Android程序开发之ListView 与PopupWindow实现从左向右滑动删除功能


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);
}
}

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;

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

以上所述是小编给大家介绍的Android程序开发之ListView 与PopupWindow实现滑动删除功能,如果大家有任何疑问请给我留言,小编会及时回复大家的。在此也非常感谢大家对phpstudy网站的支持!


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