gen_checker

gen_checker_region ( : RegionChecker : WidthRegion, HeightRegion, WidthPattern, HeightPattern : )

Create a checkered region.

The operator gen_checker_region returns a checkered region. Every black field of the checkerboard belongs to the region. The horizontal and vertical expansion of the region is limited by WidthRegion, HeightRegion respectively, the size of the fields of the checkerboard by WidthPattern * HeightPattern.

Attention

If a very small pattern is chosen (WidthPattern < 4) the created region requires much storage.

Parameters

`RegionChecker` (output_object)	region `->` object
Created checkerboard region.

`WidthRegion` (input_control)	extent.x `->` integer
Largest occurring x value of the region.
Default value: 511
Suggested values: 10, 20, 31, 63, 127, 255, 300, 400, 511
Typical range of values: `1 <= WidthRegion <= 1024` (lin)
Minimum increment: 1
Recommended increment: 10
Restriction: `WidthRegion >= 1`

`HeightRegion` (input_control)	extent.y `->` integer
Largest occurring y value of the region.
Default value: 511
Suggested values: 10, 20, 31, 63, 127, 255, 300, 400, 511
Typical range of values: `1 <= HeightRegion <= 1024` (lin)
Minimum increment: 1
Recommended increment: 10
Restriction: `HeightRegion >= 1`

`WidthPattern` (input_control)	extent.x `->` integer
Width of a field of the checkerboard.
Default value: 64
Suggested values: 1, 2, 4, 8, 16, 20, 32, 64, 100, 128, 200, 300, 500
Typical range of values: `1 <= WidthPattern <= 1024` (lin)
Minimum increment: 1
Recommended increment: 10
Restriction: `(WidthPattern > 0) && (WidthPattern < WidthRegion)`

`HeightPattern` (input_control)	extent.y `->` integer
Height of a field of the checkerboard.
Default value: 64
Suggested values: 1, 2, 4, 8, 16, 20, 32, 64, 100, 128, 200, 300, 500
Typical range of values: `1 <= HeightPattern <= 1024` (lin)
Minimum increment: 1
Recommended increment: 10
Restriction: `(HeightPattern > 0) && (HeightPattern < HeightRegion)`

Example

gen_checker_region(Checker,512,512,32,64:) 
set_draw(WindowHandle,'fill')
set_part(WindowHandle,0,0,511,511)
disp_region(Checker,WindowHandle)

Complexity

The required storage (in bytes) for the region is:

O((WidthRegion * HeightRegion) / WidthPattern)

Result

The operator gen_checker_region returns the value 2 (H_MSG_TRUE) if the parameter values are correct. 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'>).

Parallelization Information

gen_checker_region is reentrant and processed without parallelization.

Possible Successors

paint_region

Alternatives

gen_grid_region, gen_region_polygon_filled, gen_region_points, gen_region_runs, gen_rectangle1, concat_obj, gen_random_region, gen_random_regions

Module

Foundation