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CentOS 7.0 - man page for tk_freecursor (centos section 3)

Tk_AllocCursorFromObj(3)	      Tk Library Procedures		 Tk_AllocCursorFromObj(3)


       Tk_AllocCursorFromObj,  Tk_GetCursor,  Tk_GetCursorFromObj, Tk_GetCursorFromData, Tk_Name-
       OfCursor, Tk_FreeCursorFromObj, Tk_FreeCursor - maintain database of cursors

       #include <tk.h>

       Tk_AllocCursorFromObj(interp, tkwin, objPtr)

       Tk_GetCursor(interp, tkwin, name)

       Tk_GetCursorFromObj(tkwin, objPtr)

       Tk_GetCursorFromData(interp, tkwin, source, mask, width, height, xHot, yHot, fg, bg)

       const char *
       Tk_NameOfCursor(display, cursor)

       Tk_FreeCursorFromObj(tkwin, objPtr)

       Tk_FreeCursor(display, cursor)

       Tcl_Interp *interp (in)		     Interpreter to use for error reporting.

       Tk_Window tkwin (in)		     Token for window in which the cursor will be used.

       Tcl_Obj *objPtr (in/out) 	     Description of cursor;  see below for possible  val-
					     ues.  Internal rep will be modified to cache pointer
					     to corresponding Tk_Cursor.

       char *name (in)			     Same as  objPtr  except  description  of  cursor  is
					     passed  as  a  string and resulting Tk_Cursor is not

       const char *source (in)		     Data for cursor cursor, in standard cursor format.

       const char *mask (in)		     Data for mask cursor, in standard cursor format.

       int width (in)			     Width of source and mask.

       int height (in)			     Height of source and mask.

       int xHot (in)			     X-location of cursor hot-spot.

       int yHot (in)			     Y-location of cursor hot-spot.

       Tk_Uid fg (in)			     Textual description of foreground color for cursor.

       Tk_Uid bg (in)			     Textual description of background color for cursor.

       Display *display (in)		     Display for which cursor was allocated.

       Tk_Cursor cursor (in)		     Opaque Tk	identifier  for  cursor.   If  passed  to
					     Tk_FreeCursor,  must have been returned by some pre-
					     vious call to Tk_GetCursor or Tk_GetCursorFromData.

       These procedures manage a collection of cursors being used by an application.  The  proce-
       dures  allow cursors to be re-used efficiently, thereby avoiding server overhead, and also
       allow cursors to be named with character strings.

       Tk_AllocCursorFromObj takes as argument an object describing  a	cursor,  and  returns  an
       opaque  Tk identifier for a cursor corresponding to the description.  It re-uses an exist-
       ing cursor if possible and creates a  new  one  otherwise.   Tk_AllocCursorFromObj  caches
       information  about  the return value in objPtr, which speeds up future calls to procedures
       such as Tk_AllocCursorFromObj and Tk_GetCursorFromObj. If an error occurs in creating  the
       cursor,	such  as  when objPtr refers to a non-existent file, then None is returned and an
       error message will be stored in interp's result if interp is not NULL.  ObjPtr  must  con-
       tain a standard Tcl list with one of the following forms:

       name [fgColor [bgColor]]
	      Name  is	the  name  of  a cursor in the standard X cursor cursor, i.e., any of the
	      names defined in cursorcursor.h, without the XC_.  Some example values  are  X_cur-
	      sor, hand2, or left_ptr.	Appendix B of "The X Window System" by Scheifler & Gettys
	      has illustrations showing what each of these cursors looks like.	 If  fgColor  and
	      bgColor  are  both specified, they give the foreground and background colors to use
	      for the cursor (any of the forms acceptable to Tk_GetColor may be used).	 If  only
	      fgColor  is specified, then there will be no background color:  the background will
	      be transparent.  If no colors are specified, then the cursor will use black for its
	      foreground color and white for its background color.

	      The  Macintosh version of Tk supports all of the X cursors and will also accept any
	      of the standard Mac cursors including ibeam, crosshair, watch, plus, and arrow.  In
	      addition,  Tk  will  load  Macintosh cursor resources of the types crsr (color) and
	      CURS (black and white) by the name of the resource.  The application  and  all  its
	      open  dynamic  library's	resource files will be searched for the named cursor.  If
	      there are conflicts color cursors will always be loaded in preference to black  and
	      white cursors.

       @sourceName maskName fgColor bgColor
	      In this form, sourceName and maskName are the names of files describing cursors for
	      the cursor's source bits and mask.  Each file must be in standard X11 or X10 cursor
	      format.	FgColor  and bgColor indicate the colors to use for the cursor, in any of
	      the forms acceptable to Tk_GetColor.  This form of the command  will  not  work  on
	      Macintosh or Windows computers.

