namespace eval ::ix {
    proc random_int {} {
	return [expr "int(floor(rand()*16))"]
    }
    proc random_clr {} {
        return [format "\#%1X%1X%1X%1X%1X%1X" [random_int] [random_int] [random_int] [random_int] [random_int] [random_int]]
    }
    variable _
    proc filter_update {path target n} {
	set type [$path.filter itemcget type_$n -text]
	set q [$path.filter itemcget q_$n -text]
	set loc [$path.filter coords sqr_$n]
	set x [expr 5 + [lindex $loc 0]]
	set y [expr 5 + [lindex $loc 1]]
	set inv [filter_invtr $path $target $x $y]
	set freq [lindex $inv 0]
	set mag [lindex $inv 1]
	filter_bqp $path $target $n $type $freq $mag $q
    }
    proc filter_bqp {path target n type f0 dBgain Q} {
	variable _
	set A [expr pow(10,($dBgain/40.0))]
	set Fs $_($target:rate)
	set pi [expr {atan(1) * 4}]
	set w0 [expr 2 * $pi * $f0 / $Fs]
	set alpha [expr sin($w0) / (2 * $Q)]
	switch $type {
	    notch {
		set b0 1
		set b1 [expr -2 * cos($w0)]
		set b2 1
		set a0 [expr 1 + $alpha]
		set a1 $b1
		set a2 [expr 1 - $alpha]
	    }
	    lowpass {
		set b0 [expr (1 - cos($w0))/2]
		set b1 [expr 1 - cos($w0)]
		set b2 $b0
		set a0 [expr 1 + $alpha]
		set a1 [expr -2 * cos($w0)]
		set a2 [expr 1 - $alpha]
	    }
	    highpass {
		set b0 [expr (1 + cos($w0))/2]
		set b1 [expr -(1 + cos($w0))]
		set b2 $b0
		set a0 [expr 1 + $alpha]
		set a1 [expr -2 * cos($w0)]
		set a2 [expr 1 - $alpha]
	    }
	    qbandpass {
		set b0 [expr sin($w0)/2]
		set b1 0
		set b2 [expr -$b0]
		set a0 [expr 1 + $alpha]
		set a1 [expr -2 * cos($w0)]
		set a2 [expr 1 - $alpha]
	    }
	    bandpass {
		set b0 $alpha
		set b1 0
		set b2 [expr -$alpha]
		set a0 [expr 1 + $alpha]
		set a1 [expr -2 * cos($w0)]
		set a2 [expr 1 - $alpha]
	    }
	    allpass {
		set b0 [expr 1 - $alpha]
		set b1 [expr -2 * cos($w0)]
		set b2 [expr 1 + $alpha]
		set a0 $b2
		set a1 $b1
		set a2 $b0
	    }
	    peakingEQ {
		set b0 [expr 1 + $alpha * $A]
		set b1 [expr -2 * cos($w0)]
		set b2 [expr 1 - $alpha * $A]
		set a0 [expr 1 + $alpha / $A]
		set a1 $b1
		set a2 [expr 1 - $alpha / $A]
	    }
	    lowShelf {
		set b0 [expr   $A*(($A+1)-($A-1)*cos($w0)+2*sqrt($A)*$alpha)]
		set b1 [expr 2*$A*(($A-1)-($A+1)*cos($w0))]
		set b2 [expr   $A*(($A+1)-($A-1)*cos($w0)-2*sqrt($A)*$alpha)]
		set a0 [expr       ($A+1)+($A-1)*cos($w0)+2*sqrt($A)*$alpha]
		set a1 [expr   -2*(($A-1)+($A+1)*cos($w0))]
		set a2 [expr       ($A+1)+($A-1)*cos($w0) - 2*sqrt($A)*$alpha ]
	    }
	    highShelf {
		set b0 [expr    $A*(($A+1)+($A-1)*cos($w0)+2*sqrt($A)*$alpha)]
		set b1 [expr -2*$A*(($A-1)+($A+1)*cos($w0))]
		set b2 [expr    $A*(($A+1)+($A-1)*cos($w0)-2*sqrt($A)*$alpha)]
		set a0 [expr        ($A+1)-($A-1)*cos($w0)+2*sqrt($A)*$alpha]
		set a1 [expr     2*(($A-1)-($A+1)*cos($w0))]
		set a2 [expr        ($A+1)-($A-1)*cos($w0) - 2*sqrt($A)*$alpha ]
	    }
	}
	set f 0
	set fr {}
	set _($target:fmag_$n) {1}
	set h [winfo height $path.filter]
	set h2 [expr $h / 2]
	while {$f < [winfo width $path.filter]} {
	    incr f
	    set w [expr $pi * [filter_invtr_x $path $target $f] / $_($target:nyquist)]
	    set mag [expr sqrt(pow(($b0+$b1*cos($w)+$b2*cos(2*$w)),2)+pow(($b1*sin($w)+$b2*sin(2*$w)),2))/sqrt(pow(($a0+$a1*cos($w)+$a2*cos(2*$w)),2)+pow(($a1*sin($w)+$a2*sin(2*$w)),2))]
