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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(); } }
在MainActivity中进行调用
package com.example.test; import android.os.Bundle; import android.support.v4.app.FragmentActivity; import android.view.LayoutInflater; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; public class MainActivity extends Activity { private Button openButton; private Button closeButton; private SlidingMenu mSlidingMenu; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mSlidingMenu = new SlidingMenu(this, LayoutInflater .from(this).inflate(R.layout.fragment1, null), LayoutInflater .from(this).inflate(R.layout.fragment2, null)); setContentView(mSlidingMenu);//注意setContentView需要换为我们的SlidingMenu openButton = (Button) findViewById(R.id.button1); closeButton = (Button) findViewById(R.id.button_close); openButton.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { // TODO Auto-generated method stub mSlidingMenu.open(); } }); closeButton.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { // TODO Auto-generated method stub mSlidingMenu.close(); } }); } }
更多关于滑动功能的文章,请点击专题: 《Android滑动功能》
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