Essential ActionScript 2.0

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The CurrencyConverter Class

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We chose this implementation to separate the application’s display layer from its

data layer (which might retrieve conversion rates from a server-side application). An

alternative, less flexible implementation might embed the currency conversion rates

directly in the

data property of each ComboBox item.

The convertButton Button component

We’ve already seen that the user can convert a value simply by pressing the Enter key

while typing in the

input text field. We’ll now add an explicit Convert button to the

application for users who prefer not to use the Enter key.

The

convertButton component is an instance of the mx.controls.Button component

class, not to be confused with the native Button class that represents instances of

Button symbols in a movie. Because we imported the mx.controls.* package earlier,

the compiler knows to treat unqualified references to Button as references to the

mx.controls.Button class.

To create and position the

convertButton component, we use now-familiar techniques:

// Create the Convert button.

var convertButton:Button = converter_mc.createClassObject(Button,

"convertButton",

4);

convertButton.move(currencyPicker.x + currencyPicker.width + 5,

currencyPicker.y);

To specify the text on convertButton, we assign a string to its label ...