Create a circle.
The operator gen_circle generates one or more circles described by the center and Radius. If several circles shall be generated the coordinates must be passed in the form of tuples.
gen_circle only creates symmetric circles. To achieve this, the radius is internally rounded down to a multiple of 0.5. If an integer number is specified for the radius (i.e., 1, 2, 3, ...) an even diameter is obtained, and hence the circle can only be symmetric with respect to a center with coordinates that have a fractional part of 0.5. Consequently, internally the coordinates of the center are adapted to the closest coordinates that have a fractional part of 0.5. Here, integer coordinates are rounded down to the next smaller values with a fractional part of 0.5. For odd diameters (i.e., radius = 1.5, 2.5, 3.5, ...), the circle can only be symmetric with respect to a center with integer coordinates. Hence, internally the coordinates of the center are rounded to the nearest integer coordinates. It should be noted that the above algorithm may lead to the fact that circles with an even diameter are not contained in circles with the next larger odd diameter, even if the coordinates specified in Row and Column are identical.
If the circle extends beyond the image edge it is clipped to the current image format if the value of the system flag 'clip_region' is set to 'true' (set_system).
|
Circle (output_object) |
region(-array) -> object |
| Generated circle. | |
|
Row (input_control) |
circle.center.y(-array) -> real / integer |
| Line index of center. | |
| Default value: 200.0 | |
| Suggested values: 0.0, 10.0, 50.0, 100.0, 200.0, 300.0 | |
| Typical range of values: 1.0 <= Row <= 1024.0 (lin) | |
| Minimum increment: 1.0 | |
|
Recommended increment: 10.0 | |
|
Column (input_control) |
circle.center.x(-array) -> real / integer |
| Column index of center. | |
| Default value: 200.0 | |
| Suggested values: 0.0, 10.0, 50.0, 100.0, 200.0, 300.0 | |
| Typical range of values: 1.0 <= Column <= 1024.0 (lin) | |
| Minimum increment: 1.0 | |
|
Recommended increment: 10.0 | |
|
Radius (input_control) |
circle.radius(-array) -> real / integer |
| Radius of circle. | |
| Default value: 100.5 | |
| Suggested values: 1.0, 1.5, 2.0, 2.5, 3, 3.5, 4, 4.5, 5.5, 6.5, 7.5, 9.5, 11.5, 15.5, 20.5, 25.5, 31.5, 50.5 | |
| Typical range of values: 1.0 <= Radius <= 1024.0 (lin) | |
| Minimum increment: 1.0 | |
|
Recommended increment: 10.0 | |
| Restriction: Radius > 0.0 | |
open_window(0,0,-1,-1,'root','visible','',WindowHandle) read_image(Image,'meer') gen_circle(Circle,300.0,200.0,150.5) reduce_domain(Image,Circle,Mask) disp_color(Mask,WindowHandle).
Runtime complexity: O(Radius * 2)
Storage complexity (byte): O(Radius * 8)
If the parameter values are correct, the operator gen_circle returns the value 2 (H_MSG_TRUE). Otherwise an exception handling is raised. The clipping according to the current image format is set via the operator set_system('clip_region',<'true'/'false'>). If an empty region is created by clipping (the circle is completely outside of the image format) the operator set_system('store_empty_region',<true/false>) determines whether the empty region is put out.
gen_circle is reentrant and processed without parallelization.
gen_ellipse, gen_region_polygon_filled, gen_region_points, gen_region_runs, draw_circle
disp_circle, set_shape, smallest_circle, reduce_domain
Foundation
