Android GridView添加头部问题的解决
我们都知道ListView有addHeaderView和addFooterView两个方法。其中addHeaderView是添加头部布局，addFooterView是添加底部布局。但是GridView却没有这两个方法这个时候就需要重写GridView了。geogle官方给出了重写的HeaderGridView不知道为什么没有添加到官方api里面。代码如下:
publicclassHeaderGridViewextendsGridView{
privatestaticfinalStringTAG="HeaderGridView";
/**
*Aclassthatrepresentsafixedviewinalist,forexampleaheaderatthetop
*orafooteratthebottom.
*/
privatestaticclassFixedViewInfo{
/**Theviewtoaddtothegrid*/
publicViewview;
publicViewGroupviewContainer;
/**Thedatabackingtheview.Thisisreturnedfrom{@linkListAdapter#getItem(int)}.*/
publicObjectdata;
/**trueifthefixedviewshouldbeselectableinthegrid*/
publicbooleanisSelectable;
}
privateArrayListmHeaderViewInfos=newArrayList();
privatevoidinitHeaderGridView(){
super.setClipChildren(false);
}
publicHeaderGridView(Contextcontext){
super(context);
initHeaderGridView();
}
publicHeaderGridView(Contextcontext,AttributeSetattrs){
super(context,attrs);
initHeaderGridView();
}
publicHeaderGridView(Contextcontext,AttributeSetattrs,intdefStyle){
super(context,attrs,defStyle);
initHeaderGridView();
}
@SuppressLint("NewApi")
@Override
protectedvoidonMeasure(intwidthMeasureSpec,intheightMeasureSpec){
super.onMeasure(widthMeasureSpec,heightMeasureSpec);
ListAdapteradapter=getAdapter();
if(adapter!=null&&adapterinstanceofHeaderViewGridAdapter){
((HeaderViewGridAdapter)adapter).setNumColumns(getNumColumns());
}
}
@Override
publicvoidsetClipChildren(booleanclipChildren){
//Ignore,sincetheheaderrowsdependonnotbeingclipped
}
/**
*Addafixedviewtoappearatthetopofthegrid.IfaddHeaderViewis
*calledmorethanonce,theviewswillappearintheordertheywere
*added.Viewsaddedusingthiscallcantakefocusiftheywant.
*
*NOTE:CallthisbeforecallingsetAdapter.ThisissoHeaderGridViewcanwrap
*thesuppliedcursorwithonethatwillalsoaccountforheaderviews.
*
*@paramvTheviewtoadd.
*@paramdataDatatoassociatewiththisview
*@paramisSelectablewhethertheitemisselectable
*/
publicvoidaddHeaderView(Viewv,Objectdata,booleanisSelectable){
ListAdapteradapter=getAdapter();
if(adapter!=null&&!(adapterinstanceofHeaderViewGridAdapter)){
thrownewIllegalStateException(
"Cannotaddheaderviewtogrid--setAdapterhasalreadybeencalled.");
}
FixedViewInfoinfo=newFixedViewInfo();
FrameLayoutfl=newFullWidthFixedViewLayout(getContext());
fl.addView(v);
info.view=v;
info.viewContainer=fl;
info.data=data;
info.isSelectable=isSelectable;
mHeaderViewInfos.add(info);
//inthecaseofre-addingaheaderview,oraddingonelateron,
//weneedtonotifytheobserver
if(adapter!=null){
((HeaderViewGridAdapter)adapter).notifyDataSetChanged();
}
}
/**
*Addafixedviewtoappearatthetopofthegrid.IfaddHeaderViewis
*calledmorethanonce,theviewswillappearintheordertheywere
*added.Viewsaddedusingthiscallcantakefocusiftheywant.
*
*NOTE:CallthisbeforecallingsetAdapter.ThisissoHeaderGridViewcanwrap
*thesuppliedcursorwithonethatwillalsoaccountforheaderviews.
*
*@paramvTheviewtoadd.
*/
publicvoidaddHeaderView(Viewv){
addHeaderView(v,null,true);
}
publicintgetHeaderViewCount(){
returnmHeaderViewInfos.size();
}
/**
*Removesapreviously-addedheaderview.
