chickadee » s9fes-char-graphics » canvas-paste

canvas-paste CANVAS SOURCE-CANVAS #!optional X Y TRANSprocedure

Paste the SOURCE-CANVAS into CANVAS at lower-left X Y, clipping the SOURCE-CANVAS to fit if necessary.

X
integer : x, default is 0
Y
integer : y, default is 0
TRANS
(char char fixnum fixnum -> char) ; result char is function of source char+index & target+index.

The operation is performed, in the absence of a transformation function, as if (lambda (t s i j) s) was specified, i.e. overwrite.

Example of transform as used by the image shape:

(define ((compositor-alpha #!optional
                           (c (current-plotter-bkgd-char)))
          tc sc i j)
  (if (char=? c sc) tc sc) )