安卓沿Path运动轨迹

来源：互联网发布：sql not in() 编辑：程序博客网时间：2024/05/16 08:54

当然是先看效果拉～中间那个圆圈，顺着圆圈的轨迹运动。

实现一个跟随Path路径运动的效果

思路

1.绘制一个路径

2.得到路径的每个点的坐标

3.用属性动画沿着路径点的坐标运动

实现

1.用

mPathMeasure = new PathMeasure(mPath,false);mPathMeasure.getPosTan(0, mCurrentPosition, null);

得到每个点的坐标（我是根据 http://blog.csdn.net/tianjian4592/article/details/47067161 这篇博客学习的）

PathMeasure 就是把 Path “拉直”，然后给了我们一个接口(getLength)告诉我们path的总长度，我们再根据具体的长度取得相应坐标

2.属性动画，用的是ValueAniamtor

代码

package com.example.myapp.view;import android.animation.Animator;import android.animation.ValueAnimator;import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.Path;import android.graphics.PathMeasure;import android.util.AttributeSet;import android.view.View;import android.view.animation.AccelerateDecelerateInterpolator;/** * Created by zyr * DATE: 16-3-7 * Time: 上午11:52 * Email: yanru.zhang@renren-inc.com */public class HeartView extends View {    private Paint mPaint;    private Path mPath;    private Path mPath2;    private Paint mPaint2;    private ValueAnimator valueAnimator;    private PathMeasure mPathMeasure;    private float[] mCurrentPosition = new float[2];    public HeartView(Context context) {        this(context, null);    }    public HeartView(Context context, AttributeSet attrs) {        this(context, attrs, 0);    }    public HeartView(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        init();    }    private void init() {        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);        mPaint.setColor(Color.RED);        mPaint.setTextSize(40);        mPaint.setStyle(Paint.Style.STROKE);        mPaint2 = new Paint(Paint.ANTI_ALIAS_FLAG);        mPaint2.setColor(Color.BLUE);        mPaint2.setTextSize(40);        mPaint2.setStyle(Paint.Style.FILL);        mPath = new Path();        mPath.addCircle(200, 200, 200, Path.Direction.CW);        mPath2 = new Path();        mPathMeasure = new PathMeasure(mPath,false);        mPathMeasure.getPosTan(0, mCurrentPosition, null);        mPath2.moveTo(mCurrentPosition[0], mCurrentPosition[1]);        setLayerType(View.LAYER_TYPE_SOFTWARE, null);//关闭硬件加速        valueAnimator = ValueAnimator.ofFloat(0,mPathMeasure.getLength());        valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {            @Override            public void onAnimationUpdate(ValueAnimator animation) {                float value = (Float)animation.getAnimatedValue();                mPathMeasure.getPosTan(value, mCurrentPosition, null);                mPath2.lineTo(mCurrentPosition[0],mCurrentPosition[1]);                postInvalidate();            }        });        valueAnimator.addListener(new Animator.AnimatorListener() {            @Override            public void onAnimationStart(Animator animation) {            }            @Override            public void onAnimationEnd(Animator animation) {            }            @Override            public void onAnimationCancel(Animator animation) {            }            @Override            public void onAnimationRepeat(Animator animation) {                mPath2 = new Path();                mPathMeasure = new PathMeasure(mPath,false);                mPathMeasure.getPosTan(0, mCurrentPosition, null);                mPath2.moveTo(mCurrentPosition[0], mCurrentPosition[1]);                if(mPaint2.getColor() ==  Color.BLUE){                    mPaint2.setColor(Color.YELLOW);                }else{                    mPaint2.setColor(Color.BLUE);                }            }        });        valueAnimator.setDuration(5000);        valueAnimator.setRepeatCount(-1);        valueAnimator.setInterpolator(new AccelerateDecelerateInterpolator());        valueAnimator.start();    }    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        setMeasuredDimension(500,500);    }    @Override    protected void onDraw(Canvas canvas) {        super.onDraw(canvas);        canvas.drawColor(Color.BLACK);        canvas.save();        canvas.translate(50, 50);        canvas.drawPath(mPath, mPaint);        canvas.drawCircle(mCurrentPosition[0], mCurrentPosition[1], 20, mPaint);        canvas.drawPath(mPath2, mPaint2);        canvas.restore();    }}

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