set_gray🔗
Short description🔗
set_gray — Define gray values for region output.
Signature🔗
set_gray( window WindowHandle, integer GrayValues )
Description🔗
set_gray defines the gray values for region
output. Gray values are defined as the range of the color lookup
table that is used for gray value output with disp_image
in conjunction with set_paint(::WindowHandle,'gray':). These entries
can be modified by set_lut. So a ‘gray value’ is the
color in which a pixel with the same value is displayed (not
necessarily really gray). In general, when changing the color lookup
table with set_lut, the colors of the displayed image
will change too.
If a gray value is needed as a color for image output (i.e. no color
changes with set_lut are possible), it can be set with
set_color(::WindowHandle,'gray':).
If only a single gray value is passed, all output will take place in that gray value. If a tuple of gray values is passed, all output will take place in gray values modulo the number of tuple elements. In the example below, the first circle is displayed with gray value 100, the second with 200 and the third with 100 again. Every output operator starts with the first gray value. Note, that the number of output gray values depends on the number of objects that are displayed in one operator call. If only single objects are displayed, they always appear in the first gray value, even if the consist of more than one connected components.
When the operators set_gray, set_color,
set_rgb, set_hsi are called, the overwrite
the existing values. If not all gray values are displayable on the
output device, the number range of GrayValues (0..255) is
dithered to the range of displayable gray values. In any case 0 is
displayed as black and 255 as white. The displayable gray values can
be queried with the operator query_gray.
With texttt{set_check(::’~color’:)} error messages can be
suppressed if a gray value can’t be displayed on the screen. In that
case, a similar gray value is displayed.
Execution information🔗
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🔗
WindowHandle (input_control) window → (handle)
Window handle.
GrayValues (input_control) integer(-array) → (integer)
Gray values for region output.
Default: 255
Suggested values: 0, 1, 2, 10, 16, 32, 64, 100, 120, 128, 250, 251, 252, 253, 254, 255
Value range: 0 ≤ GrayValues ≤ 255
Example🔗
(HDevelop)
set_gray(WindowHandle,[100,200])
disp_circle(WindowHandle,[100,200,300],[200,300,100],[100,100,100])
Result🔗
set_hsi returns 2 (H_MSG_TRUE) if the window is valid and the
given gray value is displayable. Otherwise an exception is raised.
Combinations with other operators🔗
Module🔗
Foundation