ActionScript: The Definitive Guide

Name

MovieClip.globalToLocal( ) Method — convert a point on the main Stage to clip coordinates

Availability

Flash 5

Synopsis

mc.globalToLocal(point)

Arguments

point

A reference to an object with two properties, x and y, that describe a point on the main Stage of the Player (i.e., on _root). Both x and y may be any floating-point number.

Description

The globalToLocal( ) method converts the x and y properties of point from coordinates on the main Stage to coordinates in the coordinate space of mc. Note that globalToLocal( ) does not return a new object, it merely modifies the existing x and y values of point.

To use globalToLocal( ), we must first create an object with x and y properties. For example:

var myPoint = new Object( );
myPoint.x = 10;
myPoint.y = 20;

The x and y properties of our object are positions on the horizontal and vertical axes of the main Stage, relative to its top-left corner. For example, an x of 10 is 10 pixels to the right of the Stage’s left edge, and a y of 20 is 20 pixels below the Stage’s top border. With our object created and our x and y properties set, we then pass the object to the globalToLocal( ) method, as in:

myClip.globalToLocal(myPoint);

When globalToLocal( ) is executed, the values of myPoint’s x and y properties are transformed to represent a point in the space of myClip, measured from myClip’s registration point. By examining the new values of our myPoint object’s properties, we answer the question, “Where does the point (x, y) of the main Stage appear ...