Android自定义view实现水波进度条控件

通过自定义view实现了一个水滴滴落到水波面，溅起水花并且水波流动上涨的进度条控件。之前看到过好多水波流动的进度条，感觉欠缺些东西，就想到了水滴到水平面，溅起水花然后水流动上涨的进度条效果，于是自己动手写了出来。效果如下，视频录制有些卡顿，实际会流畅很多。

一.用法

1.布局文件中添加WaveProgressView，circleColor属性为圆环颜色，waterColor属性为水波水滴的颜色，progress属性为初始的进度

<com.yhongm.wave_progress_view.WaveProgressView
  android:id="@+id/wave_progress_view"
  android:layout_width="300dp"
  android:layout_height="300dp"
  android:layout_centerInParent="true"
  app:circleColor="#e38854"
  app:progress="0"
  app:waterColor="#5488e3" />

2.WaveProgressView.setProgress()方法设置当前的进度

二.本文实现的逻辑

1,画水波流动，通过三阶贝塞尔曲线画波形，通过不断的改变waveOffsetX和waveOffsetY的值实现流动的效果

/**
   * 生成水波流动
   *
   * @param begin    水波形开始的位置
   * @param waveLength 水波的长度
   * @param waveOffsetX 水波水平的偏移
   * @param waveOffsetY 水波垂直方向的偏移
   * @return
   */
  private Path getWavePath(float begin, int waveLength, int waveOffsetX, int waveOffsetY) {
    Path mPath = new Path();
    mPath.reset();
    mPath.moveTo(waveLength * begin, mCurrentHeight);
    for (int i = 0; i < mWaveCount; i++) {
      mPath.quadTo(waveLength * (begin + 0.25f) + (i * waveLength) + waveOffsetX, mCurrentHeight + waveOffsetY, (waveLength * (begin + 0.5f) + (i * waveLength) + waveOffsetX), mCurrentHeight);
      mPath.quadTo(waveLength * (begin + 0.75f) + (i * waveLength) + waveOffsetX, mCurrentHeight - waveOffsetY, (waveLength * (begin + 1f) + (i * waveLength) + waveOffsetX), mCurrentHeight);
    }
    mPath.lineTo(mWidth, mHeight);
    mPath.lineTo(0, mHeight);
    mPath.close();
    return mPath;
  } 

2.画水滴的形状，水滴的形状是通过一个三角形和一个弧形组成的

/**
   * 水滴的Path
   *
   * @param x  水滴坐标x
   * @param y  水滴坐标y
   * @param size 水滴尺寸
   * @return
   */
  private Path waterDrop(float x, float y, int size) {
    Path mDropPath = new Path();
    mDropPath.moveTo(x - size, y);
    mDropPath.lineTo(x, (float) (y - size * 2.5));
    mDropPath.lineTo(x + size, y);
    mDropPath.addArc(x - size, y - size, x + size, y + size, 0, 180);
    return mDropPath;
  }

3.画水滴滴落到水波的效果，就是沿轴Y轴不断的移动水滴

/**
   * 根据位置画水滴
   *
   * @param x
   * @param y
   * @param canvas
   */
  private void drawDropByLocation(Canvas canvas, int x, int y) {
    Path mDropPath = waterDrop(x, y, 30);
    if (y == (mCurrentHeight + 50)) {
      mDropPaint.setAlpha(0);
    }
    canvas.drawPath(mDropPath, mDropPaint);
  }

4.画最外两侧溅落的水滴，通过三阶贝塞尔曲线模拟左右两侧水滴溅落的路径，随机生成的水滴溅落路径都在这左右两侧内

/**
   * 画两侧水滴飞溅的效果，并且随机生成水滴
   *
   * @param canvas
   * @param x
   * @param y   当前高度
   */
  private synchronized void drawDropSplash(Canvas canvas, int x, int y) {
    PathMeasure mLeftPathMeasure = getOnBothSidesOfPathMeasure(x, y, true);
    PathMeasure mRightPathMeasure = getOnBothSidesOfPathMeasure(x, y, false);

    float[] mLeftPos = new float[2];
    float[] mRightPos = new float[2];
    float[] mLeftTan = new float[2];
    float[] mRightTan = new float[2];

    for (int i = 0; i < 200; i++) {
      float percent = i / 200f;
      mLeftPathMeasure.getPosTan(mLeftPathMeasure.getLength() * percent, mLeftPos, mLeftTan);
      mRightPathMeasure.getPosTan(mRightPathMeasure.getLength() * percent, mRightPos, mRightTan);
      mLeftHashMapPath.put(Math.round(mLeftPos[1]), mLeftPos[0]);
      mRightHashMapPath.put(Math.round(mRightPos[1]), mRightPos[0]);
    }

    if (mRandomHashMap.isEmpty() && mRandomHashMap.size() == 0) {
      pushRandomDrag(y);
    }
    drawRandomDrag(canvas, x, y, mLeftHashMapPath, mRightHashMapPath);

    drawOnBothSidesOfWaterDrop(canvas, mLeftPathMeasure);

    drawOnBothSidesOfWaterDrop(canvas, mRightPathMeasure);

}

/**
   * 产生随机的水滴
   *
   * @param y
   */
  private void pushRandomDrag(int y) {
    Random r = new Random();
    for (int i = 0; i < 20; i++) {
      int randomY = r.nextInt(y);
      if (mLeftHashMapPath.containsKey(randomY)) {
        Float rightValue = mRightHashMapPath.get(randomY);
        Float leftValue = mLeftHashMapPath.get(randomY);
        int roundLeftValue = Math.round(leftValue);
        int roundRightValue = Math.round(rightValue);
        if (roundRightValue == roundLeftValue) {
          roundRightValue++;
        }
        int roundMinus = Math.round(roundRightValue - roundLeftValue);//左右差值
        float randomX = r.nextInt(roundMinus) + mLeftHashMapPath.get(randomY);//左右差值加上最小值,保证随机值在两者之间
        mRandomHashMap.put(randomX, randomY);

      }
    }
}

5.随机生成的水滴沿着三阶贝塞尔曲线移动，形成溅落的效果

/**
   * 画随机生成水滴溅起
   *
   * @param canvas
   * @param x
   * @param y
   * @param size
   * @param randomY
   * @param randomX
   */
  private void drawSmartDropOnPath(Canvas canvas, int x, int y, int size, int randomY, float randomX) {
    Path smartDropPath = new Path();
    smartDropPath.moveTo(x, y + 50);
    if (x < randomX) {
      smartDropPath.cubicTo(x, y + 50, randomX + 30, randomY - 20, randomX, randomY);
    } else {
      smartDropPath.cubicTo(x, y + 50, randomX - 30, randomY - 20, randomX, randomY);
    }
    smartDropPath.lineTo(randomX, randomY + 150);
    PathMeasure pathMeasure = new PathMeasure();
    pathMeasure.setPath(smartDropPath, false);
    float[] pos = new float[2];
    float[] tan = new float[2];
    pathMeasure.getPosTan(pathMeasure.getLength() * mPercent, pos, tan);
    Path path = waterDrop(pos[0], pos[1], size);
    canvas.drawPath(path, mSplashPaint);
  }

完整代码详见 点击打开Github本项目 感兴趣的话帮我点个Star

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