如何在Android应用中实现一个列表悬浮效果
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具体方法如下:
package com.xiaos.view; import android.content.Context; import android.graphics.Canvas; import android.util.AttributeSet; import android.view.MotionEvent; import android.view.View; import android.view.ViewGroup; import android.widget.AbsListView; import android.widget.AbsListView.OnScrollListener; import android.widget.ExpandableListAdapter; import android.widget.ExpandableListView; import android.widget.ExpandableListView.OnGroupClickListener; public class PinnedHeaderExpandableListView extends ExpandableListView implements OnScrollListener,OnGroupClickListener { public PinnedHeaderExpandableListView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); registerListener(); } public PinnedHeaderExpandableListView(Context context, AttributeSet attrs) { super(context, attrs); registerListener(); } public PinnedHeaderExpandableListView(Context context) { super(context); registerListener(); } /** * Adapter 接口 . 列表必须实现此接口 . */ public interface HeaderAdapter { public static final int PINNED_HEADER_GONE = 0; public static final int PINNED_HEADER_VISIBLE = 1; public static final int PINNED_HEADER_PUSHED_UP = 2; /** * 获取 Header 的状态 * @param groupPosition * @param childPosition * @return PINNED_HEADER_GONE,PINNED_HEADER_VISIBLE,PINNED_HEADER_PUSHED_UP 当中之中的一个 */ int getHeaderState(int groupPosition, int childPosition); /** * 配置 Header, 让 Header 知道显示的内容 * @param header * @param groupPosition * @param childPosition * @param alpha */ void configureHeader(View header, int groupPosition,int childPosition, int alpha); /** * 设置组按下的状态 * @param groupPosition * @param status */ void setGroupClickStatus(int groupPosition, int status); /** * 获取组按下的状态 * @param groupPosition * @return */ int getGroupClickStatus(int groupPosition); } private static final int MAX_ALPHA = 255; private HeaderAdapter mAdapter; /** * 用于在列表头显示的 View,mHeaderViewVisible 为 true 才可见 */ private View mHeaderView; /** * 列表头是否可见 */ private boolean mHeaderViewVisible; private int mHeaderViewWidth; private int mHeaderViewHeight; public void setHeaderView(View view) { mHeaderView = view; AbsListView.LayoutParams lp = new AbsListView.LayoutParams( ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT); view.setLayoutParams(lp); if (mHeaderView != null) { setFadingEdgeLength(0); } requestLayout(); } private void registerListener() { setOnScrollListener(this); setOnGroupClickListener(this); } /** * 点击 HeaderView 触发的事件 */ private void headerViewClick() { long packedPosition = getExpandableListPosition(this.getFirstVisiblePosition()); int groupPosition = ExpandableListView.getPackedPositionGroup(packedPosition); if (mAdapter.getGroupClickStatus(groupPosition) == 1) { this.collapseGroup(groupPosition); mAdapter.setGroupClickStatus(groupPosition, 0); } else{ this.expandGroup(groupPosition); mAdapter.setGroupClickStatus(groupPosition, 1); } this.setSelectedGroup(groupPosition); } private float mDownX; private float mDownY; /** * 假设 HeaderView 是可见的 , 此函数用于推断是否点击了 HeaderView, 并对做对应的处理 , * 由于 HeaderView 是画上去的 , 所以设置事件监听是无效的 , 仅仅有自行控制 . */ @Override public boolean onTouchEvent(MotionEvent ev) { if (mHeaderViewVisible) { switch (ev.getAction()) { case MotionEvent.ACTION_DOWN: mDownX = ev.getX(); mDownY = ev.getY(); if (mDownX <= mHeaderViewWidth && mDownY <= mHeaderViewHeight) { return true; } break; case MotionEvent.ACTION_UP: float x = ev.getX(); float y = ev.getY(); float offsetX = Math.abs(x - mDownX); float offsetY = Math.abs(y - mDownY); // 假设 HeaderView 是可见的 , 点击在 HeaderView 内 , 那么触发 headerClick() if (x <= mHeaderViewWidth && y <= mHeaderViewHeight && offsetX <= mHeaderViewWidth && offsetY <= mHeaderViewHeight) { if (mHeaderView != null) { headerViewClick(); } return true; } break; default: break; } } return super.onTouchEvent(ev); } @Override public void setAdapter(ExpandableListAdapter adapter) { super.setAdapter(adapter); mAdapter = (HeaderAdapter) adapter; } /** * * 点击了 Group 触发的事件 , 要依据依据当前点击 Group 的状态来 */ @Override public boolean onGroupClick(ExpandableListView parent,View v,int groupPosition,long id) { if (mAdapter.getGroupClickStatus(groupPosition) == 0) { mAdapter.setGroupClickStatus(groupPosition, 1); parent.expandGroup(groupPosition); //Header自己主动置顶 //parent.setSelectedGroup(groupPosition); } else if (mAdapter.getGroupClickStatus(groupPosition) == 1) { mAdapter.setGroupClickStatus(groupPosition, 