android inheritance View, onDraw methods to achieve fastpositioning initials

 

  

package com.example.contactssort; 
 
import android.annotation.SuppressLint; 
import android.annotation.TargetApi; 
import android.content.Context; 
import android.graphics.Canvas; 
import android.graphics.Paint; 
import android.graphics.Paint.FontMetrics; 
import android.graphics.Paint.Style; 
import android.graphics.RectF; 
import android.os.Build; 
import android.util.AttributeSet; 
import android.view.MotionEvent; 
import android.view.View; 
import android.widget.ListView; 
import android.widget.SectionIndexer; 
 
public class SideBar extends View { 
    private int textColor = 0xFFA6A9AA; 
    private int backgroundColor = 0x55DDDDDD; 
    private int backgroundActionDownColor = 0xFFCCCCCC; 
    private boolean isDown = false; 
 
    @TargetApi(Build.VERSION_CODES.HONEYCOMB) 
    public SideBar(Context context, AttributeSet attrs, int defStyle) { 
        super(context, attrs, defStyle); 
    } 
 
    private char[] l = new char[0]; 
    private SectionIndexer sectionIndexter = null; 
    private ListView list; 
    private int m_nItemHeight = 29; 
    private int selfHeight; 
    private int selfWidth; 
    private float textSize; 
    private int selectIndex = -1; 
 
    public SideBar(Context context) { 
        super(context); 
        init(); 
    } 
 
    private void init() { 
        // setBackgroundColor(backgroundColor); 
    } 
 
    public SideBar(Context context, AttributeSet attrs) { 
        super(context, attrs); 
        init(); 
    } 
 
    public void setListView(ListView _list) { 
        list = _list; 
        sectionIndexter = (SectionIndexer) _list.getAdapter(); 
    } 
 
    @Override 
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 
        this.textSize = getResources().getDimension(R.dimen.index_text_size); 
        super.onMeasure(widthMeasureSpec, heightMeasureSpec); 
        int height = MeasureSpec.getSize(heightMeasureSpec); 
        int width = MeasureSpec.getSize(widthMeasureSpec); 
        this.selfHeight = height; 
        this.selfWidth = width; 
        m_nItemHeight = selfHeight / l.length; 
        int newWidth = MeasureSpec.makeMeasureSpec((int) this.textSize + 5, MeasureSpec.AT_MOST); 
        setMeasuredDimension(newWidth, heightMeasureSpec); 
    } 
 
    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; 
            } 
            this.selectIndex = idx; 
            list.setSelection(position); 
            isDown = true; 
            invalidate(); 
        } 
        if (event.getAction() == MotionEvent.ACTION_UP) { 
            isDown = false; 
            this.selectIndex = -1; 
            invalidate(); 
        } 
        return true; 
    } 
 
    @SuppressLint("DrawAllocation") 
    protected void onDraw(Canvas canvas) { 
        Paint paint = new Paint(); 
        paint.setTextAlign(Paint.Align.CENTER); 
        paint.setTextSize(this.textSize); 
        paint.setColor(textColor); 
        FontMetrics fm = paint.getFontMetrics(); 
        int textHeight = (int) (Math.ceil(fm.descent - fm.ascent) + 2); 
        float widthCenter = getMeasuredWidth() / 2; 
        RectF rect = null; 
        Paint bg_paint = new Paint(paint); 
 
        if (isDown) { 
            rect = new RectF(0, 0, getWidth(), getHeight()); 
            bg_paint.setColor(backgroundActionDownColor); 
 
        } else { 
            rect = new RectF(0, 0, getWidth(), getHeight()); 
            bg_paint.setColor(backgroundColor); 
        } 
        canvas.save(); 
        canvas.drawRoundRect(rect, 15, 15, bg_paint); 
        canvas.restore(); 
        for (int i = 0; i < l.length; i++) { 
            if (selectIndex == i) { 
                Paint item_bg_paint = new Paint(paint); 
                item_bg_paint.setColor(0xffccffcc); 
                canvas.save(); 
                RectF item_rect = new RectF(0, i * m_nItemHeight, getWidth(), m_nItemHeight + i * m_nItemHeight); 
                canvas.drawRoundRect(item_rect, 15, 15, item_bg_paint); 
                canvas.restore(); 
            } else if (selectIndex == l.length - 1) { 
                Paint item_bg_paint = new Paint(paint); 
                item_bg_paint.setColor(0xffccffcc); 
                canvas.save(); 
                RectF item_rect = new RectF(0, l.length * m_nItemHeight, getWidth(), getHeight()); 
                canvas.drawRoundRect(item_rect, 15, 15, item_bg_paint); 
                canvas.restore(); 
            }

  

float offsetY = ((i) * m_nItemHeight ) + (( m_nItemHeight -textHeight) / 2 + textHeight-8) ;/ / font vertically centered , 20130530 Updates

