Android 自定义LineLayout实现满屏任意拖动功能的示例代码
1.前言
在开发中，会有需求实现控件在屏幕随意拖动，这就需要自定义View,然后在OnTouchEvent事件中，处理MotionEvent.ACTION_MOVE事件，然后通过坐标点传值给onlayout方法,来实现控件的任意拖动，具体代码如下：
importandroid.content.Context;
importandroid.util.AttributeSet;
importandroid.view.Display;
importandroid.view.MotionEvent;
importandroid.view.WindowManager;
importandroid.widget.LinearLayout;
publicclassDragLineLayoutextendsLinearLayout{
privateintmWidth;
privateintmHeight;
privateintmScreenWidth;
privateintmScreenHeight;
privateContextmContext;
privateonLocationListenermLocationListener;/*listentotheRect*/
//是否拖动
privatebooleanisDrag=false;
publicbooleanisDrag(){
returnisDrag;
}
publicDragView(Contextcontext,AttributeSetattrs){
super(context,attrs);
this.mContext=context;
}
@Override
protectedvoidonMeasure(intwidthMeasureSpec,intheightMeasureSpec){
super.onMeasure(widthMeasureSpec,heightMeasureSpec);
mWidth=getMeasuredWidth();
mHeight=getMeasuredHeight();
mScreenWidth=getScreenWidth(mContext);
mScreenHeight=getScreenHeight(mContext)-getStatusBarHeight();
}
publicintgetStatusBarHeight(){
intresourceId=mContext.getResources().getIdentifier("status_bar_height","dimen","android");
returnmContext.getResources().getDimensionPixelSize(resourceId);
}
publicintgetScreenWidth(Contextcontext){
WindowManagermanager=(WindowManager)context
.getSystemService(Context.WINDOW_SERVICE);
Displaydisplay=manager.getDefaultDisplay();
returndisplay.getWidth();
}
publicintgetScreenHeight(Contextcontext){
WindowManagermanager=(WindowManager)context
.getSystemService(Context.WINDOW_SERVICE);
Displaydisplay=manager.getDefaultDisplay();
returndisplay.getHeight();
}
privatefloatmDownX;
privatefloatmDownY;
@Override
publicbooleanonTouchEvent(MotionEventevent){
super.onTouchEvent(event);
if(this.isEnabled()){
switch(event.getAction()){
caseMotionEvent.ACTION_DOWN:
isDrag=false;
mDownX=event.getX();
mDownY=event.getY();
break;
caseMotionEvent.ACTION_MOVE:
finalfloatmXdistance=event.getX()-mDownX;
finalfloatmYdistance=event.getY()-mDownY;
intl,r,t,b;
//当水平或者垂直滑动距离大于10,才算是拖动事件
if(Math.abs(mXdistance)>10||Math.abs(mYdistance)>10){
isDrag=true;
l=(int)(getLeft()+mXdistance);
r=l+mWidth;
t=(int)(getTop()+mYdistance);
b=t+mHeight;
//边界判断,不让布局滑出界面
if(l<0){
l=0;
r=l+mWidth;
}elseif(r>mScreenWidth){
r=mScreenWidth;
l=r-mWidth;
}
if(t<0){
t=0;
b=t+mHeight;
}elseif(b>mScreenHeight){
b=mScreenHeight;
t=b-mHeight;
}
//回调移动后的坐标点
if(mLocationListener!=null){
mLocationListener.locationRect((l+r)/2,(t+b)/2);
}
this.layout(l,t,r,b);
}
break;
caseMotionEvent.ACTION_UP:
setPressed(false);
break;
caseMotionEvent.ACTION_CANCEL:
setPressed(false);
break;
}
returntrue;
}
returnfalse;
}
publicvoidsetLocationListener(onLocationListenerLocationListener){
this.mLocationListener=LocationListener;
}
publicinterfaceonLocationListener{
voidlocationRect(floatlocationX,floatlocationY);
}
}
2.在代码中的运用
3.这样就可以在Activity加载这个xml来实现任意拖动功能
总结
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