Swing Hacks

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Chapter 10, Audio

#78 Provide Audio Controls During Playback

HACK

units represented by the control (like “dB” for a gain-related control, or

“frames per second” for one that is timing-related).

Anyways, you’ve probably figured out that you can build a GUI by using

Swing to provide a view to these

Control

s. In fact, it’s fairly straightforward

to take a factory approach to handing out

JComponent

s based on

Control

s, as

shown in Table 10-1.

The

CompoundControl can’t be handled as easily because you can’t know how

far you’ll have to recursively dig into its hierarchy of controls, nor how to

represent them in relation to one another. For what it’s worth, JavaSound

does not define any

CompoundControl.Type constants, and it’s not clear that

any

CompoundControls exist in J2SE; the Javadoc only speaks in theory of

supporting something like a graphic equalizer, which would need to be a

CompoundControl.

Theory to Practice

To handle the different types of controls that can be encountered, one nice

approach would be to build a factory: you hand it a

Control, and it gives you

back a

JComponent that you can add to your GUI. Example 10-12 shows a

simple implementation of this.

Table 10-1. Controls and their Swing representation

Control type Swing representation

BooleanControl JCheckBox

EnumControl JComboBox

FloatControl JSlider

Example 10-12. Factory to generate Swing widgets for JavaSound controls

import javax.sound.sampled.*; ...