代码的灵感和原理主要来自于android自定义开关控件-SlideSwitch 这篇文章！
1.效果iphone上有开关控件，很漂亮，其实android4.0以后也有switch控件，但是只能用在4.0以后的系统中，这就失去了其使用价值，，而且我觉得它的界面也不是很好看。最近看到了百度魔拍上面的一个控件，觉得很漂亮啊，然后反编译了下，尽管没有混淆过，但是还是不好读，然后就按照自己的想法写了个，功能和百度魔拍类似。
效果图入下：
2.原理继承自view类，override其onDraw函数，把两个背景图（一个灰的一个红的）和一个开关图（圆开关）通过canvas画出来；同时override其onTouchEvent函数，实现滑动效果；最后开启一个线程做动画，实现缓慢滑动的效果。3. 代码
代码SwitchButton如下：
package net.loonggg.switchbutton;import android.content.Context;import android.content.res.Resources;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.Rect;import android.graphics.Typeface;import android.util.AttributeSet;import android.view.MotionEvent;import android.view.View;import android.view.ViewGroup.LayoutParams;public class SwitchButton extends View {public static final int SWITCH_OFF = 0;// 关闭状态public static final int SWITCH_ON = 1;// 打开状态public static final int SWITCH_SCROLING = 2;// 滚动状态// 用于显示的文本,默认为打开和关闭private String mOnText = "打开";private String mOffText = "关闭";/** * SwitchButton切换开关的状态，默认为关闭状态 */private int mSwitchStatus = SWITCH_OFF;private int mBmpWidth = 0;private int mBmpHeight = 0;private int mThumbWidth = 0;private OnSwitchChangedListener listener;private int mSrcX = 0, mDstX = 0;private boolean mHasScrolled = false;// 表示是否发生过滚动// 开关状态图Bitmap mSwitch_off, mSwitch_on, mSwitch_thumb;private Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);public SwitchButton(Context context) {this(context, null);}public SwitchButton(Context context, AttributeSet attrs) {super(context, attrs);initView();}public SwitchButton(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);initView();}/** * 初始化图片 */private void initView() {Resources res = getResources();mSwitch_off = BitmapFactory.decodeResource(res,R.drawable.switch_off_bg);mSwitch_on = BitmapFactory.decodeResource(res, R.drawable.switch_on_bg);mSwitch_thumb = BitmapFactory.decodeResource(res,R.drawable.switch_thumb);mBmpWidth = mSwitch_on.getWidth();mBmpHeight = mSwitch_on.getHeight();mThumbWidth = mSwitch_thumb.getWidth();}@Overridepublic void setLayoutParams(LayoutParams params) {params.width = mBmpWidth;params.height = mBmpHeight;super.setLayoutParams(params);}/** * 设置开关上面的文本 * * @param onText *控件打开时要显示的文本 * @param offText *控件关闭时要显示的文本 */public void setText(String onText, String offText) {mOnText = onText;mOffText = offText;invalidate();// 使整个视图无效，重新绘制，用来刷新View}/** * 设置开关的状态 * * @param flag *true为开，false为关闭 */public void setStatus(boolean flag) {mSwitchStatus = flag ? SWITCH_ON : SWITCH_OFF;}@Overridepublic boolean onTouchEvent(MotionEvent event) {int action = event.getAction();switch (action) {case MotionEvent.ACTION_DOWN:mSrcX = (int) event.getX();break;case MotionEvent.ACTION_MOVE:mDstX = Math.max((int) event.getX(), 10);mDstX = Math.min(mDstX, 62);if (mSrcX == mDstX)return true;mHasScrolled = true;TranslateAnimationRunnable move_runnable = new TranslateAnimationRunnable(mSrcX, mDstX, 0);new Thread(move_runnable).start();mSrcX = mDstX;break;case MotionEvent.ACTION_UP:if (mHasScrolled == false)// 如果没有发生过滑动，就意味着这是一次单击过程{mSwitchStatus = Math.abs(mSwitchStatus – 1);int xFrom = 10, xTo = 62;if (mSwitchStatus == SWITCH_OFF) {xFrom = 62;xTo = 10;}TranslateAnimationRunnable runnable = new TranslateAnimationRunnable(xFrom, xTo, 1);new Thread(runnable).start();} else {invalidate();mHasScrolled = false;}// 状态改变的时候 回调事件函数if (listener != null) {listener.onSwitchChanged(this, mSwitchStatus);}break;default:break;}return true;}@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);// 绘图的时候 内部用到了一些数值的硬编码，其实不太好，// 主要是考虑到图片的原因，图片周围有透明边界，所以要有一定的偏移// 硬编码的数值只要看懂了代码，其实可以理解其含义，可以做相应改进。