Android App中ListView仿QQ实现滑动删除效果的要点解析
作者：鸿洋_
这篇文章主要介绍了Android App中ListView仿QQ实现滑动删除效果的要点解析,重点是要判断手势按下的位置坐标,需要的朋友可以参考下
本来准备在ListView的每个Item的布局上设置一个隐藏的Button，当滑动的时候显示。但是因为每次只要存在一个Button，发现每个Item上的Button相互间不好控制。所以决定继承ListView然后结合PopupWindow。
首先是布局文件：
delete_btn.xml：这里只需要一个Button
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical" >
<Button
android:id="@+id/id_item_btn"
android:layout_width="60dp"
android:singleLine="true"
android:layout_height="wrap_content"
android:text="删除"
android:background="@drawable/d_delete_btn"
android:textColor="#ffffff"
android:paddingLeft="15dp"
android:paddingRight="15dp"
android:layout_alignParentRight="true"
android:layout_centerVertical="true"
android:layout_marginRight="15dp"
/>
</LinearLayout>
主布局文件：activity_main.xml，ListView的每个Item的样式直接使用了系统的android.R.layout.simple_list_item_1
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<com.example.listviewitemslidedeletebtnshow.QQListView
android:id="@+id/id_listview"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
</com.example.listviewitemslidedeletebtnshow.QQListView>
</RelativeLayout>
接下来看看QQListView的实现：
package com.example.listviewitemslidedeletebtnshow;
import android.content.Context;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.PopupWindow;
public class QQListView extends ListView
{
private static final String TAG = "QQlistView";
// private static final int VELOCITY_SANP = 200;
// private VelocityTracker mVelocityTracker;
/**
* 用户滑动的最小距离
*/
private int touchSlop;
/**
* 是否响应滑动
*/
private boolean isSliding;
/**
* 手指按下时的x坐标
*/
private int xDown;
/**
* 手指按下时的y坐标
*/
private int yDown;
/**
* 手指移动时的x坐标
*/
private int xMove;
/**
* 手指移动时的y坐标
*/
private int yMove;
private LayoutInflater mInflater;
private PopupWindow mPopupWindow;
private int mPopupWindowHeight;
private int mPopupWindowWidth;
private Button mDelBtn;
/**
* 为删除按钮提供一个回调接口
*/
private DelButtonClickListener mListener;
/**
* 当前手指触摸的View
*/
private View mCurrentView;
/**
* 当前手指触摸的位置
*/
private int mCurrentViewPos;
/**
* 必要的一些初始化
*
* @param context
* @param attrs
*/
public QQListView(Context context, AttributeSet attrs)
{
super(context, attrs);
mInflater = LayoutInflater.from(context);
touchSlop = 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);
/**
* 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 dispatchTouchEvent(MotionEvent ev)
{
int action = ev.getAction();
int x = (int) ev.getX();
int y = (int) ev.getY();
switch (action)
{
case MotionEvent.ACTION_DOWN:
xDown = x;
yDown = y;
/**
* 如果当前popupWindow显示，则直接隐藏，然后屏蔽ListView的touch事件的下传
*/
if (mPopupWindow.isShowing())
{
dismissPopWindow();
return false;
}
// 获得当前手指按下时的item的位置
mCurrentViewPos = pointToPosition(xDown, yDown);
// 获得当前手指按下时的item
View view = getChildAt(mCurrentViewPos - getFirstVisiblePosition());
mCurrentView = view;
break;
case MotionEvent.ACTION_MOVE:
xMove = x;
yMove = y;
int dx = xMove - xDown;
int dy = yMove - yDown;
/**
* 判断是否是从右到左的滑动
*/
if (xMove < xDown && Math.abs(dx) > touchSlop && Math.abs(dy) < touchSlop)
{
// Log.e(TAG, "touchslop = " + touchSlop + " , dx = " + dx +
// " , dy = " + dy);
isSliding = true;
}
break;
}
return super.dispatchTouchEvent(ev);
}
@Override
public boolean onTouchEvent(MotionEvent ev)
{
int action = ev.getAction();
/**
* 如果是从右到左的滑动才相应
*/
if (isSliding)
{
switch (action)
{
case MotionEvent.ACTION_MOVE:
int[] location = new int[2];
// 获得当前item的位置x与y
mCurrentView.getLocationOnScreen(location);
// 设置popupWindow的动画
mPopupWindow.setAnimationStyle(R.style.popwindow_delete_btn_anim_style);
mPopupWindow.update();
mPopupWindow.showAtLocation(mCurrentView, Gravity.LEFT | Gravity.TOP,
location[0] + mCurrentView.getWidth(), location[1] + mCurrentView.getHeight() / 2
- mPopupWindowHeight / 2);
// 设置删除按钮的回调
mDelBtn.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v)
{
if (mListener != null)
{
mListener.clickHappend(mCurrentViewPos);
mPopupWindow.dismiss();
}
}
});
// Log.e(TAG, "mPopupWindow.getHeight()=" + mPopupWindowHeight);
break;
case MotionEvent.ACTION_UP:
isSliding = false;
}
// 相应滑动期间屏幕itemClick事件，避免发生冲突
return true;
}
return super.onTouchEvent(ev);
}
/**
* 隐藏popupWindow
*/
private void dismissPopWindow()
{
if (mPopupWindow != null && mPopupWindow.isShowing())
{
mPopupWindow.dismiss();
}
}
public void setDelButtonClickListener(DelButtonClickListener listener)
{
mListener = listener;
}
interface DelButtonClickListener
{
public void clickHappend(int position);
}
}
代码注释写得很详细，简单说一下，在dispatchTouchEvent中设置当前是否响应用户滑动，然后在onTouchEvent中判断是否响应，如果响应则popupWindow以动画的形式展示出来。当然屏幕上如果存在PopupWindow则屏幕ListView的滚动与Item的点击，以及从右到左滑动时屏幕Item的click事件。
接下来是MainActivity.java，这里代码很简单不做介绍了。
package com.example.listviewitemslidedeletebtnshow;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.Toast;
import com.example.listviewitemslidedeletebtnshow.QQListView.DelButtonClickListener;
public class MainActivity extends Activity
{
private QQListView mListView;
private ArrayAdapter<String> mAdapter;
private List<String> mDatas;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mListView = (QQListView) findViewById(R.id.id_listview);
// 不要直接Arrays.asList
mDatas = new ArrayList<String>(Arrays.asList("HelloWorld", "Welcome", "Java", "Android", "Servlet", "Struts",
"Hibernate", "Spring", "HTML5", "Javascript", "Lucene"));
mAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, mDatas);
mListView.setAdapter(mAdapter);
mListView.setDelButtonClickListener(new DelButtonClickListener()
{
@Override
public void clickHappend(final int position)
{
Toast.makeText(MainActivity.this, position + " : " + mAdapter.getItem(position), 1).show();
mAdapter.remove(mAdapter.getItem(position));
}
});
mListView.setOnItemClickListener(new OnItemClickListener()
{
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id)
{
Toast.makeText(MainActivity.this, position + " : " + mAdapter.getItem(position), 1).show();
}
});
}
}
效果图如下：楼主使用asm.jar以及gifcamera截的gif，由于button的动画很短感觉截图效果很卡不流畅，大家有什么好的截图，还望推荐。有兴趣的还是下载源码看看效果i。
