Android中自定义View实现圆环等待及相关的音量调节效果

圆环交替、等待效果

效果就这样，分析了一下，大概有这几个属性，两个颜色，一个速度，一个圆环的宽度。
自定View的几个步骤：
1、自定义View的属性
2、在View的构造方法中获得我们自定义的属性
3、重写onMesure 
4、重写onDraw

1、自定义属性：

<?xml version="1.0" encoding="utf-8"?> 
<resources> 
  <attr name="firstColor" fORMat="color" /> 
  <attr name="secondColor" format="color" /> 
  <attr name="circleWidth" format="dimension" /> 
  <attr name="speed" format="integer" /> 
  <declare-styleable name="CustomProgressBar"> 
    <attr name="firstColor" /> 
    <attr name="secondColor" /> 
    <attr name="circleWidth" /> 
    <attr name="speed" /> 
  </declare-styleable> 
</resources> 

2、在View的构造方法中获得我们自定义的属性

 
  private int mFirstColor; 
   
  private int mSecondColor; 
   
  private int mCircleWidth; 
   
  private Paint mPaint; 
   
  private int mProgress; 
   
  private int mSpeed; 
   
  private boolean isNext = false; 
  public CustomProgressBar(Context context, AttributeSet attrs) 
  { 
    this(context, attrs, 0); 
  } 
  public CustomProgressBar(Context context) 
  { 
    this(context, null); 
  } 
   
  public CustomProgressBar(Context context, AttributeSet attrs, int defStyle) 
  { 
    super(context, attrs, defStyle); 
    TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.CustomProgressBar, defStyle, 0); 
    int n = a.getIndexCount(); 
    for (int i = 0; i < n; i++) 
    { 
      int attr = a.getIndex(i); 
      switch (attr) 
      { 
      case R.styleable.CustomProgressBar_firstColor: 
        mFirstColor = a.getColor(attr, Color.GREEN); 
        break; 
      case R.styleable.CustomProgressBar_secondColor: 
        mSecondColor = a.getColor(attr, Color.RED); 
        break; 
      case R.styleable.CustomProgressBar_circleWidth: 
        mCircleWidth = a.getDimensionPixelSize(attr, (int) TypedValue.applyDimension( 
            TypedValue.COMPLEX_UNIT_PX, 20, getResources().getDisplayMetrics())); 
        break; 
      case R.styleable.CustomProgressBar_speed: 
        mSpeed = a.getInt(attr, 20);// 默认20 
        break; 
      } 
    } 
    a.recycle(); 
    mPaint = new Paint(); 
    // 绘图线程 
    new Thread() 
    { 
      public void run() 
      { 
        while (true) 
        { 
          mProgress++; 
          if (mProgress == 360) 
          { 
            mProgress = 0; 
            if (!isNext) 
              isNext = true; 
            else 
              isNext = false; 
          } 
          postInvalidate(); 
          try 
          { 
            Thread.sleep(mSpeed); 
          } catch (InterruptedException e) 
          { 
            e.printStackTrace(); 
          } 
        } 
      }; 
    }.start(); 
  } 

3、直接重写onDraw，这不需要重写onMeasure

@Override 
  protected void onDraw(canvas canvas) 
  { 
    int centre = getWidth() / 2; // 获取圆心的x坐标 
    int radius = centre - mCircleWidth / 2;// 半径 
    mPaint.setStrokeWidth(mCircleWidth); // 设置圆环的宽度 
    mPaint.setAntiAlias(true); // 消除锯齿 
    mPaint.setStyle(Paint.Style.STROKE); // 设置空心 
    RectF oval = new RectF(centre - radius, centre - radius, centre + radius, centre + radius); // 用于定义的圆弧的形状和大小的界限 
    if (!isNext) 
    {// 第一颜色的圈完整，第二颜色跑 
      mPaint.setColor(mFirstColor); // 设置圆环的颜色 
      canvas.drawCircle(centre, centre, radius, mPaint); // 画出圆环 
      mPaint.setColor(mSecondColor); // 设置圆环的颜色 
      canvas.drawArc(oval, -90, mProgress, false, mPaint); // 根据进度画圆弧 
    } else 
    { 
      mPaint.setColor(mSecondColor); // 设置圆环的颜色 
      canvas.drawCircle(centre, centre, radius, mPaint); // 画出圆环 
      mPaint.setColor(mFirstColor); // 设置圆环的颜色 
      canvas.drawArc(oval, -90, mProgress, false, mPaint); // 根据进度画圆弧 
    } 
  } 

