#  can2svg.tcl ---
#  
#      This file provides translation from canvas commands to XML/SVG format.
#      
#  Copyright (c) 2002  Mats Bengtsson
#
# ########################### USAGE ############################################
#
#   NAME
#      can2svg - translate canvas command to SVG.
#      
#   SYNOPSIS
#      can2svg canvasCmd ?options?
#           canvasCmd is everything except the widget path name.
#           
#      canvas2file widgetPath fileName ?options?
#           options:   -height
#                      -width
#      
#
# ########################### CHANGES ##########################################
#
#   0.1      first release
#
# ########################### TODO #############################################
# 
#   handle units (m->mm etc.) 
#   better support for stipple patterns
#   how to handle tk editing? DOM?
#   URI encoding
#   
#   ...

package provide can2svg 0.1

namespace eval ::can2svg:: {

    namespace export can2svg canvas2file
    
    variable formatArrowMarker
    variable formatArrowMarkerLast
    
    # The key into this array is 'arrowMarkerDef_$col_$a_$b_$c', where
    # col is color, and a, b, c are the arrow's shape.
    variable defsArrowMarkerArr

    # Similarly for stipple patterns.
    variable defsStipplePatternArr

    # This shouldn't be hardcoded!
    variable defaultFont {Helvetica 12}

    variable anglesToRadians expr 3.14159265359/180.0
    variable grayStipples {gray75 gray50 gray25 gray12}
        
    # Make 4x4 squares. Perhaps could be improved.
    variable stippleDataArr
    
    set stippleDataArr(gray75)  \
      {M 0 0 h3 M 0 1 h1 m 1 0 h2 M 0 2 h2 m 1 0 h1 M 0 3 h3}
    set stippleDataArr(gray50)  \
      {M 0 0 h1 m 1 0 h1 M 1 1 h1 m 1 0 h1 \
      M 0 2 h1 m 1 0 h1 M 1 3 h1 m 1 0 h1}
    set stippleDataArr(gray25)  \
      {M 0 0 h1 M 2 1 h1 M 1 2 h1 M 3 3 h1}
    set stippleDataArr(gray12) {M 0 0 h1 M 2 2 h1}
    
}

# ::can2svg::can2svg --
#
#       Make xml out of a canvas command, widgetPath removed.
#       
# Arguments:
#       cmd         canvas command without prepending widget path.
#       args    -usetags    0|all|first|last
#       
# Results:
#   xml data

proc ::can2svg::can2svg {cmd args} {

    variable defsArrowMarkerArr
    variable defsStipplePatternArr
    variable anglesToRadians
    variable defaultFont
    variable grayStipples
    
    set nonum_ {^0-9}
    set wsp_ {+}
    set xml ""
    
    array set argsArr {-usetags all}
    array set argsArr $args
    
    switch -- lindex $cmd 0 {
        
        create {
            set type lindex $cmd 1
            set rest lrange $cmd 2 end
            regexp -indices -- "-${nonum_}" $rest ind
            set ind1 lindex $ind 0
            set coo string trim [string range $rest 0 [expr $ind1 - 1]
            set opts string range $rest $ind1 end
            array set optArr $opts
            
            # Figure out if we've got a spline.
            set haveSpline 0
            if {info exists optArr(-smooth) && ($optArr(-smooth) != "0") &&  \
              info exists optArr(-splinesteps) && ($optArr(-splinesteps) > 2)} {
                set haveSpline 1
            }
            if {info exists optArr(-fill)} {
                set fillValue $optArr(-fill)
            } else {
                set fillValue black
            }
            if {($argsArr(-usetags) != "0") && info exists optArr(-tags)} {
                switch -- $argsArr(-usetags) {
                    all {                        
                        set idAttr list "id" $optArr(-tags)
                    }
                    first {
                        set idAttr [list "id" [lindex $optArr(-tags) 0]
                    }
                    last {
                        set idAttr [list "id" [lindex $optArr(-tags) end]
                    }
                }
            } else {
                set idAttr ""
            }
                
            # If we need a marker (arrow head) need to make that first.
            if {info exists optArr(-arrow)} {
                if {info exists optArr(-arrowshape)} {
                    
