颤动: 如何更改 AlertDialog 的宽度？

小开

You could try to wrap your AlertDialog widget with ConstrainedBox widget as suggested in here and set your desired value for maxWidth parameter.

UPDATED

I just looked at the code of the parent of the AlertDialog widget which is the Dialog widget and found out that it wrapped its child with a ConstrainedBox widget with a minWidth of 280 pixels. This is the reason why we can't change the width of the AlertDialog widget.

Fortunately, there are two things that we can do. First option would be to alter the default minWidth of the Dialog Widget inside the dialog.dart file. Note that changing this would affect all of your flutter projects that uses the Dialog widget.

//inside dialog.dart


class Dialog extends StatelessWidget {


...


@override
Widget build(BuildContext context) {
final DialogTheme dialogTheme = DialogTheme.of(context);
return AnimatedPadding(
padding: MediaQuery.of(context).viewInsets + const EdgeInsets.symmetric(horizontal: 40.0, vertical: 24.0),
duration: insetAnimationDuration,
curve: insetAnimationCurve,
child: MediaQuery.removeViewInsets(
removeLeft: true,
removeTop: true,
removeRight: true,
removeBottom: true,
context: context,
child: Center(
child: ConstrainedBox(
constraints: const BoxConstraints(minWidth: 280.0), // You can set your desired value for minWidth here
child: Material(
elevation: 24.0,


...

You can then use the AlertDialog like this:

showDialog(
context: context,
builder: (_) => AlertDialog(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.all(Radius.circular(10.0))
),
contentPadding: EdgeInsets.all(0.0),
content: ProductPreviewScreen(),
)
)
);

The other way would be to create our own customize dialog.

showDialog(
context: context,
builder: (_) => Center( // Aligns the container to center
child: Container( // A simplified version of dialog.
width: 100.0,
height: 56.0,
color: Colors.pink,
)
)
);

小开

Using built-in dialog:

To increase the width:

AlertDialog(
title: Text("AlertDialog"),
insetPadding: EdgeInsets.zero,
)

To decrease the width:

AlertDialog(
title: Text("AlertDialog"),
insetPadding: EdgeInsets.symmetric(horizontal: 100),
)

Using custom dialog:

Call this method:

showGeneralDialog(
context: context,
barrierColor: Colors.black.withOpacity(0.5),
pageBuilder: (_, __, ___) {
return Material(
color: Colors.transparent,
child: Center(
child: Container(
color: Colors.white, // Dialog background
width: 120, // Dialog width
height: 50, // Dialog height
child: SingleChildScrollView(
child: Column(
children: [
Text('I am a small Dialog'),
],
),
),
),
),
);
},
);

小开

My solution is to enclose the Dialog in a widget that defeats the extra padding added by the Dialog class by modifying the MediaQueryData.

import 'package:myapp/widgets/dialog_inset_defeat.dart';
...


showDialog(
context: context,
builder: (_) => DialogInsetDefeat(
context: context,
child: SimpleDialog(...),
)
);

... or use showDialogWithInsets() for custom values:

showDialogWithInsets(
context: context,
edgeInsets: EdgeInsets.symmetric(horizontal: 8),
builder: (_) => SimpleDialog(...),
)
);

File dialog_inset_defeat.dart

   import 'package:flutter/material.dart';


/// A widget to defeat the hard coded insets of the [Dialog] class which
/// are [EdgeInsets.symmetric(horizontal: 40.0, vertical: 24.0)].
///
/// See also:
///
///  * [Dialog], for dialogs that have a message and some buttons.
///  * [showDialog], which actually displays the dialog and returns its result.
///  * <https://material.io/design/components/dialogs.html>
///  * <https://stackoverflow.com/questions/53913192/flutter-change-the-width-of-an-alertdialog>
class DialogInsetDefeat extends StatelessWidget {
final BuildContext context;
final Widget child;
final deInset = EdgeInsets.symmetric(horizontal: -40, vertical: -24);
final EdgeInsets edgeInsets;


DialogInsetDefeat({@required this.context, @required this.child, this.edgeInsets});


@override
Widget build(BuildContext context) {
var netEdgeInsets = deInset + (edgeInsets ?? EdgeInsets.zero);
return MediaQuery(
data: MediaQuery.of(context).copyWith(viewInsets: netEdgeInsets),
child: child,
);
}
}


/// Displays a Material dialog using the above DialogInsetDefeat class.
/// Meant to be a drop-in replacement for showDialog().
///
/// See also:
///
///  * [Dialog], on which [SimpleDialog] and [AlertDialog] are based.
///  * [showDialog], which allows for customization of the dialog popup.
///  * <https://material.io/design/components/dialogs.html>
Future<T> showDialogWithInsets<T>({
@required BuildContext context,
bool barrierDismissible = true,
@required WidgetBuilder builder,
EdgeInsets edgeInsets,
}) {
return showDialog(
context: context,
builder: (_) => DialogInsetDefeat(
context: context,
edgeInsets: edgeInsets,
child: Builder(builder: builder),
),
// Edited! barrierDismissible: barrierDismissible = true,
barrierDismissible: barrierDismissible,
);
}

