content: package com.zhongou.widget;
  
  import android.content.Context;
  import android.graphics.Canvas;
  import android.graphics.Color;
  import android.graphics.Paint;
  import android.graphics.Typeface;
  import android.graphics.drawable.ColorDrawable;
  import android.util.AttributeSet;
  import android.view.MotionEvent;
  import android.view.View;
  import android.widget.TextView;
  
  import com.zhongou.R;
  
  public class SideBar extends View {
  	// 触摸事件
  	private OnTouchingLetterChangedListener onTouchingLetterChangedListener;
  	// 26个字母
  	public static String[] b = { "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", "#" };
  	private int choose = -1;// 选中
  	private Paint paint = new Paint();
  
  	private TextView mTextDialog;
  
  	public void setTextView(TextView mTextDialog) {
  		this.mTextDialog = mTextDialog;
  	}
  
  
  	public SideBar(Context context, AttributeSet attrs, int defStyle) {
  		super(context, attrs, defStyle);
  	}
  
  	public SideBar(Context context, AttributeSet attrs) {
  		super(context, attrs);
  	}
  
  	public SideBar(Context context) {
  		super(context);
  	}
  
  	/**
  	 * 重写这个方法
  	 */
  	protected void onDraw(Canvas canvas) {
  		super.onDraw(canvas);
  		// 获取焦点改变背景颜色.
  		int height = getHeight();// 获取对应高度
  		int width = getWidth(); // 获取对应宽度
  		int singleHeight = height / b.length;// 获取每一个字母的高度
  
  		for (int i = 0; i < b.length; i++) {
  			paint.setColor(Color.rgb(33, 65, 98));
  			// paint.setColor(Color.WHITE);
  			paint.setTypeface(Typeface.DEFAULT_BOLD);
  			paint.setAntiAlias(true);
  			paint.setTextSize(20);
  			// 选中的状态
  			if (i == choose) {
  				paint.setColor(Color.parseColor("#3399ff"));
  				paint.setFakeBoldText(true);
  			}
  			// x坐标等于中间-字符串宽度的一半.
  			float xPos = width / 2 - paint.measureText(b[i]) / 2;
  			float yPos = singleHeight * i + singleHeight;
  			canvas.drawText(b[i], xPos, yPos, paint);
  			paint.reset();// 重置画笔
  		}
  
  	}
  
  	@Override
  	public boolean dispatchTouchEvent(MotionEvent event) {
  		final int action = event.getAction();
  		final float y = event.getY();// 点击y坐标
  		final int oldChoose = choose;
  		final OnTouchingLetterChangedListener listener = onTouchingLetterChangedListener;
  		final int c = (int) (y / getHeight() * b.length);// 点击y坐标所占总高度的比例*b数组的长度就等于点击b中的个数.
  
  		switch (action) {
  		case MotionEvent.ACTION_UP:
  			setBackgroundDrawable(new ColorDrawable(0x00000000));
  			choose = -1;//
  			invalidate();
  			if (mTextDialog != null) {
  				mTextDialog.setVisibility(View.INVISIBLE);
  			}
  			break;
  
  		default:
  			setBackgroundResource(R.drawable.sidebar_background);
  			if (oldChoose != c) {
  				if (c >= 0 && c < b.length) {
  					if (listener != null) {
  						listener.onTouchingLetterChanged(b[c]);
  					}
  					if (mTextDialog != null) {
  						mTextDialog.setText(b[c]);
  						mTextDialog.setVisibility(View.VISIBLE);
  					}
  					
  					choose = c;
  					invalidate();
  				}
  			}
  
  			break;
  		}
  		return true;
  	}
  
  	/**
  	 * 向外公开的方法
  	 * 
  	 * @param onTouchingLetterChangedListener
  	 */
  	public void setOnTouchingLetterChangedListener(
  			OnTouchingLetterChangedListener onTouchingLetterChangedListener) {
  		this.onTouchingLetterChangedListener = onTouchingLetterChangedListener;
  	}
  
  	/**
  	 * 接口
  	 * 
  	 * @author coder
  	 * 
  	 */
  	public interface OnTouchingLetterChangedListener {
  		public void onTouchingLetterChanged(String s);
  	}
  
  }