Android卫星菜单

Android小白第一次写博客，心情无比激动。下面给大家展示一下卫星菜单的实现。
1.简单介绍卫星菜单
在应用程序中，有很多展示菜单的方式，但其功能都是大同小异，这样一来，菜单的美观以及展示方式就显的尤为重要，卫星菜单就是很不错的一种。下面是本案例的gif图：

2.学习本案例需要的知识点
（1）动画
（2）自定义ViewGroup
（3）自定义属性
a、attr.xml
b、在布局中使用自定义属性
c、在代码中获取自定义属性值
3.首先分析我们的卫星菜单需要那些自定义属性并书写代码
首先，菜单可以显示在屏幕的四个角，所以我们需要一个属性来确定它的位置，菜单在屏幕的四个角比较美观，在这里用到枚举。
其次，我们还需要一个展开半径，因此还需要自定义半径。
下面是attr.xml

<?xml version="1.0" encoding="utf-8"?><resources>    <attr name="position">        <enum name="left_top" value="0" />        <enum name="left_bottom" value="1" />        <enum name="right_top" value="2" />        <enum name="right_bottom" value="3" />    </attr>    <attr name="radius" format="dimension"/>    <declare-styleable name="SateMenu">        <attr name="radius"  />        <attr name="position"  />    </declare-styleable></resources>

4.自定义ViewGroup

–继承ViewGroup 以相关属性

public class SateMenu extends ViewGroup implements View.OnClickListener {    private int animationTime;    //动画时间    private int radius;    //展开半径    private int pos;    //从自定义属性中获取的菜单位置    private State state;    //菜单状态    private int l = 0, t = 0;    //左上值    private View centerBtn = null;    //展开按钮    private MenuItemListener menuItemListener;    //菜单项点击监听    private Position position;    //枚举型菜单位置    private enum Position {    //位置枚举        LEFT_TOP, LEFT_BOTTOM, RIGHT_TOP, RIGHT_BOTTOM    }    private enum State {    //菜单状态枚举        OPEN, COLSE    }

–构造方法

public SateMenu(Context context) {        //一个参数构造方法调用两个参数构造方法        this(context, null);    }    public SateMenu(Context context, AttributeSet attrs) {        //两个参数构造方法调用三个个参数构造方法        this(context, attrs, 0);    }    public SateMenu(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        animationTime = 500;    //设置动画展开时间        TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.SateMenu, defStyleAttr, 0); //获取自定义属性值集合        radius = (int) a.getDimension(R.styleable.SateMenu_radius,                TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 100, getResources().getDisplayMetrics()));  //获取半径并转化为像素值        state = State.COLSE;    //设置菜单默认关闭        pos = a.getInt(R.styleable.SateMenu_position, 0);    //获取位置        //将位置转化为枚举值 （这样就把无意义的int转化为有意义的枚举值）        switch (pos) {            case 0:                position = Position.LEFT_TOP;                break;            case 1:                position = Position.LEFT_BOTTOM;                break;            case 2:                position = Position.RIGHT_TOP;                break;            case 3:                position = Position.RIGHT_BOTTOM;                break;        }    }

–重写onMeasure方法

    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        super.onMeasure(widthMeasureSpec, heightMeasureSpec);        int count = getChildCount();        //测量子view        for (int i = 0; i < count; i++) {            measureChild(getChildAt(i), widthMeasureSpec, heightMeasureSpec);        }    }

–重写onLayout方法

    @Override    protected void onLayout(boolean changed, int l, int t, int r, int b) {        if (changed)            btnLayout();    }    private void btnLayout() {        centerBtn = getChildAt(0);        if (position == Position.RIGHT_BOTTOM || position == Position.RIGHT_TOP) {            //如果菜单设置在屏幕的右侧，那么展开按钮的l值=ViewGroup宽度-按钮宽度            l = getMeasuredWidth() - centerBtn.getMeasuredWidth();        }        if (position == Position.LEFT_BOTTOM || position == Position.RIGHT_BOTTOM) {            //如果菜单设置在屏幕的下边，那么展开按钮的t值=ViewGroup高度-按钮高度            t = getMeasuredHeight() - centerBtn.getMeasuredHeight();        }        //设置展开按钮位置        centerBtn.layout(l, t, l + centerBtn.getMeasuredWidth(), t + centerBtn.getMeasuredHeight());        childBtnlayout();    //设置子按钮位置        centerBtn.setOnClickListener(this);    }

–设置子按钮位置需要一点点数学知识，下面我以主菜单在右下角为例，画一个简图，图片对应右侧第一个公式

    private void childBtnlayout() {        int childMuneCount = getChildCount() - 1;        //角度等于90度/子按钮个数-1        float a = (float) (Math.PI / 2 / (childMuneCount - 1));        int cl, ct;    //分别是子按钮的 左 上         for (int i = 0; i < childMuneCount; i++) {            if (position == Position.RIGHT_BOTTOM || position == Position.RIGHT_TOP) {                cl = (int) (l - radius * Math.cos(i * a));            } else {                cl = (int) (l + radius * Math.cos(i * a));            }            if (position == Position.LEFT_TOP || position == Position.RIGHT_TOP) {                ct = (int) (t + radius * Math.sin(i * a));            } else {                ct = (int) (t - radius * Math.sin(i * a));            }            View childView = getChildAt(i + 1);            childView.layout(cl, ct, cl + childView.getMeasuredWidth(), ct + childView.getMeasuredHeight());            childView.setOnClickListener(this);            childView.setTag(i);            childView.setVisibility(View.GONE);        }    }

