28自定义View 模仿联系人字母侧栏

来源：互联网发布：jenkins 内置数据库编辑：程序博客网时间：2024/06/08 15:52

这里写图片描述

自定义View
LetterView.java

package com.qf.sxy.customview02;import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.util.AttributeSet;import android.view.MotionEvent;import android.view.View;import android.widget.TextView;/** * Created by sxy on 2016/9/29. */public class LetterView extends View {    // 索引的字母    public  static final String[] LETTES ={"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 Paint mTextPaint;    //指定一个位置  不在索引范围内    private int pressedPosition = -1;    //获取展示的View    private TextView mSelectView;    public void setSelectTextView(TextView tv){        this.mSelectView = tv;    }    public LetterView(Context context, AttributeSet attrs) {        super(context, attrs);        //初始化画笔        initPaint();    }    private void initPaint() {        mTextPaint = new Paint();        mTextPaint.setAntiAlias(true);        mTextPaint.setColor(Color.RED);        mTextPaint.setTextSize(30);    }    public LetterView(Context context) {        this(context,null);    }    /**     * 进行绘制     * @param canvas     */    @Override    protected void onDraw(Canvas canvas) {        super.onDraw(canvas);        //获取 宽和高        int height = getHeight();        int width = getWidth();        //字符串序列的长度        int lettersLength = LETTES.length;        //获取每个字符的高度        int singleHeight = height/lettersLength;        //开始绘制        for(int i=0;i<lettersLength;i++){            //获取x的位置            int xPos = (int)(width/2-mTextPaint.measureText(LETTES[i])/2);            //获取Y的位置            int yPos = singleHeight+i*singleHeight;            //设置文字颜色            if(pressedPosition == i){                mTextPaint.setColor(Color.BLUE);            }else{                mTextPaint.setColor(Color.BLACK);            }            //绘制文本            canvas.drawText(LETTES[i],xPos,yPos,mTextPaint);        }    }    /**     * 触摸事件     *     * true  消费事件  false 不处理     * @param event     * @return     */    @Override    public boolean onTouchEvent(MotionEvent event) {        switch (event.getAction()){            case MotionEvent.ACTION_DOWN://按下            case MotionEvent.ACTION_MOVE://移动                //获取手指的Y位置                float eventY = event.getY();                //每个字母单独的高度                int singleHeight = getMeasuredHeight()/LETTES.length;                //获取你当前索引位置                pressedPosition = (int)(eventY/singleHeight);                //显示提示的VIew  设置内容                if(mSelectView!=null){                    if(pressedPosition>=0&&pressedPosition<LETTES.length){                        mSelectView.setVisibility(View.VISIBLE);                        mSelectView.setText(LETTES[pressedPosition]);                    }                }                invalidate();//刷新                break;            case  MotionEvent.ACTION_UP://抬起                //还原当前位置                pressedPosition = -1;                //隐藏提示的View                if (mSelectView!=null){                    mSelectView.setVisibility(View.GONE);                }                invalidate();//刷新                break;        }        return true;    }}

MainActivity.java

package com.qf.sxy.customview02;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.widget.TextView;public class MainActivity extends AppCompatActivity {    private TextView tv;    private LetterView letterView;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        tv = ((TextView) findViewById(R.id.select_tv));        letterView = ((LetterView) findViewById(R.id.letterView));        //传递展示的View        letterView.setSelectTextView(tv);    }}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context="com.qf.sxy.customview02.MainActivity">    <com.qf.sxy.customview02.LetterView        android:id="@+id/letterView"        android:layout_width="40dp"        android:layout_height="match_parent"        android:layout_alignParentRight="true"      />    <TextView        android:id="@+id/select_tv"        android:layout_width="60dp"        android:layout_height="60dp"        android:layout_centerInParent="true"        android:gravity="center"        android:background="#00ff00"        android:textSize="30sp"        android:visibility="gone"        android:text="A"        /></RelativeLayout>

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