PathPainterEffect.java

package com.mcxtzhang.cstviewdemo.widget;

import android.animation.ValueAnimator;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.DashPathEffect;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PathEffect;
import android.graphics.PathMeasure;
import android.util.AttributeSet;
import android.view.View;
import android.view.animation.LinearInterpolator;

public class PathPainterEffect extends View implements View.OnClickListener{

    private Paint mPaint;
    private Path mPath;
    private PathMeasure mPathMeasure;
    private PathEffect mEffect;
    private float fraction = 0;
    private ValueAnimator mAnimator;

    public PathPainterEffect(Context context) {
        super(context);
    }

    public PathPainterEffect(Context context, AttributeSet attrs) {
        super(context, attrs);
        mPath = new Path();
        mPath.reset();
        mPath.moveTo(100, 100);
        mPath.lineTo(100, 500);
        mPath.lineTo(400, 300);
        mPath.close();//三角形

        //我画一个圆
        //mPath.addRoundRect(200,200,600,600,50,50, Path.Direction.CCW);
/*
        mPath.moveTo(50,100);
        mPath.lineTo(getWidth(),100);*/

        mPaint = new Paint();
        mPaint.setColor(Color.BLACK);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeWidth(5);

        mPathMeasure = new PathMeasure(mPath, false);
        final float length = mPathMeasure.getLength();

        mAnimator = ValueAnimator.ofFloat(1, 0);
        mAnimator.setInterpolator(/*new AccelerateDecelerateInterpolator()*/ new LinearInterpolator());
        mAnimator.setDuration(5000);
        mAnimator.setRepeatCount(ValueAnimator.INFINITE);
        mAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator valueAnimator) {
                fraction = (float) valueAnimator.getAnimatedValue();
/*                mEffect = new DashPathEffect(new float[]{length, length}, fraction * length);
                mPaint.setPathEffect(mEffect);*/
                invalidate();
            }
        });
        setOnClickListener(this);
    }

    public PathPainterEffect(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

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

        //第二个参数表示先吞掉多少
        //第一个参数的 数组里 表示实线和虚线
        mEffect = new DashPathEffect(new float[]{mPathMeasure.getLength(), 200},  mPathMeasure.getLength()*0.5f);
        mPaint.setPathEffect(mEffect);

        canvas.drawPath(mPath, mPaint);
    }

    @Override
    public void onClick(View view) {
        mAnimator.start();
    }
}