–动画的展开与关闭，这里没有用属性动画，原理是：当用户关闭菜单的时候，将子按钮隐藏，打开才打的时候在把子按钮显示出来

    private void changeState() {        int childMuneCount = getChildCount() - 1;        //设置展开按钮旋转动画        Animation animation = new RotateAnimation(0, 360, centerBtn.getMeasuredWidth() / 2, centerBtn.getMeasuredHeight() / 2);        animation.setDuration(animationTime);        centerBtn.setAnimation(animation);        animation.start();        View childView;        //子按钮有两个动画（位移、旋转），所以这里用到动画集，这里也涉及到一些数学知识，和之前设置子按钮位置差不多        AnimationSet animationSet;        Animation translateAnimation;        Animation rotateAnimation;        int cl, ct;        float a = (float) (Math.PI / 2 / (childMuneCount - 1));        if (state == State.OPEN) {            state = State.COLSE;            for (int i = 0; i < childMuneCount; i++) {                if (position == Position.RIGHT_BOTTOM || position == Position.RIGHT_TOP)                    cl = (int) (radius * Math.cos(i * a));                else                    cl = (int) (-radius * Math.cos(i * a));                if (position == Position.LEFT_TOP || position == Position.RIGHT_TOP)                    ct = (int) (-radius * Math.sin(i * a));                else                    ct = (int) (radius * Math.sin(i * a));                childView = getChildAt(i + 1);                childView.setVisibility(View.GONE);                translateAnimation = new TranslateAnimation(0, cl, 0, ct);                translateAnimation.setDuration(animationTime);                rotateAnimation = new RotateAnimation(0, 360, childView.getMeasuredHeight() / 2, childView.getMeasuredHeight() / 2);                rotateAnimation.setDuration(animationTime);                animationSet = new AnimationSet(true);                animationSet.addAnimation(rotateAnimation);                animationSet.addAnimation(translateAnimation);                childView.setAnimation(animationSet);                animationSet.start();                childView.setVisibility(View.GONE);            }        } else {            state = State.OPEN;            for (int i = 0; i < childMuneCount; i++) {                if (position == Position.RIGHT_BOTTOM || position == Position.RIGHT_TOP)                    cl = (int) (radius * Math.cos(i * a));                else                    cl = (int) (-radius * Math.cos(i * a));                if (position == Position.LEFT_TOP || position == Position.RIGHT_TOP)                    ct = (int) (-radius * Math.sin(i * a));                else                    ct = (int) (radius * Math.sin(i * a));                childView = getChildAt(i + 1);                childView.setVisibility(View.GONE);                translateAnimation = new TranslateAnimation(cl, 0, ct, 0);                translateAnimation.setDuration(animationTime);                rotateAnimation = new RotateAnimation(360, 0, childView.getMeasuredHeight() / 2, childView.getMeasuredHeight() / 2);                rotateAnimation.setDuration(animationTime);                animationSet = new AnimationSet(true);                animationSet.addAnimation(rotateAnimation);                animationSet.addAnimation(translateAnimation);                childView.setAnimation(animationSet);                animationSet.start();                childView.setVisibility(View.VISIBLE);            }        }    }

–写到这里我们的卫星菜单已经可以展现出来的，运行一下，效果还是不错的。美中不足的是，子按钮还没有点击事件，下面我们就将这个小小的不足补充一下。我们可以通过给子按钮添加点击事件来监听它，但点击之后要做的事情不可能写在ViewGroup中，这就需要用接口进行回调。大家看一下在设置子按钮位置的时候有这样一句代码 childView.setTag(i); 它的目的就是给子按钮添加索引，接下来看一下具体怎样实现的。

    @Override    public void onClick(View v) {        if (v.getId() == centerBtn.getId()) {            changeState();        } else {            if (menuItemListener != null) {                menuItemListener.onclick((Integer) v.getTag());            }        }    }    public interface MenuItemListener {        void onclick(int position);    }    public void setMenuItemListener(MenuItemListener menuItemListener) {        this.menuItemListener = menuItemListener;    }

–到这里我们已经完全实现了卫星菜单的所有功能，但大家有没有发现，一些菜单在展开之后，我们点击其他区域，菜单会自动收起来，所以我们还要给我们的ViewGroup添加onTouchEvent事件，在菜单展开的时候，他把菜单收起来，并将此次点击拦截。

    @Override    public boolean onTouchEvent(MotionEvent event) {        if (state == State.OPEN) {            changeState();            return true;    //拦截        }        return super.onTouchEvent(event);    }

5.下面试用一下我们编写的卫星菜单，看一下成果。
activity_main.xml

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    xmlns:wzw="http://schemas.android.com/apk/res/com.satemenudemo"    android:layout_width="match_parent"    android:layout_height="match_parent">    <com.satemenudemo.SateMenu        android:id="@+id/menu_id"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:layout_margin="3dp"        wzw:position="right_bottom"        wzw:radius="150dp">        <ImageButton            android:id="@+id/center_btn"            android:layout_width="40dp"            android:layout_height="40dp"            android:background="@drawable/add" />        <ImageButton            android:id="@+id/menu1"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:background="@drawable/find" />        <ImageButton            android:id="@+id/menu2"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:background="@drawable/shop" />        <ImageButton            android:id="@+id/menu3"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:background="@drawable/people" />        <ImageButton            android:id="@+id/menu4"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:background="@drawable/love" />    </com.satemenudemo.SateMenu></RelativeLayout>

MainActivity.java

public class MainActivity extends Activity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        SateMenu sateMenu = (SateMenu) findViewById(R.id.menu_id);        sateMenu.setMenuItemListener(new SateMenu.MenuItemListener() {            @Override            public void onclick(int position) {                Toast.makeText(MainActivity.this, "--  "+position, Toast.LENGTH_SHORT).show();            }        });    }}