http://purl.org/tcl/home/man/tcl8.4/TkCmd/cursors.htm
How would one script things to dynamically provide the user with the range of cursors available on their platform? [aka a tk_chooseCursors that works dynamically for the platform, and includes hopefully application/user defined cursors]
How would one go about defining a new cursor via Tk scripting?
SO Oct 12, 2001 - A minimalist tk script that displays the 77 cross-platform cursors in a listbox, and configures the label above the listbox to use the currently selected cursor:
set cursors {arrow based_arrow_down based_arrow_up boat bogosity\
bottom_left_corner bottom_right_corner bottom_side bottom_tee\
box_spiral center_ptr circle clock coffee_mug cross cross_reverse\
crosshair diamond_cross dot dotbox double_arrow draft_large\
draft_small draped_box exchange fleur gobbler gumby hand1\
hand2 heart icon iron_cross left_ptr left_side left_tee leftbutton\
ll_angle lr_angle man middlebutton mouse pencil pirate plus\
question_arrow right_ptr right_side right_tee rightbutton rtl_logo\
sailboat sb_down_arrow sb_h_double_arrow sb_left_arrow\
sb_right_arrow sb_up_arrow sb_v_double_arrow shuttle sizing\
spider spraycan star target tcross top_left_arrow top_left_corner\
top_right_corner top_side top_tee trek ul_angle umbrella ur_angle\
watch X_cursor xterm}
listbox .list -width 20 -height 10 -bg white -selectmode single -yscrollcommand ".scroll set"
scrollbar .scroll -command ".list yview"
foreach index $cursors {
.list insert end $index
}
frame .top
label .top.label -textvariable current -width 20 -relief groove
set current [.list get active]
bind .list <ButtonRelease-1> {config}
proc config { } {
global current cursors
set idx [.list curselection]
set current [lindex $cursors $idx]
.top.label configure -cursor $current
return $current
}
pack .top
pack .top.label
pack .scroll -side right -fill y
pack .list -side left -expand 1 -fill both
wm title . "Cursors"From a subsequent discussion in the Tcl chatroom:
suchenwi: Steve: another style note - as the window title goes on top of the window, I like to place the "wm title . ..." command also high on top.
A more general note: the script works as written, but for clearer code, I would structure it as follows:
proc main {} {...}
proc config {} {...}
main For this one-page script the flat code is no problem. But if it gets longer, the context is not so clear to see - better break it in procs not longer than half a page each. Also, this way you have to register the globals that you need (not using globals is of course better ;-)
For instance, a listbox with a scrollbar is such a frequent component that it may be worth putting into a proc, which creates a frame and packs/grids the listbox and the scrollbar.
On toplevel you then have only two widgets to pack, the label and the lbframe, so you can use the idiom
eval pack [winfo children .]
which removes the need of changing two places when you add or remove other widgets.
This is one thing I dislike about Tk - definition and management of a widget in two distinct places. In simple cases, I help myself with
pack [text .t ...] pack [canvas .c ...]
..and the "eval pack [winfo children ..]" trick for more complex layouts. That relieves you of the need to know what children "." has, because it knows itself - the power of introspection...
Here is another variant of a cursor viewer from Reinhard Max.
It looks up the cursor names in the respective header file (works on Linux, but should be OK for other *nixes, too), and creates a table of labels which show the cursor names and have the respective cursors bound to them.
proc main {} {
set fd [open /usr/X11R6/include/X11/cursorfont.h r]
set i 0
while {[gets $fd line] > -1} {
if {
[regexp {XC_([^ ]+) } $line -> c] &&
![catch {
# not everything that begins with XC_ is a cursor name
label .$c -cursor $c -text $c -bd 2 -relief raised \
-width 20 -height 3 -fg grey40
}]
} then {
lappend labels .$c
if {[incr i] == 6} {
eval grid $labels
set labels ""
set i 0
}
}
}
}
mainPath for Solaris: /usr/openwin/include/X11 RS
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