[PD-dev] much better scrolling algorithm (pd-extended 0.42.5)

[Ivica Ico Bukvic]

OK, try the one below instead (with ::scroll call removed). Also, plase
don't forget to do the followign test with large graphics objects and
test scrollbar behavior:

1) create iemlib's number2
2) adjust its height to 60 and its font size to 50
3) drag it as far to the top as possible and what you will likely
discover is that it fails to reach the top corner *or* creates
scrollbars even though the object fits comfortably within the window.
This is not the case AFAIK with the version below.

Ico


proc pdtk_canvas_getscroll {name} {
    global pdtk_canvas_mouseup_name
    global pdtk_canvas_mouseup_xminval
    global pdtk_canvas_mouseup_xmaxval
    global pdtk_canvas_mouseup_yminval
    global pdtk_canvas_mouseup_ymaxval

	#bbox all is not accurate enough
	#particularly when using large iemlib objects
	#so we calculate canvas size manually
    #set size [$name bbox all]

	#borrowed from http://wiki.tcl.tk/4844
	set x1 1.0e30; set x2 -1.0e30 ;
	set y1 1.0e30; set y2 -1.0e30 ;
	foreach item [$name find all] {
	    switch -exact [$name type $item] {
			"arc" -
			"line" -
			"oval" -
			"polygon" -
			"rectangle" {
				set coords [$name coords $item]
				foreach {x y} $coords {
					if { $x < $x1 } {set x1 $x}
					if { $x > $x2 } {set x2 $x}
					if { $y < $y1 } {set y1 $y}
					if { $y > $y2 } {set y2 $y}
				}
			}
	    }
	}
	
	if {$x1 != 1.0e30} {

		set xminval 0
		set yminval 0
		set xmaxval 100
		set ymaxval 20
		#set x1 [lindex $size 0]
		#set x2 [lindex $size 2]
		#set y1 [lindex $size 1]
		#set y2 [lindex $size 3]

		#pdtk_post "bbox all: $x1 $x2 $y1 $y2\n"
		#pdtk_post "new bbox all: $xbox1 $xbox2 $ybox1 $ybox2\n"

		#these work much better than the ones below
		#they allow for intelligent translation of the canvas
		#rather than introducing redundant scrollbars
		set xminval $x1
		set yminval $y1

		set xmaxval [expr $x1+($x2-$x1)]
		set ymaxval [expr $y1+($y2-$y1)]

		#if {$x1 < $xminval} {set xminval $x1}
		#if {$y1 < $yminval} {set yminval $y1}

		#if {$x2 > $xmaxval} {set xmaxval $x2}
		#if {$y2 > $ymaxval} {set ymaxval $y2}

		#pdtk_post "$xminval $xmaxval $yminval $ymaxval\n"

		set parentname [winfo parent $name]
		set winwidth [winfo width $parentname]
		set winheight [winfo height $parentname]

		set canvaswidth [ expr {abs($xmaxval-$xminval)} ]
		set canvasheight [ expr {abs($ymaxval-$yminval)} ]
		#set canvaswidth [ expr {abs($xminval)+$xmaxval} ]
		#set canvasheight [ expr {abs($yminval)+$ymaxval} ]

		#pdtk_post "$canvaswidth $canvasheight\n"

		#pdtk_post "$parentname [$parentname.scroll cget -state]\n"

			#pdtk_post "scroll=yes $winwidth $canvaswidth\n"
			if {$winwidth > $canvaswidth} {pack forget $parentname.scrollhort}
			if {$winheight > $canvasheight} {pack forget $parentname.scrollvert}
			if {$winwidth < $canvaswidth} {pack $parentname.scrollhort -fill x \
					                           -side bottom -before $parentname.c}
			if {$winheight < $canvasheight} {pack $parentname.scrollvert -fill y
\
					                             -side right -before $parentname.c}

	
		if {$pdtk_canvas_mouseup_name != $name || \
				$pdtk_canvas_mouseup_xminval != $xminval || \
				$pdtk_canvas_mouseup_xmaxval != $xmaxval || \
				$pdtk_canvas_mouseup_yminval != $yminval || \
				$pdtk_canvas_mouseup_ymaxval != $ymaxval } {
		
			set newsize "$xminval $yminval $xmaxval $ymaxval"
			$name configure -scrollregion $newsize
			set pdtk_canvas_mouseup_name $name
			set pdtk_canvas_mouseup_xminval $xminval
			set pdtk_canvas_mouseup_xmaxval $xmaxval
			set pdtk_canvas_mouseup_yminval $yminval
			set pdtk_canvas_mouseup_ymaxval $ymaxval
		}
	}
    pdtk_canvas_checkgeometry [canvastosym $name]
}