Operator Reference
get_region_chain (Operator)
get_region_chain
— Contour of an object as chain code.
Warning
get_region_chain
is obsolete and is only provided for
reasons of backward compatibility.
Signature
Description
The operator get_region_chain
returns the contour of a region.
A contour is a series of
pixels describing the outline of the region.
The contour “lies on” the region.
It starts at the smallest line number;
in that line at the pixel with the largest column index.
The rotation occurs clockwise.
Holes of the region are ignored.
The direction code (chain code) is defined as follows:
3 2 1
4 * 0
5 6 7
The operator get_region_chain
returns the code in the form of a tuple.
In case of an empty region the parameters Row
and
Column
are zero and Chain
is the empty tuple.
Attention
Holes of the region are ignored. Only one region may be passed, and it must have exactly one connection component.
Execution Information
- Multithreading type: reentrant (runs in parallel with non-exclusive operators).
- Multithreading scope: global (may be called from any thread).
- Processed without parallelization.
Parameters
Region
(input_object) region →
object
Region to be transformed.
Row
(output_control) chain.begin.y →
(integer)
Line of starting point.
Column
(output_control) chain.begin.x →
(integer)
Column of starting point.
Chain
(output_control) chain.code-array →
(integer)
Direction code of the contour (from starting point).
Value range:
0
≤
Chain
≤
7
Result
The operator get_region_chain
normally returns the value 2 (
H_MSG_TRUE)
.
If more than one connection component is passed an exception is raised.
The behavior in case of empty input (no input regions available) is set via
the operator set_system('no_object_result',<Result>)
.
The behavior in case of empty region (the region is the empty set) is set via
the operator set_system('empty_region_result',<Result>)
.
If necessary an exception is raised.
Possible Predecessors
sobel_amp
,
threshold
,
skeleton
,
edges_image
,
gen_rectangle1
,
gen_circle
Possible Successors
approx_chain
,
approx_chain_simple
See also
copy_obj
,
get_region_contour
,
get_region_polygon
Module
Foundation