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扩大View的点击范围

2014-04-01 19:51 447 查看

扩大View的点击范围本人知道的有两种方法，在不影响界面效果的前提下：

1、在View的外面添加一个透明容器

2、就是本文要说的，代码如下：

publicvoidaddToParentArea(finalViewview){

DisplayMetricsmetric=newDisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metric);
finalfloatdensity=metric.density;

finalViewparent=(View)view.getParent();
parent.post(newRunnable(){
publicvoidrun(){
//View的点击范围向四周扩大30个单位
finalRectr=newRect();
view.getHitRect(r);
r.right+=30*density;
r.left+=30*density;
r.bottom+=30*density;
r.top+=30*density;
parent.setTouchDelegate(newTouchDelegate(r,view));
}
});
}

参考文章：http://developer.android.com/training/gestures/viewgroup.html

Androidprovidesthe

TouchDelegate

classtomakeitpossibleforaparenttoextendthetouchableareaofachildviewbeyondthechild'sbounds.Thisisusefulwhenthechildhastobesmall,butshouldhavealargertouchregion.Youcanalsousethisapproachtoshrinkthechild'stouchregionifneedbe.

Inthefollowingexample,an

ImageButton

isthe"delegateview"(thatis,thechildwhosetouchareatheparentwillextend).Hereisthelayoutfile:

<RelativeLayoutxmlns:android="http://schemas.android.com/apk/res/android"

android:id="@+id/parent_layout"

android:layout_width="match_parent"

android:layout_height="match_parent"

tools:context=".MainActivity">

<ImageButtonandroid:id="@+id/button"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:background="@null"

android:src="@drawable/icon"/>

</RelativeLayout>

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Thesnippetbelowdoesthefollowing:

Getstheparentviewandpostsa

Runnable

ontheUIthread.Thisensuresthattheparentlaysoutitschildrenbeforecallingthe

getHitRect()

method.The

getHitRect()

methodgetsthechild'shitrectangle(touchablearea)intheparent'scoordinates.
Findsthe

ImageButton

childviewandcalls

getHitRect()

togettheboundsofthechild'stouchablearea.
Extendstheboundsofthe

ImageButton

'shitrectangle.
Instantiatesa

TouchDelegate

,passingintheexpandedhitrectangleandthe

ImageButton

childviewasparameters.
Setsthe

TouchDelegate

ontheparentview,suchthattoucheswithinthetouchdelegateboundsareroutedtothechild.
Initscapacityastouchdelegateforthe

ImageButton

childview,theparentviewwillreceivealltouchevents.Ifthetoucheventoccurredwithinthechild'shitrectangle,theparentwillpassthetoucheventtothechildforhandling.

publicclassMainActivityextendsActivity{

@Override
protectedvoidonCreate(BundlesavedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Gettheparentview
ViewparentView=findViewById(R.id.parent_layout);

parentView.post(newRunnable(){
//Postintheparent'smessagequeuetomakesuretheparent
//laysoutitschildrenbeforeyoucallgetHitRect()
@Override
publicvoidrun(){
//Theboundsforthedelegateview(anImageButton
//inthisexample)
RectdelegateArea=newRect();
ImageButtonmyButton=(ImageButton)findViewById(R.id.button);
myButton.setEnabled(true);
myButton.setOnClickListener(newView.OnClickListener(){
@Override
publicvoidonClick(Viewview){
Toast.makeText(MainActivity.this,
"TouchoccurredwithinImageButtontouchregion.",
Toast.LENGTH_SHORT).show();
}
});

//ThehitrectanglefortheImageButton
myButton.getHitRect(delegateArea);

//ExtendthetouchareaoftheImageButtonbeyonditsbounds
//ontherightandbottom.
delegateArea.right+=100;
delegateArea.bottom+=100;

//InstantiateaTouchDelegate.
//"delegateArea"istheboundsinlocalcoordinatesof
//thecontainingviewtobemappedtothedelegateview.
//"myButton"isthechildviewthatshouldreceivemotion
//events.
TouchDelegatetouchDelegate=newTouchDelegate(delegateArea,
myButton);

//SetstheTouchDelegateontheparentview,suchthattouches
//withinthetouchdelegateboundsareroutedtothechild.
if(View.class.isInstance(myButton.getParent())){
((View)myButton.getParent()).setTouchDelegate(touchDelegate);
}
}
});
}
}

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