android中的索引列表

一.定義控件

首先定義一個列表側邊的字母索引項控件

package com.shjy.jingin.ui;

import com.shjy.jingin.R;

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;

public class SideBar extends View {

        // 觸摸事件

        private OnTouchingLetterChangedListener onTouchingLetterChangedListener ;

        // 26個字母

        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;// 選中

        private Paint paint = new Paint();

        private TextView mTextDialog ;

        /**

        * 爲SideBar設置顯示字母的TextView

        * @param 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);

       }

        /**

        * 重寫這個方法

        */

        protected void onDraw(Canvas canvas) {

               super.onDraw(canvas);

               // 獲取焦點改變背景顏色.

               int height = getHeight();// 獲取對應高度

               int width = getWidth(); // 獲取對應寬度

               int singleHeight = height / b.length;// 獲取每一個字母的高度

               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);

                      // 選中的狀態

                      if (i == choose ) {

                            paint.setColor(Color. parseColor("#3399ff"));

                            paint.setFakeBoldText( true);

                     }

                      // x座標等於中間-字符串寬度的一半.

                      float xPos = width / 2 - paint .measureText(b[i]) / 2;

                      float yPos = singleHeight * i + singleHeight;

                     canvas.drawText( b[i], xPos, yPos, paint);

                      paint.reset(); // 重置畫筆

              }

       }

        @Override

        public boolean dispatchTouchEvent(MotionEvent event) {

               final int action = event.getAction();

               final float y = event.getY();// 點擊y座標

               final int oldChoose = choose;

               final OnTouchingLetterChangedListener listener = onTouchingLetterChangedListener ;

               final int c = (int) (y / getHeight() * b.length);// 點擊y座標所佔總高度的比例*b數組的長度就等於點擊b中的個數.

               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 ;

       }

        /**

        * 向外公開的方法

        *

        * @param onTouchingLetterChangedListener

        */

        public void setOnTouchingLetterChangedListener(

                     OnTouchingLetterChangedListener onTouchingLetterChangedListener) {

               this.onTouchingLetterChangedListener = onTouchingLetterChangedListener;

       }

        /**

        * 接口

        *

        * @author coder

        *

        */

        public interface OnTouchingLetterChangedListener {

               public void onTouchingLetterChanged(String s);

       }

}

二.使用