Make sure that the FigureCanvas and the View are deallocated.

Previously, the Py_INCREF ensured that the reference count of FigureCanvas
never reaches zero. The FigureCanvas was therefore never deallocated, and
the View remained in memory.
See bug #2889570 on bugzilla, reported by Nicholas Lederer.

svn path=/trunk/matplotlib/; revision=7918

Author: mdehoon

src/_macosx.m

@@ -340,7 +340,8 @@ @interface View : NSView
 - (void)dealloc;
 - (void)drawRect:(NSRect)rect;
 - (void)windowDidResize:(NSNotification*)notification;
-- (View*)initWithFrame:(NSRect)rect canvas:(PyObject*)fc;
+- (View*)initWithFrame:(NSRect)rect;
+- (void)setCanvas: (PyObject*)newCanvas;
 - (BOOL)windowShouldClose:(NSNotification*)notification;
 - (BOOL)isFlipped;
 - (void)mouseDown:(NSEvent*)event;
@@ -2896,10 +2897,22 @@ static void _data_provider_release(void* info, const void* data, size_t size)
     if(!PyArg_ParseTuple(args, "ii", &width, &height)) return -1;
 
     NSRect rect = NSMakeRect(0.0, 0.0, width, height);
-    self->view = [self->view initWithFrame: rect canvas: (PyObject*)self];
+    self->view = [self->view initWithFrame: rect];
+    [self->view setCanvas: (PyObject*)self];
     return 0;
 }
 
+static void
+FigureCanvas_dealloc(FigureCanvas* self)
+{
+    if (self->view)
+    {
+        [self->view setCanvas: NULL];
+        [self->view release];
+    }
+    self->ob_type->tp_free((PyObject*)self);
+}
+
 static PyObject*
 FigureCanvas_repr(FigureCanvas* self)
 {
@@ -3243,7 +3256,7 @@ static void _data_provider_release(void* info, const void* data, size_t size)
     "_macosx.FigureCanvas",    /*tp_name*/
     sizeof(FigureCanvas),      /*tp_basicsize*/
     0,                         /*tp_itemsize*/
-    0,                         /*tp_dealloc*/
+    (destructor)FigureCanvas_dealloc,     /*tp_dealloc*/
     0,                         /*tp_print*/
     0,                         /*tp_getattr*/
     0,                         /*tp_setattr*/
@@ -4483,27 +4496,25 @@ - (BOOL)isFlipped
     return NO;
 }
 
-- (View*)initWithFrame:(NSRect)rect canvas: (PyObject*)fc
+- (View*)initWithFrame:(NSRect)rect
 {
     self = [super initWithFrame: rect];
     rubberband = NSZeroRect;
-    if (canvas)
-    {
-        Py_DECREF(canvas);
-    }
-    canvas = fc;
-    Py_INCREF(canvas);
     return self;
 }
 
 - (void)dealloc
 {
     FigureCanvas* fc = (FigureCanvas*)canvas;
-    fc->view = NULL;
-    Py_DECREF(canvas);
+    if (fc) fc->view = NULL;
     [super dealloc];
 }
 
+- (void)setCanvas: (PyObject*)newCanvas
+{
+    canvas = newCanvas;
+}
+
 -(void)drawRect:(NSRect)rect
 {
     PyObject* result;