[Paraview] Write a reader plugin

[Xunlei Wu]

Hi David and all,
I am writing a reader plugin for ParaView. A test program without the VTK wrapping approves that I can get all the header (metadata) and grid data correctly. However, when I following the examples posted in
http://www.vtk.org/Wiki/ParaView/Examples/Plugins/Reader
http://www.kitware.com/products/html/WritingAParaViewReaderPlug-in.html
and vtkStructuredGridReader.h/.cxx

I got confused. Shall I subclass vtkStructuredGridAlgorithm or vtkStructuredGridReader? What are the differences? With minor differences in the code, i.e. defining char* FileName, I have both scenarios built fine. 

Let's say, we are subclassing vtkStructuredGridAlgorithm for now on. After I populate values as the following

int vtkGRIB2Reader::RequestInformation(vtkInformation* vtkNotUsed(request), 								vtkInformationVector** vtkNotUsed(inputVector),							vtkInformationVector *outputVector)
{
	...
	vtkInformation* outInfo = outputVector->GetInformationObject(0);
	
	outInfo->Set(vtkStreamingDemandDrivenPipeline::WHOLE_EXTENT(),	ext, 6);
	outInfo->Set(vtkDataObject::SPACING(),	this->Spacing, 3);
	outInfo->Set(vtkDataObject::ORIGIN(), 	this->Origin, 3);	

	return 1;
}

In ParaView Object Inspector / Information widget, I did not see any update in all the fields except Statistics / Type: Structured (Curvilinear) Grid. Would you please help me? Did I populate outInof in the wrong place? Thanks a lot.

Best,
xunlei