自定义控件一般的几个步骤： 1.初始化相关背景图片，布局文件，自定义属性 2.设置控件宽高OnMeasure() 3.布局或者排版OnLayout() 4.绘制控件OnDraw() 5.处理触摸事件OnTouchEvent()

1 public class SwitchView extends View implements View.OnTouchListener {  2   3     //开关状态图片  4     private Bitmap mSwitch_on, mSwitch_off, mSwitch_circle;  5   6     //开关状态 默认关闭  7     private boolean mCurrentState = false;  8   9     //开关切换回调接口 10     private OnSwitchChangedListener mOnSwitchChangedListener; 11  12     //X轴按下坐标 13     private int downX; 14     //X轴移动时触点坐标 15     private int moveX; 16     //X轴偏移量 17     private int left = 0; 18     //最大可移动距离 19     private int max; 20  21     public SwitchView(Context context) { 22         super(context); 23         init(); 24     } 25  26     public SwitchView(Context context, AttributeSet attrs) { 27         super(context, attrs); 28         init(); 29     } 30  31     public SwitchView(Context context, AttributeSet attrs, int defStyle) { 32         super(context, attrs, defStyle); 33         init(); 34     } 35  36     //1 初始化图片（加载） 37     private void init() { 38         Resources resr = getResources(); 39         mSwitch_on = BitmapFactory.decodeResource(resr, R.mipmap.switch_on); 40         mSwitch_off = BitmapFactory.decodeResource(resr, R.mipmap.switch_off); 41         mSwitch_circle = BitmapFactory.decodeResource(resr, R.mipmap.switch_circle); 42         setOnTouchListener(this); 43     } 44  45     //2 设置控件宽高（测量） 46     @Override 47     protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 48         int widthSize = mSwitch_off.getWidth(); 49         int heightSize = mSwitch_off.getHeight(); 50         max = mSwitch_off.getWidth() - mSwitch_circle.getWidth(); 51         setMeasuredDimension(widthSize, heightSize); 52     } 53  54     //3 布局（排版） 55     @Override 56     protected void onLayout(boolean changed, int left, int top, int right, int bottom) { 57         super.onLayout(changed, left, top, right, bottom); 58     } 59  60     //4 最后绘制控件 61     @Override 62     protected void onDraw(Canvas canvas) { 63         super.onDraw(canvas); 64         Matrix m = new Matrix(); 65         Paint p = new Paint(); 66         if (mCurrentState) { 67             canvas.drawBitmap(mSwitch_on, m, p); 68         } else { 69             canvas.drawBitmap(mSwitch_off, m, p); 70         } 71         canvas.drawBitmap(mSwitch_circle, left, 0, p); 72     } 73  74     //5 触摸事件 75     @Override 76     public boolean onTouch(View v, MotionEvent event) { 77         switch (event.getAction()) { 78             case MotionEvent.ACTION_DOWN: 79                 downX = (int) event.getX();//初始X轴按下坐标 80                 break; 81             case MotionEvent.ACTION_MOVE: 82                 moveX = (int) event.getX(); 83                 left = moveX - downX; 84                 if (!mCurrentState) { 85                     //关闭状态边界处理 86                     if (left < 0) { 87                         left = 0; 88                     } else if (left > max) { 89                         left = max; 90                     } 91                 } else { 92                     //开启状态边界处理 93                     left = moveX - downX; 94                     if (left > 0) {
   //向右滑 95                         left = max; 96                     } else if (Math.abs(left) > max) { 97                         left = 0; 98                     } else { 99                         left = max - Math.abs(left);100                     }101                 }102                 break;103             case MotionEvent.ACTION_UP:104             case MotionEvent.ACTION_CANCEL://抬起时的判断105                 int upX = (int) event.getX();106                 boolean state = false; //滑动是否成功107                 //1 关闭状态108                 if (!mCurrentState) {109                     //滑动是否成功110                     //a 移动距离超过 1/2 的滑动宽度111                     //b 触摸点在滑动区域，开启按钮112                     state = (moveX - downX) >= max / 2 || upX >= max;113                     if (state) {114                         left = max;115                         mCurrentState = true;116                     } else {117                         left = 0;118                     }119                 } else {120                     //2 开启状态，判断滑动是否成功121                     //a 移动距离超过 1/2 的滑动宽度122                     //b 触摸点在滑动区域，关闭按钮123                     state = (downX - moveX) >= max / 2 || upX <= max;124                     if (state) {125                         left = 0;126                         mCurrentState = false;127                     } else {128                         left = max;129                     }130                 }131                 //滑动成功 且 回调接口不能空 触发回调方法132                 if (state && null != mOnSwitchChangedListener) {133                     mOnSwitchChangedListener.onSwitchChanged(mCurrentState);134                 }135                 break;136         }137         invalidate();138         return true;139     }140 141     //开关切换回调接口142     public interface OnSwitchChangedListener {143         void onSwitchChanged(boolean isOpen);144     }145 146     public void setOnSwitchChangedListener(OnSwitchChangedListener listener) {147         this.mOnSwitchChangedListener = listener;148     }149 150     public void setCurrentState(boolean isOpen) {151         mCurrentState = isOpen;152         left = isOpen ? max : 0;153         invalidate();154     }155 156 }