursorFile
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handle. After reading, the file pointer will be left
at some random place in the file.
XcursorImage *XcursorFileLoadImage (FILE *file, int size)
XcursorImages *XcursorFileLoadImages (FILE *file, int size)
XcursorImages *XcursorFileLoadAllImages (FILE *file)
XcursorBool XcursorFileLoad (FILE *file, XcursorComments **com-
mentsp, XcursorImages **imagesp)
XcursorBool XcursorFileSaveImages (FILE *file, const XcursorIm-
ages *images)
XcursorBool XcursorFileSave (FILE * file, const XcursorComments
*comments, const XcursorImages *images)
These read and write cursors from a stdio FILE handle.
Writing flushes before returning so that any errors
should be detected.
XcursorImage *XcursorFilenameLoadImage (const char *filename, int
size)
XcursorImages *XcursorFilenameLoadImages (const char *filename,
int size)
XcursorImages *XcursorFilenameLoadAllImages (FILE *file)
XcursorBool XcursorFilenameLoad (const char *file, XcursorCom-
ments **commentsp, XcursorImages **imagesp)
XcursorBool XcursorFilenameSaveImages (const char *filename,
const XcursorImages *images)
XcursorBool XcursorFilenameSave (const char *file, const Xcursor-
Comments *comments, const XcursorImages *images)
These parallel the stdio FILE interfaces above, but
take filenames.
Reading library images
XcursorImage *XcursorLibraryLoadImage (const char *name, const
char *theme, int size)
XcursorImages *XcursorLibraryLoadImages (const char *name, const
char *theme, int size)
These search the library path, loading the first file
found. If 'theme' is not NULL, these functions first
try appending -theme to name and then name alone.
Cursor APIs
Cursor XcursorFilenameLoadCursor (Display *dpy, const char *file)
XcursorCursors *XcursorFilenameLoadCursors (Display *dpy, const
char *file)
These load cursors from the specified file.
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Cursor XcursorLibraryLoadCursor (Display *dpy, const char *name)
XcursorCursors *XcursorLibraryLoadCursors (Display *dpy, const
char *name)
These load cursors using the specified library name.
The theme comes from the display.
X Cursor Name APIs
XcursorImage *XcursorShapeLoadImage (unsigned int shape, const
char *theme, int size)
XcursorImages *XcursorShapeLoadImages (unsigned int shape, const
char *theme, int size)
These map 'shape' to a library name using the standard
X cursor names and then load the images.
Cursor XcursorShapeLoadCursor (Display *dpy, unsigned int shape)
XcursorCursors *XcursorShapeLoadCursors (Display *dpy, unsigned
int shape)
These map 'shape' to a library name and then load the
cursors.
Display Information APIs
XcursorBool XcursorSupportsARGB (Display *dpy)
Returns whether the display supports ARGB cursors or
whether cursors will be mapped to a core X cursor.
XcursorBool XcursorSetDefaultSize (Display *dpy, int size)
Sets the default size for cursors on the specified
display. When loading cursors, those who's nominal size
is closest to this size will be preferred.
int XcursorGetDefaultSize (Display *dpy)
Gets the default cursor size.
XcursorBool
XcursorSetTheme (Display *dpy, const char *theme) Sets
the current theme name.
char * XcursorGetTheme (Display *dpy) Gets the current
theme name.
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RESTRICTIONS
Xcursor will probably change radically in the future; weak
attempts will be made to retain some level of source-file
compatibility.
AUTHOR
Keith Packard, member of the XFree86 Project, Inc.
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