可动态布局的Android抽屉之基础

本文来自http://blog.csdn.net/hellogv/ ，欢迎转摘，引用必须注明出处！

以前曾经介绍过《Android提高第十九篇之"多方向"抽屉》，当这个抽屉组件不与周围组件发生压挤的情况下(周围组件布局不变)，是比较好使的，但是如果需要对周围组件挤压，则用起来欠缺美观了。

如下图。在对周围压挤的情况下，抽屉是先把周围的组件一次性压挤，再通过动画效果展开/收缩的，这种做法的好处是快速简单，坏处是如果挤压范围过大，则效果生硬。

本文实现的自定义抽屉组件，主要针对这种压挤效果做出改良，渐进式压挤周围组件，使得过渡效果更加美观。如下图。

本文实现的抽屉原理是酱紫：

1.抽屉组件主要在屏幕不可视区域，手柄在屏幕边缘的可视区域。即 抽屉.rightMargin=-XXX + 手柄.width

2.指定一个周围组件为可压挤，即LayoutParams.weight=1;当然用户也可以指定多个View.

3.使用AsyncTask来实现弹出/收缩的动画，弹出：抽屉.rightMargin+=XX，收缩：抽屉.rightMargin-=XX

总结，本文的自定义抽屉虽然对压挤周围组件有过渡效果，但是比较耗资源，读者可以针对不同的情况考虑使用。

本文的源码可以到http://download.csdn.net/detail/hellogv/3615686下载。

接下来贴出本文全部源代码：

main.xml的源码:

<span style="font-family: Comic Sans MS; font-size: 18px;"><?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
	android:layout_width="fill_parent" android:layout_height="fill_parent"
	android:id="@+id/container">
	<GridView android:id="@+id/gridview" android:layout_width="fill_parent"
		android:layout_height="fill_parent" android:numColumns="auto_fit"
		android:verticalSpacing="10dp" android:gravity="center"
		android:columnWidth="50dip" android:horizontalSpacing="10dip" />
</LinearLayout></span>

GridView的Item.xml的源码：

<span style="font-family: Comic Sans MS; font-size: 18px;"><?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
	android:layout_height="wrap_content" android:paddingBottom="4dip"
	android:layout_width="fill_parent">
	<ImageView android:layout_height="wrap_content" android:id="@+id/ItemImage"
		android:layout_width="wrap_content" android:layout_centerHorizontal="true">
	</ImageView>
	<TextView android:layout_width="wrap_content"
		android:layout_below="@+id/ItemImage" android:layout_height="wrap_content"
		android:text="TextView01" android:layout_centerHorizontal="true"
		android:id="@+id/ItemText">
	</TextView>
</RelativeLayout>  </span>

Panel.java是本文核心，抽屉组件的源码，这个抽屉只实现了从右往左的弹出/从左往右的收缩，读者可以根据自己的需要修改源码来改变抽屉动作的方向：

<span style="font-family: Comic Sans MS; font-size: 18px;">public class Panel extends LinearLayout{
	
	public interface PanelClosedEvent {
		void onPanelClosed(View panel);
	}
	
	public interface PanelOpenedEvent {
		void onPanelOpened(View panel);
	}
	/**Handle的宽度，与Panel等高*/
	private final static int HANDLE_WIDTH=30;
	/**每次自动展开/收缩的范围*/
	private final static int MOVE_WIDTH=20;
	private Button btnHandle;
	private LinearLayout panelContainer;
	private int mRightMargin=0;
	private Context mContext;
	private PanelClosedEvent panelClosedEvent=null;
	private PanelOpenedEvent panelOpenedEvent=null;

	/**
	 * otherView自动布局以适应Panel展开/收缩的空间变化
	 * @author GV
	 *
	 */	
	public Panel(Context context,View otherView,int width,int height) {
		super(context);
		this.mContext=context;
	
		//改变Panel附近组件的属性
		LayoutParams otherLP=(LayoutParams) otherView.getLayoutParams();
		otherLP.weight=1;//支持压挤
		otherView.setLayoutParams(otherLP);
		
		//设置Panel本身的属性
		LayoutParams lp=new LayoutParams(width, height);
		lp.rightMargin=-lp.width+HANDLE_WIDTH;//Panel的Container在屏幕不可视区域，Handle在可视区域
		mRightMargin=Math.abs(lp.rightMargin);
		this.setLayoutParams(lp);
		this.setOrientation(LinearLayout.HORIZONTAL);
		
		//设置Handle的属性
		btnHandle=new Button(context);
		btnHandle.setLayoutParams(new LayoutParams(HANDLE_WIDTH,height));
		btnHandle.setOnClickListener(new OnClickListener(){

			@Override
			public void onClick(View arg0) {
				LayoutParams lp = (LayoutParams) Panel.this.getLayoutParams();
				if (lp.rightMargin < 0)// CLOSE的状态
					new AsynMove().execute(new Integer[] { MOVE_WIDTH });// 正数展开
				else if (lp.rightMargin >= 0)// OPEN的状态
					new AsynMove().execute(new Integer[] { -MOVE_WIDTH });// 负数收缩
			}
			
