高仿网易严选底部弹出菜单

在网易严选的看东西的时候在商品详情页里看到他的底部弹出菜单，本能反应是想用DottomSheetDialog或者PopupWindow来实现，可是发现实现不了他那种效果，于是就自己模仿一个像严选这样的底部弹出菜单。

不管是DottomSheetDialog或者PopupWindow他们的阴影背景都是全部覆盖的，这就造成除了菜单内容的View之外其他都是阴影的，而严选不是这样的。唠叨到此，首先展示效果图如下：

是不是还可以呢，由于代码量不多却注释详细，所以先贴出代码再一一详说:

BottomPopupWindowView类：
“`

public class BottomPopupWindowView extends LinearLayout{

private AnimatorListener animatorListener;//底部内容的Viewprivate FrameLayout base_view;//内容的Viewprivate FrameLayout content_view;//背景的Viewprivate RelativeLayout popup_bg;//xml加载的Viewprivate View bottomPopouView;//外部加载的内容Viewprivate View contentView;//外部加载的底部内容Viewprivate View baseView;//手势的最小值private float minVelocity=0;//加载一次的判断值private boolean mDrawable=true;public void setAnimatorListener(AnimatorListener animatorListener) {    this.animatorListener = animatorListener;}public void setBaseView(View baseView){    this.baseView=baseView;}public void setContextView(View view){    this.contentView=view;}public void setContentView(int id){    this.contentView=LayoutInflater.from(getContext()).inflate(id,null);}public BottomPopupWindowView(Context context) {    this(context,null);}public BottomPopupWindowView(Context context, @Nullable AttributeSet attrs) {    this(context,attrs,0);}public BottomPopupWindowView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {    super(context, attrs, defStyleAttr);    //初始化各种数值    minVelocity=ViewConfiguration.get(getContext()).getScaledTouchSlop();    bottomPopouView= LayoutInflater.from(getContext()).inflate(R.layout.layout_bottom_popup,null);    base_view=(FrameLayout)bottomPopouView.findViewById(R.id.bottom_view);    content_view=(FrameLayout)bottomPopouView.findViewById(R.id.content_view);    popup_bg=(RelativeLayout)bottomPopouView.findViewById(R.id.popup_bg);    //把整个View都加载在LinearLayout里以显示出来    addView(bottomPopouView);    //背景颜色监听    popup_bg.setOnClickListener(new OnClickListener() {        @Override        public void onClick(View v) {            disMissPopupView();        }    });    //屏蔽内容区域点击事件    content_view.setOnClickListener(new OnClickListener() {        @Override        public void onClick(View view){}    });    //屏蔽底部内容区域点击事件    base_view.setOnClickListener(new OnClickListener() {        @Override        public void onClick(View view){}    });    //内容区域判断是否向下，手势向下就关闭弹框    content_view.setOnTouchListener(new OnTouchListener() {        @Override        public boolean onTouch(View view, MotionEvent motionEvent) {            float y1=0,y2=0;            if(motionEvent.getAction() == MotionEvent.ACTION_DOWN) {                y1 = motionEvent.getY();            }            if(motionEvent.getAction() == MotionEvent.ACTION_UP){                y2 = motionEvent.getY();                if((y2-y1)>minVelocity){                    disMissPopupView();                }            }            return false;        }    });}@Overrideprotected void onDraw(Canvas canvas) {    super.onDraw(canvas);    if(mDrawable&&baseView!=null){        //刚开始加载底部内容区域，只需一次就行，多次报错        base_view.addView(baseView);        mDrawable=false;    }}public void showPopouView(){    if(contentView!=null){        //开始动画数据        startAnimation();        //开启背景颜色的渐变动画        popup_bg.setVisibility(View.VISIBLE);        popup_bg.setAnimation(AnimationUtils.loadAnimation(getContext(), R.anim.bp_bottom_bg_in));        //把这个区域全部显示出来        ((BottomPopupWindowView)this).setLayoutParams(new RelativeLayout.LayoutParams(                RelativeLayout.LayoutParams.MATCH_PARENT,RelativeLayout.LayoutParams.MATCH_PARENT));        //假如内容区域        content_view.addView(contentView,0);        content_view.setVisibility(View.VISIBLE);        //开启内容区域动画        content_view.setAnimation(AnimationUtils.loadAnimation(getContext(),R.anim.bp_bottom_view_in));    }}public void disMissPopupView(){    //开始关闭动画数据    endAnimation();    //开启内容区域动画    content_view.setVisibility(View.GONE);    Animation animation=AnimationUtils.loadAnimation(getContext(),R.anim.bp_bottom_view_out);    animation.setAnimationListener(new Animation.AnimationListener() {        @Override        public void onAnimationStart(Animation animation) {}        @Override        public void onAnimationRepeat(Animation animation) {}        @Override        public void onAnimationEnd(Animation animation) {            //等内容区域动画结束后，清楚所有View            content_view.removeAllViews();            //开启背景颜色的渐变动画            popup_bg.setVisibility(View.GONE);            popup_bg.setAnimation(AnimationUtils.loadAnimation(getContext(), R.anim.bp_bottom_bg_out));            //把整个控件的大小恢复到底部View区域的大小            RelativeLayout.LayoutParams layoutParams=new RelativeLayout.LayoutParams(                    RelativeLayout.LayoutParams.MATCH_PARENT,getViewHeight((BottomPopupWindowView)BottomPopupWindowView.this));            layoutParams.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM,-1);            ((BottomPopupWindowView)BottomPopupWindowView.this).setLayoutParams(layoutParams);        }    });    //开始动画    content_view.setAnimation(animation);}//获取View的高度public int getViewHeight(View view){    int width =View.MeasureSpec.makeMeasureSpec(0,View.MeasureSpec.UNSPECIFIED);    int height =View.MeasureSpec.makeMeasureSpec(0,View.MeasureSpec.UNSPECIFIED);    view.measure(width,height);    return view.getMeasuredHeight();}//开始动画数据变化public void startAnimation(){    ValueAnimator valueAnimator = ValueAnimator.ofInt(0,40);    valueAnimator.setDuration(250);    valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {        @Override        public void onAnimationUpdate(ValueAnimator valueAnimator) {            if(animatorListener!=null){                animatorListener.startValue((int) valueAnimator.getAnimatedValue());            }        }    });    valueAnimator.start();}//结束动画数值变化public void endAnimation() {    ValueAnimator valueAnimator = ValueAnimator.ofInt(40,0);    valueAnimator.setDuration(250);    valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {        @Override        public void onAnimationUpdate(ValueAnimator valueAnimator) {            if(animatorListener!=null){                animatorListener.endValue((int) valueAnimator.getAnimatedValue());            }        }    });    valueAnimator.start();}