*
*@paramvTheviewtoremove
*@returntrueiftheviewwasremoved,falseiftheviewwasnotaheader
*view
*/
publicbooleanremoveHeaderView(Viewv){
if(mHeaderViewInfos.size()>0){
booleanresult=false;
ListAdapteradapter=getAdapter();
if(adapter!=null&&((HeaderViewGridAdapter)adapter).removeHeader(v)){
result=true;
}
removeFixedViewInfo(v,mHeaderViewInfos);
returnresult;
}
returnfalse;
}
privatevoidremoveFixedViewInfo(Viewv,ArrayListwhere){
intlen=where.size();
for(inti=0;i0){
HeaderViewGridAdapterhadapter=newHeaderViewGridAdapter(mHeaderViewInfos,adapter);
intnumColumns=getNumColumns();
if(numColumns>1){
hadapter.setNumColumns(numColumns);
}
super.setAdapter(hadapter);
}else{
super.setAdapter(adapter);
}
}
privateclassFullWidthFixedViewLayoutextendsFrameLayout{
publicFullWidthFixedViewLayout(Contextcontext){
super(context);
}
@Override
protectedvoidonMeasure(intwidthMeasureSpec,intheightMeasureSpec){
inttargetWidth=HeaderGridView.this.getMeasuredWidth()
-HeaderGridView.this.getPaddingLeft()
-HeaderGridView.this.getPaddingRight();
widthMeasureSpec=MeasureSpec.makeMeasureSpec(targetWidth,
MeasureSpec.getMode(widthMeasureSpec));
super.onMeasure(widthMeasureSpec,heightMeasureSpec);
}
}
/**
*ListAdapterusedwhenaHeaderGridViewhasheaderviews.ThisListAdapter
*wrapsanotheroneandalsokeepstrackoftheheaderviewsandtheir
*associateddataobjects.
*Thisisintendedasabaseclass;youwillprobablynotneedto
*usethisclassdirectlyinyourowncode.
*/
privatestaticclassHeaderViewGridAdapterimplementsWrapperListAdapter,Filterable{
//Thisisusedtonotifythecontainerofupdatesrelatingtonumberofcolumns
//orheaderschanging,whichchangesthenumberofplaceholdersneeded
privatefinalDataSetObservablemDataSetObservable=newDataSetObservable();
privatefinalListAdaptermAdapter;
privateintmNumColumns=1;
//ThisArrayListisassumedtoNOTbenull.
ArrayListmHeaderViewInfos;
booleanmAreAllFixedViewsSelectable;
privatefinalbooleanmIsFilterable;
publicHeaderViewGridAdapter(ArrayListheaderViewInfos,ListAdapteradapter){
mAdapter=adapter;
mIsFilterable=adapterinstanceofFilterable;
if(headerViewInfos==null){
thrownewIllegalArgumentException("headerViewInfoscannotbenull");
}
mHeaderViewInfos=headerViewInfos;
mAreAllFixedViewsSelectable=areAllListInfosSelectable(mHeaderViewInfos);
}
publicintgetHeadersCount(){
returnmHeaderViewInfos.size();
}
@Override
publicbooleanisEmpty(){
return(mAdapter==null||mAdapter.isEmpty())&&getHeadersCount()==0;
}
publicvoidsetNumColumns(intnumColumns){
if(numColumns<1){
thrownewIllegalArgumentException("Numberofcolumnsmustbe1ormore");
}
if(mNumColumns!=numColumns){
mNumColumns=numColumns;
notifyDataSetChanged();
}
}
privatebooleanareAllListInfosSelectable(ArrayListinfos){
if(infos!=null){
for(FixedViewInfoinfo:infos){
if(!info.isSelectable){
returnfalse;
}
}
}
returntrue;
}
publicbooleanremoveHeader(Viewv){
for(inti=0;i=numHeadersAndPlaceholders){
intadjPosition=position-numHeadersAndPlaceholders;
intadapterCount=mAdapter.getCount();
if(adjPosition=numHeadersAndPlaceholders){
intadjPosition=position-numHeadersAndPlaceholders;
intadapterCount=mAdapter.getCount();
if(adjPosition
用法和ListView的addHeaderView一样。
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