学步园

如果想让屏幕下方容纳某个组件， 当向上滑动的时候显示出来。可是android 的布局没有支持屏幕底下预留位置。

所以用Scroller实现滑动， 然后动态改变隐藏部分的高度（起始是0）是一个不错的解决方案。

实现步骤

1.自定义View使用Scroller实现滑动。

package com.example.scroller.view;

import android.content.Context;
import android.util.AttributeSet;
import android.widget.LinearLayout;
import android.widget.Scroller;

public class ScrollCustomView extends LinearLayout {
	
	
	private Scroller mScroller;

	SizeChangeListener listener;
	
	final int DURATION = 500;
	
	final int HEIGHT = 100;
	
	public SizeChangeListener getListener() {
		return listener;
	}


	public void setListener(SizeChangeListener listener) {
		this.listener = listener;
	}


	public ScrollCustomView(Context context, AttributeSet attrs) {
		super(context, attrs);
		init(context);
	}

	
	void init(Context context) {
		//View.inflate(context, R.layout.layout_bttom, this);
		mScroller = new Scroller(context);
	}
	
	
	public void scrollUp() {
		mScroller.startScroll(0, 0, 0, HEIGHT, DURATION);
		invalidate();
	}
	
	
	public void scrollDown() {
		mScroller.startScroll(0, HEIGHT, 0, -HEIGHT, DURATION);
		invalidate();
	}
	
	@Override
	public void computeScroll() {
		if (mScroller.computeScrollOffset()) {
			int scrollY = mScroller.getCurrY();
			scrollTo(mScroller.getCurrX(), scrollY);
			if (listener != null)
				listener.onShowBottom(scrollY);
			invalidate();
		}
		
	}
	
	public interface SizeChangeListener {
		void onShowBottom(int height);
	}
}

2.主Activity， 通过设置滑动时的监听事件， 动态改变底部view的高度。

package com.example.scroller;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup.LayoutParams;
import android.widget.Button;
import android.widget.LinearLayout;

import com.example.scroller.view.ScrollCustomView;
import com.example.scroller.view.ScrollCustomView.SizeChangeListener;

public class MainActivity extends Activity implements OnClickListener {

	ScrollCustomView customView;
	
	Button button1, button2;
	
	LinearLayout linear2;
	
	
	
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        customView = (ScrollCustomView) findViewById(R.id.custom_btm);
        
        
        button1 = (Button) findViewById(R.id.button1);
        button2 = (Button) findViewById(R.id.button2);
        
        linear2 = (LinearLayout) findViewById(R.id.linear2);
        
        button1.setOnClickListener(this);
        button2.setOnClickListener(this);
        
        customView.setListener(new SizeChangeListener() {
			
			@Override
			public void onShowBottom(int height) {
				LayoutParams layoutParams = linear2.getLayoutParams();
				layoutParams.height = height;
				linear2.setLayoutParams(layoutParams);
				
			}
		});
        
    }


	@Override
	public void onClick(View v) {
		
		switch(v.getId()) {
		case R.id.button1:
			customView.scrollUp();
			break;
		case R.id.button2:
			customView.scrollDown();
			break;
			
		}
		
	}

    
}

3. 布局文件如下

   <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"
    android:background="#ff220000"
    tools:context=".MainActivity" >

    
      <LinearLayout
          android:id="@+id/linear1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >
        
          <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:clickable="true"
        android:text="@string/hello_world" />
     <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button" />
     
    </LinearLayout>
    
    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true" >

        <LinearLayout
            android:id="@+id/linear2"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:orientation="vertical" >

            <include
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                layout="@layout/layout_bttom" />
        </LinearLayout>
    </FrameLayout>

    <com.example.scroller.view.ScrollCustomView
        android:id="@+id/custom_btm"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/transparent"
        android:layout_below="@id/linear1"
        android:orientation="vertical" >
        <RatingBar
            android:id="@+id/ratingBar1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />

        <TimePicker
            android:layout_marginTop="100dp"
            android:id="@+id/timePicker1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />

        
        
        </com.example.scroller.view.ScrollCustomView>

    
    
</RelativeLayout>

示意图片