get_region_runs — Access the runlength coding of a region.
get_region_runs 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).
get_region_runs returns the three components of the chords
in the form of tuples. In case of an empty region three empty tuples are returned.
Only one region may be passed.
Line numbers of the chords.
Column numbers of the starting points of the chords.
Number of elements: ColumnBegin == Row
Column numbers of the ending points of the chords.
Number of elements: ColumnEnd == Row
get_region_runs normally returns the value TRUE.
If more than one region is passed an exception is raised.
The behavior in case of empty input (no input regions available) is set via