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[操作系统]ListView + PopupWindow实现滑动删除


 

原文:ListView滑动删除 ,仿腾讯QQ(鸿洋_)

文章实现的功能是:在ListView的Item上从右向左滑时,出现删除按钮,点击删除按钮把Item删除。

 

看过文章后,感觉没有必要把dispatchTouchEvent()和onTouchEvent()两个方法都重写,只要重写onTouchEvent就好了。于是对代码作了一些调整:

public class MyListView extends ListView {  private static final String TAG = "MyListView";  private int mTouchSlop;  private int mXDown;  private int mYDown;  private int mCurrentPosition;  private View mCurrentView;  private PopupWindow mPopupWindow;  private LayoutInflater mInflater;  private boolean isSliding = false;  // 为删除按钮提供一个回调接口  private DelButtonClickListener mListener;  private Button mDelBtn;  private int mPopupWindowHeight;  private int mPopupWindowWidth;  public MyListView(Context context, AttributeSet attrs) {    super(context, attrs);    mInflater = LayoutInflater.from(context);    mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();    View view = mInflater.inflate(R.layout.delete_btn, null);    mDelBtn = (Button) view.findViewById(R.id.id_item_btn);    mPopupWindow = new PopupWindow(view, LinearLayout.LayoutParams.WRAP_CONTENT,        LinearLayout.LayoutParams.WRAP_CONTENT);    // 如果需要通过点击PopupWindow之外的地方使其消失,则需要setFocusable(true).    mPopupWindow.setFocusable(true);    // Android 6.0以前的版本需要setBackgroundDrawable(),    // 才能实现通过点击PopupWindow之外的地方使其消失的功能。    mPopupWindow.setBackgroundDrawable(new ColorDrawable(0));    // 先调用下measure,否则拿不到宽和高    mPopupWindow.getContentView().measure(0, 0);    mPopupWindowHeight = mPopupWindow.getContentView().getMeasuredHeight();    mPopupWindowWidth = mPopupWindow.getContentView().getMeasuredWidth();  }  @Override  public boolean onTouchEvent(MotionEvent ev) {    int action = ev.getAction();    int x = (int) ev.getX();    int y = (int) ev.getY();    switch (action){      case MotionEvent.ACTION_DOWN:        isSliding = false;        mXDown = x;        mYDown = y;        mCurrentPosition = pointToPosition(mXDown, mYDown);        View view = getChildAt(mCurrentPosition - getFirstVisiblePosition());        mCurrentView = view;        break;      case MotionEvent.ACTION_MOVE:        int dx = x - mXDown;        int dy = y - mYDown;        Log.d(TAG, "mTouchSlop = " + mTouchSlop + ", dx = " + dx + ", dy = " + dy);        if(mXDown > x && Math.abs(dx) > mTouchSlop && Math.abs(dy) < mTouchSlop){          Log.d(TAG, "isSliding");          isSliding = true;          int[] location = new int[2];          mCurrentView.getLocationOnScreen(location);          mPopupWindow.setAnimationStyle(R.style.popwindow_delete_btn_anim_style);          mPopupWindow.update();          Log.d(TAG, "Height: " + mCurrentView.getHeight() + "," + mPopupWindow.getHeight());          mPopupWindow.showAtLocation(mCurrentView, Gravity.NO_GRAVITY,              location[0] + mCurrentView.getWidth(),              location[1] + mCurrentView.getHeight() / 2 - mPopupWindowHeight / 2);          mDelBtn.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {              mListener.clickHappend(mCurrentPosition);              mPopupWindow.dismiss();            }          });        }      case MotionEvent.ACTION_UP:        // isSliding 如果这里恢复为false,则后面会执行super.onTouchEvent事件,        // 而AbsListView的onTouchEvent调用了onTouchUp方法,在onTouchUp方法中有可能执行        // performClick.run() --> performItemClick() --> super.performItemClick        // --> mOnItemClickListener.onItemClick,这样最终触发Item的点击。        // 因此此处依旧保持isSliding为true的状态,而在ACTION_DOWN事件中恢复isSliding为false,        // 毕竟每个事件都以ACTION_DOWN开始。        //isSliding = false;    }    if(isSliding){      return true;    }    return super.onTouchEvent(ev);  }  public void setDelButtonClickListener(DelButtonClickListener listener){    mListener = listener;  }  interface DelButtonClickListener{    public void clickHappend(int position);  }}

MyListView.java

 

通过这个例子学习到:

1、ListView的Item点击事件的触发过程:

自定义ListView的onTouchEvent()  ---调用super.onTouchEvent()---> AbsListView.onTouchEvent() ---MotionEvent.ACTION_UP---> AbsListView.onTouchUp()

---(有可能)调用performClick.run()---> AbsListView.PerformClick.run() ---调用performItemClick()---> AbsListView.performItemClick()

---(有可能)调用super.performItemClick()---> AdapterView.performItemClick() ---mOnItemClickListener.onItemClick---> OnItemClickListener.onItemClick()

也就是Item的点击事件是在MotionEvent.ACTION_UP事件完成的,这样在自定义ListView的onTouchEvent()中,对MotionEvent.ACTION_UP直接return true消费掉事件,而不要调用super.onTouchEvent。这样就避免了删除按钮与Item点击事件的冲突。

 

2、PopupWindow--通过点击PopupWindow之外的地方使其消失

a、需要调用setFocusable()方法(PopupWindow中showAtLocation() --> createPopupLayoutParams() --> computeFlags() --> 设置FLAG_NOT_FOCUSABLE);

b、Android 6.0以前的版本需要setBackgroundDrawable()(具体原因见:PopupWindow的使用)。