老早用过小红书app，对于他们客户端笔记这块的设计非常喜欢，恰好去年在小红书的竞争对手公司，公司基于产品的考虑和产品的发展，也需要将app社交化，于是在社区分享这块多多少少参照了小红书的设计，这里面就有一个比较有意思的贴纸，标签等设计，这里用到了GpuImage的库，这个demo我也将代码开源了，有需要的去fork我的github的代码，今天要说的是详情页面的AnimatedPathView实现可以动起来的标签。（之前我们项目中由于时间问题，将这种效果用h5实现了，不过现在回React Native之后，发现实现起来更简单了），今天要说的是用Android实现这种效果。
且看个效果图：
要实现我们这样的效果，首先分析下，线条的绘制和中间圆圈的实现，以及文字的绘制。
对于线条的绘制我们不多说，直接canvas.DrawLine，不过这种线条是死的，不能实现运动的效果，还好Java为我们提供了另一个方法，我们可以用Path去实现，之前做腾讯手写板的时候也是这么做的(可以点击链接查看效果，不过代码没办法公开)，点击打开链接，通过上面说的，我们改变PathEffect的偏移量就可以改变path显示的长度，从而实现动画的效果。而PathEffect有很多子类，从而满足不同的效果，这里不再说明。
[html] view plain copy print ? float percentage = 0.0f; PathEffect effect = new DashPathEffect(new float[]{pathLength, pathLength}, pathLength - pathLength*percentage); 这里贴出AnimatedPathView的完整代码： [html] view plain copy print ? public class AnimatedPathView extends View { private Paint mPaint; private Path mPath; private int mStrokeColor = Color.parseColor("#ff6c6c"); private int mStrokeWidth = 8; private float mProgress = 0f; private float mPathLength = 0f; private float circleX = 0f; private float circleY = 0f; private int radius = 0; private String pathText="化妆包..."; private int textX,textY; public AnimatedPathView(Context context) { this(context, null); init(); } public AnimatedPathView(Context context, AttributeSet attrs) { this(context, attrs, 0); init(); } public AnimatedPathView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.AnimatedPathView); mStrokeColor = a.getColor(R.styleable.AnimatedPathView_pathColor, Color.parseColor("#ff6c6c")); mStrokeWidth = a.getInteger(R.styleable.AnimatedPathView_pathWidth, 8); a.recycle(); init(); } private void init() { mPaint = new Paint(); mPaint.setColor(mStrokeColor); mPaint.setStyle(Paint.Style.STROKE); mPaint.setStrokeWidth(mStrokeWidth); mPaint.setAntiAlias(true); setPath(new Path()); } public void setPath(Path p) { mPath = p; PathMeasure measure = new PathMeasure(mPath, false); mPathLength = measure.getLength(); } public void setPathText(String pathText,int textX,int textY ) { this.pathText=pathText; this.textX=textX; this.textY=textY; } public void setPath(float[]... points) { if (points.length == 0) throw new IllegalArgumentException("Cannot have zero points in the line"); Path p = new Path(); p.moveTo(points[0][0], points[0][1]); for (int i = 1; i < points.length; i++) { p.lineTo(points[i][0], points[i][1]); } //将第一个xy坐标点作为绘制的原点 circleX = points[0][0] - radius / 2; circleY = points[0][1] - radius / 2; setPath(p); } public void setPercentage(float percentage) { if (percentage < 0.0f || percentage > 1.0f) throw new IllegalArgumentException("setPercentage not between 0.0f and 1.0f"); mProgress = percentage; invalidate(); } public void scalePathBy(float x, float y) { Matrix m = new Matrix(); m.postScale(x, y); mPath.transform(m); PathMeasure measure = new PathMeasure(mPath, false); mPathLength = measure.getLength(); } public void scaleCircleRadius(int radius) { this.radius = radius; } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); //绘制圆形 // drawCircle(canvas); //绘线条 drawPathEffect(canvas); //绘制文字 drawText(canvas); canvas.restore(); } private void drawText(Canvas canvas) { mPaint.setTextSize(28); mPaint.setColor(Color.parseColor("#ffffff")); if (canvas!=null&& !TextUtils.isEmpty(pathText)){ canvas.drawText(pathText,textX,textY,mPaint); } invalidate(); } private void drawPathEffect(Canvas canvas) { PathEffect pathEffect = new DashPathEffect(new float[]{mPathLength, mPathLength}, (mPathLength - mPathLength * mProgress)); mPaint.setPathEffect(pathEffect); mPaint.setStrokeWidth(4); mPaint.setColor(Color.parseColor("#ffffff")); canvas.save(); canvas.translate(getPaddingLeft(), getPaddingTop()); canvas.drawPath(mPath, mPaint); } private void drawCircle(Canvas canvas) { int strokenWidth = 25; mPaint.setStrokeWidth(strokenWidth); mPaint.setColor(Color.parseColor("#ffffff")); canvas.drawCircle(circleX, circleY, radius , mPaint); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); int widthSize = MeasureSpec.getSize(widthMeasureSpec); int heightSize = MeasureSpec.getSize(heightMeasureSpec); int widthMode = MeasureSpec.getMode(widthMeasureSpec); int heightMode = MeasureSpec.getMode(widthMeasureSpec); int measuredWidth, measuredHeight; if (widthMode == MeasureSpec.AT_MOST) throw new IllegalStateException("AnimatedPathView cannot have a WRAP_CONTENT property"); else measuredWidth = widthSize; if (heightMode == MeasureSpec.AT_MOST) throw new IllegalStateException("AnimatedPathView cannot have a WRAP_CONTENT property"); else measuredHeight = heightSize; setMeasuredDimension(measuredWidth, measuredHeight); } } 这段代码借鉴了 点击打开链接 