你没看错，右上角的那个大圆就是传说中的太阳，^_^
这个动画的难点在于这个“食物”的绘制上吧，不用怀疑，你还是没看错，那些小点就是传说中的食物
首先一步步来，看到这种效果，第一个想到的就是一个普通的小圆，而这个大圆就用贝塞尔绘制，至于为什么用贝塞尔而不是直接绘制一个半圆呢，因为食物是绕着半圆的，紧贴着，你需要拿这个半圆做参照物，不然随便改改布局就乱套了，
然后是小圆也需要围着半圆绕圈，这两个都需要一个已知的point
接下来就开始绘制半圆了，小圆就直接被忽略了
半圆采用 drawPath.cubicTo 来绘制，需要四个点，其中有两个控制点
具体怎么绘制看后面的代码
接下来绘制食物，这下可能一部分人会有点困惑，食物怎么绘制，怎么让食物紧贴着这个半圆去绘制，那我是不是可以照着这个半圆把Y轴的坐标改改，这样另外一个半圆就出现了，只是需要改变下样式，因为食物是一个个小点
这里设置paint的effect就可以改变绘制的样式了
就这样食物出现了
然后就是一个难点了，小圆怎么沿着食物一路吃下去呢，很显然不能直接按照食物的绘制方法来绘制了，因为小圆是会动的，需要加入动画，而不是一下子全绘制，这样就需要知道食物的坐标了，这样才能让小圆绕着食物吃下去
这里需要用到 Evaluator 根据控制点去计算出它本身的一个绘制坐标，贝塞尔是一个公式，可以推算出它的一个坐标点
package com.fragmentapp.view; import android.graphics.PointF; /** * Created by liuzhen on 2018/1/24. */ public class BezierUtil { /** * B(t) = (1 - t)^2 * P0 + 2t * (1 - t) * P1 + t^2 * P2, t ∈ [0,1] * * @param t 曲线长度比例 * @param p0 起始点 * @param p1 控制点 * @param p2 终止点 * @return t对应的点 */ public static PointF CalculateBezierPointForQuadratic(float t, PointF p0, PointF p1, PointF p2) { PointF point = new PointF(); float temp = 1 - t; point.x = temp * temp * p0.x + 2 * t * temp * p1.x + t * t * p2.x; point.y = temp * temp * p0.y + 2 * t * temp * p1.y + t * t * p2.y; return point; } /** * B(t) = P0 * (1-t)^3 + 3 * P1 * t * (1-t)^2 + 3 * P2 * t^2 * (1-t) + P3 * t^3, t ∈ [0,1] * * @param t 曲线长度比例 * @param p0 起始点 * @param p1 控制点1 * @param p2 控制点2 * @param p3 终止点 * @return t对应的点 */ public static PointF CalculateBezierPointForCubic(float t, PointF p0, PointF p1, PointF p2, PointF p3) { PointF point = new PointF(); float temp = 1 - t; point.x = p0.x * temp * temp * temp + 3 * p1.x * t * temp * temp + 3 * p2.x * t * t * temp + p3.x * t * t * t; point.y = p0.y * temp * temp * temp + 3 * p1.y * t * temp * temp + 3 * p2.y * t * t * temp + p3.y * t * t * t; return point; } }
package com.fragmentapp.view; import android.animation.TypeEvaluator; import android.graphics.PointF; /** * Created by liuzhen on 2018/1/24. */ public class PathEvaluator implements TypeEvaluator<PointF> { private PointF mControlPoint1,mControlPoint2; // public PathEvaluator(PointF controlPoint) { // this.mControlPoint1 = controlPoint; // } public PathEvaluator(PointF controlPoint1,PointF controlPoint2) { this.mControlPoint1 = controlPoint1; this.mControlPoint2 = controlPoint2; } @Override public PointF evaluate(float t, PointF startValue, PointF endValue) { return BezierUtil.CalculateBezierPointForCubic(t, startValue, mControlPoint1,mControlPoint2, endValue); } }
有了这些坐标那小圆就可以沿着食物吃下去了，但是随着吃的动作又会发现怎么吃这个问题了，这显然也不是很好操作，本人想了一会，发现这条路行不通，技术还没达标，于是另辟蹊径，用另外的办法去做了，想想是绘制，那就干脆在绘制一条背景色的线
这样食物就会出现被吃掉的效果了，所以在上面有个clears.add的操作
在给小圆添加一张嘴吧
控制angle这个参数，小圆终于可以吃了，然后为了追求更高的一个层次，又添加了一个移动的动画，然后动画开始的时候先让半圆有个上升的过程，这样顿时看起来高大上一些了
最后stop
使用就是两个方法，一个start动画，一个开始吃的动画操作，两个方法，在合适的时候调用就行了，直接上代码
