The PixelIterator class an iterator class that iteratos over all the pixels in an grid (or subsection of it) More...

#include <pixeliterator.h>

Inheritance diagram for Ilwis::PixelIterator:

Public Types
enum	Flow { fXYZ, fYXZ, fXZY, fYZX, fZXY, fZYX }

Public Member Functions
bool	isValid () const
	isValid tells if an iterator is in a valid state. More...

	PixelIterator ()
	The empty constructor for PixelIterator. More...

	PixelIterator (const IRasterCoverage &raster, const BoundingBox &box=BoundingBox())
	Constructs a PixelIterator from a raster and a bounding box. More...

	PixelIterator (const PixelIterator &iter)

	PixelIterator (PixelIterator &&iter)
	Copy constructor. More...

PixelIterator &	operator= (const PixelIterator &iter)

PixelIterator &	operator= (const PixelIterator &&iter)

PixelIterator &	operator++ ()
	Adds 1 to this PixelIterator the direction moved in the raster depends on the boundingbox in combination with the flow. More...

PixelIterator &	operator-- ()
	Substracts 1 from this PixelIterator the direction moved in the raster depends on the boundingbox in combination with the flow. More...

PixelIterator &	operator+= (int n)
	Adds n to this PixelIterator the direction moved in the raster depends on the boundingbox in combination with the flow. More...

PixelIterator &	operator-= (int n)
	Substracts n from this PixelIterator the direction moved in the raster depends on the boundingbox in combination with the flow. More...

double &	operator[] (quint32 index)
	Random acces operator. More...

QVariant	operator() (const QString &column, Coverage::AttributeType attType=Coverage::atCOVERAGE)

PixelIterator &	operator() (const Pixel &pix)
	Moves the PixelIterator to the given Pixel. More...

PixelIterator	operator++ (int)
	Adds 1 to this PixelIterator the direction moved in the raster depends on the boundingbox in combination with the flow. More...

PixelIterator	operator-- (int)
	Substracts 1 from this PixelIterator the direction moved in the raster depends on the boundingbox in combination with the flow. More...

PixelIterator &	operator[] (const Pixel &pix)
	Random acces operator. More...

bool	operator== (const PixelIterator &iter) const
	Checks if this PixelIterator has the same linearPosition as another PixelIterator. More...

bool	operator!= (const PixelIterator &iter) const
	Checks if this PixelIterator has a different linearPosition as another PixelIterator. More...

bool	operator< (const PixelIterator &iter) const
	Checks if this PixelIterator has a smaller linearPosition as another PixelIterator. More...

bool	operator<= (const PixelIterator &iter) const
	Checks if this PixelIterator has a smaller or equal linearPosition as another PixelIterator. More...

bool	operator> (const PixelIterator &iter) const
	Checks if this PixelIterator has a bigger linearPosition as another PixelIterator. More...

bool	operator>= (const PixelIterator &iter) const
	Checks if this PixelIterator has a bigger or equal linearPosition as another PixelIterator. More...

double &	operator* ()
	Query for a reference to the current value of the PixelIterator. More...

const double &	operator* () const
	Query for a reference to the current vallue of the PixelIterator. More...

double *	operator-> ()
	Query for the current value of the PixelIterator. More...

PixelIterator	end () const
	Returns the end position of this PixelIterator, this is 1 past the actual lastblock of the boundingbox. More...

void	setFlow (Flow flw)
	Changes the flow of this PixelIterator. More...

bool	contains (const Pixel &pix)
	Checks if a certain pixel is inside this PixelIterator. More...

bool	xchanged () const
	Checks if the x coordinate has changed in the last step taken all movement and/or position change commands automatically set the x y and z flags when appropiate. More...

bool	ychanged () const
	Checks if the y coordinate has changed in the last step taken all movement and/or position change commands automatically set the x y and z flags when appropiate. More...

bool	zchanged () const
	Checks if the z coordinate has changed in the last step taken all movement and/or position change commands automatically set the x y and z flags when appropiate. More...

bool	isAtEnd () const
	Checks if this PixelIterator is at its endpoint. More...

Pixel	position () const
	Query for the current non lineair position of this PixelIterator. More...

const BoundingBox &	box () const
	Query for the bounding box of this PixelIterator the bounding box decides which part of the raster this PixelIterator should walk, thus its size can never be bigger than the rastersize. More...

quint32	linearPosition () const
	Query for the linearPosition of this PixelIterator. More...

int	operator- (const PixelIterator &iter2)
	Substracts another pixeliterator fomr this PixelIterator the direction moved in the raster depends on the boundingbox in combination with the flow this might have unexpected results if both iterators have a different flow. More...

