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casacore::TiledShape Class Reference

Define the shape and tile shape. More...

#include <TiledShape.h>

Public Member Functions

 TiledShape ()
 Default constructor has empty shape and tile shape. More...
 TiledShape (const IPosition &shape)
 Use the given shape. More...
 TiledShape (const IPosition &shape, const IPosition &tileShape)
 Use the given shape and tile shape. More...
 TiledShape (const TiledShape &that)
 Copy constructor (copy semantics). More...
 ~TiledShape ()
TiledShapeoperator= (const TiledShape &that)
 Assignment (copy semantics). More...
Bool isTileShapeDefined () const
 Is the tile shape defined? More...
const IPositionshape () const
 Return the shape. More...
IPosition tileShape (uInt nrPixelsPerTile=32768, Double tolerance=0.5) const
 Return the tile shape. More...
IPosition defaultTileShape (uInt nrPixelsPerTile, Double tolerance) const
 Derive the default tile shape from the shape for the given number of pixels per tile. More...
IPosition defaultTileShape (uInt nrPixelsPerTile, const Vector< Double > &tolerance, const Vector< Double > &weight) const

Private Attributes

IPosition itsShape
IPosition itsTileShape
Bool itsTileDefined

Detailed Description

Define the shape and tile shape.

Intended use:

Public interface

Review Status

Reviewed By:
Peter Barnes
Date Reviewed:
Test programs:



TiledShape defines the shape and tile shape of a tiled array.


TiledShape is a class defining the shape and optionally the tile shape of a lattice. It is used in the constructors of PagedArray and PagedImage.

In principle it serves as a place holder for the lattice shape and tile shape. The functions shape and tileShape can be used to retrieve the shapes. However, when the tile shape is not given, the function tileShape calculates a default tile shape using the given maximum tile size in pixel elements. The default tile shape is calculated in such a way that the sizes of its axes are proportional to the sizes of the lattice axes. Per axis it is tried as much as possible to fit an integral number of tiles in the lattice.
In this way getting the tile shape is completely transparent.


// Do not explicitly define a tile shape.
// This results in a default tile shape (of 32,32,32).
TiledShape shape(IPosition(3,128,128,128));
cout << shape.shape() << ' ' << shape.tileShape() << endl;
// Use with an explicitly given tile shape.
TiledShape shape(IPosition(3,128,128,128), IPosition(3,64,32,8));
cout << shape.shape() << ' ' << shape.tileShape() << endl;


Classes PagedArray and PagedImage contained several duplicated constructors to be able to pass a tile shape. This class makes it possible to have only one constructor instead of two. Furthermore it contains the logic to check if the shapes are conforming and the logic to calculate a default tile shape.

Definition at line 99 of file TiledShape.h.

Constructor & Destructor Documentation

casacore::TiledShape::TiledShape ( )

Default constructor has empty shape and tile shape.

casacore::TiledShape::TiledShape ( const IPosition shape)

Use the given shape.

No tile shape is given, so function tileShape will calculate it using the size of a tile.

casacore::TiledShape::TiledShape ( const IPosition shape,
const IPosition tileShape 

Use the given shape and tile shape.

Both shapes must be conforming (i.e. have same number of elements).

casacore::TiledShape::TiledShape ( const TiledShape that)

Copy constructor (copy semantics).

casacore::TiledShape::~TiledShape ( )

Member Function Documentation

IPosition casacore::TiledShape::defaultTileShape ( uInt  nrPixelsPerTile,
Double  tolerance 
) const

Derive the default tile shape from the shape for the given number of pixels per tile.

It is tried to get the same number of tiles for each dimension. When a weight vector is given, the number of tiles for a dimension is proportional to the weight.
After the initial guess it tries to optimize it by trying to waste as little space as possible, while trying to keep as close as possible to the initial guess. The given tolerance (possibly per axis) gives the minimum and maximum possible length of a tile axis (minimum = initial_guess*tolerance; maximum = initial_guess/tolerance). The heuristic is such that a tile axis length dividing the cube length exactly is always favoured. The test program tTiledShape can be used to see how the algorithm works out for a given shape and tile size.

Referenced by tileShape().

IPosition casacore::TiledShape::defaultTileShape ( uInt  nrPixelsPerTile,
const Vector< Double > &  tolerance,
const Vector< Double > &  weight 
) const
Bool casacore::TiledShape::isTileShapeDefined ( ) const

Is the tile shape defined?

Definition at line 164 of file TiledShape.h.

References itsTileDefined.

TiledShape& casacore::TiledShape::operator= ( const TiledShape that)

Assignment (copy semantics).

const IPosition & casacore::TiledShape::shape ( ) const

Return the shape.

Definition at line 168 of file TiledShape.h.

References itsShape.

IPosition casacore::TiledShape::tileShape ( uInt  nrPixelsPerTile = 32768,
Double  tolerance = 0.5 
) const

Return the tile shape.

When the tile shape is undefined, the default tile shape will be calculated using the given tile size and tolerance.
The tolerance is used to determine the boundaries where it is tried to fit an integral number of tiles.

Definition at line 172 of file TiledShape.h.

References defaultTileShape(), itsTileDefined, and itsTileShape.

Member Data Documentation

IPosition casacore::TiledShape::itsShape

Definition at line 158 of file TiledShape.h.

Referenced by shape().

Bool casacore::TiledShape::itsTileDefined

Definition at line 160 of file TiledShape.h.

Referenced by isTileShapeDefined(), and tileShape().

IPosition casacore::TiledShape::itsTileShape

Definition at line 159 of file TiledShape.h.

Referenced by tileShape().

The documentation for this class was generated from the following file: