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NeighborCode | ![]() |
Encapsulation of direction management for 4-neighborhood. More...
#include <vigra/pixelneighborhood.hxx>
Public Types | |
enum | Direction { Error = -1, East = 0, North, West, South, DirectionCount, CausalFirst = North, CausalLast = West, AntiCausalFirst = South, AntiCausalLast = East } |
Static Public Member Functions | |
static Diff2D const & | bottom () |
static Direction | code (Diff2D const &diff) |
static Diff2D const & | diff (int code) |
static Diff2D const & | diff (Direction code) |
static int | dX (int code) |
static int | dX (Direction code) |
static int | dY (int code) |
static int | dY (Direction code) |
static Diff2D const & | east () |
static bool | isDiagonal (Direction) |
static Diff2D const & | left () |
static unsigned int | nearBorderDirectionCount (AtImageBorder b) |
static Direction | nearBorderDirections (AtImageBorder b, int index) |
static Diff2D const & | north () |
static Diff2D const & | relativeDiff (int fromCode, int toCode) |
static Diff2D const & | relativeDiff (Direction fromCode, Direction toCode) |
static Diff2D const & | right () |
static Diff2D const & | south () |
static Diff2D const & | top () |
static Diff2D const & | west () |
Encapsulation of direction management for 4-neighborhood.
This helper class allows the transformation between Freeman chain codes (East = 0, North = 1 etc.) and the corresponding Diff2D instances and back.
You can either use the chain codes by explicit qualification:
// the following three lines are equivalent FourNeighborhood::NeighborCode::Direction d = FourNeighborhood::NeighborCode::East; FourNeighborCode::Direction d = FourNeighborCode::East; FourNeighborhood::Direction d = FourNeighborhood::East;
or you can fix 4-neighborhood by importing the entire namespace in your function:
If you want to pass 4-neighborhood codes as a template parameter, use the class FourNeighborhood::NeighborCode.
#include <vigra/pixelneighborhood.hxx>
Namespace: vigra::FourNeighborhood
enum Direction |
Freeman direction codes for the 4-neighborhood. East = 0
, North = 1
etc. DirectionCount
may be used for portable loop termination conditions. CausalFirst
and CausalLast
are the first and last (inclusive) neighbors in the causal neighborhood, i.e. in the set of neighbors that have already been visited when the image is traversed in scan order. AntiCausalFirst
and AntiCausalLast
are the opposite.
static unsigned int nearBorderDirectionCount | ( | AtImageBorder | b | ) | [static] |
The number of valid neighbors if the current center is at the image border.
static Direction nearBorderDirections | ( | AtImageBorder | b, | |
int | index | |||
) | [static] |
The valid direction codes when the center is at the image border. index must be in the range 0...nearBorderDirectionCount(b)-1
.
Transform direction code into corresponding Diff2D offset. (note: there is no bounds checking on the code you pass.)
static Diff2D const& diff | ( | int | code | ) | [static] |
Equivalent to diff(static_cast<Direction>(code))
. (note: there is no bounds checking on the code you pass.)
Get the relative offset from one neighbor to the other. For example, relativeDiff(East, West) == Diff2D(-2,0)
. (note: there is no bounds checking on the code you pass.)
static Diff2D const& relativeDiff | ( | int | fromCode, | |
int | toCode | |||
) | [static] |
Equivalent to relativeDiff(static_cast<Direction>(fromCode), static_cast<Direction>(toCode)). (note: there is no bounds checking on the code you pass.)
static int dX | ( | int | code | ) | [static] |
X-component of diff()
static int dY | ( | int | code | ) | [static] |
Y-component of diff()
Transform Diff2D offset into corresponding direction code. The code Direction::Error
will be returned if diff
is not in the 4-neighborhood.
static bool isDiagonal | ( | Direction | ) | [static] |
Check whether a code refers to a diagonal direction. Useful if you want to abstract the differences between 4- and 8-neighborhood. Always false
for 4-neighborhood.
static Diff2D const& right | ( | ) | [static] |
Offset to the right neighbor
static Diff2D const& top | ( | ) | [static] |
Offset to the top neighbor
static Diff2D const& left | ( | ) | [static] |
Offset to the left neighbor
static Diff2D const& bottom | ( | ) | [static] |
Offset to the bottom neighbor
static Diff2D const& east | ( | ) | [static] |
Offset to the east neighbor
static Diff2D const& north | ( | ) | [static] |
Offset to the north neighbor
static Diff2D const& west | ( | ) | [static] |
Offset to the west neighbor
static Diff2D const& south | ( | ) | [static] |
Offset to the south neighbor
© Ullrich Köthe (ullrich.koethe@iwr.uni-heidelberg.de) |
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