PixelIterator	operator+ (int n)
	Adds n to this PixelIterator and returns it the direction moved in the raster depends on the boundingbox in combination with the flow. More...

void	setTranquilizer (const SPTranquilizer &trq)
	ProgressMeter. More...

Protected Member Functions
	PixelIterator (quint64 endpos)

void	init ()

void	initPosition ()

void	copy (const PixelIterator &iter)

bool	move (int n)

Protected Attributes
IRasterCoverage	_raster

Grid *	_grid = 0

BoundingBox	_box

qint32	_x = 0

qint32	_y = 0

qint32	_z = 0

qint32	_localOffset = 0

qint32	_currentBlock = 0

Flow	_flow

bool	_isValid

qint32	_endx

qint32	_endy

qint32	_endz

quint64	_linearposition

quint64	_endposition

bool	_xChanged =false

bool	_yChanged = false

bool	_zChanged = false

SPTranquilizer	_trq

Detailed Description

The PixelIterator class an iterator class that iteratos over all the pixels in an grid (or subsection of it)

The pixeliterator is the main access mechanism (together with the blockiterator) to pixels in 2D or 3D gridcoverages. Basically it sees the pixels as one long linear space and moves over it. The movement (flow) can have several directions which resembles directions in the 'real' world. In the default case it moves first over the x dirdction, than the y and finally the z direction. But one could just as well first move in the z direction than x, than y. Internally these movements are translated to offsets in the linear space. The pixel iterator obeys the normal rules for iterators in the STL and thus can be combined with the algorithms in this library.

Here are basically two flavors of the pixeliterator : the pixel iterator itself and the blockiterator. The pixeliterator moves over single pixels, the blockiterator moves over an [n x m x p] size block (some algorithms need this). So how does this work? Suppose you want to count all the pixels in a raster-coverage with a value greater than 100. First the crude way (there are other more elegant ways to do this)

1 PixelIterator iterator(someraster); 2 PixelIterator endlocation = end(someraster); 3 int count = 0; 4 while ( iterator != endlocation){ 5 if (*iterator > 100) 6 ++count; 7 }

In line 1 a new pixeliterator is created. The simplest constructor only needs the raster-coverage as parameter. In line 2 we create the end iterator. By definition (in c++) the end iterator is located at one container cell beyond the last valid location within the container. With the pixel iterator this means +1 layer beyond the last pixel in the last layer. The end method in line 2 is a convenience method that generates an iterator that satisfies this. Line 4 is end-condition for the traversing the raster-coverage. In line 5 the data of a pixel is accessed by using the ‘*’ operator on the iterator. This operator returns a reference to a double (64-bit) numerical value that is the value of the pixels.

A more modern way (using lambda’s)

1 int count = 0; 2 std::for_each (begin(someraster), end(someraster) , [&](double& v)){ 3 if v > 100) ++count; 4 });

It becomes more interesting when we are combining iterators. Suppose in the example above we want to create a new raster-coverage that only contains the pixels with a numerical value greater than 100

1 PixelIterator iterInput(someraster); 2 std::for_each(begin(outputRaster), end(outputRaster) , [&](double& v)){ 3 if v > 100) v = *iterInput; 4 ++iterInput; 5 });

In line 1 we define a iterator for the input, the output operator(invisible) is hidden behind convenience begin() and end() methods. Remember that the ‘*’operator gives a reference to the value of (in this case output) raster-coverage. ‘for_each’ uses this operator to give access to values of the container and exposes this through the double& (so also a reference). We only need to set this value to actually change values in the output raster-coverage. That’s all. Assuming that input and output have the same geometry. The other interesting part is that the pixeliterator integrates with the existing STL library of C++. Giving access to a large number of existing basic algorithms. Suppose You need to copy all of the values of a raster-coverage to a vector(array) and do some operation on it. Due to memory limitations this might not always be a good idea, but there are certainly enough use cases were this is useful.

std::vector<double> data(someraster.size().totalSize()); std::copy(begin(someraster), end(someraster), data.begin());

or swapping of the pixels of two raster-coverages

swap_ranges(begin(someraster),end(someraster), begin(otherraster));

Note that because the iterator ‘automatically’ moves in layer-index direction all algorithms also work on stacks of raster layers.

