How to use SurfaceView in Android audio development?

1 year ago
Emily Johnson
2 minutes

SurfaceView is a view component that allows for images to be drawn in the background thread, commonly used for scenarios such as video playback, game development, and image processing. In Android audio development, SurfaceView can be used to achieve audio visualization effects.

Here is a simple example code that displays audio waveforms using SurfaceView.

  1. Create a custom SurfaceView class that extends SurfaceView and implements the SurfaceHolder.Callback interface.
public class AudioVisualizerView extends SurfaceView implements SurfaceHolder.Callback {
    private SurfaceHolder mHolder;
    
    public AudioVisualizerView(Context context) {
        super(context);
        mHolder = getHolder();
        mHolder.addCallback(this);
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        // 在SurfaceView创建时初始化画布等操作
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        // SurfaceView尺寸发生变化时的操作
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        // 释放资源等操作
    }
}
  1. Using a custom SurfaceView in an Activity:
public class MainActivity extends AppCompatActivity {
    private AudioVisualizerView mVisualizerView;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        mVisualizerView = new AudioVisualizerView(this);
        FrameLayout frameLayout = findViewById(R.id.frameLayout);
        frameLayout.addView(mVisualizerView);
        
        // 开启后台线程获取音频数据，并在SurfaceView中绘制波形
        new Thread(new Runnable() {
            @Override
            public void run() {
                // 获取音频数据并绘制波形
            }
        }).start();
    }
}

In the code above, we first create a custom SurfaceView class called AudioVisualizerView and use this custom view in the Activity. In the onCreate method of the Activity, we add the custom SurfaceView to a FrameLayout and then retrieve audio data and draw waveforms on a background thread.

It is important to note that the canvas should be initialized in the surfaceCreated method and the waveform should be drawn on a background thread. Resources should be released in the surfaceDestroyed method. By following these steps, we can achieve the effect of displaying an audio waveform on a SurfaceView.

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