HPUX GetCursor[3]
GetCursor in anderen Kapiteln des hpux Handbuch:
Tk_GetCursor(3) Tk Tk_GetCursor(3)
Tk Library Procedures Tk Library Procedures
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NAME
Tk_GetCursor, Tk_GetCursorFromData, Tk_NameOfCursor, Tk_FreeCursor -
maintain database of cursors
SYNOPSIS
#include <tk.h>
Cursor
Tk_GetCursor(interp, tkwin, nameId)
Cursor
Tk_GetCursorFromData(interp, tkwin, source, mask, width, height, xHot, yHot, fg, bg)
char *
Tk_NameOfCursor(display, cursor) |
Tk_FreeCursor(display, cursor) |
ARGUMENTS
Tcl_Interp *interp (in) Interpreter to use for error
reporting.
Tk_Window tkwin (in) Token for window in which the
cursor will be used.
Tk_Uid nameId (in) Description of cursor; see
below for possible values.
char *source (in) Data for cursor bitmap, in
standard bitmap format.
char *mask (in) Data for mask bitmap, in
standard bitmap format.
unsigned int width (in) Width of source and mask.
unsigned int height (in) Height of source and mask.
unsigned int xHot (in) X-location of cursor hot-spot.
unsigned 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.
- 1 - Formatted: August 11, 1996
Tk_GetCursor(3) Tk Tk_GetCursor(3)
Tk Library Procedures Tk Library Procedures
Display *display (in) Display for which cursor was
allocated. |
Cursor cursor (in) X identifier for cursor. If
passed toTk_FreeCursor, must
have been returned by some
previous call to Tk_GetCursor or
Tk_GetCursorFromData.
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DESCRIPTION
These procedures manage a collection of cursors being used by an
application. The procedures allow cursors to be re-used efficiently,
thereby avoiding server overhead, and also allow cursors to be named
with character strings (actually Tk_Uids).
Tk_GetCursor takes as argument a Tk_Uid describing a cursor, and
returns the X identifier for a cursor corresponding to the
description. It re-uses an existing cursor if possible and creates a
new one otherwise. NameId must be 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 font, i.e.,
any of the names defined in cursorfont.h, without the XC_. Some
example values are X_cursor, 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.
@sourceName maskName fgColor bgColor
In this form, sourceName and maskName are the names of files
describing bitmaps for the cursor's source bits and mask. Each
file must be in standard X11 or X10 bitmap format. FgColor and
bgColor indicate the colors to use for the cursor, in any of the
forms acceptable to Tk_GetColor.
@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.
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Tk_GetCursor(3) Tk Tk_GetCursor(3)
Tk Library Procedures Tk Library Procedures
Tk_GetCursorFromData allows cursors to be created from in-memory
descriptions of their source and mask bitmaps. Source points to
standard bitmap data for the cursor's source bits, and mask points to
standard bitmap 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).
Typically, 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:
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_GetCursor and Tk_GetCursorFromData will
return an identifier for the requested cursor. If an error occurs in
creating the cursor, such as when nameId refers to a non-existent
file, then None is returned and an error message will be stored in
interp->result.
Tk_GetCursor and Tk_GetCursorFromData maintain a database of all the
cursors they have created. Whenever possible, a call to 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 XCreatePixmapCursor,
which create a new cursor on each call.
The procedure Tk_NameOfCursor is roughly the inverse of Tk_GetCursor.
If its cursor argument was created by Tk_GetCursor, then the return
value is the nameId 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_NameOfCursor is only guaranteed to persist until the
next call to Tk_NameOfCursor.
When a cursor returned by Tk_GetCursor or Tk_GetCursorFromData is no
longer needed, Tk_FreeCursor should be called to release it. There
should be exactly one call to Tk_FreeCursor for each call to
Tk_GetCursor or Tk_GetCursorFromData. When a cursor is no longer in
use anywhere (i.e. it has been freed as many times as it has been
gotten) Tk_FreeCursor will release it to the X server and remove it
from the database.
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Tk_GetCursor(3) Tk Tk_GetCursor(3)
Tk Library Procedures Tk Library Procedures
BUGS
In determining whether an existing cursor can be used to satisfy a new
request, 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
directory 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.
KEYWORDS
cursor
- 4 - Formatted: August 11, 1996