added Box for easy layout

@@ -28,6 +28,7 @@ class TikZ (object) :
                  "arrayscope": {},
                  "structscope": {},
                  "heapscope": {},
+                 "boxscope": {},
                  "valueread" : {"very thick": None,
                                 "draw": "blue!50!black",
                                 "fill": "blue!20"},
@@ -44,6 +45,7 @@ class TikZ (object) :
                  "heap": {"grow": "left",
                           "distance": "15mm"},
                  "group": {"opacity": 0,
+                           "draw": "yellow",
                            "very thick": None,
                            "inner sep": "0pt",
                            "outer sep": "0pt"},
@@ -93,8 +95,8 @@ class CAniTikZ (CAni) :
           {head}{code}{tail}
         \end{{tikzpicture}}
         """).format(opt=opt,
-                    head=(head + "\n") if head else "",
-                    tail=("\n" + tail) if tail else "",
+                    head=(head.strip("\n") + "\n") if head else "",
+                    tail=("\n" + tail.strip("\n")) if tail else "",
                     code="\n  ".join(self.tikz(**tikz).splitlines()))
 
 class Pointer (CAniTikZ) :
@@ -379,8 +381,7 @@ class Struct (Aggregate) :
             self.__dict__[name] = value
 
 class Heap (CAniTikZ) :
-    _defaults = {"group": {"opacity": 0,
-                           "inner sep": "5mm"}}
+    _defaults = {"group": {"inner sep": "5mm"}}
     def __init__ (self, **tikz) :
         super().__init__(tikz)
         self._alloc = {}
@@ -418,3 +419,51 @@ class Heap (CAniTikZ) :
         children = " ".join(f"({nid})" for nid in fit)
         yield fr"  \node[{opt.group},fit={children}] ({self.nodeid}) {{}};"
         yield r"\end{scope}"
+
+_flip = {"right": "below",
+         "below": "right",
+         "left": "above",
+         "above": "left"}
+
+class Box (CAniTikZ) :
+    def __init__ (self, *content, grow="right", distance="15mm", parent=None, **tikz) :
+        super().__init__(tikz)
+        self._grow = grow
+        self._dist = distance
+        self._parent = parent
+        self._data = tuple(self._init(content))
+    def _init (self, content) :
+        for obj in content :
+            if isinstance(obj, CAniTikZ) :
+                yield obj
+            elif isinstance(obj, list) :
+                yield self.__class__(*obj,
+                                     grow=(_flip.get(self._grow) if self._parent is None
+                                           else self._parent._grow),
+                                     distance=self._dist,
+                                     parent=self,
+                                     **self._o.dict())
+            else :
+                raise ValueError("invalid %s content: %r"
+                                 % (self.__class__.__name__, obj))
+    def tikz (self, **tikz) :
+        opt = TikZ(tikz) + self._o
+        classname = self.__class__.__name__
+        nodeid = self.nodeid
+        return (f"%% {classname} {nodeid} ({self._grow})\n"
+                + "\n".join(self._tikz(opt))
+                + f"\n%% /{classname} {nodeid}")
+    def _tikz (self, opt) :
+        fit = []
+        yield fr"\begin{{scope}}[{opt.boxscope}]"
+        for data in self._data :
+            fit.append(data.nodeid)
+            yield fr"  %% box {self.nodeid} content"
+            for line in data.tikz(**opt.dict()).splitlines() :
+                yield "    " + line
+            opt = opt + {"pos": {self._grow:
+                                 "{dist} of {prev}".format(dist=self._dist,
+                                                           prev=(data@None).nodeid)}}
+        children = " ".join(f"({nid})" for nid in fit)
+        yield fr"  \node[{opt.group},fit={children}] ({self.nodeid}) {{}};"
+        yield r"\end{scope}"

@@ -6,11 +6,10 @@ mp4: qs-partition.mp4 qs-main.mp4 stack-push.mp4
 	rm -f out.*
 	PYTHONPATH=..:$$PYTHONPATH python3 $<
 	pdflatex tpl
-	pdflatex tpl
 	mv -f tpl.pdf $@
 
 %.gif: %.pdf
-	rm -rf _gif
+	rm -rf _gif $@
 	mkdir _gif
 	gs -dSAFER -DBATCH -dNOPAUSE -sDEVICE=png16m -r400 -sOutputFile=_gif/%03d.png $<
 	mogrify -resize 800x600 -format gif _gif/*.png
@@ -18,7 +17,7 @@ mp4: qs-partition.mp4 qs-main.mp4 stack-push.mp4
 	rm -rf _gif
 