大功完成了，当然了，唯一比较纠结的地方就是两个颜色何时切换，如何切换，我采用上面的办法，你也可以自己想想怎么实现。

视频音量调控

这样一个效果使用自定义View来实现的话和圆环的思路差不多，所以我们一起来看：
1、先分许需要的属性，两个小块的颜色、一张中间的图片、间隙大小、一个多少个块块。分析完毕，开始写attr.xml

<?xml version="1.0" encoding="utf-8"?> 
<resources> 
  <attr name="firstColor" format="color" /> 
  <attr name="secondColor" format="color" /> 
  <attr name="circleWidth" format="dimension" /> 
  <attr name="dotCount" format="integer" /> 
  <attr name="splitSize" format="integer" /> 
  <attr name="bg" format="reference"></attr> 
  <declare-styleable name="CustomVolumControlBar"> 
    <attr name="firstColor" /> 
    <attr name="secondColor" /> 
    <attr name="circleWidth" /> 
    <attr name="dotCount" /> 
    <attr name="splitSize" /> 
    <attr name="bg" /> 
  </declare-styleable> 
</resources> 

2、在构造中获取这些属性：

 
  private int mFirstColor; 
   
  private int mSecondColor; 
   
  private int mCircleWidth; 
   
  private Paint mPaint; 
   
  private int mCurrentCount = 3; 
   
  private Bitmap mImage; 
   
  private int mSplitSize; 
   
  private int mCount; 
  private Rect mRect; 
  public CustomVolumControlBar(Context context, AttributeSet attrs) 
  { 
    this(context, attrs, 0); 
  } 
  public CustomVolumControlBar(Context context) 
  { 
    this(context, null); 
  } 
   
  public CustomVolumControlBar(Context context, AttributeSet attrs, int defStyle) 
  { 
    super(context, attrs, defStyle); 
    TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.CustomVolumControlBar, defStyle, 0); 
    int n = a.getIndexCount(); 
    for (int i = 0; i < n; i++) 
    { 
      int attr = a.getIndex(i); 
      switch (attr) 
      { 
      case R.styleable.CustomVolumControlBar_firstColor: 
        mFirstColor = a.getColor(attr, Color.GREEN); 
        break; 
      case R.styleable.CustomVolumControlBar_secondColor: 
        mSecondColor = a.getColor(attr, Color.CYAN); 
        break; 
      case R.styleable.CustomVolumControlBar_bg: 
        mImage = BitmapFactory.decodeResource(getResources(), a.getResourceId(attr, 0)); 
        break; 
      case R.styleable.CustomVolumControlBar_circleWidth: 
        mCircleWidth = a.getDimensionPixelSize(attr, (int) TypedValue.applyDimension( 
            TypedValue.COMPLEX_UNIT_PX, 20, getResources().getDisplayMetrics())); 
        break; 
      case R.styleable.CustomVolumControlBar_dotCount: 
        mCount = a.getInt(attr, 20);// 默认20 
        break; 
      case R.styleable.CustomVolumControlBar_splitSize: 
        mSplitSize = a.getInt(attr, 20); 
        break; 
      } 
    } 
    a.recycle(); 
    mPaint = new Paint(); 
    mRect = new Rect(); 
  } 