0); parent.collapseGroup(groupPosition); } // 返回 true 才干够弹回第一行 , 不知道为什么 return true; } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); if (mHeaderView != null) { measureChild(mHeaderView, widthMeasureSpec, heightMeasureSpec); mHeaderViewWidth = mHeaderView.getMeasuredWidth(); mHeaderViewHeight = mHeaderView.getMeasuredHeight(); } } private int mOldState = -1; @Override protected void onLayout(boolean changed, int left, int top, int right,int bottom) { super.onLayout(changed, left, top, right, bottom); final long flatPostion = getExpandableListPosition(getFirstVisiblePosition()); final int groupPos = ExpandableListView.getPackedPositionGroup(flatPostion); final int childPos = ExpandableListView.getPackedPositionChild(flatPostion); int state = mAdapter.getHeaderState(groupPos, childPos); if (mHeaderView != null && mAdapter != null && state != mOldState) { mOldState = state; mHeaderView.layout(0, 0, mHeaderViewWidth, mHeaderViewHeight); } configureHeaderView(groupPos, childPos); } public void configureHeaderView(int groupPosition, int childPosition) { if (mHeaderView == null || mAdapter == null || ((ExpandableListAdapter) mAdapter).getGroupCount() == 0) { return; } int state = mAdapter.getHeaderState(groupPosition, childPosition); switch (state) { case HeaderAdapter.PINNED_HEADER_GONE: { mHeaderViewVisible = false; break; } case HeaderAdapter.PINNED_HEADER_VISIBLE: { mAdapter.configureHeader(mHeaderView, groupPosition,childPosition, MAX_ALPHA); if (mHeaderView.getTop() != 0){ mHeaderView.layout(0, 0, mHeaderViewWidth, mHeaderViewHeight); } mHeaderViewVisible = true; break; } case HeaderAdapter.PINNED_HEADER_PUSHED_UP: { View firstView = getChildAt(0); int bottom = firstView.getBottom(); // intitemHeight = firstView.getHeight(); int headerHeight = mHeaderView.getHeight(); int y; int alpha; if (bottom < headerHeight) { y = (bottom - headerHeight); alpha = MAX_ALPHA * (headerHeight + y) / headerHeight; } else { y = 0; alpha = MAX_ALPHA; } mAdapter.configureHeader(mHeaderView, groupPosition,childPosition, alpha); if (mHeaderView.getTop() != y) { mHeaderView.layout(0, y, mHeaderViewWidth, mHeaderViewHeight + y); } mHeaderViewVisible = true; break; } } } @Override /** * 列表界面更新时调用该方法(如滚动时) */ protected void dispatchDraw(Canvas canvas) { super.dispatchDraw(canvas); if (mHeaderViewVisible) { //分组栏是直接绘制到界面中。而不是增加到ViewGroup中 drawChild(canvas, mHeaderView, getDrawingTime()); } } @Override public void onScroll(AbsListView view, int firstVisibleItem,int visibleItemCount, int totalItemCount) { final long flatPos = getExpandableListPosition(firstVisibleItem); int groupPosition = ExpandableListView.getPackedPositionGroup(flatPos); int childPosition = ExpandableListView.getPackedPositionChild(flatPos); configureHeaderView(groupPosition, childPosition); } @Override public void onScrollStateChanged(AbsListView view, int scrollState) { } }
PinnedHeaderExpandableAdapter.java 适配器
实现了PinnedHeaderExpandableListView中HeaderAdapter接口
package com.xiaos.adapter; import android.content.Context; import android.util.SparseIntArray; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.BaseExpandableListAdapter; import android.widget.ImageView; import android.widget.TextView; import com.xiaos.pinnedheaderexpandable.R; import com.xiaos.view.PinnedHeaderExpandableListView; import com.xiaos.view.PinnedHeaderExpandableListView.HeaderAdapter; public class PinnedHeaderExpandableAdapter extends BaseExpandableListAdapter implements HeaderAdapter{ private String[][] childrenData; private String[] groupData; private Context context; private PinnedHeaderExpandableListView listView; private LayoutInflater inflater; public PinnedHeaderExpandableAdapter(String[][] childrenData,String[] groupData ,Context context,PinnedHeaderExpandableListView listView){ this.groupData = groupData; this.childrenData = childrenData; this.context = context; this.listView = listView; inflater = LayoutInflater.from(this.context); } @Override public Object getChild(int groupPosition, int childPosition) { return childrenData[groupPosition][childPosition]; } @Override public long getChildId(int groupPosition, int childPosition) { return 0; } @Override public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) { View view = null; if (convertView != null) { view = convertView; } else { view = createChildrenView(); } TextView text = (TextView)view.findViewById(R.id.childto); text.setText(childrenData[groupPosition][childPosition]); return