的部分代码，并在此基础上做了更多的判断和改变，以满足本文开头说说的那种需要，上面的代码只是实现了画线条的效果，那么如何实现中间圆圈的闪烁呢，其实也很简单，我们可以用动画来实现（View动画），这里我们大可以自己自定义一个View实现，而这个View包含了圆圈闪烁和画线，按照上面的逻辑我们写一个自定义的View，代码如下： [html] view plain copy print ? public class PointView extends FrameLayout { private Context mContext; private List<PointScaleBean> points; private FrameLayout layouPoints; private AnimatedPathView animatedPath; private int radius=10; private String text="图文标签 $99.00"; public PointView(Context context) { this(context, null); } public PointView(Context context, AttributeSet attrs) { this(context, attrs, 0); } public PointView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); initView(context, attrs); } private void initView(Context context, AttributeSet attrs) { this.mContext = context; View imgPointLayout = inflate(context, R.layout.layout_point, this); layouPoints = (FrameLayout) imgPointLayout.findViewById(R.id.layouPoints); animatedPath=(AnimatedPathView) imgPointLayout.findViewById(R.id.animated_path); } public void addPoints(int width, int height) { addPoint(width, height); } public void setPoints(List<PointScaleBean> points) { this.points = points; } private void addPoint(int width, int height) { layouPoints.removeAllViews(); for (int i = 0; i < points.size(); i++) { double width_scale = points.get(i).widthScale; double height_scale = points.get(i).heightScale; LinearLayout view = (LinearLayout) LayoutInflater.from(mContext).inflate(R.layout.layout_img_point, this, false); ImageView imageView = (ImageView) view.findViewById(R.id.imgPoint); imageView.setTag(i); AnimationDrawable animationDrawable = (AnimationDrawable) imageView.getDrawable(); animationDrawable.start(); LayoutParams layoutParams = (LayoutParams) view.getLayoutParams(); layoutParams.leftMargin = (int) (width * width_scale); layoutParams.topMargin = (int) (height * height_scale); // imageView.setOnClickListener(this); layouPoints.addView(view, layoutParams); } initView(); initPathAnimated(); } private void initPathAnimated() { ViewTreeObserver observer = animatedPath.getViewTreeObserver(); if(observer != null){ observer.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() { @Override public void onGlobalLayout() { animatedPath.getViewTreeObserver().removeGlobalOnLayoutListener(this); animatedPath.scaleCircleRadius(radius); animatedPath.scalePathBy(animatedPath.getWidth()/2,animatedPath.getHeight()/2); float[][] points = new float[][]{ {animatedPath.getWidth()/2-radius/2,animatedPath.getHeight()/2-radius/2}, {animatedPath.getWidth()/2- UIUtils.dp2px(mContext,30), animatedPath.getHeight()/2- UIUtils.dp2px(mContext,40)}, {animatedPath.getWidth()/2-UIUtils.dp2px(mContext,150), animatedPath.getHeight()/2- UIUtils.dp2px(mContext,40)}, }; animatedPath.setPath(points); // animatedPath.setPathText(text,animatedPath.getWidth()/2-UIUtils.dp2px(mContext,150), animatedPath.getHeight()/2- UIUtils.dp2px(mContext,50)); } }); } } private void initView() { animatedPath.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { ObjectAnimator anim = ObjectAnimator.ofFloat(view, "percentage", 0.0f, 1.0f); anim.setDuration(2000); anim.setInterpolator(new LinearInterpolator()); anim.start(); } }); } } 上面对应的布局和资源文件：layou_point.xml
[html] view plain copy print ? <?xml version="1.0" encoding="utf-8"?> <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="wrap_content" > <com.yju.app.widght.path.AnimatedPathView android:id="@+id/animated_path" android:layout_width="match_parent" android:layout_height="wrap_content" /> <FrameLayout android:id="@+id/layouPoints" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_gravity="center" /> </FrameLayout> layout_img_point.xml [html] view plain copy print ? <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:gravity="center" android:orientation="vertical"> <ImageView android:id="@+id/imgPoint" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/point_img" /> </LinearLayout> 文中用到的Anim就是帧动画了， [html] view plain copy print ? <?xml version="1.0" encoding="utf-8"?> <animation-list xmlns:android="http://schemas.android.com/apk/res/android" android:oneshot="false"> <item android:drawable="@drawable/point_img1" android:duration="100" /> ....省略n多图片资源 <item android:drawable="@drawable/point_img13" android:duration="100" /> </animation-list> 而最后我们只需要在我们自己的MainActivity中添加简单的代码既可实现上面的效果： [html] view plain copy print ? private void initPointView() { List<PointScaleBean> list=new ArrayList<>(); PointScaleBean point=new PointScaleBean(); point.widthScale = 0.36f; point.heightScale = 0.75f; list.add(point); pointView.setPoints(list); pointView.addPoints(ViewGroup.LayoutParams.MATCH_PARENT,ViewGroup.LayoutParams.MATCH_PARENT); } 对于布局我是这么做的，将View的父布局的背景加一个图片，实际的开发中大家可以写一个相对的布局，这个就能实现实时的效果了，好了就写到这里，有疑问请留言或者加群(278792776)。 相关资源：AnimatedPathView.zip