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;;;; canvas-language.lisp -- a drawing api for canvas instances
(in-package #:wheelwork)
(defvar *current-canvas* nil)
(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-current-pen-state ( &body body)
"Saves the current pen state (color width position) so that it can
be restored from using (restore-pen-state) from within the BODY.
After BODY executes the state is restored to whatever it was
before WITH-CURRENT-PEN-STATE was evaluated."
`(let
((*saved-state*
(list *current-pen-width*
*current-pen-position*
*current-pen-color*)))
,@body))
(defmacro with-pen ((&key position (color nil color-supplied-p) width) &body body)
"Like WITH-CURRENT-PEN-STATE, but lets you set the state of the pen
EXECUTION BODY. After BODY executes, the state is restored to
whatever it was before WITH-PEN-STATE was evaluated."
`(let ((*current-pen-position* ,(if position nil '*current-pen-position*))
(*current-pen-color* ,(if color-supplied-p nil '*current-pen-color*))
(*current-pen-width* ,(if width nil '*current-pen-width*)))
,(when position
`(move-to ,@position))
,(when color-supplied-p
`(canvas-pen-color ,color))
,(when width
`(canvas-pen-width ,width))
(with-current-pen-state
,@body)))
(defmacro with-pen-color (list-or-fn &body body)
"Temporarily bind pen color to the value of LIST-OR-FN and execute BODY."
`(let ((*current-pen-color* nil))
(canvas-pen-color ,list-or-fn)
,@body))
(defmacro with-canvas (canvas &body body)
"Perform drawing commands in BODY using the value of CANVAS as the
target of any drawing operations."
`(let ((*current-canvas* ,canvas)
(*current-pen-width* 1)
(*current-pen-position* (list 0 0))
(*current-pen-color* (list 0 0 0 255)))
(with-current-pen-state
,@body)))
(defun restore-pen ()
"Restore the state of the pan (width position color) as previously
saved by WITH-PEN-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)
"Set the pens color in the current context. NEWPEN, if supplied, can be one of:
NIL - set the color to black.
A list of four unsigned 8 bit integers that looks like (R G B A).
A function (or symbol naming a function) that accepts the
coordinates X Y of the pixel being drawn and returns a list as in
the above case.
All RGBA component values obtained from a pen (either from the
return of a functional pen or as members of a list value) are
clamped between 0 and 255."
(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))
(defun fill-bezier (control-pts &optional (curve-samples 10))
(let (path)
(with-grid-bezier (x y) (control-pts :count curve-samples)
(push (list x y) path))
(fill-path (reverse path))))
(defun fill-rel-bezier (rel-control-points &optional (curve-samples 10))
(fill-bezier (cons *current-pen-position*
(rel-to-current-pos rel-control-points))
curve-samples))
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