	    lappend fr $f [expr $h - $h2 * $mag]
	    lappend _($target:fmag_$n) $mag
	}
	$path.filter coords resp_$n $fr
	pd [concat $target.rp _cb params $n [expr -1 * $a1 / $a0] [expr -1 * $a2 / $a0] [expr $b0 / $a0] [expr $b1 / $a0] [expr $b2 / $a0] \;]
	filter_resp $path $target
    }
    proc filter_resp {path target} {
	variable _
	if {$_($target:init) == 1} {
	    set f 0
	    set fr {}
	    set h [winfo height $path.filter]
	    set h2 [expr $h / 2]
	    while {$f < [winfo width $path.filter]} {
		incr f
		set cx 0
		set ci 1
		while {$cx < $_($target:n)} {
		    incr cx
		    set ci [expr $ci * [lindex $_($target:fmag_$cx) $f]]
		}
		lappend fr $f [expr $h - $h2 * $ci]
	    }
	    $path.filter coords resp $fr
	}
    }
    proc filter_motion {path target x y} {
	set v [filter_invtr $path $target $x $y]
	$path itemconfigure freq -text "[expr int([lindex $v 0])] hz"
# 	$path itemconfigure dB -text "[expr int([lindex $v 1])] dB"
    }
    proc filter_invtr {path target x y} {
	return [list [filter_invtr_x $path $target $x] [filter_invtr_y $path $target $y]]
    }
    proc filter_invtr_x {path target x} {
	variable _
	set gw [winfo width $path]
	if {$_($target:log) > 0} {
	    return [expr $_($target:scale) * exp($_($target:log) * $x / $gw.0)]
	} else {
	    return freq [expr $_($target:nyquist) * $x / $gw.0]
	}
    }
    proc filter_invtr_y {path target y} {
	set gh [winfo height $path]
	return [expr (12 * ($y / $gh.0 - 0.5) * - 1.0)]
    }
    proc filter_new {path target w h bg div log rate n} {
	variable _
	set _($target:init) 0
	set _($target:n) $n
	set _($target:log) $log
	set _($target:rate) $rate
	set _($target:nyquist) [expr $rate / 2]
	set _($target:scale) [expr $_($target:nyquist) / exp($_($target:log))]
	if {[winfo exists $path.filter] != 1} {
	    canvas $path.filter -bg $bg -width $w -height $h
	    pack $path.filter -side left
	    bind $path.filter <Motion> "::ix::filter_motion %W $target %x %y"
#	    bind $path.filter <ButtonRelease> "::ix::filter_resp $path $target"
	    bind $path.filter <Leave> {
		%W itemconfigure freq -text ""
		%W itemconfigure dB -text ""
	    }
	    bind $path.filter <1> "::ix::filter_click $path $target %x %y"
	    bind $path.filter <B1-Motion> [bind $path.filter <1>]
	    filter_gridlines $path $target $div
	    filter_filters $path $target $n
	    $path.filter create text 2 1 -tags freq -text "" -anchor nw -justify left -font {{Bitstream Vera Sans} 9}
#	    $path.filter create text 96 1 -tags dB -text "" -anchor ne -justify right -font {{Bitstream Vera Sans} 9}
	    $path.filter create line 0 0 0 0 -tags resp -fill grey44 -width 1.6
	    set fn 0 
	    while {$fn < $n} {
		incr fn	 
		foreach a [list sqr_$fn type_$fn q_$fn] {$path.filter raise $a}
	    }
	    set bd [expr {[$path cget -bd] * 2}]
	    $path configure -bg $bg -width [expr [winfo width $path.filter] + $bd] -height [expr [winfo height $path.filter] + $bd]
	}
	pd "$target.rp _cb n $n;"
	set _($target:init) 1
    }
    proc filter_filters {path target n} {
	set gh [winfo height $path.filter]
	set gw [winfo width $path.filter]
	set fn 0 
	while {$fn < $n} {
	    incr fn
	    set px [expr $gw.0 * $fn.0 / $n.0]
	    set py [expr $gh.0 / 2.0]
