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;;;; canvas-language.lisp -- a drawing api for canvas instances
(in-package #:wheelwork)
(defvar *current-canvas* nil
"Bound by with-canvas")
(defvar *current-pen-color* '(0 0 0 255))
(defvar *current-pen-width* 1)
(defvar *current-pen-position* '(0 0))
(defvar *saved-state* nil)
(defmacro with-canvas-state (&body body)
`(let
((*saved-state*
(list *current-pen-width*
*current-pen-position*
*current-pen-color*)))
,@body))
(defmacro with-pen-color (list-or-fn &body body)
`(let ((*current-pen-color* nil))
(canvas-pen-color ,list-or-fn)
,@body))
(defmacro with-canvas (canvas &body body)
`(let ((*current-canvas* ,canvas)
(*current-pen-width* 1)
(*current-pen-position* (list 0 0))
(*current-pen-color* (list 0 0 0 255)))
(with-canvas-state
,@body)))
(defun restore-canvas-state ()
(destructuring-bind (pw pp pc) *saved-state*
(setf *current-pen-width* pw
*current-pen-position* pp
*current-pen-color* pc)))
(defun colfix (c)
(round (clamp 0 c 255)))
(defun canvas-pen-color (&optional newpen)
(setf *current-pen-color*
(etypecase newpen
(null nil)
((or symbol function)
(lambda (x y)
(mapcar #'colfix (funcall newpen x y))))
(list
(mapcar #'colfix newpen)))))
(defun canvas-pen-width (n)
(setf *current-pen-width* (round n)))
(defun can-fill-canvas-at-p (x y)
(with-slots (pixel-width pixel-height) *current-canvas*
(and (< -1 x pixel-width)
(< -1 y pixel-height))))
(defun rel-to-current-pos (path)
(destructuring-bind (cx cy) *current-pen-position*
(loop for (x y) in path collect (list (+ cx x) (+ cy y)))))
(defun move-to (x y)
(setf *current-pen-position* (list x y)))
(defun move-rel (dx dy)
(setf *current-pen-position*
(mapcar #'+ *current-pen-position* (list dx dy))))
(defun apply-pen-at (x y)
(let ((w
(max 0 (floor (* 0.5 *current-pen-width*)))))
(destructuring-bind
(cr cg cb ca)
(etypecase *current-pen-color*
(null (list 0 0 0 255))
(list *current-pen-color*)
(function (funcall *current-pen-color* x y)))
(with-grid-rect (rx ry) ((- x w) (- y w) (+ x w) (+ y w))
(when (can-fill-canvas-at-p rx ry)
(with-pixel (r g b a) (pixel *current-canvas* rx ry)
(setf r cr g cg b cb a ca)))))))
(defun stroke-to (ex ey)
(destructuring-bind (sx sy) *current-pen-position*
(with-grid-line (x y) (sx sy) (ex ey)
(apply-pen-at x y)))
(setf *current-pen-position* (list ex ey)))
(defun stroke-rel (dx dy)
(apply #'stroke-to (mapcar #'+ *current-pen-position* (list dx dy))))
(defun stroke-path (path)
(with-grid-path (x y) (path) (apply-pen-at x y))
(setf *current-pen-position* (copy-list (first (last path)))))
(defun stroke-rel-path (path)
(stroke-path
(cons *current-pen-position*
(rel-to-current-pos path))))
(defun fill-path (path)
(let ((*current-pen-width* 1))
(with-grid-path (x y) (path :interiorp t)
(apply-pen-at x y))))
(defun fill-rel-path (path)
(fill-path
(cons *current-pen-position*
(rel-to-current-pos path))))
(defun stroke-rect (left bottom right top)
(stroke-path (list (list left bottom)
(list left top)
(list right top)
(list right bottom)
(list left bottom))))
(defun stroke-rel-rect (dx dy)
(destructuring-bind (sx sy) *current-pen-position*
(let ((left
(if (plusp dx) sx (+ sx dx)))
(right
(if (plusp dx) (+ sx dx) sx))
(bottom
(if (plusp dy) sy (+ sy dy)))
(top
(if (plusp dy) (+ sy dy) sy)))
(stroke-rect left bottom right top))))
(defun fill-rect (left bottom right top)
(let ((*current-pen-width* 1))
(with-grid-rect (x y) (left bottom right top)
(apply-pen-at x y)))
(setf *current-pen-position* (list left bottom)))
(defun fill-rel-rect (dx dy)
(destructuring-bind (sx sy) *current-pen-position*
(let ((left
(if (plusp dx) sx (+ sx dx)))
(right
(if (plusp dx) (+ sx dx) sx))
(bottom
(if (plusp dy) sy (+ sy dy)))
(top
(if (plusp dy) (+ sy dy) sy)))
(fill-rect left bottom right top))))
(defun stroke-bezier (control-pts &optional (curve-samples 10))
(let (path)
(with-grid-bezier (x y) (control-pts :count curve-samples)
(push (list x y) path))
(stroke-path (reverse path))))
(defun stroke-rel-bezier (rel-control-points &optional (curve-samples 10))
(stroke-bezier (cons *current-pen-position*
(rel-to-current-pos rel-control-points))
curve-samples))
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