VLGETCONTROLINFO(3dm)VLGETCONTROLINFO(3dm)NAME
vlGetControlInfo, vlFreeControlInfo - get and free information about VL
controls
SYNOPSIS
#include <dmedia/vl.h>
VLControlInfo *vlGetControlInfo(VLServer svr, VLPath path,
VLNode node, VLControlType type);
int vlFreeControlInfo(VLServer svr, VLControlInfo *info);
PARAMETERS
svr Specifies the video server handle.
path Specifies the path of interest.
node Specifies the source or drain of interest. May be VL_ANY if
either a source or drain control is acceptable, or if the
control is not associated with either a source or drain.
type Specifies the control type of interest.
info Specifies a pointer to a VLControlInfo structure which was
previously allocated by vlGetControlInfo.
DESCRIPTION
The vlGetControlInfo function is used to find information about valid
settings for a VL control. It uses the path, node, and type parameters to
locate a VL control, and returns a VLControlInfo structure which
describes the desired control.
The returned VLControlInfo structure will describe the control in one of
two ways. It will specify either the range (or ranges) of values
supported by the control, or it will specify the set of discrete values
supported by the control. If the VL control is described by a range of
values, then the VLControlInfo structure will indicate a value range with
a pointer to an array of VLFractionRange structures. If the VL control
is described by a set of discrete values, then the VLControlInfo
structure will indicate the legal set of values with a pointer to an
array of VLControlItem structures. Only one of these two arrays will
exist in the VLControlInfo structure.
For example, a control for VL_SIZE has a value of type VL_CT_XY, which
represents the legal range of (X, Y) coordinates for this control, and
may be described by a two entry array of type VLFractionRange with one
entry for the X coordinate, and one for the Y coordinate. A control for
VL_FORMAT has a value of type VL_CT_INT, which represents the set of
legal video formats for this control, and may be described by an array of
type VLControlItem with one entry for each possible value which the
control may take.
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VLGETCONTROLINFO(3dm)VLGETCONTROLINFO(3dm)
The vlFreeControlInfo function should be used to deallocate the
VLControlInfo data which has been allocated by a call to
vlGetControlInfo.
RETURN VALUE
If successful, vlGetControlInfo returns a pointer to a VLControlInfo
structure which describes the specified control, otherwise it returns
NULL.
If successful, vlFreeControlInfo returns VLSuccess, otherwise it returns
a VL error code.
SEE ALSOvlGetControl(3dm), vlSetControl(3dm)
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