                    # Make a key of the arrowshape list into the array.
                    regsub -all -- $wsp_ $optArr(-arrowshape) _ shapeKey
                    set arrowKey ${fillValue}_${shapeKey}
                    set arrowShape $optArr(-arrowshape)
                } else {
                    set arrowKey ${fillValue}
                    set arrowShape {8 10 3}
                }
                if {!info exists defsArrowMarkerArr($arrowKey)} {
                    set defsArrowMarkerArr($arrowKey)  \
                      eval {MakeArrowMarker} $arrowShape {$fillValue}
                    append xml $defsArrowMarkerArr($arrowKey)
                    append xml "\n\t"
                }
            }
            
            # If we need a stipple bitmap, need to make that first. Limited!!!
            # Only: gray12, gray25, gray50, gray75
            foreach key {-stipple -outlinestipple} {
                if {info exists optArr($key) &&  \
                  (lsearch $grayStipples $optArr($key) >= 0)} {
                    set stipple $optArr($key)
                    if {!info exists defsStipplePatternArr($stipple)} {
                        set defsStipplePatternArr($stipple)  \
                          MakeGrayStippleDef $stipple
                    }
                    append xml $defsStipplePatternArr($stipple)
                    append xml "\n\t"
                }
            }
                        
            switch -- $type {
                
                arc {
                    
                    # Had to do it the hard way! (?)
                    # "Wrong" coordinate system :-(
                    set elem "path"
                    set style MakeStyle $type $opts
                    foreach {x1 y1 x2 y2} $coo {}
                    set cx expr ($x1 + $x2)/2.0
                    set cy expr ($y1 + $y2)/2.0
                    set rx expr abs($x1 - $x2)/2.0
                    set ry expr abs($y1 - $y2)/2.0
                    set rmin expr $rx > $ry ? $ry : $rx
                    
                    # This approximation gives a maximum half pixel error.
                    set deltaPhi expr 2.0/sqrt($rmin)
                    set extent expr $anglesToRadians * $optArr(-extent)
                    set start expr $anglesToRadians * $optArr(-start)
                    set nsteps expr int(abs($extent)/$deltaPhi) + 2
                    set delta expr $extent/$nsteps
                    set data [format "M %.1f %.1f L"   \
                      expr $cx + $rx*cos($start) [expr $cy - $ry*sin($start)]
                    for {set i 0} {$i <= $nsteps} {incr i} {
                        set phi expr $start + $i * $delta
                        append data [format " %.1f %.1f"  \
                          expr $cx + $rx*cos($phi) [expr $cy - $ry*sin($phi)]
                    }
                    if {info exists optArr(-style)} {
                        switch -- $optArr(-style) {
                            chord {
                                append data " Z"
                            }
                            pieslice {
                                append data format " %.1f %.1f Z" $cx $cy
                            }
                        }
                    } else {
                        
                        # Pieslice is the default.
                        append data format " %.1f %.1f Z" $cx $cy
                    }
                    set attr list "d" $data "style" $style
                    if {string length $idAttr > 0} {
                        set attr concat $attr $idAttr
                    }
                    set xmlList MakeXMLList $elem -attrlist $attr
                }
                image - bitmap {
                    set elem "image"
                    set attr MakeImageAttr $coo $opts
                    if {string length $idAttr > 0} {
                        set attr concat $attr $idAttr
                    }
                    set xmlList MakeXMLList $elem -attrlist $attr
                }
                line {
                    if {$haveSpline} {
                        set elem "path"
                        set style MakeStyle $type $opts
                        set data "M lrange $coo 0 1 Q"
                        set i 4
                        foreach {x y} lrange $coo 2 end-4 {
                            set x0 expr ($x + [lindex $coo $i)/2.0]
                            incr i
                            set y0 expr ($y + [lindex $coo $i)/2.0]
                            incr i
                            append data " $x $y $x0 $y0"                            
                        }
                        append data " lrange $coo end-3 end"
                        set attr list "d" $data "style" $style
                    } else {
                        set elem "polyline"
                        set style MakeStyle $type $opts
                        set attr list "points" $coo "style" $style
                    }
                    if {string length $idAttr > 0} {
                        set attr concat $attr $idAttr
                    }
                    set xmlList MakeXMLList $elem -attrlist $attr
                }
                oval {
                    foreach {x y w h} NormalizeRectCoords $coo {}
                    if {expr $w == $h} {
                        set elem "circle"
                        set attr [list  \
                          "cx" expr $x + $w/2.0  \
                          "cy" expr $y + $h/2.0  \
                          "r"  [expr $w/2.0]
                    } else {
                        set elem "ellipse"
                        set attr [list  \
                          "cx" expr $x + $w/2.0  \
                          "cy" expr $y + $h/2.0  \
                          "rx" expr $w/2.0       \
                          "ry" [expr $h/2.0]
                    }
                    set style MakeStyle $type $opts
                    lappend attr "style" $style
                    if {string length $idAttr > 0} {
                        set attr concat $attr $idAttr
                    }
                    set xmlList MakeXMLList $elem -attrlist $attr
                }
                polygon {
                    if {$haveSpline} {
                        set elem "path"
                        set style MakeStyle $type $opts

