Android音谱

import android.content.Context;

import android.graphics.Canvas;

import android.graphics.Paint;

import android.graphics.Rect;

import android.util.AttributeSet;

import android.view.View;

public class VisualizerView extends View {

private byte[] mBytes;

private float[] mPoints;

private float[] mPointsx;

private Rect mRect = new Rect();

private Paint mForePaint = new Paint();

private Paint mForePaintx = new Paint();

private int mSpectrumNum = 35;

private boolean mFirst = true;

public VisualizerView(Context context, AttributeSet attrs, int defStyle) {

super(context, attrs, defStyle);

init();

}

public VisualizerView(Context context, AttributeSet attrs) {

this(context, attrs, 0);

init();

}

public VisualizerView(Context context) {

this(context, null, 0);

init();

}

private void init() {

mBytes = null;

mForePaint.setStrokeWidth(20f);

mForePaint.setAntiAlias(true);

mForePaint.setARGB(255, 176, 203, 162);

mForePaintx.setStrokeWidth(20f);

mForePaintx.setAntiAlias(true);

mForePaintx.setARGB(255, 81, 138, 58);

}

public void updateVisualizer(byte[] fft) {

if (mFirst) {

mFirst = false;

}

byte[] model = new byte[fft.length / 2 + 1];

model[0] = (byte) Math.abs(fft[0]);

for (int i = 2, j = 1; j < mSpectrumNum;) {

model[j] = (byte) Math.hypot(fft[i], fft[i + 1]);

i += 2;

j++;

}

mBytes = model;

invalidate();

}

@Override

protected void onDraw(Canvas canvas) {

super.onDraw(canvas);

if (mBytes == null) {

return;

}

if (mPoints == null || mPoints.length < mBytes.length * 4) {

mPoints = new float[mBytes.length * 4];

}

if (mPointsx == null || mPointsx.length < mBytes.length * 4) {

mPointsx = new float[mBytes.length * 4];

}

mRect.set(0, 0, getWidth(), getHeight());

// 绘制波形

// for (int i = 0; i < mBytes.length - 1; i++) {

// mPoints[i * 4] = mRect.width() * i / (mBytes.length - 1);

// mPoints[i * 4 + 1] = mRect.height() / 2

// + ((byte) (mBytes[i] + 128)) * (mRect.height() / 2) / 128;

// mPoints[i * 4 + 2] = mRect.width() * (i + 1) / (mBytes.length - 1);

// mPoints[i * 4 + 3] = mRect.height() / 2

// + ((byte) (mBytes[i + 1] + 128)) * (mRect.height() / 2) / 128;

// }

// 绘制频谱

final int baseX = mRect.width() / mSpectrumNum;

final int height = mRect.height() / 2;

final int heightx = mRect.height() / 2 + 5;

for (int i = 0; i < mSpectrumNum; i++) {

if (mBytes[i] < 0) {

mBytes[i] = 127;

}

final int xi = baseX * i + baseX / 2;

mPoints[i * 4] = xi;

mPoints[i * 4 + 1] = height;

mPoints[i * 4 + 2] = xi;

mPoints[i * 4 + 3] = height - mBytes[i];

mPointsx[i * 4] = xi;

mPointsx[i * 4 + 1] = heightx;

mPointsx[i * 4 + 2] = xi;

mPointsx[i * 4 + 3] = heightx + mBytes[i];

}

canvas.drawLines(mPoints, mForePaint);

canvas.drawLines(mPointsx, mForePaintx);

}

}

private void initVisualizer() {

// 以MediaPlayer的AudioSessionId创建Visualizer

// 相当于设置Visualizer负责显示该MediaPlayer的音频数据

mVisualizer = new Visualizer(mMediaPlayer.getAudioSessionId());

// 设置需要转换的音乐内容长度，专业的说这就是采样，该采样值一般为2的指数倍，如64,128,256,512,1024。

mVisualizer.setCaptureSize(1024);

final int maxCR = Visualizer.getMaxCaptureRate();

mVisualizer.setDataCaptureListener(new Visualizer.OnDataCaptureListener() {

public void onWaveFormDataCapture(Visualizer visualizer, byte[] bytes, int samplingRate) {

// 这个回调应该采集的是波形数据

vv_music.updateVisualizer(bytes);

}

public void onFftDataCapture(Visualizer visualizer, byte[] fft, int samplingRate) {

// 这个回调应该采集的是快速傅里叶变换有关的数据

vv_music.updateVisualizer(fft);

}

}, maxCR / 2, false, true);

mVisualizer.setEnabled(true);

}