}

对应的加载的xml布局是：layout_bottom_popou.xml如下：

1.在BottomPopupWindowView是继承LinearLayout，而layout_bottom_popou.xml是这整个BottomPopupWindowView里的骨架，然后在BottomPopupWindowView初始化的时候通过addView()来加载整个骨架布局。在onDraw()里只需加载一次baseView就可以了，不然后重复加载导致报错。这样就初始化成功了，刚开始只会加载baseView的界面，就相当于严选最下面的购物车立即购买等界面。![baseView.png](http://upload-images.jianshu.io/upload_images/925576-b6d39da3e30437a3.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)2.当调用showPopouView()时显示菜单的。startAnimation()方法只是为了产生动画的数据。```popup_bg.setVisibility(View.VISIBLE);popup_bg.setAnimation(AnimationUtils.loadAnimation(getContext(), R.anim.bp_bottom_bg_in)); ```只是为了开启背景渐变的动画没什么说的。最重要的是显示菜单实现是把BottomPopupWindowView的大小扩展到全屏，所以设置```((BottomPopupWindowView)this).setLayoutParams(new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT,RelativeLayout.LayoutParams.MATCH_PARENT)); ```,然后把弹出菜单的View即contentView装进content_view即可，然后开启弹出动画就实现了。3.最后是disMissPopupView()方法关闭弹窗。endAnimation()方法只是为了产生动画的数据。再启动内容域View即content_View的退出动画，在动画结束后用```content_view.removeAllViews(); ```起初菜单内容，再像上面一样开启背景颜色渐变动画，最后只需使BottomPopupWindowView恢复原来的baseView的大小及可以了，具体如下:```  RelativeLayout.LayoutParams layoutParams=new RelativeLayout.LayoutParams(                        RelativeLayout.LayoutParams.MATCH_PARENT,getViewHeight((BottomPopupWindowView)BottomPopupWindowView.this));                layoutParams.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM,-1);                ((BottomPopupWindowView)BottomPopupWindowView.this).setLayoutParams(layoutParams); ```。这就是核心的代码功能了，代码量不多具体细节看上面的源码。有人或许会问返回动画的数据有什么用，很简单就是为了实现严选菜单框出来时整个上面详情的缩放。具体看如下demo,首先给出界面xml,如下:

这就是上面效果图的界面布局，没什么可以说的，再看事例代码如下：

public class MainActivity extends AppCompatActivity implements View.OnClickListener, AnimatorListener {

private BottomPopupWindowView bottomPopupWindowView;private View contentView;private View bottomView;private LinearLayout mainView;@Overrideprotected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    mainView=(LinearLayout)findViewById(R.id.main_view);    bottomView=LayoutInflater.from(this).inflate(R.layout.layout_bottom_view,null);    (bottomView.findViewById(R.id.promptly_buy)).setOnClickListener(this);    (findViewById(R.id.guige)).setOnClickListener(this);    bottomPopupWindowView=(BottomPopupWindowView)findViewById(R.id.bottom_popup);    bottomPopupWindowView.setOnClickListener(this);    bottomPopupWindowView.setBaseView(bottomView);    contentView=LayoutInflater.from(this).inflate(R.layout.layout_content_view,null);    bottomPopupWindowView.setContextView(contentView);    (contentView.findViewById(R.id.ic_cancel)).setOnClickListener(this);    bottomPopupWindowView.setAnimatorListener(this);}@Overridepublic void onClick(View view) {    switch(view.getId()){        case R.id.promptly_buy:        case R.id.ic_cancel:            bottomPopupWindowView.disMissPopupView();            break;        case R.id.guige:            bottomPopupWindowView.showPopouView();            break;    }}@Overridepublic void startValue(int value) {    setMargins (mainView,value-10,value,value-10,value);}@Overridepublic void endValue(int value) {    setMargins (mainView,value,value,value,value);}public static void setMargins (View v, int l, int t, int r, int b) {    if (v.getLayoutParams() instanceof ViewGroup.MarginLayoutParams) {        ViewGroup.MarginLayoutParams p = (ViewGroup.MarginLayoutParams) v.getLayoutParams();        p.setMargins(l, t, r, b);        v.requestLayout();    }}

}


其中设置内容菜单的View
BottomPopupWindowView.setContextView(bottomView);
设置没有显示菜单时候显示的View(注:bottomView的高度要和BottomPopupWindowView的高度一样，具体看demo)
BottomPopupWindowView.setBaseView(bottomView);“`而回调的
public void startValue(int value)和public void endValue(int value)设置动画监听放回的数据，以便根据数据实现动画，严选的弹出和显示商品详情动画很简单就是不断设设置View的间距就可以了。

最后附上demo和源码链接https://github.com/jack921/BottomPopupWindowDemo