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;;;; 14-canvas-paint.lisp
(defpackage #:ww.examples/14
(:use #:cl)
(:export #:start))
(in-package #:ww.examples/14)
(defclass pixel-whomp (ww:application)
((canvas-size :initarg :size :initform 800 :reader canvas-size)))
(defclass pwcanvas (ww:canvas)
((pen-down-pos :accessor pen-down-pos :initform nil)
(mode :initform :draw :accessor mode)
(pen-width :initform 1 :accessor pen-width)))
(defun scale-pos-to-canvas (can ex ey)
(let
((scale (ww::scale-x can))
(x (ww:x can))
(y (ww:y can)))
(values (/ (- ex x) scale)
(/ (- ey y) scale))))
(defun set-pen-position (can ex ey)
"x and y are as received from mouse events. adjust the pen position
to account for scale, or set to nil of x and y are curren toff the
canvas"
(let
((pos
(or (pen-down-pos can)
(list 0 0))))
(multiple-value-bind (nx ny) (scale-pos-to-canvas can ex ey)
(setf (car pos) nx
(cadr pos) ny
(pen-down-pos can) pos))
pos))
(defun shift-mod-p (mods)
(or (member :rshift mods)
(member :lshift mods)))
(ww::defhandler keyboard-commands
(ww::on-keydown (target scancode mods)
(case scancode
(:scancode-equals
(when (shift-mod-p mods)
(incf (pen-width target))))
(:scancode-minus
(setf (pen-width target)
(max 0 (1- (pen-width target))))))))
(ww::defhandler change-mode-start
(ww::on-keydown ()
(case scancode
((:scancode-lshift :scancode-rshift)
(setf (mode target) :drag)))))
(ww::defhandler change-mode-stop
(ww::on-keyup ()
(setf (mode target) :draw)))
(ww::defhandler zoom
(ww::on-mousewheel (u h v)
(multiple-value-bind
(ox oy)
(apply #'scale-pos-to-canvas u *last-mouse-pos*)
(ww:scale-by u (if (plusp v) 1.1 0.9))
(multiple-value-bind
(nx ny)
(apply #'scale-pos-to-canvas u *last-mouse-pos*)
(incf (ww:x u) (* (ww:scale-x u) (- nx ox)))
(incf (ww:y u) (* (ww:scale-x u) (- ny oy)))))))
(ww:defhandler canvas-mousebutton-down
(ww:on-mousedown (target x y clicks button winx winy)
(unless (pen-down-pos target)
(set-pen-position target x y))))
(ww::defhandler canvas-mousebutton-up
(ww::on-mouseup (target)
(when (eq :draw (mode target))
(ww::with-canvas target
(ww:with-pen (:width (pen-width target))
(apply 'ww:apply-pen-at (mapcar #'floor (pen-down-pos target))))
(ww:blit target)))
(setf (pen-down-pos target) nil)))
(defvar *last-draw-time* 0)
(defvar *draw-sample-pause* 40)
(setf *draw-sample-pause* 40)
(defun is-time-to-draw-p ()
(let ((ticks (sdl2:get-ticks)))
(when (<= (+ *last-draw-time* *draw-sample-pause*) ticks)
(setf *last-draw-time* ticks))))
(defun draw (canvas x y)
(when (is-time-to-draw-p)
(let ((old-pos (copy-seq (pen-down-pos canvas))))
(destructuring-bind (nx ny) (set-pen-position canvas x y)
(ww:with-canvas canvas
(ww:with-pen (:position old-pos :width (pen-width canvas))
(ww:stroke-to nx ny))))
(ww:blit canvas))))
(defun drag (canvas x y)
(multiple-value-bind (cx cy) (scale-pos-to-canvas canvas x y)
(destructuring-bind (px py) (pen-down-pos canvas)
(let ((tx (* (ww:scale-x canvas)
(- cx px)))
(ty (* (ww:scale-x canvas)
(- cy py))))
(incf (ww:x canvas) tx)
(incf (ww:y canvas) ty)))))
(defvar *last-mouse-pos* (list 0 0))
(ww::defhandler canvas-mouse-move
(ww::on-mousemotion (target x y)
(setf (car *last-mouse-pos*) x
(cadr *last-mouse-pos*) y)
(when (pen-down-pos target)
(ecase (mode target)
(:draw (draw target x y))
(:drag (drag target x y))))))
(defmethod initialize-instance :after ((ob pwcanvas) &key)
(ww:add-handler ob #'keyboard-commands)
(ww:add-handler ob #'change-mode-start)
(ww:add-handler ob #'change-mode-stop)
(ww:add-handler ob #'zoom)
(ww:add-handler ob #'canvas-mousebutton-up)
(ww:add-handler ob #'canvas-mousebutton-down)
(ww:add-handler ob #'canvas-mouse-move))
(defmethod ww:boot ((app pixel-whomp))
(let ((canvas
(make-instance 'pwcanvas
:pixel-width (canvas-size app)
:pixel-height (canvas-size app))))
(setf *last-draw-time* 0)
(ww:add-unit canvas)
(ww:refocus-on canvas))
(instructions))
(defun instructions ()
(format
t
"
INSTRUCTIONS
------------------------
Click and drag to draw.
Use +/- to increase/decrease the size of the pencil.
Use the mousewheel (or however you scroll) to zoom in/out.
Hold shift to click and drag.
"))
(defun start (&key (size 800) (window 800))
(ww:start
(make-instance
'pixel-whomp
:width window
:height window
:title "Not a Pixel Art Editor"
:size size)
:x 2350))
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