       @sourceName fgColor
	      This form is similar to the one above, except that the source is used as mask also.
	      This means that the cursor's background is transparent.  This form of  the  command
	      will not work on Macintosh or Windows computers.

	      This  form  only	works  on Windows, and will load a Windows system cursor (.ani or
	      .cur) from the file specified in sourceName.

       Tk_GetCursor is identical to Tk_AllocCursorFromObj except that the description of the cur-
       sor  is	specified  with  a  string instead of an object.  This prevents Tk_GetCursor from
       caching the return value, so Tk_GetCursor is less efficient than Tk_AllocCursorFromObj.

       Tk_GetCursorFromObj returns the token  for  an  existing  cursor,  given  the  window  and
       description  used  to create the cursor.  Tk_GetCursorFromObj does not actually create the
       cursor; the cursor must already have been created with a previous call to  Tk_AllocCursor-
       FromObj	or  Tk_GetCursor.   The  return value is cached in objPtr, which speeds up future
       calls to Tk_GetCursorFromObj with the same objPtr and tkwin.

       Tk_GetCursorFromData allows cursors to be created from  in-memory  descriptions	of  their
       source  and  mask  cursors.  Source points to standard cursor data for the cursor's source
       bits, and mask points to standard cursor data describing which pixels of source are to  be
       drawn and which are to be considered transparent.  Width and height give the dimensions of
       the cursor, xHot and yHot indicate the location of the cursor's hot-spot (the  point  that
       is  reported  when  an  event  occurs), and fg and bg describe the cursor's foreground and
       background colors textually (any of the forms suitable for Tk_GetColor may be used).  Typ-
       ically,	the  arguments	to  Tk_GetCursorFromData  are  created by including a cursor file
       directly into the source code for a program, as in the following example:
	      Tk_Cursor cursor;
	      #include "source.cursor"
	      #include "mask.cursor"
	      cursor = Tk_GetCursorFromData(interp, tkwin, source_bits,
		  mask_bits, source_width, source_height, source_x_hot,
		  source_y_hot, Tk_GetUid("red"), Tk_GetUid("blue"));

       Under normal conditions Tk_GetCursorFromData will return an identifier for  the	requested
       cursor.	If an error occurs in creating the cursor then None is returned and an error mes-
       sage will be stored in interp's result.

       Tk_AllocCursorFromObj, Tk_GetCursor, and Tk_GetCursorFromData maintain a database  of  all
       the  cursors  they  have  created.   Whenever  possible,  a call to Tk_AllocCursorFromObj,
       Tk_GetCursor, or Tk_GetCursorFromData will return an existing cursor rather than  creating
       a  new  one.  This approach can substantially reduce server overhead, so the Tk procedures
       should generally be used in preference to Xlib procedures like XCreateFontCursor or  XCre-
       atePixmapCursor,  which create a new cursor on each call.  The Tk procedures are also more
       portable than the lower-level X procedures.

       The procedure Tk_NameOfCursor is roughly the inverse of Tk_GetCursor.  If its cursor argu-
       ment  was  created  by  Tk_GetCursor,  then the return value is the name argument that was
       passed to Tk_GetCursor to create  the  cursor.	If  cursor  was  created  by  a  call  to
       Tk_GetCursorFromData,  or  by  any other mechanism, then the return value is a hexadecimal
       string giving the X identifier for the cursor.  Note:  the  string  returned  by  Tk_Name-
       OfCursor is only guaranteed to persist until the next call to Tk_NameOfCursor.  Also, this
       call is not portable except for cursors returned by Tk_GetCursor.

       When a cursor returned by Tk_AllocCursorFromObj, Tk_GetCursor, or Tk_GetCursorFromData  is
       no  longer  needed,  Tk_FreeCursorFromObj or Tk_FreeCursor should be called to release it.
       For Tk_FreeCursorFromObj the cursor to release is specified with the same information used
       to  create  it;	for  Tk_FreeCursor  the cursor to release is specified with its Tk_Cursor
       token.  There should be exactly one call to Tk_FreeCursor for each call to Tk_AllocCursor-
       FromObj, Tk_GetCursor, or Tk_GetCursorFromData.

       In  determining whether an existing cursor can be used to satisfy a new request, Tk_Alloc-
       CursorFromObj, Tk_GetCursor, and Tk_GetCursorFromData consider only the	immediate  values
       of their arguments.  For example, when a file name is passed to Tk_GetCursor, Tk_GetCursor
       will assume it is safe to re-use an existing cursor created from the same file  name:   it
       will  not  check to see whether the file itself has changed, or whether the current direc-
       tory has changed, thereby causing the name to  refer  to  a  different  file.   Similarly,
       Tk_GetCursorFromData  assumes  that  if	the  same source pointer is used in two different
       calls, then the pointers refer to the same data;  it does not check to see if  the  actual
       data values have changed.


Tk					       8.1			 Tk_AllocCursorFromObj(3)

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