Identifier: epick

Type

epointer

Description

Refers to a graphic primitive selected by an immediate interactive picking operation. The user may indicate a graphic primitive within any active graphic window and the resulting hit is returned in epick. If no hit is made, a null epointer is returned.

The rules for how the system decides on a successful hit are as follows:

  1. Only graphic primitives which are members of the window’s pick_group are examined. On window creation, a window’s pick_group is the all group.

  2. Only graphic primitives which satisfy the selection criteria in window’s pick_filter are examined. On window creation, a window’s pick_filter is undefined implying no filter.

  3. Only graphic primitives which are within the window’s pick_tolerance of the mouse position are examined. A window’s pick_tolerance is measured in pixels with a value of 10 on window creation.

When a hit is successful, the system numeric found is set to 1. Confirmation of the selected graphic primitive is given on the monitor. This message is six levels deep and can be suppressed by using a lower value of err_level, e.g. err_level = 5.

On failure, found is set to 0.

See Also

Commands:

uncursor

Functions:

luglock (point), plock (point)

Identifiers:

err_level (numeric), found (numeric), ignore_node_size (numeric), tracking (procedure)

Structures:

window.pick_filter, window.pick_group, window.pick_tolerance