 %.mp4: %.pdf
-	rm -rf _mp4
+	rm -rf _mp4 $@
 	mkdir _mp4
 	gs -dSAFER -DBATCH -dNOPAUSE -sDEVICE=png16m -r400 -sOutputFile=_mp4/%03d.png $<
 	ffmpeg -r 1 -s 1024x768 -i _mp4/%03d.png -vcodec libx264 -crf 25 -pix_fmt yuv420p $@

-from codanim.data import Array, Heap
+from codanim.data import Array, Box
 from codanim.flow import FUNC, BLOCK, ENV, WS, XDECL, DECL, PY, EXPR, STMT, WHILE, IF
 
 ##
@@ -87,19 +87,6 @@ sort = FUNC(BLOCK(ENV("t", array),
                         src="while ({cond}) {{\n{body}  }}\n")),
             src="void sort (Tab t) {{{body}}}")
 
-# let's play with Heap to layout the various data blocks
-# /!\ we must do this before simulating the code
-ha = Heap()
-ha.new(array)
-hs = Heap(heap={"grow": "right",
-                "distance": "0pt"})
-hs.new(first)
-hs.new(last)
-h = Heap(heap={"grow": "right",
-               "distance": "5mm"})
-h.new(ha)
-h.new(hs)
-
 # run code and save its animation
 sort.IP += 1
 sort()
@@ -107,5 +94,7 @@ with open("out.code", "w") as out :
     out.write(sort.tex())
 
 # save data animation
+b = Box(Box(array), Box(first, last, distance="0pt"))
 with open("out.tikz", "w") as out :
-    out.write(h.tex(tikzpicture={"scale": .55}))
+    out.write(b.tex(tikzpicture={"scale": .55},
+                    tail=r"\node at (-2,1) {};"))

-from codanim.data import Array, Struct, Value, Heap
+from codanim.data import Array, Struct, Value, Box
 from codanim.flow import FUNC, BLOCK, ENV, WS, DECL, WHILE, EXPR, DO, STMT, RETURN, IF
 
 a = Array([3, 13, 5, 0, 7, 11, 4, 9, 14, 2, 10, 1, 12, 8, 6],
           index=["a", "b"])
 t = Struct({"len": Value(15), "val": a.ptr()})
 
-h = Heap()
-h.new(a)
-h.new(t)
-
 partition = FUNC(BLOCK(ENV("t", t),
                        WS("  "),
                        DECL("pivot", EXPR("t.val[(t.len-1)//2]",
@@ -55,5 +51,7 @@ with open("out.code", "w") as out :
     out.write(partition.tex())
 
 # save data animation
+b = Box(a, t, grow="left")
 with open("out.tikz", "w") as out :
-    out.write(h.tex(tikzpicture={"scale": .6}))
+    out.write(b.tex(tikzpicture={"scale": .6},
+                    tail=r"\node at (0,-2) {};"))

-from codanim.data import Heap, Struct, Value
+from codanim.data import Heap, Struct, Value, Box
 from codanim.flow import FUNC, BLOCK, ENV, WS, DECL, EXPR, STMT
 
 heap = Heap()
@@ -8,15 +8,6 @@ stack = heap.new(Struct({"val": Value(2), "next": stack}))
 s = Value(stack, nodeid="s")
 t = Value(None, nodeid="t", value={"xshift": "-25mm"})
 
-v = Heap(heap={"grow": "above",
-               "separation": "0pt"})
-h = Heap(heap={"grow": "right"},
-         )
-h.new(t)
-h.new(s)
-v.new(heap)
-v.new(h)
-
 push = FUNC(BLOCK(ENV("s", s),
                   ENV("u", Value(3)),
                   ENV("top", t),
@@ -43,8 +34,9 @@ with open("out.code", "w") as out :
     out.write(push.tex())
 
 # save data and animation
+b = Box(heap, Box(t, s, grow="right"), grow="above")
 with open("out.tikz", "w") as out :
-    out.write(v.tex(tail=r"""
+    out.write(b.tex(tail=r"""
     \node[above] at (s.north) {\texttt{s}};
     \node[above] at (t.north) {\texttt{top}};
     """))