mPaint.setTextSize(14);// 设置画笔文字大小mPaint.setTypeface(Typeface.DEFAULT_BOLD);// 设置文字字体if (mSwitchStatus == SWITCH_OFF) {drawBitmap(canvas, null, null, mSwitch_off);drawBitmap(canvas, null, null, mSwitch_thumb);mPaint.setColor(Color.rgb(105, 105, 105));canvas.translate(mSwitch_thumb.getWidth(), 0);canvas.drawText(mOffText, 0, 20, mPaint);} else if (mSwitchStatus == SWITCH_ON) {drawBitmap(canvas, null, null, mSwitch_on);int count = canvas.save();canvas.translate(mSwitch_on.getWidth() – mSwitch_thumb.getWidth(),0);drawBitmap(canvas, null, null, mSwitch_thumb);mPaint.setColor(Color.WHITE);canvas.restoreToCount(count);canvas.drawText(mOnText, 17, 20, mPaint);} else {mSwitchStatus = mDstX > 35 ? SWITCH_ON : SWITCH_OFF;// 首先画出打开按钮样式drawBitmap(canvas, new Rect(0, 0, mDstX, mBmpHeight), new Rect(0,0, (int) mDstX, mBmpHeight), mSwitch_on);mPaint.setColor(Color.WHITE);canvas.drawText(mOnText, 17, 20, mPaint);// 在画出关闭按钮的样式int count = canvas.save();canvas.translate(mDstX, 0);drawBitmap(canvas, new Rect(mDstX, 0, mBmpWidth, mBmpHeight),new Rect(0, 0, mBmpWidth – mDstX, mBmpHeight), mSwitch_off);canvas.restoreToCount(count);// 画出关闭的文字count = canvas.save();// clipRect()截取画布中的一个区域,在这个区域的基础上画上关闭的文字canvas.clipRect(mDstX, 0, mBmpWidth, mBmpHeight);canvas.translate(mThumbWidth, 0);mPaint.setColor(Color.rgb(105, 105, 105));canvas.drawText(mOffText, 0, 20, mPaint);canvas.restoreToCount(count);// 画出那个圆点按钮count = canvas.save();canvas.translate(mDstX – mThumbWidth / 2, 0);drawBitmap(canvas, null, null, mSwitch_thumb);canvas.restoreToCount(count);}}/** * 画出Bitmap * * @param canvas * @param src * @param dst * @param bitmap */private void drawBitmap(Canvas canvas, Rect src, Rect dst, Bitmap bitmap) {dst = (dst == null ? new Rect(0, 0, bitmap.getWidth(),bitmap.getHeight()) : dst);Paint paint = new Paint();canvas.drawBitmap(bitmap, src, dst, paint);}public interface OnSwitchChangedListener {/** * 状态改变 回调函数 ** @param status *SWITCH_ON表示打开 SWITCH_OFF表示关闭 */public abstract void onSwitchChanged(SwitchButton switchButton,int status);}/** * 为开关控件设置状态改变监听函数 * * @param listener */public void setOnSwitchChangedListener(OnSwitchChangedListener listener) {if (listener != null) {this.listener = listener;}}/** * 改变控件状态的动画线程 * * @author loonggg * */private class TranslateAnimationRunnable implements Runnable {private int srcX, dstX;private int duration;/** * 滑动动画 ** @param srcX *滑动起始点 * @param dstX *滑动终止点 * @param duration *是否采用动画，1采用，0不采用 */public TranslateAnimationRunnable(float srcX, float dstX, int duration) {this.srcX = (int) srcX;this.dstX = (int) dstX;this.duration = duration;}@Overridepublic void run() {final int patch = (dstX > srcX ? 5 : -5);if (duration == 0) {SwitchButton.this.mSwitchStatus = SWITCH_SCROLING;SwitchButton.this.postInvalidate();} else {int x = srcX + patch;while (Math.abs(x – dstX) > 5) {mDstX = x;SwitchButton.this.mSwitchStatus = SWITCH_SCROLING;SwitchButton.this.postInvalidate();x += patch;try {Thread.sleep(10);} catch (InterruptedException e) {e.printStackTrace();}}mDstX = dstX;SwitchButton.this.mSwitchStatus = mDstX > 35 ? SWITCH_ON: SWITCH_OFF;SwitchButton.this.postInvalidate();}}}}布局文件的代码如下：<RelativeLayout xmlns:android=""xmlns:tools=""android:layout_width="match_parent"android:layout_height="80dp"android:gravity="center_vertical"android:orientation="horizontal" ><TextViewandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_marginLeft="10dp"android:text="是否打开蓝牙" /><net.loonggg.switchbutton.SwitchButtonandroid:id="@+id/sb"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_alignParentRight="true" /></RelativeLayout>到这里控件的自定义生成就已经完了，当然咱的这篇文章还要学习一下onDraw()方法，对于onDraw()方法的使用，里面的代码的解释如下：我躺下来，以一张报纸当枕头。高高在我上方的，
