【Android】 给我一个Path，还你一个动画View

好的，以下是一个简单的实现：

public class PathAnimationView extends View {

    private static final int DEFAULT_DURATION = 2000; // 默认动画时长为2秒

    private Path mPath;
    private Paint mPaint;
    private PathMeasure mPathMeasure;
    private float mPathLength;

    private ValueAnimator mValueAnimator;

    private float mAnimatedValue;

    private float[] mPos;
    private float[] mTan;

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

    public PathAnimationView(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public PathAnimationView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        mPaint = new Paint();
        mPaint.setColor(Color.RED);
        mPaint.setStrokeWidth(5);
        mPaint.setStyle(Paint.Style.STROKE);

        mPath = new Path();
        mPath.addCircle(0, 0, 100, Path.Direction.CW);

        mPathMeasure = new PathMeasure(mPath, false);
        mPathLength = mPathMeasure.getLength();

        mPos = new float[2];
        mTan = new float[2];

        mValueAnimator = ValueAnimator.ofFloat(0, 1);
        mValueAnimator.setDuration(DEFAULT_DURATION);
        mValueAnimator.setRepeatCount(ValueAnimator.INFINITE);
        mValueAnimator.setInterpolator(new LinearInterpolator());
        mValueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator animation) {
                mAnimatedValue = (float) animation.getAnimatedValue();
                invalidate();
            }
        });
    }

    public void startAnimation() {
        mValueAnimator.start();
    }

    public void stopAnimation() {
        mValueAnimator.cancel();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawColor(Color.WHITE);

        float distance = mPathLength * mAnimatedValue;
        mPathMeasure.getPosTan(distance, mPos, mTan);

        canvas.drawPath(mPath, mPaint);
        canvas.drawCircle(mPos[0], mPos[1], 20, mPaint);
    }
}

使用方法：

PathAnimationView pathAnimationView = new PathAnimationView(context);
addView(pathAnimationView);

pathAnimationView.startAnimation(); // 开始动画

pathAnimationView.stopAnimation(); // 停止动画

这是一个简单的 Path 动画，通过 ValueAnimator 来控制动画进度，再根据 PathMeasure 获取路径上的点，最后绘制圆点实现动画效果。你可以根据具体需求修改 Path，以及动画时长等参数。