Object snap

Setting object snap on/off:

lcPropPutBool ( hLcWnd, LC_PROP_WND_OSNAP, true );
lcPropPutBool ( hLcWnd, LC_PROP_WND_OSNAP, false );

Setting object snap mode:

lcPropPutInt ( hLcWnd, LC_PROP_WND_OSNAP, Value );

where the Value parameter is a combination of the following constants:

Constant	Object snap mode
LC_OSNAP_NODE	to a Point object, dimension definition point, or dimension text origin.
LC_OSNAP_ENDPOINT	to the closest endpoint of an Arc, Elliptical Arc, Line, Multiline, Polyline segment, Ray
LC_OSNAP_MIDPOINT	to the midpoint of an arc, ellipse, elliptical arc, line, multiline, polyline segment, region, solid, spline, or xline.
LC_OSNAP_CENTER	to the center of an arc, circle, ellipse, or elliptical arc.
LC_OSNAP_NEAREST	to the nearest point on an arc, circle, ellipse, elliptical arc, line, multiline, point, polyline, ray, spline, or xline
LC_OSNAP_INTER	to the intersection of an arc, circle, ellipse, elliptical arc, line, multiline, polyline, ray, region, spline, or xline
LC_OSNAP_PERPEND	to a point perpendicular to an arc, circle, ellipse, elliptical arc, line, multiline, polyline, ray, region, solid, spline, or xline
LC_OSNAP_TANGENT	to the tangent of an arc, circle, ellipse, elliptical arc, or spline
LC_OSNAP_QUADRANT	to a quadrant point of an arc, circle, ellipse, or elliptical arc
LC_OSNAP_INSERT	to the insertion point of an attribute, a block, a shape, or text
No combination constants
LC_OSNAP_NULL	No object snap
LC_OSNAP_ALL	All modes

Global properties for object snapping:

Property	Type	Access	Meaning
LC_PROP_G_OSNAP_MARK	bool	RW	Display object snap marker
LC_PROP_G_OSNAP_APER	bool	RW	Display object snap aperture box
LC_PROP_G_OSNAP_MARKSIZE	int	RW	Half-size of marker indicating snap point, pixels (1-15)
LC_PROP_G_OSNAP_APERSIZE	int	RW	Half-size of square around cursor, used for snap, pixels (1-15)
LC_PROP_G_OSNAP_MARKCOLOR	int	RW	Color of object snap marker (COLORREF)

Layer properties for object snapping:

Property	Type	Access	Meaning
LC_PROP_LAYER_OSNAP	bool	RW	Enable object snap for entities of the layer

Commands:

Command	Meaning
LC_CMD_OSNAP	Calls dialog "Object Snap"
LC_CMD_SW_OSNAP	Toggles "Object Snap" mode

Object snap menu is called by <Shift> + <Right click>
In order to enable/disable this menu use LC_PROP_WND_OSNAPMENU property.

Code sample:

  int OSnap;
  OSnap = LC_OSNAP_ENDPOINT | LC_OSNAP_MIDPOINT | LC_OSNAP_CENTER;
  lcPropPutInt( hLcWnd, LC_PROP_WND_OSNAP, OSnap );
  lcPropPutBool( hLcWnd, LC_PROP_WND_OSNAP, true );