Member Enumeration Documentation

enum Ilwis::PixelIterator::Flow

The possible flows, not all are implemented (yet).
atm only xyz works

Constructor & Destructor Documentation

PixelIterator::PixelIterator ( )

The empty constructor for PixelIterator.

This constructor creates an empty PixelIterator

PixelIterator::PixelIterator	(	const IRasterCoverage &	raster,
		const BoundingBox &	box = `BoundingBox()`
	)

Constructs a PixelIterator from a raster and a bounding box.

Constructs a PixelIterator from the raster and the bounding box
The bounding box is the area within the raster which should be walked by the PixelIterator
If one of the parameters was invalid the PixelIterator will also be invalid

Parameters

raster	The raster from which this PixelIterator should be created
box	The bounding box which desides what part of the raster should be walked

PixelIterator::PixelIterator ( const PixelIterator & iter )

Copy's all the values from the existing PixelIterator onto this one

Parameters

iter	The iterator whose values should be duplicated

PixelIterator::PixelIterator ( PixelIterator && iter )

Copy constructor.

Parameters

iter	PixelIterator that must be copied

Member Function Documentation

const BoundingBox & PixelIterator::box ( ) const

Query for the bounding box of this PixelIterator the bounding box decides which part of the raster this PixelIterator should walk, thus its size can never be bigger than the rastersize.

Returns: the bounding box of this PixelIterator

bool PixelIterator::contains ( const Pixel & pix )

Checks if a certain pixel is inside this PixelIterator.

Parameters

pix	the pixel to be checked

Returns: true when the pixel is in this PixelIterator

PixelIterator PixelIterator::end ( ) const

Returns the end position of this PixelIterator, this is 1 past the actual lastblock of the boundingbox.

Returns: the endvalue of the lineairposition

bool Ilwis::PixelIterator::isAtEnd ( ) const

inline

Checks if this PixelIterator is at its endpoint.

Returns: true if it is at the end

bool Ilwis::PixelIterator::isValid ( ) const

inline

isValid tells if an iterator is in a valid state.

An iterator is valid if bounding box and grid are a valid combination.

Returns: true if the bounding box fits in the grid.

quint32 PixelIterator::linearPosition ( ) const

Query for the linearPosition of this PixelIterator.

Returns: the lineairposition

bool PixelIterator::operator!= ( const PixelIterator & iter ) const

Checks if this PixelIterator has a different linearPosition as another PixelIterator.

Parameters

iter	another PixelIterator

Returns: true when linearPosition is not equal

PixelIterator& Ilwis::PixelIterator::operator() ( const Pixel & pix )

inline

Moves the PixelIterator to the given Pixel.

Moves the PixelIterator to the given Pixel, also adjusts the lineairposition (index) of this iterator
the voxel should have all three coordinates defined.
invalid voxel will cause this iterator to become invalid.

Parameters

vox	the Pixel to move to

Returns: this at the given Pixel

double& Ilwis::PixelIterator::operator* ( )

inline

Query for a reference to the current value of the PixelIterator.

Returns: reference to the currentvalue

const double& Ilwis::PixelIterator::operator* ( ) const

inline

Query for a reference to the current vallue of the PixelIterator.

Returns: reference to the currentvalue

PixelIterator Ilwis::PixelIterator::operator+ ( int n )

inline

Adds n to this PixelIterator and returns it the direction moved in the raster depends on the boundingbox in combination with the flow.

Parameters

n	the amount to be added

Returns: this iterator moved n

PixelIterator& Ilwis::PixelIterator::operator++ ( )

inline

Adds 1 to this PixelIterator the direction moved in the raster depends on the boundingbox in combination with the flow.

Returns: This iterator moved 1

PixelIterator PixelIterator::operator++ ( int )

inline

Adds 1 to this PixelIterator the direction moved in the raster depends on the boundingbox in combination with the flow.

Returns: this iterator moved 1

PixelIterator& Ilwis::PixelIterator::operator+= ( int n )

inline

Adds n to this PixelIterator the direction moved in the raster depends on the boundingbox in combination with the flow.

Parameters

n	amount to add to this PixelIterator

Returns: this iterator moved n

int PixelIterator::operator- ( const PixelIterator & iter2 )

Substracts another pixeliterator fomr this PixelIterator the direction moved in the raster depends on the boundingbox in combination with the flow
this might have unexpected results if both iterators have a different flow.

