Lingo Dictionary > A-C > constraint

 

constraint

Syntax

sprite(whichSprite).constraint
the constraint of sprite whichSprite

Description

Sprite property; determines whether the registration point of the sprite specified by whichSprite is constrained to the bounding rectangle of another sprite (1 or TRUE) or not (0 or FALSE, default).

The constraint sprite property is useful for constraining a moveable sprite to the bounding rectangle of another sprite to simulate a track for a slider control or to restrict where on the screen a user can drag an object in a game.

The constraint sprite property affects moveable sprites and the locH and locV sprite properties. The constraint point of a moveable sprite cannot be moved outside the bounding rectangle of the constraining sprite. (The constraint point for a bitmap sprite is the registration point. The constraint point for a shape sprite is its top left corner.) When a sprite has a constraint set, the constraint limits override any locH and locV sprite property settings.

This property can be tested and set.

Example

This statement removes a constraint sprite property:

Dot syntax:

sprite(whichSprite).constraint = 0

Verbose syntax:

set the constraint of sprite whichSprite to 0

Example

This statement constrains sprite (i + 1) to the boundary of sprite 14:

sprite(i + 1).constraint = 14

Example

This statement checks whether sprite 3 is constrained and activates the handler showConstraint if it is: (The operator <> performs a not-equal-to operation.)

if sprite(3).constraint <> 0 then showConstraint

See also

constrainH(), constrainV(), locH, locV