Android自定义View实现波浪动画

<developer.shivam.waveview.Wave
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  app:amplitude="100"
  app:quadrant="0.5"
  app:speed="0.15"/>

<?xml version="1.0" encoding="utf-8"?>
<resources>
 <declare-styleable name="Wave">
  <!--波浪颜色-->
  <attr name="waveColor" format="color"/>
  <!--波浪背景颜色-->
  <attr name="waveBackgroundColor" format="color"/>
  <!--波浪速度-->
  <attr name="speed" format="float"/>
  <!--正弦曲线相关-->
  <!--波浪振幅-->
  <attr name="amplitude" format="integer"/>
  <!--波浪相对于控件的位置-->
  <attr name="quadrant" format="float"/>
  <!--波浪的频率-->
  <attr name="frequency" format="float"/>
 </declare-styleable>
</resources>

final TypedArray array = context.obtainStyledAttributes(set, R.styleable.Wave);
  mSpeed = array.getFloat(R.styleable.Wave_speed, DEFAULT_SPEED);
  mWaveColor = array.getColor(R.styleable.Wave_waveColor, DEFAULT_WAVE_COLOR);
  mWaveBKColor = array.getColor(R.styleable.Wave_waveBackgroundColor, DEFAULT_WAVE_BK_COLOR);
  mAmplitude = array.getInt(R.styleable.Wave_amplitude, DEFAULT_AMPLITUDE);
  mQuadrant = array.getFloat(R.styleable.Wave_quadrant, DEFAULT_QUADRANT);
  mFrequency = array.getFloat(R.styleable.Wave_frequency, DEFAULT_FREQUENCY);
  array.recycle();

@Override
protected void onDraw(Canvas canvas) {
 super.onDraw(canvas);
 final int width = getWidth();
 final int height = getHeight();

 final int waveHeight = (int) (getHeight() * mQuadrant);
 // 绘制背景
 canvas.drawColor(mWaveBKColor);
 mWavePath.moveTo(0, height);
 mWavePath.lineTo(0, waveHeight);
 for (int i = 1; i <= width; i++) {
  // 绘制正弦曲线 y = A Sin(ωt+ ρ) = A sin(2πft + ρ)
  final float y = (float) (waveHeight + mAmplitude * Math.sin(2 * Math.PI * i * mFrequency + mShift));
  mWavePath.lineTo(i, y);
 }
 // 将曲线闭合
 mWavePath.lineTo(width, height);
 canvas.drawPath(mWavePath, mWavePaint);
}

// 创建一个周期任务,它的职责是改变正弦曲线的偏移量
 final class WaveAnimation implements Runnable {

  @Override
  public void run() {
   mWavePath.reset();
   mShift += mSpeed;
   invalidate();
   Wave.this.postDelayed(this, DEFAULT_PERIOD);
  }
 }

// 开始波浪动画
postDelayed(new WaveAnimation(), DEFAULT_PERIOD);

public class Wave extends View {

 // 默认属性值
 private static final int DEFAULT_AMPLITUDE = 200;
 private static final int DEFAULT_PERIOD = 16;
 private static final float DEFAULT_SPEED = .1F;
 private static final float DEFAULT_QUADRANT = .33F;
 private static final float DEFAULT_FREQUENCY = 1F / 360F;
 private static final int DEFAULT_WAVE_COLOR = Color.parseColor("#64B5F6");
 private static final int DEFAULT_WAVE_BK_COLOR = Color.parseColor("#EEEEEE");

 @SuppressWarnings("FieldCanBeLocal")
 @ColorInt
 private int mWaveColor;
 @ColorInt
 private int mWaveBKColor;
 // 振幅
 private int mAmplitude;
 // 波浪位于View的位置
 private float mQuadrant;
 // 波浪的频率,这个值越大,波浪越密集
 private float mFrequency;

 // 速度
 private float mSpeed;
 private float mShift;

 private final Paint mWavePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
 private final Path mWavePath = new Path();



 public Wave(Context context) {
  this(context, null);
 }

 public Wave(Context context, AttributeSet attrs) {
  this(context, attrs, 0);
 }

 public Wave(Context context, AttributeSet attrs, int defStyleAttr) {
  super(context, attrs, defStyleAttr);
  init(context, attrs);
 }

 private void init(Context context, AttributeSet set) {
  final TypedArray array = context.obtainStyledAttributes(set, R.styleable.Wave);
  mSpeed = array.getFloat(R.styleable.Wave_speed, DEFAULT_SPEED);
  mWaveColor = array.getColor(R.styleable.Wave_waveColor, DEFAULT_WAVE_COLOR);
  mWaveBKColor = array.getColor(R.styleable.Wave_waveBackgroundColor, DEFAULT_WAVE_BK_COLOR);
  mAmplitude = array.getInt(R.styleable.Wave_amplitude, DEFAULT_AMPLITUDE);
  mQuadrant = array.getFloat(R.styleable.Wave_quadrant, DEFAULT_QUADRANT);
  mFrequency = array.getFloat(R.styleable.Wave_frequency, DEFAULT_FREQUENCY);
  array.recycle();

  mWavePaint.setStrokeWidth(2);
  mWavePaint.setColor(mWaveColor);

  // 开始波浪动画
  postDelayed(new WaveAnimation(), DEFAULT_PERIOD);
 }


 @Override
 protected void onDraw(Canvas canvas) {
  super.onDraw(canvas);
  final int width = getWidth();
  final int height = getHeight();

  final int waveHeight = (int) (getHeight() * mQuadrant);
  // 绘制背景
  canvas.drawColor(mWaveBKColor);
  mWavePath.moveTo(0, height);
  mWavePath.lineTo(0, waveHeight);
  for (int i = 1; i <= width; i++) {
   // 绘制正弦曲线 y = A Sin(ωt+ ρ) = A sin(2πft + ρ)
   final float y = (float) (waveHeight + mAmplitude * Math.sin(2 * Math.PI * i * mFrequency + mShift));
   mWavePath.lineTo(i, y);
  }
  // 将曲线闭合
  mWavePath.lineTo(width, height);
  canvas.drawPath(mWavePath, mWavePaint);
 }


 final class WaveAnimation implements Runnable {

  @Override
  public void run() {
   mWavePath.reset();
   mShift += mSpeed;
   invalidate();
   Wave.this.postDelayed(this, DEFAULT_PERIOD);
  }
 }
}