User Guide

Using Matrix objects 425

matrix.rotate(rotation);

myDisplayObject.transform.matrix = matrix;

The first line sets a Matrix object to the existing transformation matrix used by the

myDisplayObject display object (the matrix property of the transformation property of

the

myDisplayObject display object). This way, the Matrix class methods that you call will

have a cumulative effect on the display object’s existing position, scale, and rotation.

Defining a Matrix object for use with a gradient

You use the beginGradientFill() and lineGradientStyle() methods of the

flash.display.Graphics class to define gradients for use in shapes. When you define a gradient,

you supply a matrix as one of the parameters of these methods.

The easiest way to define the matrix is by using the

createGradientBox() method, which

defines a rectangle that is used to define the gradient. You define the scale, rotation, and

position of the gradient by using the parameters passed to the

createGradientBox()

method.

For example, consider a gradient with the following characteristics:

■ GradientType.LINEAR

■ Two colors, green and blue, with the ratios array set to [0, 255]

■ SpreadMethod.PAD

■ InterpolationMethod.LINEAR_RGB

NOTE

The ColorTransform class is also included in the flash.geometry package. This class

is used to set the colorTransform property of a Transform object. Since it does not

apply any sort of geometrical transformation, it is not discussed in this chapter. For

more information, see the ColorTransform class in the ActionScript 3.0 Language

Reference.