如何通过定位和填充小部件为平板电脑增加响应能力？

如何解决如何通过定位和填充小部件为平板电脑增加响应能力？

我正在尝试在LayoutBuilder中使用MediaQuery并为所有“定位-材质”按钮使用平板电脑，小型电话和大型电话添加不同的逻辑，并且我想通过mediaQuery添加if和else语句

当我将if语句置于位置之下时，此if语句显示错误。

@override
  Widget build(BuildContext context) {
    var deviceData = MediaQuery.of(context);
    double _width = MediaQuery.of(context).size.width;
    double _height = MediaQuery.of(context).size.height;
    var screenSize = MediaQuery.of(context).size;
    return LayoutBuilder(builder: (context,constraints) {
      return OrientationBuilder(builder: (context,orientation) {
      Size size = MediaQuery.of(context).size;
double width = size.width > size.height ? size.height : size.width;      
        if (MediaQuery.of(context).size.width > 600) {
          isLargeScreen = true;
        } else {
          isLargeScreen = false;
        }
        SizeConfig().init(constraints,orientation);


  Positioned (
                                // height: context.heightPct(.99),// width: context.widthPct(.99),// Container(
                                // alignment: Alignment(,-.3),//  child:   FractionallySizedBox(
                                // widthFactor: 30,if (isLargeScreen){
                                width: 213 * SizeConfig.imageSizeMultiplier,height: 92 * SizeConfig.heightMultiplier,}else{
                                height: 92 * SizeConfig.heightMultiplier,width: 213 * SizeConfig.imageSizeMultiplier,child: Opacity(
                                  opacity: 0.9,// left: width*0.5,// top: 900,// top: 100,child: _visible
                                      ? MaterialButton(
                                          // minWidth:screenSize.width*0.1,// 0.1 = 10% of the screen,0.5 = 50% of the screen
                                          // ios sizes usually are 620...
                                          // height: screenSize.height*0.1,onPressed: () => changeTextArabic1(),onLongPress: () =>
                                              changeTextEnglish1(),// shape: new RoundedRectangleBorder(borderRadius: new BorderRadius.circular(60.0)
                                          // child: Text(labels[i]),// ),child: Ink(
                                            child: Text(surah0),//  disabledTextColor: Colors.transparent,//                       color: Colors.cyan[300],//                       // color: Colors.purple[300],//                       highlightColor: Colors.blue,//                       // shape: new RoundedRectangleBorder(borderRadius: new BorderRadius.circular(60.0)
//                       // ),//                       textColor: Colors.white,// color: Colors.cyan[400],padding: EdgeInsets.all(21.0),// padding: EdgeInsets.only(
                                            //     left: 28,//     top: 25,//     right: 28,//     bottom: 25),decoration: BoxDecoration(
                                              gradient: LinearGradient(
                                                colors: [
// all together looks COOL royal Blue:
                                                  Colors.red,Colors.blue,// Color(0xff374ABE),// Color(0xff64B6FF),// Color(0xff0E0077),// Color(0xff1B00EE)
                                                ],// begin: Alignment.centerLeft,// end: Alignment.centerRight,),// color: Colors.blue[300],// highlightColor: Colors.blue,textColor: Colors.white,)
                                      : Container(),//  ):Container()
                                ),}),

解决方法

您可以使用：

isLargeScreen 
? Positioned()
: Positioned()

或：

Positioned(
  height: isLargeScreen ? something : something,width: isLargeScreen ? something : something
)