                        # Translating a closed polygon into a qubic bezier
                        # path is a little bit tricky.
                        set x0 expr ([lindex $coo end-1 + lindex $coo 0)/2.0]
                        set y0 expr ([lindex $coo end + lindex $coo 1)/2.0]
                        set data "M $x0 $y0 Q"
                        set i 2
                        foreach {x y} lrange $coo 0 end-2 {
                            set x1 expr ($x + [lindex $coo $i)/2.0]
                            incr i
                            set y1 expr ($y + [lindex $coo $i)/2.0]
                            incr i
                            append data " $x $y $x1 $y1"                            
                        }
                        append data " lrange $coo end-1 end $x0 $y0"
                        set attr list "d" $data "style" $style
                    } else {
                        set elem "polygon"
                        set style MakeStyle $type $opts
                        set attr list "points" $coo "style" $style
                    }
                    if {string length $idAttr > 0} {
                        set attr concat $attr $idAttr
                    }
                    set xmlList MakeXMLList $elem -attrlist $attr
                }
                rectangle {
                    set elem "rect"
                    set style MakeStyle $type $opts

                    # width and height must be non-negative!
                    foreach {x y w h} NormalizeRectCoords $coo {}
                    set attr list "x" $x "y" $y "width" $w "height" $h
                    lappend attr "style" $style
                    if {string length $idAttr > 0} {
                        set attr concat $attr $idAttr
                    }
                    set xmlList MakeXMLList $elem -attrlist $attr                    
                }
                text {
                    set elem "text"
                    set style MakeStyle $type $opts
                    set nlines 1
                    if {info exists optArr(-text)} {
                        set chdata $optArr(-text)
                        set nlines expr [regexp -all "\n" $chdata + 1]
                    } else {
                        set chdata ""
                    }
                    
                    # Figure out the coords of the first baseline.
                    set anchor center
                    if {info exists optArr(-anchor)} {
                        set anchor $optArr(-anchor)
                    }                                        
                    if {info exists optArr(-font)} {
                        set theFont $optArr(-font)
                    } else {
                        set theFont $defaultFont
                    }
                    set ascent font metrics $theFont -ascent
                    set lineSpace font metrics $theFont -linespace

                    foreach {xbase ybase}  \
                      GetTextSVGCoords $coo $anchor $chdata $theFont $nlines {}
                                        
                    set attr list "x" $xbase "y" $ybase
                    lappend attr "style" $style
                    if {string length $idAttr > 0} {
                        set attr concat $attr $idAttr
                    }
                    set dy 0
                    if {$nlines > 1} {
                        
                        # Use the 'tspan' trick here.
                        set subList {}
                        foreach line split $chdata "\n" {
                            lappend subList [MakeXMLList "tspan"  \
                              -attrlist list "x" $xbase "dy" $dy -chdata $line]
                            set dy $lineSpace
                        }
                        set xmlList [MakeXMLList $elem -attrlist $attr \
                          -subtags $subList]
                    } else {
                        set xmlList [MakeXMLList $elem -attrlist $attr \
                          -chdata $chdata]
                    }
                }
            }
        }
        move {
            foreach {tag dx dy} lrange $cmd 1 3 {}
            set attr [list "transform" "translate($dx,$dy)"  \
              "xlink:href" "#$tag"]
            set xmlList MakeXMLList "use" -attrlist $gattr
        }
        scale {
            
        }
    }
    append xml MakeXML $xmlList
    return $xml
}

# ::can2svg::MakeStyle --
#
#       Produce the SVG style attribute from the canvas item options.
#
# Arguments:
#       type        tk canvas widget item type
#       opts
#       
# Results:
#       The SVG style attribute as a a string.