3、重写onDraw

@Override 
  protected void onDraw(Canvas canvas) 
  { 
    mPaint.setAntiAlias(true); // 消除锯齿 
    mPaint.setStrokeWidth(mCircleWidth); // 设置圆环的宽度 
    mPaint.setStrokeCap(Paint.Cap.ROUND); // 定义线段断电形状为圆头 
    mPaint.setAntiAlias(true); // 消除锯齿 
    mPaint.setStyle(Paint.Style.STROKE); // 设置空心 
    int centre = getWidth() / 2; // 获取圆心的x坐标 
    int radius = centre - mCircleWidth / 2;// 半径 
     
    drawOval(canvas, centre, radius); 
     
    int relRadius = radius - mCircleWidth / 2;// 获得内圆的半径 
     
    mRect.left = (int) (relRadius - Math.sqrt(2) * 1.0f / 2 * relRadius) + mCircleWidth; 
     
    mRect.top = (int) (relRadius - Math.sqrt(2) * 1.0f / 2 * relRadius) + mCircleWidth; 
    mRect.bottom = (int) (mRect.left + Math.sqrt(2) * relRadius); 
    mRect.right = (int) (mRect.left + Math.sqrt(2) * relRadius); 
     
    if (mImage.getWidth() < Math.sqrt(2) * relRadius) 
    { 
      mRect.left = (int) (mRect.left + Math.sqrt(2) * relRadius * 1.0f / 2 - mImage.getWidth() * 1.0f / 2); 
      mRect.top = (int) (mRect.top + Math.sqrt(2) * relRadius * 1.0f / 2 - mImage.getHeight() * 1.0f / 2); 
      mRect.right = (int) (mRect.left + mImage.getWidth()); 
      mRect.bottom = (int) (mRect.top + mImage.getHeight()); 
    } 
    // 绘图 
    canvas.drawBitmap(mImage, null, mRect, mPaint); 
  } 
   
  private void drawOval(Canvas canvas, int centre, int radius) 
  { 
     
    float itemSize = (360 * 1.0f - mCount * mSplitSize) / mCount; 
    RectF oval = new RectF(centre - radius, centre - radius, centre + radius, centre + radius); // 用于定义的圆弧的形状和大小的界限 
    mPaint.setColor(mFirstColor); // 设置圆环的颜色 
    for (int i = 0; i < mCount; i++) 
    { 
      canvas.drawArc(oval, i * (itemSize + mSplitSize), itemSize, false, mPaint); // 根据进度画圆弧 
    } 
    mPaint.setColor(mSecondColor); // 设置圆环的颜色 
    for (int i = 0; i < mCurrentCount; i++) 
    { 
      canvas.drawArc(oval, i * (itemSize + mSplitSize), itemSize, false, mPaint); // 根据进度画圆弧 
    } 
  } 

这里需要注意下：
画块：首先根据块数量和间隙计算，每个块所占的比例。
画图：当图比较大时，直接使用该环内切正方形大小进行约束，当图片比较小时，在正中心的位置绘制。有些数学运算过程，楼主在草稿上画了一会，不复杂，大家自己画画，我就不贴草稿了。

4、添加触摸监听：

 
  public void up() 
  { 
    mCurrentCount++; 
    postInvalidate(); 
  } 
   
  public void down() 
  { 
    mCurrentCount--; 
    postInvalidate(); 
  } 
  private int xDown, xUp; 
  @Override 
  public boolean onTouchEvent(MotionEvent event) 
  { 
    switch (event.getAction()) 
    { 
    case MotionEvent.ACTION_DOWN: 
      xDown = (int) event.getY(); 
      break; 
    case MotionEvent.ACTION_UP: 
      xUp = (int) event.getY(); 
      if (xUp > xDown)// 下滑 
      { 
        down(); 
      } else 
      { 
        up(); 
      } 
      break; 
    } 
    return true; 
  } 

触摸监听也得很简单哈，基本能实现，大家也可以加个最小距离加速度什么的，都行。

最后，效果图：

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