Android自定义控件实现滑动开关效果

//在布局中使用该控件的时候，而且有额外的style属性的时候调用该构造方法，
public ToggleView(Context context, AttributeSet attrs, int defStyle)；
//在布局中使用该控件的时候调用该构造方法
public ToggleView(Context context, AttributeSet attrs)
//在Java代码中直接new该控件的时候，调用该构造方法
public ToggleView(Context context)

<?xml version="1.0" encoding="utf-8"?>
<resources>
  <declare-styleable name="toggle">

   <attr name="switchBackground" format="reference" />
   <attr name="slidingBackground" format="reference" />
   <attr name="toggleState" format="boolean" />
  </declare-styleable>
</resources>

<RelativeLayout 
 xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:hss="http://schemas.android.com/apk/res/com.hss.toggle"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
  >

 <com.hss.toggle.ToggleView
  android:id="@+id/toggleView"
  android:layout_height="wrap_content"
  android:layout_width="wrap_content"
  android:layout_centerInParent="true"
  hss:switchBackground="@drawable/switch_background"
  hss:slidingBackground="@drawable/slide_button_background"
  hss:toggleState="true"
  >
  </com.hss.toggle.ToggleView>

</RelativeLayout>

String namespace = "http://schemas.android.com/apk/res/com.hss.toggle";
  int toggle_switchbackground = attrs.getAttributeResourceValue(namespace, "switchBackground", -1);
  int toggle_slidingbackground = attrs.getAttributeResourceValue(namespace, "slidingBackground", -1);
  toggle_state = attrs.getAttributeBooleanValue(namespace, "toggleState", false);

package com.hss.toggle;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;

/**
 * 自定义开关控件
 * @author hss
 */
public class ToggleView extends View {
 private static final String TAG = "ToogleView";
 private Bitmap sliding_background;
 private Bitmap switch_background;
 private boolean isSliding = false;
 private boolean toggle_state = false;
 private int downX;
 private mToggleStateChangeListener;

 // 构造方法，在xml文件布局的时候，指定了style的时候调用
 public ToggleView(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
 }

 // 构造方法，在xml文件中布局的时候，没有指定style的时候调用
 public ToggleView(Context context, AttributeSet attrs) {
  this(context, attrs, 0);
  //在Java代码中 获取到xml中自定义属性对应的值
  String namespace = "http://schemas.android.com/apk/res/com.hss.toggle";
  int toggle_switchbackground = attrs.getAttributeResourceValue(namespace, "switchBackground", -1);
  int toggle_slidingbackground = attrs.getAttributeResourceValue(namespace, "slidingBackground", -1);
  toggle_state = attrs.getAttributeBooleanValue(namespace, "toggleState", false);
  Log.i(TAG,""+toggle_slidingbackground+"  "+toggle_switchbackground);
  // 设置自定义开关的图片
  setToggleSwitchBackground(toggle_switchbackground);
  setToggleSlidingBackground(toggle_slidingbackground);
  setToggleState(toggle_state);
 }

 // 构造方法 在代码中new的时候调用
 public ToggleView(Context context) {
  this(context, null);

 }

 /**
  * 给滑动的控件设置背景图片
  * 
  * @param toggle_slidingbackground 图片ID
  */
 private void setToggleSlidingBackground(int toggle_slidingbackground) {
  sliding_background = BitmapFactory.decodeResource(getResources(),toggle_slidingbackground);
 }

 /**
  * 给背景的控件，设置背景图片
  * 
  * @param toggle_switchbackground 图片ID
  */
 private void setToggleSwitchBackground(int toggle_switchbackground) {
  switch_background = BitmapFactory.decodeResource(getResources(),toggle_switchbackground);
 }

 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
  //测量控件的大小，设置控件的大小为背景图片的大小
  setMeasuredDimension(switch_background.getWidth(),switch_background.getHeight());
 }