		});
		//btnHandle.setOnTouchListener(HandleTouchEvent);
		this.addView(btnHandle);
		
		//设置Container的属性
		panelContainer=new LinearLayout(context);
		panelContainer.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,
				LayoutParams.FILL_PARENT));
		this.addView(panelContainer);
	}

	/**
	 * 定义收缩时的回调函数
	 * @param event
	 */
	public void setPanelClosedEvent(PanelClosedEvent event)
	{
		this.panelClosedEvent=event;
	}
	
	/**
	 * 定义展开时的回调函数
	 * @param event
	 */
	public void setPanelOpenedEvent(PanelOpenedEvent event)
	{
		this.panelOpenedEvent=event;
	}
	
	/**
	 * 把View放在Panel的Container
	 * @param v
	 */
	public void fillPanelContainer(View v)
	{
		panelContainer.addView(v);
	}
	
	/**
	 * 异步移动Panel
	 * @author hellogv 
	 */
	class AsynMove extends AsyncTask<Integer, Integer, Void> {

		@Override
		protected Void doInBackground(Integer... params) {
			int times;
			if (mRightMargin % Math.abs(params[0]) == 0)// 整除
				times = mRightMargin / Math.abs(params[0]);
			else
				// 有余数
				times = mRightMargin / Math.abs(params[0]) + 1;

			for (int i = 0; i < times; i++) {
				publishProgress(params);
				try {
					Thread.sleep(Math.abs(params[0]));
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			return null;
		}

		@Override
		protected void onProgressUpdate(Integer... params) {
			LayoutParams lp = (LayoutParams) Panel.this.getLayoutParams();
			if (params[0] < 0)
				lp.rightMargin = Math.max(lp.rightMargin + params[0],
						(-mRightMargin));
			else
				lp.rightMargin = Math.min(lp.rightMargin + params[0], 0);

			if(lp.rightMargin==0 && panelOpenedEvent!=null){//展开之后
				panelOpenedEvent.onPanelOpened(Panel.this);//调用OPEN回调函数
			}
			else if(lp.rightMargin==-(mRightMargin) && panelClosedEvent!=null){//收缩之后
				panelClosedEvent.onPanelClosed(Panel.this);//调用CLOSE回调函数
			}
			Panel.this.setLayoutParams(lp);
		}
	}

}
</span>

main.java是主控部分，演示了Panel的使用：

<span style="font-family: Comic Sans MS; font-size: 18px;">public class main extends Activity {
	public Panel panel;
	public LinearLayout container;
	public GridView gridview;
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		this.setTitle("“可动态布局”的抽屉组件之构建基础-----hellogv");
		gridview = (GridView) findViewById(R.id.gridview);
		container=(LinearLayout)findViewById(R.id.container);
		panel=new Panel(this,gridview,200,LayoutParams.FILL_PARENT);
		container.addView(panel);//加入Panel控件
		
		//新建测试组件
		TextView tvTest=new TextView(this);
		tvTest.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,LayoutParams.FILL_PARENT));
		tvTest.setText("测试组件，红字白底");
		tvTest.setTextColor(Color.RED);
		tvTest.setBackgroundColor(Color.WHITE);
		//加入到Panel里面
		panel.fillPanelContainer(tvTest);
		
		panel.setPanelClosedEvent(panelClosedEvent);
		panel.setPanelOpenedEvent(panelOpenedEvent);
		
		//往GridView填充测试数据
		ArrayList<HashMap<String, Object>> lstImageItem = new ArrayList<HashMap<String, Object>>();
		for (int i = 0; i < 100; i++) {
			HashMap<String, Object> map = new HashMap<String, Object>();
			map.put("ItemImage", R.drawable.icon);
			map.put("ItemText", "NO." + String.valueOf(i));
			lstImageItem.add(map);
		}

		SimpleAdapter saImageItems = new SimpleAdapter(this, 
				lstImageItem,
				R.layout.item, 
				new String[] { "ItemImage", "ItemText" },
				new int[] { R.id.ItemImage, R.id.ItemText });
		gridview.setAdapter(saImageItems);
		gridview.setOnItemClickListener(new ItemClickListener());
		
	}

	PanelClosedEvent panelClosedEvent =new PanelClosedEvent(){

		@Override
		public void onPanelClosed(View panel) {
			Log.e("panelClosedEvent","panelClosedEvent");
		}
		
	};
	
	PanelOpenedEvent panelOpenedEvent =new PanelOpenedEvent(){

		@Override
		public void onPanelOpened(View panel) {
			Log.e("panelOpenedEvent","panelOpenedEvent");
		}
		
	};
	
	class ItemClickListener implements OnItemClickListener {
		@Override
		public void onItemClick(AdapterView<?> arg0,View arg1, int arg2, long arg3) {
			@SuppressWarnings("unchecked")
			HashMap<String, Object> item = (HashMap<String, Object>) arg0
					.getItemAtPosition(arg2);
			setTitle((String) item.get("ItemText"));
		}

	}</span>

后面还会继续介绍如何在Panel加入拖拉效果的处理！