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#
# This example illustrates how to construct a viewport-like widget using
# a frame and the placer geometry manager. Five listboxes are constructed
# and placed in a window which is too narrow to hold them all. A horizontal
# scrollbar allows the listboxes to be moved left or right in their viewport
# window.
# Allow the main window to be resized
wm minsize . 1 1
# Construct the horizontal scrollbar used to scroll the listboxes
scrollbar .hsb -orient horizontal -command HScroll
pack .hsb -side bottom -fill x
# The frame ".f" is the "clipping window".
frame .f -height 300 -width 600
pack .f -fill both -expand 1
# The frame ".f.f" is the window that gets clipped. This is the window
# that is moved left and right by the horizontal scrollbar. The five
# listboxes are all children of this window.
frame .f.f
# Construct the 5 listboxes and fill them with some arbitrary data
set i 1
while {$i<=5} {
listbox .f.f.lb$i -yscrollcommand ".f.f.sb$i set"
foreach j {0 1 2 3 4 5 6 7 8 9} {.f.f.lb$i insert end "$i$j"}
scrollbar .f.f.sb$i -orient vertical -command ".f.f.lb$i yview"
pack .f.f.lb$i .f.f.sb$i -side left -fill y
incr i
}
# We have to reset the scrollbar whenever either the clipping window or
# the scrolling window are resized.
bind .f.f <Configure> {HScroll $FirstUnit}
bind .f <Configure> {HScroll $FirstUnit}
# The global variable "FirstUnit" stores and integer which determines where
# the left edge of .f.f is relative to the left edge of .f. When FirstUnit==0,
# the left edges correspond. When FirstUnit==1, the left edge of .f.f is
# 10 pixels to the left of the left edge of .f. And so forth.
set FirstUnit 0
# This function causes the .f.f window to slide left and right within
# the clipping window .f. It also updates the position of the scrollbar.
#
proc HScroll {x} {
global FirstUnit
# totalUnits is an integer proportional to the width of .f.f
set totalUnits [expr int([winfo reqwidth .f.f]/10)]
# windowUnits is an integer which is proportional to the amount of
# .f.f which is actual visible. If totalUnits is, say, 100, and exactly
# half of .f.f is visible within .f, then windowUnits will be 50.
set windowUnits [expr int([winfo width .f]/10)]
# Limit the range of x so that we don't scroll too far left or right.
if {$x+$windowUnits>$totalUnits} {
set x [expr {$totalUnits - $windowUnits}]
}
if {$x<0} {
set x 0
}
set FirstUnit $x
# Adjust the position of the scrollbar thumb
.hsb set $totalUnits $windowUnits $x [expr $x+$windowUnits]
# Adjust the position of .f.f within the clipping window .f
place .f.f -anchor nw -relheight 1 -x [expr -10*$x] -y 0 \
-width [winfo reqwidth .f.f]
}
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