fetch_chord ( Region : : : Row, ColumnBegin, ColumnEnd )

Access the runlength coding of a region.

The operator fetch_chord returns the region data in the form of chord tuples. The chord representation is caused by examining a region line by line with ascending line number (= from "top" to "bottom"). Every line is passed from left to right (ascending column number); storing all starting and ending points of region segments (= chords). Thus a region can be described by a sequence of chords, a chord being defined by line number, starting and ending points (column number). The operator fetch_chord returns the three components of the chords in the form of tuples. In case of an empty region three empty tuples are returned.


Attention

Only one region may be passed.


Parameters

Region (input_object)
region -> object
Output region.

Row (output_control)
chord.y-array -> integer
Line numbers of the chords

ColumnBegin (output_control)
chord.x1-array -> integer
Column numbers of the starting points of the chords
Number of elements: ColumnBegin == Row

ColumnEnd (output_control)
chord.x2-array -> integer
Column numbers of the ending points of the chords
Number of elements: ColumnEnd == Row


Result

The operator fetch_chord normally returns the value TRUE. If more than one region is passed an exception is caused. The behavior in case of empty input (no input regions available) is set via the operator set_system(::'no_object_result',<Result>:).


Possible Predecessors

threshold__, connection


Alternatives

fetch_coord


See also

copy_obj, store_chord



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