/**
* 當view被釋放的時候處理的事情（松手）
*
* @param releasedChild 被釋放的子view
* @param xvel 水平方向的速度 幀每秒 向右為 +
* @param yvel 豎直方向的速度 向下為 +
*/
@Override
public void onViewReleased(View releasedChild, float xvel, float yvel) {
Log.d("DragLayout", "xvel : " + xvel + " yvel :" + yvel);
super.onViewReleased(releasedChild, xvel, yvel);
//判斷關閉和打開
//在這里我們首先判斷什么時候打開，然后剩下的都是關閉狀態(tài)
//首先是我的主面板的左側(cè)具體屏幕左側(cè)已經(jīng)大于mRange/2的距離并且右滑的速度大于0，此時打開
if (xvel >= 0 && mMainContent.getLeft() > mRange / 2.0f) {
open();
} else if (xvel > 0) {
//第二種就是我右滑的速度大于0(這里的速度自己定義哈，根據(jù)自己想要實現(xiàn)的敏感度)
open();
} else {
//剩余的所有情況都是關閉
close();
}
}

/**
* 關閉
*/
public void close() {
int finalLeft = 0;
//調(diào)用layout方法，擺放主布局
/**
* @param l Left position, relative to parent
* @param t Top position, relative to parent
* @param r Right position, relative to parent
* @param b Bottom position, relative to parent
*/
mMainContent.layout(finalLeft, 0, finalLeft + mWidth, finalLeft + mHeight);
}

/**
* 打開
*/
public void open() {
int finalLeft = mRange;
mMainContent.layout(finalLeft, 0, finalLeft + mWidth, finalLeft + mHeight);
}

public void close() {
close(true);
}
/**
* 關閉
*
* @param isSmooth 是否平滑的關閉
*/
public void close(boolean isSmooth) {
int finalLeft = 0;
if (isSmooth) {
/**
* public boolean smoothSlideViewTo(View child, int finalLeft, int finalTop)方法的解釋
*
* Animate the view <code>child</code> to the given (left, top) position.
* If this method returns true, the caller should invoke {@link #continueSettling(boolean)}
* on each subsequent frame to continue the motion until it returns false. If this method
* returns false there is no further work to do to complete the movement.
*
* 返回true 代表還沒有移動到指定的位置，需要刷新界面，繼續(xù)移動
* 返回false 就停止工作哈
*/
//1、觸發(fā)動畫
if (mDragHelper.smoothSlideViewTo(mMainContent, finalLeft, 0)) {
//參數(shù)傳this,也就是child所在的viewgroup
ViewCompat.postInvalidateOnAnimation(this);
}
} else {
//調(diào)用layout方法，擺放主布局
/**
* @param l Left position, relative to parent
* @param t Top position, relative to parent
* @param r Right position, relative to parent
* @param b Bottom position, relative to parent
*/
mMainContent.layout(finalLeft, 0, finalLeft + mWidth, finalLeft + mHeight);
}
}
/**
* 打開
*/
public void open(boolean isSmooth) {
int finalLeft = mRange;
if (isSmooth && mDragHelper.smoothSlideViewTo(mMainContent, finalLeft, 0)) {
//參數(shù)傳this,也就是child所在的viewgroup
ViewCompat.postInvalidateOnAnimation(this);
} else {
mMainContent.layout(finalLeft, 0, finalLeft + mWidth, finalLeft + mHeight);
}
}
public void open() {
open(true);
}

/**
* 定義當前狀態(tài) 默認是關閉狀態(tài)
*/
private Status mStatus = Status.CLOSE;
/**
* 狀態(tài)枚舉
* 關閉 CLOSE
* 打開 OPEN
* 拖拽 DRAGING
*/
public enum Status {
CLOSE, OPEN, DRAGING;
}
private OnDragStatusListener mListener;
public void setDragStateListener(OnDragStatusListener listener) {
mListener = listener;
}
public interface OnDragStatusListener {
/**
* 關閉邏輯
*/
void onClose();
/**
* 打開邏輯
*/
void onOpen();
/**
* 拖拽邏輯
*
* @param percent
*/
void onDraging(float percent);
}

/**
* 狀態(tài)更新方法執(zhí)行
* 
* @param newLeft
*/
private void dispatchDragEvent(int newLeft) {
//得到的一個百分比
float percent = newLeft * 1.0f / mRange;
//0.0f--->1.0f
Log.d("DragLayout", "percent : " + percent);
if (mListener != null) {
mListener.onDraging(percent);
}
//跟新狀態(tài)執(zhí)行回調(diào)
Status lastStatus = mStatus;
mStatus = updateStatus(percent);
if (mStatus != lastStatus) {
//狀態(tài)發(fā)生變化
if (mStatus == Status.CLOSE) {
//當前狀態(tài)是關閉
if (mListener != null) {
mListener.onClose();
}
} else if (mStatus == Status.OPEN) {
if (mListener != null) {
mListener.onOpen();
}
}
}
}
/**
* 狀態(tài)更新方法
*
* @param percent
* @return
*/
private Status updateStatus(float percent) {
if (percent == 0) {
return Status.CLOSE;
} else if (percent == 1) {
return Status.OPEN;
}
return Status.DRAGING;
}