proc ::can2svg::MakeStyle {type opts} {

    # Defaults for everything except text.
    if {!string equal $type "text"} {
        array set styleArr {fill none stroke black}
    }
    set fillCol black
    
    foreach {key value} $opts {
        
        switch -- $key {
            -arrow {
                set arrowValue $value
            }
            -arrowshape {
                set arrowShape $value
            }
            -capstyle {
                if {string equal $value "projecting"} {
                    set value "square"
                }
                if {!string equal $value "butt"} {
                    set styleArr(stroke-linecap) $value
                }
            }
            -dash {
                set dashValue $value
            }
            -dashoffset {
                if {$value != 0} {
                    set styleArr(stroke-dashoffset) $value
                }
            }
            -fill {
                set fillCol $value
                if {string equal $type "line"} {
                    set styleArr(stroke) MapEmptyToNone $value
                } else {
                    set styleArr(fill) MapEmptyToNone $value
                }
            }
            -font {
                set styleArr(font-family) lindex $value 0
                if {llength $value > 1} {
                    set styleArr(font-size) lindex $value 1
                }
                if {llength $value > 2} {
                    set tkstyle lindex $value 2
                    switch -- $tkstyle {
                        bold {
                            set styleArr(font-weight) $tkstyle
                        }
                        italic {
                            set styleArr(font-style) $tkstyle
                        }
                        underline {
                            set styleArr(text-decoration) underline
                        }
                        overstrike {
                            set styleArr(text-decoration) overline
                        }
                    }
                }                
                
            }
            -joinstyle {
                set styleArr(stroke-linejoin) $value                
            }
            -outline {
                set styleArr(stroke) MapEmptyToNone $value
            }
            -outlinestipple {
                set outlineStippleValue $value
            }
            -stipple {
                set stippleValue $value
            }
            -width {
                set styleArr(stroke-width) $value
            }
        }
    }
    
    # If any arrow specify its marker def url key.
    if {info exists arrowValue} {
        if {info exists arrowShape} {        
            foreach {a b c} $arrowShape {}
            set arrowIdKey "arrowMarkerDef_${fillCol}_${a}_${b}_${c}"
            set arrowIdKeyLast "arrowMarkerLastDef_${fillCol}_${a}_${b}_${c}"
        } else {
            set arrowIdKey "arrowMarkerDef_${fillCol}"
        }
        switch -- $arrowValue {
            first {
                set styleArr(marker-start) "url(#$arrowIdKey)"
            }
            last {
                set styleArr(marker-end) "url(#$arrowIdKeyLast)"
            }
            both {
                set styleArr(marker-start) "url(#$arrowIdKey)"
                set styleArr(marker-end) "url(#$arrowIdKeyLast)"
            }
        }
    }
    
    if {info exists stippleValue} {
        
        # Overwrite any existing.
        set styleArr(fill) "url(#tile$stippleValue)"
    }
    if {info exists outlineStippleValue} {
        
        # Overwrite any existing.
        set styleArr(stroke) "url(#tile$stippleValue)"
    }
    
    # Transform dash value.
    if {info exists dashValue} {
                
        # Two different syntax here.                
        if {regexp {[\.,\-_} $dashValue]} {
            
            # .=2 ,=4 -=6 space=4    times stroke width.
            # A space enlarges the... space.
            # Not foolproof!
            regsub -all -- {^} $dashValue "& " dash
            regsub -all -- "   "  $dash  "12 " dash
            regsub -all -- "  "   $dash  "8 " dash
            regsub -all -- " "    $dash  "4 " dash
            regsub -all -- {\.}   $dash  "2 " dash
            regsub -all -- {,}    $dash  "4 " dash
            regsub -all -- {-}    $dash  "6 " dash                    
        
            # Multiply with stroke width if > 1.
            if {info exists styleArr(stroke-width) &&  \
              ($styleArr(stroke-width) > 1)} {
                set width $styleArr(stroke-width)
                set dashOrig $dash
                set dash {}
                foreach num $dashOrig {
                    lappend dash expr int($width * $num)
                }
            }
            set styleArr(stroke-dasharray) string trim $dash
        } else {
            set styleArr(stroke-dasharray) $value
        }
    }
    if {string equal $type "polygon"} {
        set styleArr(fill-rule) "evenodd"
    }
        
    set style ""
    foreach {key value} array get styleArr {
        append style "${key}: ${value}; "
    }
    return string trim $style
}

