private Path path;

private PathMeasure pathMeasure;

private Path dst; // 被截取的路径

private Paint mPaint; // 画笔

// View的宽高

private int height;

private int width;

private float radius; // 空心圆的半径

private float mLength; // path路径的长度

ValueAnimator valueAnimator; // 属性动画

private float mAnimatorValue; // 属性动画返回的百分比

private float stop; // 截取路径时的stopD值

private float start; // 截取路径时的startD值

public LoadingCircleView(Context context) {

this(context,null);

}

public LoadingCircleView(Context context, AttributeSet attrs) {

this(context, attrs,0);

}

public LoadingCircleView(Context context, AttributeSet attrs, int defStyleAttr) {

super(context, attrs, defStyleAttr);

init();

}

private void init() {

radius = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 21, getContext().getResources().getDisplayMetrics()); // 初始化半径

path = new Path();

dst = new Path();

mPaint = new Paint();

pathMeasure = new PathMeasure();

// 设置画笔属性

mPaint.setAntiAlias(true);

mPaint.setColor(0xbfe46d32);

mPaint.setStyle(Paint.Style.STROKE);

mPaint.setStrokeCap(Paint.Cap.ROUND);

mPaint.setStrokeWidth(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 3.5f, getContext().getResources().getDisplayMetrics()));

}

@Override

protected void onSizeChanged(int w, int h, int oldw, int oldh) {

super.onSizeChanged(w, h, oldw, oldh);

width = w;

height = h;

// 勾勒空心圆

path.reset();

path.addCircle(width / 2, height / 2, radius, Path.Direction.CW);

// 生成pathMeasure对象

pathMeasure.setPath(path, true);

// 获取path的长度

mLength = pathMeasure.getLength();

// 通过属性动画取得百分比值，并更新View

valueAnimator = ValueAnimator.ofFloat(0, 1);

valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {

@Override

public void onAnimationUpdate(ValueAnimator animation) {

// 获取动画进行的百分比

mAnimatorValue = (float) animation.getAnimatedValue();

postInvalidate(); // 更新界面

}

});

// 设置动画的属性

valueAnimator.setDuration(2100);

valueAnimator.setRepeatCount(1000);

valueAnimator.setRepeatMode(ValueAnimator.RESTART);

valueAnimator.start();

}

@Override

protected void onDraw(Canvas canvas) {

super.onDraw(canvas);

//为加强动画效果，每次对画布旋转不同角度

canvas.rotate(360.0f * mAnimatorValue - 45.0f, width / 2, height / 2);

//初始化截取的路径

dst.reset();

dst.lineTo(0, 0); // 消除硬件加速的影响

// 更新截取的开始值和结束值：当mAnimatorValue为0或1时，两个值相等

stop = mAnimatorValue * mLength;

start = (float) (stop - ((0.5 - Math.abs(mAnimatorValue - 0.5)) * mLength));

// 截取路径后，并绘制路径

pathMeasure.getSegment(start, stop, dst, true);

canvas.drawPath(dst, mPaint);

// canvas.translate(width/2,height/2);

// Path mPath = new Path();

// Path mDst = new Path();

// PathMeasure mPathMeasure = new PathMeasure();

//// 顺时针画 半径为400px的圆

// mPath.addCircle(0,0, 400, Path.Direction.CW);

// mPathMeasure.setPath(mPath, false);

//

//// 画直线

// mDst.moveTo(110, 0);

// mDst.lineTo(200, 300);

//

//// 截取 0.25 到 0.5 距离的圆弧放置dst中

// mPathMeasure.getSegment(mPathMeasure.getLength() * 0.25f,

// mPathMeasure.getLength() * 0.5f,

// mDst,

// true);

// canvas.drawPath(mDst, paint);

}