<declare-styleable name="ToggleView">
<attr name="switch_background" format="reference" />
<attr name="slide_button" format="reference" />
<attr name="switch_state" format="boolean" />
</declare-styleable>
/**
* 用于在xml里使用, 可指定自定义属性, 如果指定了样式, 则走此构造函数
* @param context
* @param attrs
* @param defStyle
*/
public ToggleView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// 获取配置的自定义属性
TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.ToggleView, defStyle, 0);
int switchBackgroundResource = a.getResourceId(R.styleable.ToggleView_switch_background, -1);
int slideButtonResource = a.getResourceId(R.styleable.ToggleView_slide_button, -1);
mSwitchState = a.getBoolean(R.styleable.ToggleView_switch_state, false);
//获取背景图片和开关图片后设置图片，便于在onMeasure()方法中设置View宽和高，防止Null
setSwitchBackgroundResource(switchBackgroundResource);
setSlideButtonResource(slideButtonResource);
init();
}

“xmlns:cb=”http://schemas.android.com/apk/res-auto””

- cb:switch_background=”@drawable/switch_background”

- cb:slide_button=”@drawable/slide_button”

- cb:switch_state=”false”

private ToggleView toggleView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
toggleView = (ToggleView) findViewById(R.id.toggleView);
// toggleView.setSwitchBackgroundResource(R.drawable.switch_background);
// toggleView.setSlideButtonResource(R.drawable.slide_button);
// toggleView.setSwitchState(true);
// 
// 设置开关更新监听
toggleView.setOnSwitchStateUpdateListener(new ToggleView.OnSwitchStateUpdateListener(){
@Override
public void onStateUpdate(boolean state) {
Toast.makeText(getApplicationContext(), "state: " + state, Toast.LENGTH_SHORT).show();
}
});
}

// 根据开关状态boolean, 直接设置图片位置
if(mSwitchState){// 开
int newLeft = switchBackgroupBitmap.getWidth() - slideButtonBitmap.getWidth();
canvas.drawBitmap(slideButtonBitmap, newLeft, 0, paint);
}else {// 关
canvas.drawBitmap(slideButtonBitmap, 0, 0, paint);
}

int newLeft = switchBackgroupBitmap.getWidth() - 

private OnSwitchStateUpdateListener onSwitchStateUpdateListener;
// 重写触摸事件, 响应用户的触摸.
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
isTouchMode = true;
System.out.println("event: ACTION_DOWN: " + event.getX());
currentX = event.getX();
break;
case MotionEvent.ACTION_MOVE:
System.out.println("event: ACTION_MOVE: " + event.getX());
currentX = event.getX();
break;
case MotionEvent.ACTION_UP:
isTouchMode = false;
System.out.println("event: ACTION_UP: " + event.getX());
currentX = event.getX();
float center = switchBackgroupBitmap.getWidth() / 2.0f;
// 根据当前按下的位置, 和控件中心的位置进行比较. 
boolean state = currentX > center;
// 如果开关状态变化了, 通知界面. 里边开关状态更新了.
if(state != mSwitchState && onSwitchStateUpdateListener != null){
// 把最新的boolean, 状态传出去了
onSwitchStateUpdateListener.onStateUpdate(state);
}
mSwitchState = state;
break;
default:
break;
}
// 重绘界面
invalidate(); // 会引发onDraw()被调用, 里边的变量会重新生效.界面会更新
return true; // 消费了用户的触摸事件, 才可以收到其他的事件.
}

// Canvas 画布, 画板. 在上边绘制的内容都会显示到界面上.
@Override
protected void onDraw(Canvas canvas) {
// 1. 绘制背景
canvas.drawBitmap(switchBackgroupBitmap, 0, 0, paint);
// 2. 绘制滑块
if(isTouchMode){
// 根据当前用户触摸到的位置画滑块
// 让滑块向左移动自身一半大小的位置
float newLeft = currentX - slideButtonBitmap.getWidth() / 2.0f;
int maxLeft = switchBackgroupBitmap.getWidth() - slideButtonBitmap.getWidth();
// 限定滑块范围
if(newLeft < 0){
newLeft = 0; // 左边范围
}else if (newLeft > maxLeft) {
newLeft = maxLeft; // 右边范围
}
canvas.drawBitmap(slideButtonBitmap, newLeft, 0, paint);
}else {
// 根据开关状态boolean, 直接设置图片位置
if(mSwitchState){// 开
int newLeft = switchBackgroupBitmap.getWidth() - slideButtonBitmap.getWidth();
canvas.drawBitmap(slideButtonBitmap, newLeft, 0, paint);
}else {// 关
canvas.drawBitmap(slideButtonBitmap, 0, 0, paint);
}
}
}

public interface OnSwitchStateUpdateListener{
// 状态回调, 把当前状态传出去
void onStateUpdate(boolean state);
}
public void setOnSwitchStateUpdateListener(
OnSwitchStateUpdateListener onSwitchStateUpdateListener) {
this.onSwitchStateUpdateListener = onSwitchStateUpdateListener;
}

case MotionEvent.ACTION_UP:
isTouchMode = false;
System.out.println("event: ACTION_UP: " + event.getX());
currentX = event.getX(); 
float center = switchBackgroupBitmap.getWidth() / 2.0f;
// 根据当前按下的位置, 和控件中心的位置进行比较. 
boolean state = currentX > center;
// 如果开关状态变化了, 通知界面. 里边开关状态更新了.
if(state != mSwitchState && onSwitchStateUpdateListener != null){
// 把最新的boolean, 状态传出去了
onSwitchStateUpdateListener.onStateUpdate(state);
}
mSwitchState = state;
break;

// 设置开关更新监听
toggleView.setOnSwitchStateUpdateListener(new ToggleView.OnSwitchStateUpdateListener(){
@Override
public void onStateUpdate(boolean state) {
Toast.makeText(getApplicationContext(), "state: " + state, Toast.LENGTH_SHORT).show();
}
});