examples/12-canvas-drawing-language.lisp


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;;;; examples/13-canvas-drawing-language.lisp

(defpackage #:ww.examples/12
  (:use #:cl)
  (:export #:start))

(in-package :ww.examples/12)

(defclass canvas-lang-demo (ww:application) ())

(ww:defhandler quit
    (ww::on-keydown (app scancode)
      (when (eql :scancode-q scancode)
        (ww::stop))))

(ww:defhandler clear-and-draw
    (ww::on-perframe (canvas time)
      (ww::clear-canvas canvas :r 255 :g 255 :b 255)
      (draw-stuff canvas)
      (ww::blit canvas)))

(defun triangle-at (x y)
  (ww::move-to x y)
  (ww::canvas-pen-color 0 200 200 255)
  (ww::stroke-rel 150 0)
  (ww::canvas-pen-color 0 0 200 255)
  (ww::stroke-rel -50 100)
  (ww::canvas-pen-color 0 200 0 255)
  (ww::stroke-rel -100 -100))

(defun filled-triangle-at (x y)
  (ww::move-to x y)
  (ww::fill-rel-path
   '((100 100)
     (100 -100))))

(defun lower-the-bluer (x y)
  (list (* 256 (/ x 500))
        (* 256 (/ y 500))
        255
        255))

(defun plaid1 (x y)
  (list (mod (* x x) 256)
        (mod (* y y) 256)
        (mod (* x y) 256)
        255))

(defun draw-stuff (canvas)
  (ww::with-canvas canvas
    (ww::canvas-pen-color-function #'plaid1)
    (filled-triangle-at 250 200)
    (ww::canvas-pen-color-function  #'lower-the-bluer)
    (ww::canvas-pen-width 2)
    (ww::stroke-bezier
     '((0 0) (200 120) (50 350) (200 100) (300 400))
     1000)
        ()
    (ww::canvas-pen-color-function)
    (ww::canvas-pen-width 1)
    (dotimes (x 50)
      (when (evenp x)
        (triangle-at 30 (+ 250 x))))))

(defmethod ww:boot ((app canvas-lang-demo ))
  (let ((canvas
          (make-instance 'ww:canvas
                         :pixel-width 500
                         :pixel-height 500)))
    ;; stretch canvas over the whole app
    (setf (ww:width canvas) (ww::application-width app)
          (ww:height canvas) (ww::application-height app))

    ;; add it to the display tree
    (ww:add-unit app canvas)

    ;; handlers
    (ww:add-handler canvas #'clear-and-draw)
    (ww:add-handler app #'quit)
    (ww:add-handler canvas #'quit)))

(defun start (&optional (side 500))
  (ww::start
   (make-instance
    'canvas-lang-demo
    :fps 10
    :width side
    :height side
    :title "Canvas demo")))