# Source this into wish. Test with
#
# drawlines [makepts $count] $width
#
# where $count is number of points, $width is width of lines
# in pixels.
#
# Works well on unix. Time required depends linearly on the
# number of points, with thick lines (width>1) taking only
# marginally longer than thin lines.
#
# On Windows, thin lines (width=1) work well, with time
# required depending linearly on the number of points.
# Thick lines are rendered slowly, with time required
# increasing much worse than linear once the number of
# points is more than say 100. On my Win98 box, with
# Tcl/Tk 8.4.1, 'drawlines [makepts 1638] 2' raises
# an illegal operation fault. More points than this
# results in nothing being drawn. On Win2k, system
# response becomes very sluggish as the number of points
# moves into the thousands.
set canvas_width 301
set canvas_height 301
set canvas .c
if {[winfo exists $canvas]} {
$canvas delete all
$canvas configure -width $canvas_width -height $canvas_height \
-background white
} else {
canvas $canvas -width $canvas_width -height $canvas_height \
-background white
pack $canvas
}
proc makepts { count } {
global canvas_width canvas_height
for {set i 0} {$i<$count} {incr i} {
set x [expr {$i%$canvas_width}]
set y [expr {($i%2)*$canvas_height}]
lappend pts $x $y
}
return $pts
}
proc drawlines { pts width } {
global canvas
$canvas delete all
$canvas create line $pts -width $width
}
#drawlines [makepts 500] 2