Parameters

iter2 another PixelIterator

Returns: this iterator moved -iter2.linearPosition()

PixelIterator& Ilwis::PixelIterator::operator-- ( )

inline

Substracts 1 from this PixelIterator the direction moved in the raster depends on the boundingbox in combination with the flow.

Returns: This iterator moved -1

PixelIterator PixelIterator::operator-- ( int )

inline

Substracts 1 from this PixelIterator the direction moved in the raster depends on the boundingbox in combination with the flow.

Returns: this iterator moved -1

PixelIterator& Ilwis::PixelIterator::operator-= ( int n )

inline

Substracts n from this PixelIterator the direction moved in the raster depends on the boundingbox in combination with the flow.

Parameters

n	amount to substract

Returns: this iterator moved -n

double* Ilwis::PixelIterator::operator-> ( )

inline

Query for the current value of the PixelIterator.

Returns: ->value(this(current))

bool PixelIterator::operator< ( const PixelIterator & iter ) const

Checks if this PixelIterator has a smaller linearPosition as another PixelIterator.

Parameters

iter	another PixelIterator

Returns: true when linearPosition(this)<linearPosition(iter)

bool PixelIterator::operator<= ( const PixelIterator & iter ) const

Checks if this PixelIterator has a smaller or equal linearPosition as another PixelIterator.

Parameters

iter	another PixelIterator

Returns: true when linearPosition(this)<=linearPosition(iter)

PixelIterator & PixelIterator::operator= ( const PixelIterator & iter )

override of the operator=
copies the values of the supplied iterator onto this one
so: this=iter;
results in this getting the same values as iter

Parameters

iter	pixeliterator that must be copied

Returns: this, with the modified values

PixelIterator & PixelIterator::operator= ( const PixelIterator && iter )

override of the operator=
copies the values of the supplied iterator onto this one
so: this=iter;
results in this getting the same values as iter

Parameters

iter	pixeliterator that must be copied

Returns: this, with the modified values

bool PixelIterator::operator== ( const PixelIterator & iter ) const

Checks if this PixelIterator has the same linearPosition as another PixelIterator.

Parameters

iter	another PixelIterator

Returns: true when linearPosition is equal

bool PixelIterator::operator> ( const PixelIterator & iter ) const

Checks if this PixelIterator has a bigger linearPosition as another PixelIterator.

Parameters

iter	another PixelIterator

Returns: true when linearPosition(this)>linearPosition(iter)

bool PixelIterator::operator>= ( const PixelIterator & iter ) const

Checks if this PixelIterator has a bigger or equal linearPosition as another PixelIterator.

Parameters

iter	another PixelIterator

Returns: true when linearPosition(this)>=linearPosition(iter)

double& Ilwis::PixelIterator::operator[] ( quint32 index )

inline

Random acces operator.

Moves to the specified index and returns a pointer to the value at this index

Parameters

index the target index

Returns: the value at the index

PixelIterator& Ilwis::PixelIterator::operator[] ( const Pixel & pix )

inline

Random acces operator.

Moves to the specified voxel, requires a valid voxel

Parameters

index the target index

Returns: this iterator at the specified voxel

Pixel PixelIterator::position ( ) const

Query for the current non lineair position of this PixelIterator.

Returns: a Pixel with the current non lineair position of this PixelIterator

void PixelIterator::setFlow ( Flow flw )

Changes the flow of this PixelIterator.

Changes the flow according to the submitted value for flw,
if flw =fXYZ
this means that the pixeliterator will start at the first row in x direction,
at the end of this row, it will go 1 in y direction and start over in x direction,
at the end of the y row, it will go 1 in z direction and start over

note at this moment only the xyz flow is implemented

Parameters

flw	the requested flow

void Ilwis::PixelIterator::setTranquilizer ( const SPTranquilizer & trq )

inline

ProgressMeter.

Parameters

trq

bool PixelIterator::xchanged ( ) const

Checks if the x coordinate has changed in the last step taken all movement and/or position change commands automatically set the x y and z flags when appropiate.

Returns: true if the x has changed

bool PixelIterator::ychanged ( ) const

Checks if the y coordinate has changed in the last step taken all movement and/or position change commands automatically set the x y and z flags when appropiate.

Returns: true if the y has changed

bool PixelIterator::zchanged ( ) const

Checks if the z coordinate has changed in the last step taken all movement and/or position change commands automatically set the x y and z flags when appropiate.

Returns: true if the z has changed

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

ilwisobjects/coverage/pixeliterator.h
ilwisobjects/coverage/pixeliterator.cpp

Public Types

Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation