[vtkusers] vtkImageIterator: seg fault fixed !

[Mathieu Malaterre]

Ken,
	As you seems to be the one who wrote this class, you'll be the one I'll 
blame ;)

	I had some problems with vtkImageIterator within the past few days. But 
after modifying the NextSpan() method everything went ok.
Here is my new NextSpan:

template <class DType>
void vtkImageIterator<DType>::NextSpan()
{
   this->Pointer += this->Increments[1];  //+= is faster !
   this->SpanEndPointer += this->Increments[1];
   if (this->Pointer >= this->SliceEndPointer)
     {
     this->Pointer += this->ContinuousIncrements[2]; //+= is faster !
     this->SpanEndPointer += this->ContinuousIncrements[2]; //important
     this->SliceEndPointer += this->Increments[2];
     }
}

---

Does this sound right ? You need to update SpanEndPointer each time you 
modify Pointer, right ?

In case this is right, could someone explain me why this has never shown 
up when used in a 'real' vtk pipeline (ie: used in vtkImageCast for 
example ?)

Finally, how does this class handle image of more than one scalar ?
Shouldn't we use:

this->SpanEndPointer =
this->Pointer + this->Increments[0]*(ext[1] - ext[0] + 
1)*id->GetNumberOfScalarComponents();
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

---

I hope this time someone from Kitware could put some light on it, thanks.

mathieu

-- 
Mathieu Malaterre
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