仿QQ空间下拉头部缩放

Activity代码：

public class MainActivity extends Activity {    private ParallaxListView pListView;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main_activity);        View headerView = View.inflate(this, R.layout.header_view, null);        ImageView ivBackground = (ImageView) headerView.findViewById(R.id.ivBackground);        pListView = (ParallaxListView) findViewById(R.id.listView);        pListView.addHeaderView(headerView);        pListView.setParallaxImageView(ivBackground);        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,                android.R.layout.simple_list_item_1, new String[] { "星期一  上班", "星期二  打豆豆","星期三  看星星", "星期四    学习", "星期五 放假", "星期六  拍拖", "星期天  看电影","...." });        pListView.setAdapter(adapter);    }//在view加载完成时设定缩放级别    @Override    public void onWindowFocusChanged(boolean hasWindowFocus) {        super.onWindowFocusChanged(hasWindowFocus);        if (hasWindowFocus) {            pListView.setViewsBounds(2);        }    }}

主页面布局（main_activity.xml）：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" ><ke.qq.tzparallaxlistview.ParallaxListView     android:id="@+id/listView"    android:layout_width="match_parent"    android:layout_height="match_parent"    /></LinearLayout>

头部布局（header_view.xml）：

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent" >    <ImageView        android:id="@+id/ivBackground"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_alignParentLeft="true"        android:layout_alignParentTop="true"        android:contentDescription="@string/app_name"        android:scaleType="centerCrop"        android:src="@drawable/header" />    <ImageView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentBottom="true"        android:layout_marginLeft="20dp"        android:contentDescription="@string/app_name"        android:paddingBottom="20dp"        android:src="@drawable/lf" /></RelativeLayout>

关键部分->自定义ListView：ParallaxListView

public class ParallaxListView extends ListView {    protected static final String TAG = ParallaxListView.class.getName();    private ImageView mImageView;    // 定义ImageView的最大可拉伸的高度    private int mDrawableMaxHeight = -1;    // 定义ImageView初始加载的高度    private int mImageViewHeight = -1;    // 定义ImageView的默认高度    private int mDefaultImageViewHeight = 0;    public ParallaxListView(Context context) {        super(context);        init(context);    }    public ParallaxListView(Context context, AttributeSet attrs) {        super(context, attrs);        init(context);    }    public ParallaxListView(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        init(context);    }    public void setParallaxImageView(ImageView iv) {        mImageView = iv;        mImageView.setScaleType(ScaleType.CENTER_CROP);    }    // 设置缩放级别---控制图片的最大拉伸高度    // 在界面加载完毕的时候调用    public void setViewsBounds(double zoomRatio) {        // mDrawableMaxHeight=zoomRatio*mDefaultImageViewHeight;        if (mDrawableMaxHeight == -1) {            mImageViewHeight = mImageView.getHeight();            if (mImageViewHeight < 0) {                mImageViewHeight = mDefaultImageViewHeight;            }        }    }    /**     * 初始化     *      * @param context     */    private void init(Context context) {        setVerticalScrollBarEnabled(false);        mDefaultImageViewHeight = 449;    }    //内部滑动时调用    @Override    protected void onScrollChanged(int l, int t, int oldl, int oldt) {        // 监听listView的滑动        super.onScrollChanged(l, t, oldl, oldt);        // 如何控制图片见效的高度？---监听listView的头部滑出去的距离        View header = (View) mImageView.getParent();        // 得到头部划出去的距离----<0        if (header.getTop() < 0 && mImageView.getHeight() > mImageViewHeight) {            mImageView.getLayoutParams().height = Math.max(                    mImageView.getHeight() - Math.abs(header.getTop()), mDefaultImageViewHeight);            header.layout(header.getLeft(), 0, header.getRight(), header.getHeight());            // 调整ImageView所在容器的高度            mImageView.requestLayout();        }    }    //在划出屏幕时调用    @Override    protected boolean overScrollBy(int deltaX, int deltaY, int scrollX, int scrollY,            int scrollRangeX, int scrollRangeY, int maxOverScrollX, int maxOverScrollY,            boolean isTouchEvent) {        // 当listView，ScrollView滑动过头的时候回调的方法        // 不断地控制ImageView的高度        boolean isCollapse = resizeOverScrollby(deltaX, deltaY, scrollX, scrollY, scrollRangeX,                scrollRangeY, maxOverScrollX, maxOverScrollY, isTouchEvent);        return isCollapse ? true : super.overScrollBy(deltaX, deltaY, scrollX, scrollY,                scrollRangeX, scrollRangeY, maxOverScrollX, maxOverScrollY, isTouchEvent);    }    /**     * 处理listView，ScrollView滑动过头     * @param deltaX     * @param deltaY     * @param scrollX     * @param scrollY     * @param scrollRangeX     * @param scrollRangeY     * @param maxOverScrollX     * @param maxOverScrollY     * @param isTouchEvent     * @return     */    private boolean resizeOverScrollby(int deltaX, int deltaY, int scrollX, int scrollY,            int scrollRangeX, int scrollRangeY, int maxOverScrollX, int maxOverScrollY,            boolean isTouchEvent) {        if (deltaY < 0) {            mImageView.getLayoutParams().height = Math.max(                    mImageView.getHeight() + Math.abs(deltaY), mDefaultImageViewHeight);            // 重新调整ImageView的宽高            mImageView.requestLayout();        } else {            if (mImageView.getHeight() > mDefaultImageViewHeight)                mImageView.getLayoutParams().height = mImageView.getHeight() - Math.abs(deltaY);            // 重新调整ImageView的宽高            mImageView.requestLayout();        }        return true;    }    @SuppressLint("ClickableViewAccessibility")    @Override    public boolean onTouchEvent(MotionEvent ev) {        //松开手时，展示动画效果        if (ev.getAction() == MotionEvent.ACTION_UP) {            ResetAnimation anim = new ResetAnimation(mImageView, mDefaultImageViewHeight);            anim.setDuration(500);            mImageView.startAnimation(anim);        }        return super.onTouchEvent(ev);    }    //自定义动画效果    public class ResetAnimation extends Animation {        private ImageView mView;        // private int targetHeight;        private int originalHeith;        private int extraHeight;        public ResetAnimation(ImageView mView, int targetHeight) {            // 图片动画地减小高度            this.mView = mView;            // this.targetHeight = targetHeight;            this.originalHeith = mView.getHeight();            extraHeight = originalHeith - targetHeight;        }        @Override        protected void applyTransformation(float interpolatedTime, Transformation t) {            super.applyTransformation(interpolatedTime, t);            //interpolatedTime的值为0.0~1.0f            mView.getLayoutParams().height = (int) (originalHeith - extraHeight * interpolatedTime);            mView.requestLayout();        }    }}

demo链接

效果图：