# ::can2svg::MakeImageAttr --
#
#       Special code is needed to make the attributes for an image item.
#       
# Arguments:
#       elem 
#       
# Results:
#   

proc ::can2svg::MakeImageAttr {coo opts} {
    
    array set optArr {-anchor nw}
    array set optArr $opts
    set theImage $optArr(-image)
    set w image width $theImage
    set h image height $theImage
    
    # We should make this an URI.
    set theFile $theImage cget -file
    set uri UriFromLocalFile $theFile
    foreach {x0 y0} $coo {}
    switch -- $optArr(-anchor) {
        nw {
            set x $x0
            set y $y0
        }
        n {
            set x expr $x0 - $w/2.0
            set y $y0
        }
        ne {
            set x expr $x0 - $w
            set y $y0
        }
        e {
            set x $x0
            set y expr $y0 - $h/2.0
        }
        se {
            set x expr $x0 - $w
            set y expr $y0 - $h
        }
        s {
            set x expr $x0 - $w/2.0
            set y expr $y0 - $h
        }
        sw {
            set x $x0
            set y expr $y0 - $h
        } 
        w {
            set x $x0
            set y expr $y0 - $h/2.0
        }
        center {
            set x expr $x0 - $w/2.0
            set y expr $y0 - $h/2.0
        }
    }
    set attrList [list "x" $x "y" $y "width" $w "height" $h  \
      "xlink:href" $uri]
    return $attrList
}

# ::can2svg::GetTextSVGCoords --
# 
#       Figure out the baseline coords of the svg text element from
#       the canvas text item.
#
# Arguments:
#       coo         {x y}
#       anchor
#       chdata      character data, newlines included.
#       
# Results:
#       raw xml data of the marker def element.

proc ::can2svg::GetTextSVGCoords {coo anchor chdata theFont nlines} {
    
    foreach {x y} $coo {}
    set ascent font metrics $theFont -ascent
    set lineSpace font metrics $theFont -linespace

    # If not anchored to the west it gets more complicated.
    if {!string match $anchor "*w*"} {
        
        # Need to figure out the extent of the text.
        if {$nlines <= 1} {
            set textWidth font measure $theFont $chdata
        } else {
            set textWidth 0
            foreach line split $chdata "\n" {
                set lineWidth font measure $theFont $line
                if {$lineWidth > $textWidth} {
                    set textWidth $lineWidth
                }
            }
        }
    }
    
    switch -- $anchor {
        nw {
            set xbase $x
            set ybase expr $y + $ascent
        }
        w {
            set xbase $x
            set ybase expr $y - $nlines*$lineSpace/2.0 + $ascent
        }
        sw {
            set xbase $x
            set ybase expr $y - $nlines*$lineSpace + $ascent
        }
        s {
            set xbase expr $x - $textWidth/2.0
            set ybase expr $y - $nlines*$lineSpace + $ascent
        }
        se {
            set xbase expr $x - $textWidth
            set ybase expr $y - $nlines*$lineSpace + $ascent
        }
        e {
            set xbase expr $x - $textWidth
            set ybase expr $y - $nlines*$lineSpace/2.0 + $ascent
        }
        ne {
            set xbase expr $x - $textWidth
            set ybase expr $y + $ascent
        } 
        n {
            set xbase expr $x - $textWidth/2.0
            set ybase expr $y + $ascent
        }
        center {
            set xbase expr $x - $textWidth/2.0
            set ybase expr $y - $nlines*$lineSpace/2.0 + $ascent
        }
    }
    
    return list $xbase $ybase
}

# ::can2svg::MakeArrowMarker --
# 
#       Make the xml for an arrow marker def element.
#
# Arguments:
#       a           arrows length along its symmetry line
#       b           arrows total length
#       c           arrows half width
#       col         its color
#       
# Results:
#       raw xml data of the marker def elements, both start and last.

proc ::can2svg::MakeArrowMarker {a b c col} {
    
    variable formatArrowMarker
    variable formatArrowMarkerLast
    
    catch {unset formatArrowMarker}
    
    if {!info exists formatArrowMarker} {
        
        # "M 0 c, b 0, a c, b 2*c Z" for the start marker.
        # "M 0 0, b c, 0 2*c, b-a c Z" for the last marker.
        set data "M 0 %s, %s 0, %s %s, %s %s Z"
        set style "fill: %s; stroke: %s;"
        set attr list "d" $data "style" $style
        set arrowList MakeXMLList "path" -attrlist $attr
        set markerAttr [list "id" %s "markerWidth" %s "markerHeight" %s  \
          "refX" %s "refY" %s "orient" "auto"]
        set defElemList [MakeXMLList "defs" -subtags  \
          [list [MakeXMLList "marker" -attrlist $markerAttr \
          -subtags list $arrowList ] ] ]
        set formatArrowMarker MakeXML $defElemList
        
