android 音乐波形图

把波形数据从一个点放射的画出去……挺有意思的，没有仔细研究为什么右边那个圆怎么形成的，可能是我哪里错了，也可能是因为某种数学关系

部分代码是在其他人的代码基础上改的，我加的case 3:

public class TestActivity extends BaseActivity {
public final static int TEST_PAGE_SIZE = 10;
protected static final String TAG = "TestActivity";
Visualizer mVisualizer;
MusicFrequency musicFrequency;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test);
mVisualizer = new Visualizer(0);
setFrequencyListener();
mVisualizer.setEnabled(true);
musicFrequency = (MusicFrequency) findViewById(R.id.frequency);
}

private void setFrequencyListener() {
mVisualizer.setDataCaptureListener(new Visualizer.OnDataCaptureListener() {
@Override
public void onWaveFormDataCapture(Visualizer visualizer, byte[] waveform, int samplingRate) {
Log.d("debug", "onWaveFormDataCapture");
musicFrequency.updateVisualizer(waveform);
}

@Override
public void onFftDataCapture(Visualizer visualizer, byte[] fft, int samplingRate) {
Log.d("debug", "onFftDataCapture");
//musicFrequency.updateVisualizer(fft);
}
}, Visualizer.getMaxCaptureRate(), true, false);


public class MusicFrequency extends RelativeLayout {

private int viewSize = 500;
private Paint mPaintLine;
private Paint mPaintSector;
private boolean isStart = false;
private int start = 0;
// bytes数组保存了波形抽样点的值
private byte[] bytes;
private float[] points;
private Paint paint = new Paint();
private Rect rect = new Rect();
private byte type = 0;

private final int paintWidth = 10;
Visualizer mVisualizer;

public MusicFrequency(Context context) {
super(context);
init();
}

public MusicFrequency(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}

private void init() {
bytes = null;
// 设置画笔的属性
paint.setStrokeWidth(1f);
paint.setAntiAlias(true);//抗锯齿
paint.setColor(Color.YELLOW);//画笔颜色
paint.setStyle(Paint.Style.FILL);
//test();
}

private void test() {
mVisualizer = new Visualizer(0);
mVisualizer.setEnabled(true);
setFrequencyListener();

}

private void setFrequencyListener() {
mVisualizer.setDataCaptureListener(new Visualizer.OnDataCaptureListener() {
@Override
public void onWaveFormDataCapture(Visualizer visualizer, byte[] waveform, int samplingRate) {
Log.d("debug", "onWaveFormDataCapture");
updateVisualizer(waveform);
}

@Override
public void onFftDataCapture(Visualizer visualizer, byte[] fft, int samplingRate) {
Log.d("debug", "onFftDataCapture");
updateVisualizer(fft);
}
}, Visualizer.getMaxCaptureRate() / 2, true, false);
}

public void updateVisualizer(byte[] ftt) {
bytes = ftt;
// 通知该组件重绘自己。
invalidate();
}

@Override
public boolean onTouchEvent(MotionEvent me) {
// 当用户触碰该组件时，切换波形类型
if (me.getAction() != MotionEvent.ACTION_DOWN) {
return false;
}
type++;
if (type >= 3) {
type = 0;
}
return true;
}

@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
if (bytes == null) {
return;
}
// 绘制白色背景
canvas.drawColor(Color.WHITE);
// 使用rect对象记录该组件的宽度和高度
rect.set(0, 0, getWidth(), getHeight());
type = 3;
switch (type) {
// -------绘制块状的波形图-------
case 0:
for (int i = 0; i < bytes.length - 1; i++) {
float left = getWidth() * i / (bytes.length - 1);
// 根据波形值计算该矩形的高度
float top = rect.height() - (byte) (bytes[i + 1] + 128)
* rect.height() / 128;
float right = left + 1;
float bottom = rect.height();
canvas.drawRect(left, top, right, bottom, paint);
}
break;
// -------绘制柱状的波形图（每隔18个抽样点绘制一个矩形）-------
case 1:
for (int i = 0; i < bytes.length - 1; i += 18) {
float left = rect.width() * i / (bytes.length - 1);
// 根据波形值计算该矩形的高度
float top = rect.height() - (byte) (bytes[i + 1] + 128)
* rect.height() / 128;
float right = left + 6;
float bottom = rect.height();
canvas.drawRect(left, top, right, bottom, paint);
}
break;
// -------绘制曲线波形图-------
case 2:
// 如果point数组还未初始化
if (points == null || points.length < bytes.length * 4) {
points = new float[bytes.length * 4];
}
for (int i = 0; i < bytes.length - 1; i++) {
// 计算第i个点的x坐标
points[i * 4] = rect.width() * i / (bytes.length - 1);
// 根据bytes[i]的值（波形点的值）计算第i个点的y坐标
points[i * 4 + 1] = (rect.height() / 2)
+ ((byte) (bytes[i] + 128)) * 128
/ (rect.height() / 2);
// 计算第i+1个点的x坐标
points[i * 4 + 2] = rect.width() * (i + 1)
/ (bytes.length - 1);
// 根据bytes[i+1]的值（波形点的值）计算第i+1个点的y坐标
points[i * 4 + 3] = (rect.height() / 2)
+ ((byte) (bytes[i + 1] + 128)) * 128
/ (rect.height() / 2);
}
// 绘制波形曲线
canvas.drawLines(points, paint);
break;
case 3://gif显示的是这段代码的效果
float startX = rect.right/3;
float startY = rect.bottom >> 1;
//canvas.drawCircle(startX, startY, rect.right >> 3, paint);
int count = 0;
if (bytes.length > 360) {
count = 360;
}else{
count = bytes.length;
}
int offset = bytes.length/360;
for (int i = 0; i < count; i=i+offset) {
double angle = (double) ((double) 360 / (double) bytes.length) * (double) i;
Log.d("debug", "angle:" + angle + "--bytes.length:" + bytes.length+"--bytes[i]:"+bytes[i]);
float endX = 0f;
float endY = 0f;
int length = (bytes[i]+128)/2;
if (angle >= 0f && angle < 90f) {
endY = (float) (startY + Math.sin(angle) * length);
endX = (float) (startY + Math.cos(angle) * length);
} else if (angle >= 90f && angle < 180f) {
endY = (float) (startY + Math.sin(angle-90d) * length);
endX = (float) (startX - Math.cos(angle-90d) * length);
} else if (angle >= 180f && angle < 270f) {
endY = (float) (startY - Math.sin(angle-180d) * length);
endX = (float) (startX - Math.cos(angle-180d) * length);
} else if (angle >= 270f && angle < 360f) {
endY = (float) (startY - Math.sin(angle-270d) * length);
endX = (float) (startX + Math.cos(angle-270d) * length);
} else {
endX = 0f;
endY = 0f;
}
paint.setColor(Color.BLACK);
canvas.drawLine(startX, startY, endX, endY, paint);

}
break;
}
}

}

<com.buxiaohui.myapp.widget.MusicFrequency android:id="@+id/frequency"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/white"
/>