	    set fill [random_clr]
	    $path.filter create rectangle 0 0 0 0 -tags sqr_$fn -fill $fill
	    $path.filter create line 0 0 0 0 -tags resp_$fn -fill $fill
	    $path.filter create text 0 0 -tags type_$fn -fill grey33 -font {{Bitstream Vera Sans} 8} -text "peakingEQ" -anchor e -justify right
	    $path.filter create text 0 0 -tags q_$fn -fill white -font {{Bitstream Vera Sans} 8} -text "1.0" -anchor w -justify left
	    set b1 "::ix::filter_move $path $target $fn %x %y"
	    set b2 "::ix::filter_menu $path $target $fn %X %Y"
	    set b3 "::ix::filter_move_q $path $target $fn %x %y"
	    set b4 "::ix::filter_locus $path $target $fn %x %y"
	    foreach a [list sqr_$fn type_$fn q_$fn] {
		$path.filter bind $a <1> $b1
		$path.filter bind $a <2> $b2
		$path.filter bind $a <3> $b4
		$path.filter bind $a <B3-Motion> $b3
		$path.filter bind $a <B1-Motion> $b1
	    }
	    filter_move $path $target $fn $px $py
	}	
    }
    proc filter_menu {path target n x y} {
	if {[winfo exists $path.ft] == 1} { destroy $path.ft}
	set m [menu $path.ft -tearoff no]
	foreach ft {lowpass highpass qbandpass bandpass notch allpass peakingEQ lowShelf highShelf} {
	    $m add command -label $ft -command "::ix::filter_type $path $target $n $ft"
	}
	tk_popup $path.ft $x $y
    }
    proc filter_type {path target n type} {
	$path.filter itemconfigure type_$n -text "$type"
	filter_update $path $target $n
    }
    proc filter_click {path target x y} {
	variable _
	filter_move $path $target $_($target:recent) $x $y
    }
    proc filter_move {path target n px py} {
	variable _
	$path.filter coords sqr_$n [expr $px - 5] [expr $py - 5] [expr $px + 5] [expr $py + 5]	
	$path.filter coords type_$n [expr $px - 9] [expr $py]
	$path.filter coords q_$n [expr $px + 9] [expr $py]
	filter_motion $path.filter $target $px $py
	set _($target:recent) $n
	filter_update $path $target $n
    }
    proc filter_locus {path target n px py} {
	variable _
	set _($target:lx) $px
    }
    proc filter_move_q {path target n px py} {
	variable _
	set delta [expr ($px.0 - $_($target:lx).0) / 25]
	set move [expr [$path.filter itemcget q_$n -text] + $delta]
	if {$move > 0} {
	    $path.filter itemconfigure q_$n -text $move
	}
	filter_update $path $target $n
	set _($target:lx) $px
    }
    proc filter_gridlines {path target lines} {
	variable _
	puts "gridlines"
	set color white
	set w $path.filter
	$w delete gridlines
	set gh [winfo height $w]
	set gw [winfo width $w]
	for {set x 1} {$x <= $lines} {incr x} {
	    if {$lines < 16 && $lines > 0} {
		set oh [expr $gh.0 * $x.0 / $lines.0]
		set ow [expr $gw.0 * $x.0 / $lines.0]
	      	$w create line $ow 0 $ow $gh -fill $color -tags gridlines
	      	$w create line 0 $oh $gw $oh -fill $color -tags gridlines
		set fontsize [expr int(80.0/$lines.0)]
		$w create text $ow [expr $gh - $fontsize] -font [list {Bitstream Vera Sans} $fontsize] -tags gridlines -text [expr int([filter_invtr_x $path $target $ow])]
	    }
	}
	$w raise ${target}sqr
    }
}
#> filter frame
#. -bd 3 #w 384 #h 144 #bg gray90 #div 6 #n 3
#. #log 1 #rate 44100
#. @div  ::ix::filter_gridlines .- .| .#1
#. @params ::ix::filter_lp .- .| .#args
puts "filter .- .|"
::ix::filter_new .- .| .#w .#h .#bg .#div .#log .#rate .#n