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Allow setting IndexToPhysicalMatrix in vtkImageData

Andras Lasso requested to merge lassoan/vtk:set-image-geometry-by-4x4-matrix into master

To set image geometry (origin, spacing, directions) developers had to call 3 methods. This was:

  • inconvenient: most imaging software stores image geometry in a 4x4 homogeneous matrix and need to disassemble the information to use the 3 methods
  • inefficient: Modified event is invoked 3 times, so if there are observers that react to data change they are triggered 3x for a single change
  • may lead to temporary inconsistencies: while setting the geometry, Modified event is called twice while the image data has still incorrect geometry, neither the previous nor the new one, but a mix of the two.

To resolve this, two new methods are added to vtkImageData:

void DeepCopyIndexToPhysicalMatrix(vtkMatrix4x4* source);
void DeepCopyPhysicalToIndexMatrix(vtkMatrix4x4* source);

"DeepCopy" is used instead of "Set" in the method name to make it clear that the source matrix is not stored as object in the image data but its content is used for updating the origin, spacing, and direction matrix.

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