5.7 Examples of Simple Drawing Effects
(defun cmd-rubberband () (let ((x1 0) ; x1, y1 represents the fix point (y1 0) (x2 0) ; x2,y2 represents the point that is changing (y2 0) (mouse-button-press nil) ;; press to select pivot (stream (get-frame-pane *application-frame* 'main))) (tracking-pointer (stream) (:pointer-button-press (event x y ) (setf x1 x y1 y x2 x y2 y) (draw-line* stream x1 y1 x2 y2 :ink +flipping-ink+) (setf mouse-button-press t)) (:pointer-motion (window x y) (when Mouse-button-press ;;erase (draw-line* stream x1 y1 x2 y2 :ink +flipping-ink+) ;; draw (draw-line* stream x1 y1 x y :ink +flipping-ink+) (setf x2 x y2 y))) (:pointer-button-release (event x y ) (cond ((eq mouse-button-press t) (return (list x1 y1 x2 y2))))))))
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