android 自定义滑动按钮

第一接触公司项目就让我画页面，而且还涉及到我最讨厌的自定义view  但是没办法，讨厌也必须要做啊，经过百度上资源的查找，终于写出了一个滑动控件。废话不多说，上代码。

package com.etong.cpms.widget;

import com.etong.cpms.activity.R;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;

public class WiperSwitch extends View implements OnTouchListener{
private Bitmap bg_on, bg_off, slipper_btn;
private String mOnText = "打开";
private String mOffText = "关闭";
/**
* 按下时的x和当前的x
*/
private float downX, nowX;

/**
* 记录用户是否在滑动
*/
private boolean onSlip = false;

/**
* 当前的状态
*/
private boolean nowStatus = false;

/**
* 监听接口
*/
private OnChangedListener listener;


public WiperSwitch(Context context) {
super(context);
init();
}

public WiperSwitch(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}

public void init(){
//载入图片资源
bg_on = BitmapFactory.decodeResource(getResources(), R.drawable.switch_bkg_switch1);
bg_off = BitmapFactory.decodeResource(getResources(), R.drawable.switch_bkg_switch1);
slipper_btn = BitmapFactory.decodeResource(getResources(), R.drawable.switch_btn_slip1);
setOnTouchListener(this);
}

protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
Matrix matrix = new Matrix();
Paint paint = new Paint();
float x = 0;

//根据nowX设置背景，开或者关状态
if (nowX < (bg_on.getWidth()/2)){
canvas.drawBitmap(bg_off, matrix, paint);//画出关闭时的背景
paint.setColor(Color.WHITE);
paint.setFakeBoldText(true);
paint.setTextSize(40);
canvas.drawText(mOffText, (bg_off.getWidth()-slipper_btn.getWidth())/2, (bg_off.getHeight()+30)/2, paint);
}else{
canvas.drawBitmap(bg_on, matrix, paint);//画出打开时的背景
canvas.drawBitmap(bg_on, matrix, paint);//画出打开时的背景
paint.setColor(Color.WHITE);
paint.setFakeBoldText(true);
paint.setTextSize(40);
canvas.drawText(mOnText,(bg_on.getWidth()-slipper_btn.getWidth())/2, (bg_on.getHeight()+30)/2, paint);
}

if (onSlip) {//是否是在滑动状态,
if(nowX >= bg_on.getWidth())//是否划出指定范围,不能让滑块跑到外头,必须做这个判断
x = bg_on.getWidth() - slipper_btn.getWidth()/2;//减去滑块1/2的长度
else
x = nowX - slipper_btn.getWidth()/2;
}else {
if(nowStatus){//根据当前的状态设置滑块的x值
x = bg_on.getWidth() - slipper_btn.getWidth();
}else{
x = 0;
}
}

//对滑块滑动进行异常处理，不能让滑块出界
if (x < 0 ){
x = 0;
}
else if(x > bg_on.getWidth() - slipper_btn.getWidth()){
x = bg_on.getWidth() - slipper_btn.getWidth();
}

//画出滑块
canvas.drawBitmap(slipper_btn, x , 0, paint);
}

@Override
public boolean onTouch(View v, MotionEvent event) {
switch(event.getAction()){
case MotionEvent.ACTION_DOWN:{
if (event.getX() > bg_off.getWidth() || event.getY() > bg_off.getHeight()){
return false;
}else{
onSlip = true;
downX = event.getX();
nowX = downX;
}
break;
}
case MotionEvent.ACTION_MOVE:{
nowX = event.getX();
break;
}
case MotionEvent.ACTION_UP:{
onSlip = false;
if(event.getX() >= (bg_on.getWidth()/2)){
nowStatus = true;
nowX = bg_on.getWidth() - slipper_btn.getWidth();
}else{
nowStatus = false;
nowX = 0;
}

if(listener != null){
listener.OnChanged(WiperSwitch.this, nowStatus);
}
break;
}
}
//刷新界面
invalidate();
return true;
}



/**
* 为WiperSwitch设置一个监听，供外部调用的方法
* @param listener
*/
public void setOnChangedListener(OnChangedListener listener){
this.listener = listener;
}

/**
* 设置滑动开关的初始状态，供外部调用
* @param checked
*/
public void setChecked(boolean checked){
if(checked){
nowX = bg_off.getWidth();
}else{
nowX = 0;
}
nowStatus = checked;
}
/**
* 回调接口
* @author len
*
*/
public interface OnChangedListener {
public void OnChanged(WiperSwitch wiperSwitch, boolean checkState);
}


}