view; } @Override public int getChildrenCount(int groupPosition) { return childrenData[groupPosition].length; } @Override public Object getGroup(int groupPosition) { return groupData[groupPosition]; } @Override public int getGroupCount() { return groupData.length; } @Override public long getGroupId(int groupPosition) { return 0; } @Override public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) { View view = null; if (convertView != null) { view = convertView; } else { view = createGroupView(); } ImageView iv = (ImageView)view.findViewById(R.id.groupIcon); if (isExpanded) { iv.setImageResource(R.drawable.btn_browser2); } else{ iv.setImageResource(R.drawable.btn_browser); } TextView text = (TextView)view.findViewById(R.id.groupto); text.setText(groupData[groupPosition]); return view; } @Override public boolean hasStableIds() { return true; } @Override public boolean isChildSelectable(int groupPosition, int childPosition) { return true; } private View createChildrenView() { return inflater.inflate(R.layout.child, null); } private View createGroupView() { return inflater.inflate(R.layout.group, null); } @Override public int getHeaderState(int groupPosition, int childPosition) { final int childCount = getChildrenCount(groupPosition); if (childPosition == childCount - 1) { return PINNED_HEADER_PUSHED_UP; } else if (childPosition == -1 && !listView.isGroupExpanded(groupPosition)) { return PINNED_HEADER_GONE; } else { return PINNED_HEADER_VISIBLE; } } @Override public void configureHeader(View header, int groupPosition, int childPosition, int alpha) { String groupData = this.groupData[groupPosition]; ((TextView) header.findViewById(R.id.groupto)).setText(groupData); } private SparseIntArray groupStatusMap = new SparseIntArray(); @Override public void setGroupClickStatus(int groupPosition, int status) { groupStatusMap.put(groupPosition, status); } @Override public int getGroupClickStatus(int groupPosition) { if (groupStatusMap.keyAt(groupPosition)>=0) { return groupStatusMap.get(groupPosition); } else { return 0; } } }
MainActivity.java主Activity
package com.xiaos.pinnedheaderexpandable; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.widget.ExpandableListView; import android.widget.ExpandableListView.OnGroupClickListener; import com.xiaos.adapter.PinnedHeaderExpandableAdapter; import com.xiaos.view.PinnedHeaderExpandableListView; public class MainActivity extends Activity{ private PinnedHeaderExpandableListView explistview; private String[][] childrenData = new String[10][10]; private String[] groupData = new String[10]; private int expandFlag = -1;//控制列表的展开 private PinnedHeaderExpandableAdapter adapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.layout_main); initView(); initData(); } /** * 初始化VIEW */ private void initView() { explistview = (PinnedHeaderExpandableListView)findViewById(R.id.explistview); } /** * 初始化数据 */ private void initData() { for(int i=0;i<10;i++){ groupData[i] = "分组"+i; } for(int i=0;i<10;i++){ for(int j=0;j<10;j++){ childrenData[i][j] = "好友"+i+"-"+j; } } //设置悬浮头部VIEW explistview.setHeaderView(getLayoutInflater().inflate(R.layout.group_head, explistview, false)); adapter = new PinnedHeaderExpandableAdapter(childrenData, groupData, getApplicationContext(),explistview); explistview.setAdapter(adapter); //设置单个分组展开 //explistview.setOnGroupClickListener(new GroupClickListener()); } class GroupClickListener implements OnGroupClickListener{ @Override public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) { if (expandFlag == -1) { // 展开被选的group explistview.expandGroup(groupPosition); // 设置被选中的group置于顶端 explistview.setSelectedGroup(groupPosition); expandFlag = groupPosition; } else if (expandFlag == groupPosition) { explistview.collapseGroup(expandFlag); expandFlag = -1; } else { explistview.collapseGroup(expandFlag); // 展开被选的group explistview.expandGroup(groupPosition); // 设置被选中的group置于顶端 explistview.setSelectedGroup(groupPosition); expandFlag = groupPosition; } return true; } } }
布局文件
child.xml
<?xml version="1.0" encoding="utf-8"?>
group_head.xml
<?xml version="1.0" encoding="utf-8"?>
group.xml
<?xml version="1.0" encoding="utf-8"?>
layout_main.xml
<?xml version="1.0" encoding="utf-8"?>
AndroidManifest.xml
上述就是小编为大家分享的如何在Android应用中实现一个列表悬浮效果了,如果刚好有类似的疑惑,不妨参照上述分析进行理解。如果想知道更多相关知识,欢迎关注创新互联行业资讯频道。
文章题目:如何在Android应用中实现一个列表悬浮效果
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