package custom.widget;import android.content.Context;import android.database.DataSetObserver;import android.os.Build;import android.util.AttributeSet;import android.view.GestureDetector;import android.view.MotionEvent;import android.view.View;import android.view.ViewGroup;import android.widget.Adapter;/** * Android 横向选择器 * Created by yanhongliang on 16/4/9. * 使用方法            android:id="@+id/scrollPicker"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:scrollbars="none">                    android:id="@android:id/content"            android:layout_width="wrap_content"            android:layout_height="match_parent"            android:orientation="horizontal"            android:gravity="center" />        @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_test);        final HorizontalPickerView picker = (HorizontalPickerView)findViewById(R.id.scrollPicker);        ArrayList list = new ArrayList<>();        for (int i = 0; i < 3; i++) {            list.add(i);        }        final ArrayAdapter adapter = new ArrayAdapter(this,0,list){            @Override            public View getView(int position, View convertView, ViewGroup parent) {                int value = getItem(position);                if (convertView == null) {                    LayoutInflater inflater = LayoutInflater.from(getContext());                    convertView = inflater.inflate(android.R.layout.simple_list_item_1,null);                }                TextView view = (TextView) convertView.findViewById(android.R.id.text1);                view.setText("第"+value+"个");                return convertView;            }        };        picker.setAdapter(adapter);        picker.setOnSelectedListener(new HorizontalPickerView.OnSelectedListener() {            @Override            public void selected(View v, int index) {                ViewGroup group = (ViewGroup)picker.getChildAt(0);                for (int i = 0; i < adapter.getCount(); i++) {                    View view = group.getChildAt(i);                    if (i == index) {                        view.setBackgroundColor(0xFFFF0000);                    } else {                        view.setBackgroundColor(group.getDrawingCacheBackgroundColor());                    }                }            }        });    }*/public class HorizontalPickerView extends android.widget.HorizontalScrollView {    public interface OnSelectedListener {        void selected(View v, int index);    }    public HorizontalPickerView(Context context) {        super(context);        initialize();    }    public HorizontalPickerView(Context context, AttributeSet attrs) {        super(context, attrs);        initialize();    }    public HorizontalPickerView(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        initialize();    }    public void setOnSelectedListener(OnSelectedListener listener) {        selectedListener = listener;    }    private DataSetObserver observer;    public void setAdapter(Adapter adapter) {        if (this.adapter != null) {            this.adapter.unregisterDataSetObserver(observer);        }        this.adapter = adapter;        adapter.registerDataSetObserver(observer);        updateAdapter();    }    private void updateAdapter() {        ViewGroup group = (ViewGroup)getChildAt(0);        group.removeAllViews();        for (int i = 0; i<adapter.getCount(); i++) {            group.addView(adapter.getView(i,null,group));        }    }    private Adapter adapter;    private OnSelectedListener selectedListener;    private GestureDetector gesture;    private OnTouchListener listener;    void initialize() {        observer = new DataSetObserver() {            @Override            public void onChanged() {                super.onChanged();                updateAdapter();            }            @Override            public void onInvalidated() {                super.onInvalidated();                ((ViewGroup)getChildAt(0)).removeAllViews();            }        };        gesture = new GestureDetector(getContext(), new GestureDetector.OnGestureListener() {            @Override            public boolean onDown(MotionEvent e) {                return false;            }            @Override            public void onShowPress(MotionEvent e) {            }            @Override            public boolean onSingleTapUp(MotionEvent e) {                float x = e.getRawX() + getScrollX() - getWidth() / 2;                smoothScrollTo((int)x,0);                return false;            }            @Override            public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {                return false;            }            @Override            public void onLongPress(MotionEvent e) {            }            @Override            public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {                return false;            }        });        super.setOnTouchListener(new OnTouchListener() {            @Override            public boolean onTouch(View v, MotionEvent event) {                boolean result = gesture.onTouchEvent(event);                return listener == null ? result : listener.onTouch(v, event);            }        });    }    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        super.onMeasure(widthMeasureSpec, heightMeasureSpec);        int side = getWidth() / 2;        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {            getChildAt(0).setPaddingRelative(side, 0, side, 0);        } else {            getChildAt(0).setPadding(side,0,side,0);        }    }    @Override    public void setOnTouchListener(OnTouchListener l) {        listener = l;    }    @Override    public void computeScroll() {        super.computeScroll();        int centerX = getWidth() / 2;        selectItemWithX(centerX);    }    private void selectItemWithX(float x) {        ViewGroup group = (ViewGroup)getChildAt(0);        for (int i = 0; i; i++) {            View view = group.getChildAt(i);            float minX = view.getX() - getScrollX();            float maxX = minX + view.getWidth();            if (x >= minX && x <= maxX ) {                if (selectedListener != null) {                    selectedListener.selected(view, i);                }                break;            }        }    }}