通讯录侧边栏快速滑动效果的实现

那，我原创的文章比较少，所以基本上都是自己看了，然后稍加修改的！

综合这两个帖子：
http://blog.csdn.net/ilysony/article/details/6292771
http://blog.csdn.net/yan_daoqiu/article/details/6393300

中文的还没去实验
[img]
我不知道怎么传图 - - ！
[/img]


大概思路就是在listView里面设置了 section,然后侧边栏是一个自定义的组件

侧边栏ontouch中会去 让listview 跳到相应位置list.setSelection();

listview中设置onScroll监听器，滑动时候让中间弹出windows,不滑动时候隐藏

window中显示的就是首字母。

侧边栏代码

public class SideBar extends View{

	private char[] l;  
    private SectionIndexer sectionIndexter = null;  
    private ListView list;  
    private final int m_nItemHeight = 29;  
    public SideBar(Context context) {  
        super(context);  
        init();  
    }  
    public SideBar(Context context, AttributeSet attrs) {  
        super(context, attrs);  
        init();  
    }  
    private void init() {  
        l = new char[] { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S',  
                'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };  
        setBackgroundColor(0x44FFFFFF);  
    }  
    public SideBar(Context context, AttributeSet attrs, int defStyle) {  
        super(context, attrs, defStyle);  
        init();  
    }  
    public void setListView(ListView _list) {  
        list = _list;  
        sectionIndexter = (SectionIndexer) _list.getAdapter();  
    }  
    public boolean onTouchEvent(MotionEvent event) {  
        super.onTouchEvent(event);  
        int i = (int) event.getY();  
        int idx = i / m_nItemHeight;  
        if (idx >= l.length) {  
            idx = l.length - 1;  
        } else if (idx < 0) {  
            idx = 0;  
        }  
        if (event.getAction() == MotionEvent.ACTION_DOWN || event.getAction() == MotionEvent.ACTION_MOVE) {  
            if (sectionIndexter == null) {  
                sectionIndexter = (SectionIndexer) list.getAdapter();  
            }  
            int position = sectionIndexter.getPositionForSection(l[idx]);  
            if (position == -1) {  
                return true;  
            }  
            list.setSelection(position);  
        }  
        return true;  
    }  
    protected void onDraw(Canvas canvas) {  
        Paint paint = new Paint();  
        paint.setColor(0xFFA6A9AA);  
        paint.setTextSize(20);  
        paint.setTextAlign(Paint.Align.CENTER);  
        float widthCenter = getMeasuredWidth() / 2;  
        for (int i = 0; i < l.length; i++) {  
            canvas.drawText(String.valueOf(l[i]), widthCenter, m_nItemHeight + (i * m_nItemHeight), paint);  
        }  
        super.onDraw(canvas);  
    }  
	
	

}

listView的adapter
涉及到section的显示 以及 sidebar中要获取positon的方法

public class MyAdapter extends BaseAdapter implements SectionIndexer{
	private ArrayList<String> stringArray;  
    private Context context;  
    public MyAdapter(Context _context, ArrayList<String> arr) {  
        stringArray = arr;  
        context = _context;  
    }  
    public int getCount() {  
        return stringArray.size();  
    }  
    public Object getItem(int arg0) {  
        return stringArray.get(arg0);  
    }  
    public long getItemId(int arg0) {  
        return 0;  
    }  
    public View getView(int position, View v, ViewGroup parent) {  
        LayoutInflater inflate = ((Activity) context).getLayoutInflater();  
        View view = (View) inflate.inflate(R.layout.listview_row, null);  
        LinearLayout header = (LinearLayout) view.findViewById(R.id.section);  
        String label = stringArray.get(position);  
        char firstChar = label.toUpperCase().charAt(0);  
        if (position == 0) {  
            setSection(header, label);  
        } else {  
            String preLabel = stringArray.get(position - 1);  
            char preFirstChar = preLabel.toUpperCase().charAt(0);  
            if (firstChar != preFirstChar) {  
                setSection(header, label);  
            } else {  
                header.setVisibility(View.GONE);  
            }  
        }  
        TextView textView = (TextView) view.findViewById(R.id.textView);  
        textView.setText(label);  
        return view;  
    }  
    private void setSection(LinearLayout header, String label) {  
        TextView text = new TextView(context);  
        header.setBackgroundColor(0xffaabbcc);  
        text.setTextColor(Color.WHITE);  
        text.setText(label.substring(0, 1).toUpperCase());  
        text.setTextSize(20);  
        text.setPadding(5, 0, 0, 0);  
        text.setGravity(Gravity.CENTER_VERTICAL);  
        header.addView(text);  
    }  
    public int getPositionForSection(int section) {  
        if (section == 35) {  
            return 0;  
        }  
        for (int i = 0; i < stringArray.size(); i++) {  
            String l = stringArray.get(i);  
            char firstChar = l.toUpperCase().charAt(0);  
            if (firstChar == section) {  
                return i;  
            }  
        }  
        return -1;  
    }  
    public int getSectionForPosition(int arg0) {  
        return 0;  
    }  
    public Object[] getSections() {  
        return null;  
    }  
}

主程序的中显示的window相关：

TextView overlay = (TextView) View.inflate(this, R.layout.overlay, null); 
        getWindowManager() .addView(
                        overlay, new WindowManager.LayoutParams( 
                                	LayoutParams.WRAP_CONTENT, 
                                	LayoutParams.WRAP_CONTENT, 
                                	WindowManager.LayoutParams.TYPE_APPLICATION, 
                                	WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE 
                                        | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE, 
                                    PixelFormat.TRANSLUCENT)
                        );
        
        list.setOnScrollListener(onScroll);

	OnScrollListener onScroll = new OnScrollListener() {

	    boolean visible;

	    @Override 
	    public void onScrollStateChanged(AbsListView view, int scrollState) { 
	        visible = true; 
	        if (scrollState == ListView.OnScrollListener.SCROLL_STATE_IDLE) { 
	            overlay.setVisibility(View.INVISIBLE); 
	        } 
	    }

	    @Override 
	    public void onScroll(AbsListView view, int firstVisibleItem, 
	            int visibleItemCount, int totalItemCount) { 
	        if (visible) { 
	            overlay.setText(list.getItemAtPosition(firstVisibleItem).toString().substring(0, 1)); 
	            overlay.setVisibility(View.VISIBLE); 
	        } 
	    }
	
	};