Range struct
Used in indexing to indicate a regular subset of pixels along one image dimension.
Contents
dip::Range{ start, stop } generates a range of pixels where start and
stop are the first and last indices in the range. That is, stop is
included in the range. dip::Range{ start } generates
a range for a single pixel. For example, dip::Range{ 0 } is the first pixel,
and is equivalent to dip::Range{ 0, 0 }. dip::Range{ 0, N - 1 } is
a range of the first N pixels.
dip::Range{ start, stop, step } generates a range of pixels where step is
the number of pixels between subsequent indices. The pixels indexed are the
ones generated by the following loop:
offset = start; do { // use this offset offset += step; } while( offset <= stop );
That is, it is possible that the range does not include stop, if the
step would make the range step over stop.
Negative start and stop values indicate offset from the end (-1 is the
last pixel, -2 the second to last, etc.): dip::Range{ 5, -6 } indicates
a range that skips the first and last five pixels. dip::Range{ -1, -1, 1 }
(or simply dip::Range{ -1 } indicates the last pixel only.
dip::Range{ 0, -1 } is equivalent to dip::Range{}, and indicates all
pixels.
The dip::Range::Fix method converts the negative start and stop values
to actual offsets:
dip::Range r{ 5, -6 }; r.fix( 50 ); // now r.stop == 50 - 6
If stop comes before start, then the range generates pixel indices in
the reverse order. That is, negative steps are taken to go from start to stop.
step is always a positive integer, the direction of the steps is given
solely by the ordering of start and stop.
The begin and end methods yield an iterator that dereferences to the indices
defined by the range.
Constructors, destructors, assignment and conversion operators
- Range() defaulted
- Create a range that indicates all pixels
- Range(dip::sint i) explicit
- Create a range that indicates a single pixel
- Range(dip::sint i, dip::sint j, dip::uint s = 1)
- Create a range using two or three values; it indicates all pixels between
iandj, both inclusive. The step size defaults to 1.
Classes
- class Iterator
- An iterator for the range
Functions
- void Fix(dip::uint size)
- Modify a range so that negative values are assigned correct values according to the given size. Throws if the range falls out of bounds.
- auto Size() const -> dip::uint
- Get the number of pixels addressed by the range (must be fixed first!).
- auto Offset() const -> dip::uint
- Get the offset for the range (must be fixed first!).
- auto Last() const -> dip::uint
- Get the last index in the range (must be fixed first!).
- auto Step() const -> dip::sint
- Get the signed step size for the range (must be fixed first!).
- auto begin() const -> dip::Range::Iterator
- Get an iterator to the beginning of the range (must be fixed first!).
- auto end() const -> dip::Range::Iterator
- Get an iterator to the end of the range (must be fixed first!). This iterator points one past
the
stopvalue, as is usual for the end iterator.