Tips for creating NiChannel[L1 ] style forum software implemented in TclHttpd.
Generating captcha images (http://www.captcha.net ) for anti-spam purposes.
Using ImageMagick convert routine, where the captcha code is RKS876:
convert captcha.png -gravity center -pointsize 24 -fill white -annotate 0 'RKS876' -swirl 90 captcha-done.png
Using a random sequence of numbers and letters for the captcha code.
proc randomCode {size} {
set data [list 1 2 3 4 5 6 7 8 9 0 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z]
set code [list]
for {set n 0} {$n < $size} {incr n} {
lappend code [lindex $data [expr {int(rand()*[llength $data])}]]
}
return [join $code ""]
}Generating the captcha image:
proc genCaptcha {code} {
set target captcha-$code-[clock seconds].png
set key $code
set stamp [clock seconds]
exec convert captcha.png -gravity center -pointsize 24 -fill white -annotate 0 '$code' -swirl 90 png:$target
mk::row append db.captchas key $key stamp $stamp
return $target
}I could store the image inside of a metakit database, but I'm uncertain how to use that in a tml page.
mk::file open db data.dat
mk::view layout db.captchas {key stamp data:B}
mk::row append db.captchas key $key stamp $stamp data [exec convert captcha.png -gravity center -pointsize 24 -fill white -annotate 0 '$code' -swirl 90 png:-]CJL added: The source image ('captcha.png') doesn't need to exist as a file, e.g.:
exec convert -size 120x60 xc:black -gravity center -pointsize 24 -fill white -annotate 0 '$code' -swirl 90 png:$target