User Guide

526 Chapter 12: Methods

See also

Movie

setAlpha()

Usage

imageObject.setAlpha(alphaLevel)

imageObject.setAlpha(alphaImageObject)

Description

Function; sets the alpha channel of an image object to a flat alphaLevel or to an existing

alphaImageObject. The alphaLevel must be a number from 0–255. Lower values cause the

image to appear more transparent. Higher values cause the image to appear more opaque. The

value 255 has the same effect as a value of zero. In order for the

alphaLevel to have effect, the

useAlpha() of the image object must be set to TRUE.

The image object must be 32-bit. If you specify an alpha image object, it must be 8-bit. Both

images must have the same dimensions. If these conditions are not met,

setAlpha() has no effect

and returns FALSE. The function returns TRUE when it is successful.

Example

The following Lingo statement makes the image of the bitmap cast member Foreground opaque

and disables the alpha channel altogether. This is a good method for removing the alpha layer

from an image:

member("Foreground").image.setAlpha(255)

member("Foreground").image.useAlpha = FALSE

This Lingo gets the alpha layer from the cast member Sunrise and places it into the alpha layer of

the cast member Sunset:

tempAlpha = member("Sunrise").image.extractAlpha()

member("Sunset").image.setAlpha(tempAlpha)