 @Override
 protected void onDraw(Canvas canvas) {
  //开始画自定义控件，使用canvas对象先把背景图片画上来
  canvas.drawBitmap(switch_background, 0, 0, null);
  if (isSliding) {
  //如果是滑动状态
   //控件距离左边的相对距离为：（控件每时每刻的距离自己左上方的焦点的x轴距离）-（控件本身一半的x轴宽度）
   int left = downX - sliding_background.getWidth() / 2;
   //控件最大的滑动距离（距离左边最大的距离）就是：（背景图片的宽度）-（滑块图片的宽度）
   int rightAlign = switch_background.getWidth()- sliding_background.getWidth();
   //如果距离左边的距离小于0，，就不让他继续往左边动了
   if (left < 0) {
    left = 0;
   } else if (left > rightAlign) {
    //如果距离左边的距离》应该距离左边的最大距离，也不让他往右边移动了
    left = rightAlign;
   }
   //控制好属性之后就可以时时刻刻的跟着画了
   canvas.drawBitmap(sliding_background, left, 0, null);
  } else {
   //如果不滑动，则根据控件的属性中开关的状态，来画滑块的位置
   if (toggle_state) {
    //如果开关状态为真，滑块移动到最右边
    int left = switch_background.getWidth() - sliding_background.getWidth();
    canvas.drawBitmap(sliding_background, left, 0, null);
   } else {
    //如果开关状态为假，滑块移动到最左边
    canvas.drawBitmap(sliding_background, 0, 0, null);
   }
  }
  super.onDraw(canvas);
 }

 @Override
 public boolean onTouchEvent(MotionEvent event) {
  //重写触摸事件
  int action = event.getAction();
  switch (action) {
  case MotionEvent.ACTION_DOWN:
   //开始点击的时候，是否滑动置为真，获取到当前手指的距离
   isSliding = true;
   downX = (int) event.getX();
   break;
  case MotionEvent.ACTION_MOVE:
   downX = (int) event.getX();
   break;
  case MotionEvent.ACTION_UP:
   //当点击结束的时候将是否滑动记为假，获取到移动的x轴的坐标
   downX = (int) event.getX();
   isSliding = false;
   //获取到背景图片中间的那个值
   int center = switch_background.getWidth() / 2;

   boolean state = downX > center;
   //如果先后的状态不相同，则将新的状态赋给成员变量，然后调用监听的方法
   if (toggle_state != state) {
    toggle_state = state;
    if (null != mToggleStateChangeListener) {
     mToggleStateChangeListener
       .onToggleState(toggle_state);
    }
   }
   break;
  }
  //调用一次onDraw()方法
  invalidate();
  return true;
 }
 //给自定义开关控件设置监听的方法
 public void setOnToggleStateLinstener(OnToggleStateChangeListener listen){
  mToggleStateChangeListener = listen;

 }
 public void setToggleState(boolean b) {
  toggle_state = b;
 }
 //监听回调接口，方法由实现接口的类实现
 public interface OnToggleStateChangeListener {

  public void onToggleState(boolean state);
 }
}

package com.hss.toggle;

import android.app.Activity;
import android.os.Bundle;

import com.hss.toggle.ToggleView.OnToggleStateChangeListener;
import com.hss.toggle.utils.ToastUtil;

public class MainActivity extends Activity{

 private ToggleView toggleView;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  // TODO Auto-generated method stub
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  toggleView = (ToggleView) findViewById(R.id.toggleView);
  toggleView.setOnToggleStateLinstener(new OnToggleStateChangeListener() {

   @Override
   public void onToggleState(boolean state) {
    showToast(state);
   }
  });
 }


 //这里调用到的自己封装的一个快速弹Toast的工具类
 private void showToast(boolean state) {
  ToastUtil.makeSuddenlyToast(getApplicationContext(), state?"开":"关");
 }
}

package com.hss.toggle.utils;

import android.content.Context;
import android.widget.Toast;

/**
 * @title Toast工具类
 * @author hss
 */
public class ToastUtil {
 private static Toast toast;

 /**
  * 弹出短时间Toast
  * @param context 上下文对象
  * @param text 要弹出的文字
  */
 public static void makeShortToast(Context context,String text){
  toast = Toast.makeText(context, text, Toast.LENGTH_SHORT);
  toast.show();
 }

 /**
  * 弹出长时间的Toast
  * @param context 上下文对象
  * @param text 要弹出的文字
  */
 public static void makeLongToast(Context context,String text){
  toast = Toast.makeText(context, text, Toast.LENGTH_LONG);
  toast.show();
 }
 /**
  * 单例Toast
  * @param context 上下文对象
  * @param text 要弹出的文字
  */
 public static void makeSuddenlyToast(Context context,String text){
  if(toast==null){
   toast = Toast.makeText(context, text, Toast.LENGTH_SHORT);
  }
  toast.setText(text);
  toast.show();
 }
}