  

canvas.drawText (String.valueOf ( l [i]), widthCenter, offsetY, paint);

  

 
        } 
        super.onDraw(canvas); 
    } 
 
    public void setSections(char[] charArray) { 
        this.l = charArray; 
        invalidate(); 
    } 
 
}

 

 

  

package com.example.contactssort; 
 
import java.util.ArrayList; 
import java.util.List; 
 
public class IndexItem { 
 
    List<String> indexs = new ArrayList<String>(); 
 
    /** 
     * 添加数据索引。每一个数据都要添加 
     *  
     * @param c 
     */ 
    public void addIndex(char c) { 
        indexs.add(String.valueOf(c)); 
    } 
 
    public int getCount() { 
        return indexs.size(); 
    } 
    public int indexAt(char c){ 
        return indexs.indexOf(String.valueOf(c)); 
    } 
    public String get(int position) { 
        return this.indexs.get(position); 
    } 
}

 

 

  

package com.example.contactssort; 
 
import java.util.ArrayList; 
import java.util.Locale; 
 
 
import android.app.Activity; 
import android.content.Context; 
import android.database.Cursor; 
import android.graphics.Color; 
import android.view.Gravity; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.AlphabetIndexer; 
import android.widget.BaseAdapter; 
import android.widget.SectionIndexer; 
import android.widget.TextView; 
 
public class MyAdapter extends BaseAdapter implements SectionIndexer { 
    private ArrayList<String> stringArray; 
    private Context context; 
    IndexItem indexs; 
    public MyAdapter(Context _context, ArrayList<String> arr,SideBar sidebar) { 
        stringArray = arr; 
        context = _context; 
        String alphabet=""; 
        indexs=new IndexItem(); 
        for(String frist:arr){ 
            char c = frist.charAt(0); 
            String upperCase = String.valueOf(c).toUpperCase(); 
            if(!alphabet.contains(upperCase)){ 
                alphabet+=upperCase;     
            } 
            indexs.addIndex(upperCase.charAt(0)); 
        } 
        sidebar.setSections(alphabet.toUpperCase().toCharArray()); 
    } 
 
    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); 
        TextView header = (TextView) view.findViewById(R.id.section); 
        TextView textView = (TextView) view.findViewById(R.id.textView); 
        char currentF=stringArray.get(position).charAt(0); 
        if(position==0){ 
            header.setVisibility(View.VISIBLE); 
            header.setText((""+currentF).toUpperCase()); 
        }else{ 
             
            char oldF=stringArray.get(position-1).charAt(0); 
            if(!(""+currentF).equalsIgnoreCase((""+oldF))){ 
                header.setVisibility(View.VISIBLE); 
                header.setText((""+currentF).toUpperCase()); 
            }else{ 
                header.setVisibility(View.GONE); 
                header.setText(""); 
            } 
        } 
        textView.setText(stringArray.get(position)); 
        return view; 
    } 
 
    public int getPositionForSection(int section) { 
        int position=indexs.indexAt((char) section); 
        return position; 
    } 
 
    public int getSectionForPosition(int arg0) { 
        return 0; 
    } 
 
    public Object[] getSections() { 
        return null; 
    } 
 
}

 

 

  

package com.example.contactssort; 
 
import java.util.ArrayList; 
 
import android.app.Activity; 
import android.os.Bundle; 
import android.widget.ListView; 
 
public class MainActivity extends Activity { 
 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 
        setContentView(R.layout.activity_main); 
        ListView list = (ListView) findViewById(R.id.myListView); 
        SideBar side=(SideBar)findViewById(R.id.side); 
        ArrayList<String> stringList = InitListViewData(); 
        MyAdapter adapter = new MyAdapter(this, stringList,side); 
        side.setListView(list); 
        list.setAdapter(adapter); 
    } 
 
    private ArrayList<String> InitListViewData() { 
        ArrayList<String> stringList = new ArrayList<String>(); 
        stringList.add("asdf"); 
        stringList.add("anbcd"); 
        stringList.add("bdcd"); 
        stringList.add("bfefasf"); 
        stringList.add("bcadaf"); 
        stringList.add("csdafad"); 
        stringList.add("dfdaf"); 
        stringList.add("edfdfd"); 
        stringList.add("fsdfadfasfd"); 
        stringList.add("fadsfasdf"); 
        stringList.add("fweff"); 
        stringList.add("fhghdfgh"); 
        stringList.add("gasdfasdfsa"); 
        stringList.add("gadfawe"); 
        stringList.add("haof"); 
        stringList.add("hjooiuoiuio"); 
        stringList.add("iasdfasdfas"); 
        stringList.add("zero"); 
        stringList.add("zoo"); 
        stringList.add("zeus"); 
        stringList.add("zebra"); 
        stringList.add("zest"); 
        stringList.add("zing"); 
        return stringList; 
    } 
}