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在Android应用开发中，滑动侧边栏经常使用，今天我也试着自己进行了一个简单的实践，虽然功能还不是很强大，但是可以保留下来为以后的开发使用，有需要时在进行简单的修改。实现一个滑动侧边栏思路也很简单：
1.重写一个SlidingMenu类继承ViewGroup，病危该ViewGroup添加两个子布局，分别为菜单和主界面显示；
2.为了得到一个滑动的效果，选择Scroller帮助我们实现，配合ViewGroup下的computeScroll方法实现界面的更新；
3.利用一个boolean来记录菜单是否打开，在菜单打开的状态下向右滑动不会响应，在菜单关闭的情况向左滑动不会响应；
4.为了得到一个良好的交互，我们可以为界面滑动与手指移动的距离定义一个比例，如每次触摸事件发生，界面移动的距离仅为手指移动距离的一半；
下面是两张效果图，界面没怎么布局，大家凑合看
SlidingMenu实现代码：
package com.example.test;
import android.content.Context;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Scroller;
public class SlidingMenu extends ViewGroup {
private static final String TAG = SlidingMenu.class.getName();
private enum Scroll_State {
Scroll_to_Open, Scroll_to_Close;
}
private Scroll_State state;
private int mMostRecentX;
private int downX;
private boolean isOpen = false;
private View menu;
private View mainView;
private Scroller mScroller;
private OnSlidingMenuListener onSlidingMenuListener;
public SlidingMenu(Context context, View main, View menu) {
super(context);
// TODO Auto-generated constructor stub
setMainView(main);
setMenu(menu);
init(context);
}
private void init(Context context) {
mScroller = new Scroller(context);
}
@Override
protected void onLayout(boolean arg0, int l, int t, int r, int b) {
// TODO Auto-generated method stub
mainView.layout(l, t, r, b);
menu.layout(-menu.getMeasuredWidth(), t, 0, b);
}
public void setMainView(View view) {
mainView = view;
addView(mainView);
}
public void setMenu(View view) {
menu = view;
addView(menu);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// TODO Auto-generated method stub
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
mainView.measure(widthMeasureSpec, heightMeasureSpec);
menu.measure(widthMeasureSpec - 150, heightMeasureSpec);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
mMostRecentX = (int) event.getX();
downX = (int) event.getX();
break;
case MotionEvent.ACTION_MOVE:
int moveX = (int) event.getX();
int deltaX = mMostRecentX - moveX;
// 如果在菜单打开时向右滑动及菜单关闭时向左滑动不会触发Scroll事件
if ((!isOpen && (downX - moveX) < 0)
|| (isOpen && (downX - moveX) > 0)) {
scrollBy(deltaX / 2, 0);
}
mMostRecentX = moveX;
break;
case MotionEvent.ACTION_UP:
int upX = (int) event.getX();
int dx = upX - downX;
if (!isOpen) {// 菜单关闭时
// 向右滑动超过menu一半宽度才会打开菜单
if (dx > menu.getMeasuredWidth() / 3) {
state = Scroll_State.Scroll_to_Open;
} else {
state = Scroll_State.Scroll_to_Close;
}
} else {// 菜单打开时
// 当按下时的触摸点在menu区域时，只有向左滑动超过menu的一半，才会关闭
// 当按下时的触摸点在main区域时，会立即关闭
if (downX < menu.getMeasuredWidth()) {
if (dx < -menu.getMeasuredWidth() / 3) {
state = Scroll_State.Scroll_to_Close;
} else {
state = Scroll_State.Scroll_to_Open;
}
} else {
state = Scroll_State.Scroll_to_Close;
}
}
smoothScrollto();
break;
default:
break;
}
return true;
}
private void smoothScrollto() {
int scrollx = getScrollX();
switch (state) {
case Scroll_to_Close:
mScroller.startScroll(scrollx, 0, -scrollx, 0, 500);
if (onSlidingMenuListener != null && isOpen) {
onSlidingMenuListener.close();
}
isOpen = false;
break;
case Scroll_to_Open:
mScroller.startScroll(scrollx, 0,
-scrollx - menu.getMeasuredWidth(), 0, 500);
if (onSlidingMenuListener != null && !isOpen) {
onSlidingMenuListener.close();
}
isOpen = true;
break;
default:
break;
}
}
@Override
public void computeScroll() {
if (mScroller.computeScrollOffset()) {
scrollTo(mScroller.getCurrX(), 0);
}
invalidate();
}
public void open() {
state = Scroll_State.Scroll_to_Open;
smoothScrollto();
}
public void close() {
state = Scroll_State.Scroll_to_Close;
smoothScrollto();
}
public boolean isOpen() {
return isOpen;
}
public void setOnSlidingMenuListener(
OnSlidingMenuListener onSlidingMenuListener) {
this.onSlidingMenuListener = onSlidingMenuListener;
}
public interface OnSlidingMenuListener {
public void open();
public void close();
}
}