package com.fragmentapp.view.refresh; import android.animation.ValueAnimator; import android.content.Context; import android.graphics.Canvas; import android.graphics.DashPathEffect; import android.graphics.Matrix; import android.graphics.Paint; import android.graphics.Path; import android.graphics.PathDashPathEffect; import android.graphics.PathEffect; import android.graphics.PointF; import android.graphics.RectF; import android.util.AttributeSet; import android.util.Log; import android.view.View; import android.view.animation.LinearInterpolator; import com.fragmentapp.R; import com.fragmentapp.helper.TimeUtil; import com.fragmentapp.view.PathEvaluator; import java.util.ArrayList; import java.util.List; /** * Created by liuzhen on 2018/1/24. */ public class SunHeadView extends View implements IHeadView{ private int mWidth; private int mHeight; private Paint effectPaint,facePaint,clearPaint,defPaint;//这里定义多个属性都是为了能够自定义不同的样式 private RectF rectF = null; private float angle,loadAngle = 45; private ValueAnimator faceVa,arcVa; private int left,top; private boolean isDraw = false; private Path path,foodPath; private PointF startPoint = null,movePoint1 = null,movePoint2 = null,endPoint = null; private List<PointF> clears = null; private PathEffect effect = null; private int faceRadius = 30,foodRadius = 3; public SunHeadView(Context context) { this(context, null, 0); } public SunHeadView(Context context, AttributeSet attrs) { this(context, attrs,0); } public SunHeadView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); init(); } private void init(){ path = new Path(); foodPath = new Path(); foodPath.addCircle(0, 0, foodRadius, Path.Direction.CCW); effectPaint = new Paint(); effectPaint.setAntiAlias(true); effectPaint.setStyle(Paint.Style.STROKE); effectPaint.setColor(getResources().getColor(R.color.color_a9a05c)); effect = new PathDashPathEffect(foodPath, 12, -1, PathDashPathEffect.Style.ROTATE); effectPaint.setPathEffect(effect); facePaint = new Paint(); facePaint.setAntiAlias(true); facePaint.setStyle(Paint.Style.FILL); facePaint.setColor(getResources().getColor(R.color.color_a9a05c)); defPaint = new Paint(); defPaint.setAntiAlias(true); defPaint.setStyle(Paint.Style.FILL); defPaint.setColor(getResources().getColor(R.color.color_a9a05c)); rectF = new RectF(0,0,0,0); startPoint = new PointF(); movePoint1 = new PointF(); movePoint2 = new PointF(); endPoint = new PointF(); clearPaint = new Paint(); clearPaint.setAntiAlias(true); clearPaint.setStyle(Paint.Style.FILL); clearPaint.setColor(getResources().getColor(R.color.white)); clears = new ArrayList<>(); } @Override protected void onLayout(boolean changed, int left, int top, int right, int bottom) { super.onLayout(changed, left, top, right, bottom); if (changed) { mWidth = getWidth(); mHeight = getHeight(); this.left = mWidth / 2; this.top = mHeight / 3; rectF.set(startPoint.x - faceRadius/2,startPoint.y - faceRadius,startPoint.x + faceRadius/2,startPoint.y); } } @Override protected void onDraw(Canvas canvas) { if (!isDraw) return; //绘制“食物” foodPath.reset(); foodPath.moveTo(startPoint.x,startPoint.y); foodPath.cubicTo(movePoint1.x,movePoint1.y,movePoint2.x,movePoint2.y,endPoint.x,endPoint.y); canvas.drawPath(foodPath, effectPaint); //绘制大球 path.reset(); path.moveTo(startPoint.x + faceRadius/2,startPoint.y); path.cubicTo(movePoint1.x,movePoint1.y + faceRadius/2,movePoint2.x,movePoint2.y + faceRadius/2,endPoint.x - faceRadius/2,endPoint.y); canvas.drawPath(path, defPaint); //吃掉“食物” for (PointF f : clears) { RectF