[Richard Suchenwirth] - This breakfast fun project allows symmetric
doodling (free-hand drawing) on a [canvas]. Besides drawing a line (in
selectable color) at cursor position, horizontally and/or vertically
mirrored lines are also drawn. Delete a line with right mousebutton, or
all with the C button. Enjoy!

[http://mini.net/files/symdoodle.jpg]

[KPV] Fun. I modified it slightly (in place) so that you can resize it and by right clicking on a color, you can change the background.

[KPV] My 3 year old daughter requested fatter lines, so I added the ability to select the pen size.

[GPS] Thanks Richard and Keith for sharing this.  I like it and so does my brother.  My brother wants the ability to save images, so maybe I'll play around with Img and improve this.

[MPJ] After showing this to my son he wanted to play with it on my [PocketPC] so I resized it and added some menus.  Here is my version, called iDoodle [http://mywebpages.comcast.net/jakeforce/iDoodle.tcl], and a screen shot of it running on my HP Jornada.

[http://mywebpages.comcast.net/jakeforce/iDoodle.jpg]
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 proc main {} {
    set size      400 ;# canvas height and width
    set axiscolor grey
    set bg        white
    global g
    
    frame .f -relief sunken -borderwidth 2
    checkbutton .f.hori -text -- -variable g(hori)
    set g(hori) 1
    checkbutton .f.vert -text | -variable g(vert)
    set g(vert) 1
    foreach color {purple red orange yellow green blue white black} {
        radiobutton .f.b$color -width 1 -padx 0 -pady 0 -bg $color \
            -variable g(color) -value $color
        bind .f.b$color <3> [list .c config -bg $color]
    }
    set g(color) black
    button .f.c -text C -width 3 -command {.c delete line}
    frame .f.f -bd 2 -relief raised
    label .f.f.lbl -text "Pen Size" -bd 0
    tk_optionMenu .f.f.w g(w) 1 3 5 7 9 20
    .f.f.w config -highlightthickness 0 -bd 0
    set g(w) 3
    eval pack [winfo children .f] -side left -fill y
    eval pack [winfo children .f.f] -side left -fill y
    symdoodle [canvas .c -height $size -width $size -bg $bg]
    .c create line -4000 0     4000 0    -fill $axiscolor
    .c create line 0     -4000 0    4000 -fill $axiscolor
    pack .f -side top -fill x
    pack .c -side top -fill both -expand 1

 }
 proc symdoodle w {
    bind $w <1>         {symdoodle'start %W %x %y}
    bind $w <B1-Motion> {symdoodle'move  %W %x %y}
    bind $w <3>         {%W delete current}
    bind $w <Configure> {symdoodle'center %W %h %w}
 }
 proc symdoodle'start {w x y} {
    global g
    set x [$w canvasx $x]
    set y [$w canvasy $y]
    readCheckbuttons
    set g(ids) {}
    foreach {xf yf} $g(todo) {
        set x1 [expr {$x*$xf}]
        set y1 [expr {$y*$yf}]
        lappend g(ids) [
           $w create line $x1 $y1 $x1 $y1 -fill $g(color) -tag line -width $g(w)
        ]
    }
 }
 proc symdoodle'move {w x y} {
    global g
    set x [$w canvasx $x]
    set y [$w canvasy $y]
    foreach {xf yf} $g(todo) id $g(ids) {
        set x1 [expr {$x*$xf}]
        set y1 [expr {$y*$yf}]
        eval $w coords $id [concat [$w coords $id] $x1 $y1]
    }
 }
 proc readCheckbuttons {} {
    global g
    set g(todo) [list 1 1]
    if {$g(hori)} {lappend g(todo) 1 -1}
    if {$g(vert)} {
        foreach {xf yf} $g(todo) {
            lappend g(todo) [expr {-$xf}] $yf
        }
    }
 }
 proc symdoodle'center {W h w} {
    set h [expr {$h / 2.0}]
    set w [expr {$w / 2.0}]
    $W config -scrollregion [list -$w -$h $w $h]
 }

 main
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[Arts and crafts of Tcl-Tk programming] - [Category Games]
- [Category Graphics] - [Category Application]