transform.axisBounds allows the bounds for multiple axes to be

calculated in one call.

fsl/fslview/displaycontext.py

@@ -271,6 +271,21 @@ class ImageDisplay(props.SyncableHasProperties):
                       'imageType'])
 
         
+    def getDisplayBounds(self):
+        """Calculates and returns the min/max values of a 3D bounding box,
+        in the display coordinate system, which is big enough to contain
+        the image associated with this :class:`ImageDisplay` instance.
+
+        The coordinate system in which the bounding box is defined is
+        determined by the current value of the :attr:`transform` property.
+
+        A tuple containing two values is returned, with the first value
+        a sequence of three low bounds, and the second value a sequence
+        of three high bounds.
+        """
+        return transform.axisBounds(self.image.shape[:3], self.voxToDisplayMat)
+    
+        
     def _transformChanged(self, *a):
         """Called when the :attr:`transform` property is changed.
 
@@ -615,14 +630,12 @@ class DisplayContext(props.SyncableHasProperties):
         for img in self._imageList.images:
 
             display = self._imageDisplays[img]
-            xform   = display.voxToDisplayMat
+            lo, hi  = display.getDisplayBounds()
 
             for ax in range(3):
 
-                lo, hi = transform.axisBounds(img.shape[:3], xform, ax)
-
-                if lo < minBounds[ax]: minBounds[ax] = lo
-                if hi > maxBounds[ax]: maxBounds[ax] = hi
+                if lo[ax] < minBounds[ax]: minBounds[ax] = lo[ax]
+                if hi[ax] > maxBounds[ax]: maxBounds[ax] = hi[ax]
 
         self.bounds[:] = [minBounds[0], maxBounds[0],
                           minBounds[1], maxBounds[1],

fsl/utils/transform.py

@@ -23,8 +23,18 @@ def concat(x1, x2):
     return np.dot(x1, x2)
 
 
-def axisBounds(shape, xform, axis):
-    """Returns the (lo, hi) bounds of the specified axis."""
+def axisBounds(shape, xform, axes=None):
+    """Returns the (lo, hi) bounds of the specified axis/axes."""
+
+    scalar = False
+
+    if axes is None:
+        axes = [0, 1, 2]
+        
+    elif not isinstance(axes, collections.Iterable):
+        scalar = True
+        axes   = [axes]
+    
     x, y, z = shape[:3]
 
     x -= 0.5
@@ -44,10 +54,11 @@ def axisBounds(shape, xform, axis):
 
     tx = transform(points, xform)
 
-    lo = tx[:, axis].min()
-    hi = tx[:, axis].max()
+    lo = tx[:, axes].min(axis=0)
+    hi = tx[:, axes].max(axis=0)
 
-    return (lo, hi)
+    if scalar: return (lo[0], hi[0])
+    else:      return (lo,    hi)
 
 
 def axisLength(shape, xform, axis):