rectF = new RectF(f.x-foodRadius*2,f.y-foodRadius*2,f.x+foodRadius*2,f.y+foodRadius*2); canvas.drawOval(rectF,clearPaint); } //绘制小球,需要在最后面绘制 canvas.drawArc(rectF, angle, 360 - angle * 2, true, facePaint); } @Override public View getView() { return this; } /**开始动画*/ public void upAnim(){ if (faceVa != null) faceVa.cancel(); faceVa = null; effectPaint.setColor(getResources().getColor(R.color.color_a9a05c)); facePaint.setColor(getResources().getColor(R.color.color_a9a05c)); clearPaint.setColor(getResources().getColor(R.color.white)); defPaint.setColor(getResources().getColor(R.color.color_a9a05c)); startPoint.set(mWidth*1/2 + faceRadius*2,mHeight + faceRadius); movePoint1.set(mWidth*2/3, 0); movePoint2.set(mWidth*5/6, 0); endPoint.set(mWidth - faceRadius*2,mHeight + faceRadius); clears.clear(); PathEvaluator bezierEvaluator = new PathEvaluator(movePoint1,movePoint2); arcVa = ValueAnimator.ofObject(bezierEvaluator, startPoint, endPoint); arcVa.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {//饶球移动 @Override public void onAnimationUpdate(ValueAnimator valueAnimator) { PointF point = (PointF) valueAnimator.getAnimatedValue(); // if (point.x + faceRadius <= endPoint.x) clears.add(new PointF(point.x,point.y));//保存移动的坐标 //faceRadius/2是为了让小球的中心点刚好在大球的中间 rectF.set(point.x - faceRadius/2,point.y - faceRadius/2,point.x + faceRadius/2,point.y + faceRadius/2); postInvalidate(); } }); arcVa.setInterpolator(new LinearInterpolator()); arcVa.setDuration(2000); arcVa.setRepeatMode(ValueAnimator.RESTART); arcVa.start(); rectF.set(startPoint.x - faceRadius/2,startPoint.y - faceRadius,startPoint.x + faceRadius/2,startPoint.y); angle = loadAngle; faceVa = ValueAnimator.ofFloat(loadAngle , 0); faceVa.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {//吃食物动作 @Override public void onAnimationUpdate(ValueAnimator valueAnimator) { angle = (float)valueAnimator.getAnimatedValue(); postInvalidate(); } }); faceVa.setInterpolator(new LinearInterpolator()); faceVa.setDuration(500); faceVa.setRepeatMode(ValueAnimator.RESTART); faceVa.setRepeatCount(-1); faceVa.start(); } @Override public void startAnim() {//前奏 effectPaint.setColor(getResources().getColor(R.color.transparent)); facePaint.setColor(getResources().getColor(R.color.transparent)); clearPaint.setColor(getResources().getColor(R.color.transparent)); isDraw = true; faceVa = ValueAnimator.ofFloat(0 , mHeight + faceRadius);//大球落下 faceVa.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {//吃食物动作 @Override public void onAnimationUpdate(ValueAnimator valueAnimator) { float val = (float)valueAnimator.getAnimatedValue(); startPoint.set(mWidth*1/2 + faceRadius*2,val); movePoint1.set(mWidth*2/3, 0); movePoint2.set(mWidth*5/6, 0); endPoint.set(mWidth - faceRadius*2,val); postInvalidate(); } }); faceVa.setInterpolator(new LinearInterpolator()); faceVa.setDuration(1000); faceVa.setRepeatMode(ValueAnimator.RESTART); faceVa.start(); } @Override public void stopAnim() { if (arcVa != null) arcVa.cancel(); if (faceVa != null) faceVa.cancel(); arcVa = null; faceVa = null; isDraw = false; } }
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