        # ...and the last arrow marker.
        set dataLast "M 0 0, %s %s, 0 %s, %s %s Z"
        set attrLast list "d" $dataLast "style" $style
        set arrowLastList MakeXMLList "path" -attrlist $attrLast
        set defElemLastList [MakeXMLList "defs" -subtags  \
          [list [MakeXMLList "marker" -attrlist $markerAttr \
          -subtags list $arrowLastList ] ] ]
        set formatArrowMarkerLast MakeXML $defElemLastList
    }
    set idKey "arrowMarkerDef_${col}_${a}_${b}_${c}"
    set idKeyLast "arrowMarkerLastDef_${col}_${a}_${b}_${c}"
    
    # Figure out the order of all %s substitutions.
    set markerXML [format $formatArrowMarker $idKey  \
      $b expr 2*$c 0 $c  \
      $c $b $a $c $b expr 2*$c $col $col]
    set markerLastXML [format $formatArrowMarkerLast $idKeyLast  \
      $b expr 2*$c $b $c \
      $b $c expr 2*$c expr $b-$a $c $col $col]
    
    return "$markerXML\n\t$markerLastXML"
}

# ::can2svg::MakeGrayStippleDef --
#
#

proc ::can2svg::MakeGrayStippleDef {stipple} {
    
    variable stippleDataArr
    
    set pathList [MakeXMLList "path" -attrlist  \
      [list "d" $stippleDataArr($stipple) "style" "stroke: black; fill: none;"]
    set patterAttr [list "id" "tile$stipple" "x" 0 "y" 0 "width" 4 "height" 4 \
      "patternUnits" "userSpaceOnUse"]
    set defElemList [MakeXMLList "defs" -subtags  \
      [list [MakeXMLList "pattern" -attrlist $patterAttr \
      -subtags list $pathList ] ] ]
    
    return MakeXML $defElemList
}

# ::can2svg::MapEmptyToNone --
#
#
# Arguments:
#       elem 
#       
# Results:
#   

proc ::can2svg::MapEmptyToNone {val} {

    if {string length $val == 0} {
        return "none"
    } else {
        return $val
    }
}

# ::can2svg::NormalizeRectCoords --
#
#
# Arguments:
#       elem 
#       
# Results:
#   

proc ::can2svg::NormalizeRectCoords {coo} {
    
    foreach {x1 y1 x2 y2} $coo {}
    return list [expr $x2 > $x1 ? $x1 : $x2  \
      expr $y2 > $y1 ? $y1 : $y2  \
      expr abs($x1-$x2)  \
      [expr abs($y1-$y2)]
}

# ::can2svg::makedocument --
#
#       Adds the prefix and suffix elements to make a complete XML/SVG
#       document.
#
# Arguments:
#       elem 
#       
# Results:
#   

proc ::can2svg::makedocument {width height xml} {
    
    set pre "<?xml version='1.0'?>\n\
      <!DOCTYPE svg PUBLIC \"-//W3C//DTD SVG 1.0//EN\"\
      \"http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd\ ">"
    
    set svgStart "<svg width='$width' height='$height'>"
    set svgEnd "</svg>"
    return "${pre}\n${svgStart}\n${xml}${svgEnd}"
}

# ::can2svg::canvas2file --
#
#       Takes everything on a canvas widget, translates it to XML/SVG,
#       and puts it on a file.
#       
# Arguments:
#       wcan        the canvas widget path
#       path        the file path
#       args:   -height
#               -width 
#       
# Results:
#   

proc ::can2svg::canvas2file {wcan path args} {
    
    variable defsArrowMarkerArr
    variable defsStipplePatternArr

    # Need to make a fresh start for marker def's.
    catch {unset defsArrowMarkerArr}
    catch {unset defsStipplePatternArr}

    array set argsArr  \
      list -width [winfo width $wcan -height [winfo height $wcan]
    array set argsArr $args
    
    set fd open $path w

    set xml ""
    foreach id $wcan find all {
        set type $wcan type $id
        set opts $wcan itemconfigure $id
        set opcmd {}
        foreach opt $opts {
            set op lindex $opt 0
            set val lindex $opt 4
            
