MirOS Manual: Xcursor(3)


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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XCURSOR(3)          UNIX Programmer's Manual           XCURSOR(3)

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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