UI: 带有Heard的ListView控件

自定义控件代码:

package com.example.drawable_ui.view;import com.example.drawable_ui.R;import android.content.Context;import android.util.AttributeSet;import android.util.Log;import android.view.MotionEvent;import android.view.VelocityTracker;import android.view.ViewConfiguration;import android.view.ViewGroup;import android.widget.LinearLayout;import android.widget.ListView;import android.widget.OverScroller;/** * 练习:拥有head的listview , 可以将header隐藏的layout * 知识点:1.Scroller中的 srollby / srollto / fling 函数的调用      2.速度控制       3.事件分发,拦截         * 4.view中onFinishInflate() ,onMeasure ,onTouchEvent,onInterceptTouchEvent 的调用时机 */public class StickyLayout extends LinearLayout {private ViewGroup mHeaderView;private ListView mListView;private ViewGroup mDividerView;private int mScaledSlop;private int mMaxFlingVelocity;private int mMinFlingVelocity;private OverScroller mScroller;private float lastY;private VelocityTracker mVelocityTracker;public StickyLayout(Context context, AttributeSet attrs) {super(context, attrs);setOrientation(LinearLayout.VERTICAL);mScroller = new OverScroller(context);//判断是否是合法点击的帮助类mScaledSlop = ViewConfiguration.get(context).getScaledTouchSlop();//fling最大的速度mMaxFlingVelocity = ViewConfiguration.get(context).getScaledMaximumFlingVelocity();//fling最小的速度mMinFlingVelocity = ViewConfiguration.get(context).getScaledMinimumFlingVelocity();}@Overrideprotected void onFinishInflate() {mHeaderView = (ViewGroup) findViewById(R.id.id_sticky_header);mDividerView = (ViewGroup) findViewById(R.id.id_sticky_divider);mListView = (ListView) findViewById(R.id.id_sticky_listview);}@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {super.onMeasure(widthMeasureSpec, heightMeasureSpec);//计算listview的高ViewGroup.LayoutParams params = mListView.getLayoutParams();params.height = getMeasuredHeight() - mDividerView.getMeasuredHeight();}@Overridepublic boolean onTouchEvent(MotionEvent event) {int action = event.getAction();initVelocityTracker();mVelocityTracker.addMovement(event);switch (action) {case MotionEvent.ACTION_DOWN:lastY = event.getY();return true;case MotionEvent.ACTION_MOVE:float downY = event.getY();float dY = downY - lastY;int scrollY = getScrollY();//计算滑动后的位置,从而计算滑动之后是否超过了边界范围float currScrollY = scrollY - dY;if(currScrollY >= mHeaderView.getMeasuredHeight()){scrollTo(0, mHeaderView.getMeasuredHeight());}else if(currScrollY <= 0){scrollTo(0, 0);}else {Log.e("TAG", "scrollBy");scrollBy(0, (int)-dY);}lastY = downY;break;case MotionEvent.ACTION_UP://计算滑动速度,如果大于可fling的最小值, 就让其fling起来mVelocityTracker.computeCurrentVelocity(1000, mMaxFlingVelocity);float velocityY = mVelocityTracker.getYVelocity();Log.e("TAG", "UP_velocityY : " + velocityY + ", mMinFlingVelocity :" + mMinFlingVelocity);if(Math.abs(velocityY) > mMinFlingVelocity){fling(-velocityY);}releaseVelocityTracker();break;default:break;}return super.onTouchEvent(event);}private void fling(float velocityY) {//mHeaderView.getMeasuredHeight() 表示最后停止的位置mScroller.fling(0, getScrollY(), 0, (int)velocityY, 0, 0, 0, mHeaderView.getMeasuredHeight());invalidate();}@Overridepublic void computeScroll() {if(mScroller.computeScrollOffset()){scrollTo(0, mScroller.getCurrY());invalidate();}}private void initVelocityTracker(){if(mVelocityTracker == null){mVelocityTracker = VelocityTracker.obtain();}}private void releaseVelocityTracker(){if(mVelocityTracker != null){mVelocityTracker.recycle();mVelocityTracker = null;}}@Overridepublic boolean onInterceptTouchEvent(MotionEvent ev) {int action = ev.getAction();switch (action) {case MotionEvent.ACTION_DOWN:lastY = ev.getY();break;//事件拦截: 1.headview影藏,不拦截   2.headview没有影藏,拦截   3.lisview第一个item显示,拦截  case MotionEvent.ACTION_MOVE:initVelocityTracker();mVelocityTracker.addMovement(ev);mVelocityTracker.computeCurrentVelocity(1000, mMaxFlingVelocity);float yVelocity = mVelocityTracker.getYVelocity();Log.e("TAG", "yVelocity : " +yVelocity);int scrollY = getScrollY();if(scrollY < mHeaderView.getMeasuredHeight()){//2.headview没有影藏,拦截return true;}else { if(mListView.getFirstVisiblePosition() == 0 && yVelocity > 0){ return true;}else{return false;}}default:break;}return super.onInterceptTouchEvent(ev);}}

 

xml文件:

<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"    tools:context="com.example.drawable_ui.MainActivity" >    <com.example.drawable_ui.view.StickyLayout        android:layout_width="match_parent"        android:layout_height="match_parent" >        <RelativeLayout            android:id="@id/id_sticky_header"            android:layout_width="match_parent"            android:layout_height="300dp"            android:background="#faaaaa" >            <TextView                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:layout_centerInParent="true"                android:text="详情界面"                android:textColor="#000000"                android:textSize="20sp" />        </RelativeLayout>        <LinearLayout            android:id="@id/id_sticky_divider"            android:layout_width="match_parent"            android:layout_height="50dp"            android:background="#55cc77"            android:orientation="horizontal" >            <TextView                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:text="内容标题"                android:textColor="#000000"                android:layout_gravity="center_vertical"                android:textSize="12sp" />        </LinearLayout>        <ListView            android:id="@+id/id_sticky_listview"            android:layout_width="match_parent"            android:layout_height="match_parent" >        </ListView>    </com.example.drawable_ui.view.StickyLayout></RelativeLayout>

values/ids.xml

<?xml version="1.0" encoding="utf-8"?><resources>    <item name="id_sticky_header" type="id"></item>    <item name="id_sticky_divider" type="id"></item>    <item name="id_sticky_listview" type="id"></item></resources>