Android编程实现滑动按钮功能详解

import android.app.Activity;
import android.os.Bundle;
import android.widget.Toast;
public class Main extends Activity implements OnChangedListener {
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    SlipButton myBtn =(SlipButton) findViewById(R.id.slipBtn);//获得指定控件
    myBtn.SetOnChangedListener(this);//为控件设置监听器
  }
    @Override
    public void OnChanged(boolean CheckState) {//当按钮状态被改变时
    // TODO Auto-generated method stub
    if(CheckState)
      Toast.makeText(this,"打开了..." , Toast.LENGTH_SHORT).show();
    else
      Toast.makeText(this,"关闭了..." , Toast.LENGTH_SHORT).show();
  }
}

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
public class SlipButton extends View implements OnTouchListener{
  private boolean NowChoose = false;//记录当前按钮是否打开,true为打开,flase为关闭
  private boolean OnSlip = false;//记录用户是否在滑动的变量
  private float DownX,NowX;//按下时的x,当前的x,
  private Rect Btn_On,Btn_Off;//打开和关闭状态下,游标的Rect
  private boolean isChgLsnOn = false;
  private OnChangedListener ChgLsn;
  private Bitmap bg_on,bg_off,slip_btn;
  public SlipButton(Context context) {
    super(context);
    // TODO Auto-generated constructor stub
    init();
  }
  public SlipButton(Context context, AttributeSet attrs) {
    super(context, attrs);
    // TODO Auto-generated constructor stub
    init();
  }
  private void init(){//初始化
    //载入图片资源
    bg_on = BitmapFactory.decodeResource(getResources(), R.drawable.slip_bg_on);
    bg_off = BitmapFactory.decodeResource(getResources(), R.drawable.slip_bg_off);
    slip_btn = BitmapFactory.decodeResource(getResources(), R.drawable.slip_btn);
    //获得需要的Rect数据
    Btn_On = new Rect(0,0,slip_btn.getWidth(),slip_btn.getHeight());
    Btn_Off = new Rect(
        bg_off.getWidth()-slip_btn.getWidth(),
        0,
        bg_off.getWidth(),
        slip_btn.getHeight());
    setOnTouchListener(this);//设置监听器,也可以直接复写OnTouchEvent
  }
  @Override
  protected void onDraw(Canvas canvas) {//绘图函数
    // TODO Auto-generated method stub
    super.onDraw(canvas);
    Matrix matrix = new Matrix();
    Paint paint = new Paint();
    float x;
    {
      if(NowX<(bg_on.getWidth()/2))//滑动到前半段与后半段的背景不同,在此做判断
        canvas.drawBitmap(bg_off,matrix, paint);//画出关闭时的背景
      else
        canvas.drawBitmap(bg_on,matrix, paint);//画出打开时的背景
      if(OnSlip)//是否是在滑动状态,
      {
        if(NowX >= bg_on.getWidth())//是否划出指定范围,不能让游标跑到外头,必须做这个判断
          x = bg_on.getWidth()-slip_btn.getWidth()/2;//减去游标1/2的长度...
        else
          x = NowX - slip_btn.getWidth()/2;
      }else{//非滑动状态
        if(NowChoose)//根据现在的开关状态设置画游标的位置
          x = Btn_Off.left;
        else
          x = Btn_On.left;
      }
    if(x<0)//对游标位置进行异常判断...
      x = 0;
    else if(x>bg_on.getWidth()-slip_btn.getWidth())
      x = bg_on.getWidth()-slip_btn.getWidth();
    canvas.drawBitmap(slip_btn,x, 0, paint);//画出游标.
    }
  }
  @Override
  public boolean onTouch(View v, MotionEvent event) {
    // TODO Auto-generated method stub
    switch(event.getAction())//根据动作来执行代码
    {
    case MotionEvent.ACTION_MOVE://滑动
      NowX = event.getX();
      break;
    case MotionEvent.ACTION_DOWN://按下
    if(event.getX()>bg_on.getWidth()||event.getY()>bg_on.getHeight())
   return false;
      OnSlip = true;
      DownX = event.getX();
      NowX = DownX;
      break;
    case MotionEvent.ACTION_UP://松开
      OnSlip = false;
      boolean LastChoose = NowChoose;
      if(event.getX()>=(bg_on.getWidth()/2))
        NowChoose = true;
      else
        NowChoose = false;
      if(isChgLsnOn&&(LastChoose!=NowChoose))//如果设置了监听器,就调用其方法..
        ChgLsn.OnChanged(NowChoose);
      break;
    default:
    }
    invalidate();//重画控件
    return true;
  }
  public void SetOnChangedListener(OnChangedListener l){//设置监听器,当状态修改的时候
    isChgLsnOn = true;
    ChgLsn = l;
  }
}

package CMD100.demo.slipButton;
public interface OnChangedListener {
  abstract void OnChanged(boolean CheckState);
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  >
<TextView
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:text="@string/hello"
  />
<LinearLayout
  android:orientation = "horizontal"
  android:layout_width = "fill_parent"
  android:layout_height = "wrap_content"
  android:background = "#ff0000"
  >
  <TextView
    android:text = "测试:"
    android:layout_width = "wrap_content"
    android:layout_height = "wrap_content"
    />
 <CMD100.demo.slipButton.SlipButton
    android:id = "@+id/slipBtn"
    android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_marginLeft = "10sp"
  />
</LinearLayout>
</LinearLayout>

<[包名].SlipButton
  android:id = "@+id/slipBtn"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  />

SlipButton myBtn =(SlipButton) findViewById(R.id.slipBtn);
myBtn.SetOnChangedListener(...);