title: gimp script-fu: drawing a simple line
body: <p>I'm trying to draw a line using gimp scripting. In the following script: I create a new image 512x512 and a I try to draw a diagonal (0,0)->(512,512).
  But the image (tmp.xcf) remains transparent.</p>
  
  <p>What am i doing wrong ?</p>
  
  <pre><code>(define (drawdiagonal W H)
  (let* (
        (img 0)
         (bg 0)
         (points (cons-array 4 'double) )
        )
  (set! img (car (gimp-image-new  W H 0)))
  (gimp-image-undo-group-start img)
  (gimp-context-push)
  (set! bg (car (gimp-layer-new img  W H RGBA-IMAGE "background" 100 NORMAL-MODE)))
  (gimp-image-add-layer img bg 0)
  (gimp-drawable-set-visible bg TRUE)
  (gimp-image-set-active-layer img bg)
  (gimp-context-set-brush-size 10.0)
  (gimp-context-set-opacity 100)
  (gimp-context-set-paint-mode NORMAL-MODE)
  (gimp-context-set-foreground '(255 127 0))
  (gimp-selection-all img)
  
  (aset points 0 0)
  (aset points 1 0)
  (aset points 2 W)
  (aset points 3 H)
  (gimp-paintbrush-default  bg 4 points)
  
  (gimp-context-pop)
  (gimp-image-undo-group-end img)
  
  (gimp-xcf-save 1 img img "tmp.xcf"  "tmp.xcf")
  (display "DONE")
  )
  )
  
  (drawdiagonal 512 512) (gimp-quit 0)
  </code></pre>
  
  <p>usage:</p>
  
  <pre><code>cat test.scm | gimp -i  -b -
  </code></pre>