Android PathMeasure使用

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关于Path和PathMeasure的使用 PathMeasure可以测量路径上的点和长度，可做轨迹动画效果。

public class mypathmeasure extends View {private Path p;private PathMeasure pathMeasure;public mypathmeasure(Context context) {this(context, null);// TODO Auto-generated constructor stub}public mypathmeasure(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);mPaint.setDither(true);mPaint.setColor(0xff0000ff);mPaint.setStyle(Paint.Style.STROKE);}private void init() {p = new Path();mPaint.setStyle(Paint.Style.STROKE);p.moveTo(0, getHeight() / 2);p.cubicTo(getWidth() / 2 - 60, getHeight() / 2 - 60,getWidth() / 2 + 60, getHeight() / 2 + 60, getWidth(),getHeight() / 2);pathMeasure = new PathMeasure(p, false);}@Overrideprotected void onSizeChanged(int w, int h, int oldw, int oldh) {// TODO Auto-generated method stubsuper.onSizeChanged(w, h, oldw, oldh);init();}public mypathmeasure(Context context, AttributeSet attrs) {this(context, attrs, 0);}private Paint mPaint;private float[] floats = new float[2];private boolean first = true;@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);mPaint.setColor(0xffff0000);canvas.drawPath(p, mPaint);mPaint.setColor(0xff00ff00);canvas.drawCircle(floats[0], floats[1], 10, mPaint);if (first) {first = false;startAnimation();}}void startAnimation() {ValueAnimator animation = ValueAnimator.ofFloat(0,pathMeasure.getLength());animation.setDuration(4000);animation.addUpdateListener(new AnimatorUpdateListener() {@Overridepublic void onAnimationUpdate(ValueAnimator animation) {float v = (Float) animation.getAnimatedValue();pathMeasure.getPosTan(v, floats, null);postInvalidate();}});animation.start();}}

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