            # Empty val's except -fill can be stripped off.
            if {!string equal $op "-fill" && (string length $val == 0)} {
                continue
            }
            lappend opcmd $op $val
        }
        set co $wcan coords $id
        set cmd concat "create" $type $co $opcmd
        append xml "\tcan2svg $cmd\n"        
    }
    puts $fd makedocument $argsArr(-width) $argsArr(-height) $xml
    close $fd
}

# ::can2svg::MakeXML --
#
#       Creates raw xml data from a hierarchical list of xml code.
#       This proc gets called recursively for each child.
#       It makes also internal entity replacements on character data.
#       Mixed elements aren't treated correctly generally.
#       
# Arguments:
#       xmlList     a list of xml code in the format described in the header.
#       
# Results:
#       raw xml data.

proc ::can2svg::MakeXML {xmlList} {
        
    # Extract the XML data items.
    foreach {tag attrlist isempty chdata childlist} $xmlList {}
    set rawxml "<$tag"
    foreach {attr value} $attrlist {
        append rawxml " ${attr}='${value}'"
    }
    if {$isempty} {
        append rawxml "/>"
        return $rawxml
    } else {
        append rawxml ">"
    }
    
    # Call ourselves recursively for each child element. 
    # There is an arbitrary choice here where childs are put before PCDATA.
    foreach child $childlist {
        append rawxml MakeXML $child
    }
    
    # Make standard entity replacements.
    if {string length $chdata} {
        append rawxml XMLCrypt $chdata
    }
    append rawxml "</$tag>"
    return $rawxml
}

# ::can2svg::MakeXMLList --
#
#       Build an element list given the tag and the args.
#
# Arguments:
#       tagname:    the name of this element.
#       args:       
#           -empty   0|1      Is this an empty tag? If $chdata 
#                             and $subtags are empty, then whether 
#                             to make the tag empty or not is decided 
#                             here. (default: 1)
#            -attrlist {attr1 value1 attr2 value2 ..}   Vars is a list 
#                             consisting of attr/value pairs, as shown.
#            -chdata $chdata   ChData of tag (default: "").
#            -subtags {$subchilds $subchilds ...} is a list containing xmldata
#                             of $tagname's subtags. (default: no sub-tags)
#       
# Results:
#       a list suitable for ::can2svg::MakeXML.

proc ::can2svg::MakeXMLList {tagname args} {
        
    # Fill in the defaults.
    array set xmlarr {-isempty 1 -attrlist {} -chdata {} -subtags {}}
    
    # Override the defults with actual values.
    if {llength $args > 0} {
        array set xmlarr $args
    }
    if {!(($xmlarr(-chdata) == "") && ($xmlarr(-subtags) == ""))} {
        set xmlarr(-isempty) 0
    }
    
    # Build sub elements list.
    set sublist {}
    foreach child $xmlarr(-subtags) {
        lappend sublist $child
    }
    set xmlList [list $tagname $xmlarr(-attrlist) $xmlarr(-isempty)  \
      $xmlarr(-chdata) $sublist]
    return $xmlList
}

# ::can2svg::XMLCrypt --
#
#       Makes standard XML entity replacements.
#
# Arguments:
#       chdata:     character data.
#       
# Results:
#       chdata with XML standard entities replaced.

proc ::can2svg::XMLCrypt {chdata} {

    foreach from {\& < > {"} {'}}   \
      to {{\&amp;} {\&lt;} {\&gt;} {\&quot;} {\&apos;}} {
        regsub -all $from $chdata $to chdata
    }        
    return $chdata
}

# ::can2svg::UriFromLocalFile --
#
#       Not foolproof!

proc ::can2svg::UriFromLocalFile {path} {
    
    # Windows???  
    # TODO: Encoding?
    if {string equal $::tcl_platform(platform) "windows"} {
        
        # Trim the volume specifier.
        set vol_ {(A-Z:/|A-Z:\\)}
        regexp "${vol_}+(.+)$" $path match x path
    }
    set pathList split $path "/:\\"
    set pathJoin join $pathList /
    
    # Any characters not 7bit encode as %xx hex???
    
    regsub -all -- " " $pathJoin "%20" pathJoin

    return file:///${pathJoin} 
}

#-------------------------------------------------------------------------------