ActionScript: The Definitive Guide

Name

MovieClip._y Property — vertical location of a clip or movie, in pixels

Availability

Flash 4 and later

Synopsis

mc._y

Access

Read/write

Description

The floating-point _ y property always indicates the vertical position of mc’s registration point, but it is measured relative to one of three possible coordinate spaces.

• If mc resides on the main timeline, _ y is measured relative to the Stage’s top edge. For example, a _ y of 20 would indicate that the registration point of mc is 20 pixels below the Stage’s top edge; -20 would indicate 20 pixels above.

• If mc resides on another movie clip instance’s timeline, _ y is measured relative to the registration point of that parent instance. For example, a _ y of 20 would indicate that the registration point of mc is 20 pixels below its parent instance’s registration point; -20 would indicate 20 pixels above.

• If mc is the main movie, _ y is the vertical offset of the entire .swf document relative to the Stage’s top edge. For example, a _ y of 200 would indicate that the contents of the Stage are offset 200 pixels below their author-time position; -200 would indicate 200 pixels above.

The _ y property (along with all vertical coordinates in Flash) increases downward and decreases upward—the opposite of the Cartesian coordinate system. Fractional _ y values are approximated in Flash with antialiasing (blurring).

If mc is contained by an instance that is scaled and/or rotated, the coordinate space it inhabits is also scaled and/or rotated. For example, ...