Works for me as of Flutter 1.8.3. YMMV

小开

Use Padding widget

 Padding(
padding: EdgeInsets.only(left: 50.0, right: 50.0),
child://AlertDialog or any other Dialog you can use
Dialog(
elevation: 0.0,
backgroundColor: Colors.transparent,
child: Container(
width: 10.0,
height: 50.0,
color: Colors.red,
)
))

小开

This is much more simple then the other answers make it out to be. Just use a builder to change the size of the dialog as it is being built(constructed, instantiated in other languages). This means you can also query the screen size and make a decision on how much space you want depending on said screen size. For example more space on a tablet then on a phone. You can make Scaffold a child of the Container if you need the App bar and other functions.

showDialog(
context: context,
builder: (_) => new AlertDialog(
shape: RoundedRectangleBorder(
borderRadius:
BorderRadius.all(
Radius.circular(10.0))),
content: Builder(
builder: (context) {
// Get available height and width of the build area of this widget. Make a choice depending on the size.
var height = MediaQuery.of(context).size.height;
var width = MediaQuery.of(context).size.width;


return Container(
height: height - 400,
width: width - 400,
);
},
),
)
);

Examples of different sizes:

Optionally add these to remove unneeded inner/outer border space.

          insetPadding: EdgeInsets.zero,
contentPadding: EdgeInsets.zero,
clipBehavior: Clip.antiAliasWithSaveLayer,

小开

As a workaround, you can play with the dialog title, in most cases the dialog will expand horizontally to accommodate the title. So you can create big title to make sure the dialog will take max width. Obviously you can't just put long title, but you can build your title of two text widgets, where one of them has text color matching background. For the case where no title should be shown:

showDialog(
context: context,
builder: (_) =>
new AlertDialog(
title: Text('hidden title, just set font text to the same as background.',
style: TextStyle(color: Colors.white)),
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.all(Radius.circular(10.0))
),
content: ProductPreviewScreen(),
)
);

小开

As of May 2020, if you want to change the inset padding of a dialog, all you have to do is use the Dialog class and override the 'insetPadding' property. You can make a dialog extend all the way to the screen edges if you want to.

You can also make some cool custom dialogs by making the dialog surface itself transparent and then add whatever widgets you want. For example:

showDialog(Dialog(
backgroundColor: Colors.transparent,
insetPadding: EdgeInsets.all(10),
child: Stack(
overflow: Overflow.visible,
alignment: Alignment.center,
children: <Widget>[
Container(
width: double.infinity,
height: 200,
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(15),
color: Colors.lightBlue
),
padding: EdgeInsets.fromLTRB(20, 50, 20, 20),
child: Text("You can make cool stuff!",
style: TextStyle(fontSize: 24),
textAlign: TextAlign.center
),
),
Positioned(
top: -100,
child: Image.network("https://i.imgur.com/2yaf2wb.png", width: 150, height: 150)
)
],
)
));

Results in:

小开

You can change the AlertDialog property insetPadding it will be a simple way for you.

 void alertBox() {
showDialog(
context: context,
builder: (context) => AlertDialog(
insetPadding: EdgeInsets.symmetric(horizontal: 10, vertical: 10),
// (horizontal:10 = left:10, right:10)(vertical:10 = top:10, bottom:10)
contentPadding: EdgeInsets.zero,
shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(10)),
content: Container(
width: MediaQuery.of(context).size.width - 20,
// width = device width minus insetPadding = deviceWidth - 20  (left:10, right:10 = 20)
height: MediaQuery.of(context).size.height - 20,
// height = device height minus insetPadding = deviceHeight - 20  (top:10, bottom:10 = 20)
child: ClipRRect(
borderRadius: BorderRadius.circular(10),
child: Card(
margin: EdgeInsets.zero,
color: Colors.amber,
),
),
),
),
);
}

小开

use Dialog()

Dialog(
shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(15)),
insetPadding: EdgeInsets.all(15),
child: SingleChildScrollView(
child: Container(),
),
),
);

小开

Refer this code. you can change width and height of dialogue box by setting insetPadding, because it taking default padding so we need to change like this.

showDialog(
context: context,
builder: (_) =>
Dialog(
insetPadding: EdgeInsets.symmetric(horizontal: 2.0, vertical: 2.0),
backgroundColor: Colors.transparent,
child: Container(
width: double.infinity,
height: MediaQuery.of(context).size.height*0.7 ,
decoration: BoxDecoration(
color: Colors.grey[900],
),
child: Column(
children: [
Padding(
padding: const EdgeInsets.all(10.0),
child: Row(
mainAxisAlignment: MainAxisAlignment.end,
children: [
GestureDetector(
onTap: (){
Navigator.pop(context);
},
child: Icon(Icons.close,color: Colors.grey,)),
],
),
),
Text("select your avatar",style: TextStyle(color: white,fontWeight: FontWeight.bold),),
],
),
),
),
);

小开

Medling with insetWidth and future builder etc. didn't work for me - just editing the content prop's width worked perfectly.

showDialog(
context: context,
builder: (context) {
Future.delayed(Duration(seconds: 1000), () {
Navigator.of(context).pop(true);
});
return AlertDialog(
insetPadding: EdgeInsets.all(8.0),
title: Text(
"Time to go pro!",
textAlign: TextAlign.center,
),
content: Container(
width: MediaQuery.of(context).size.width,
child: BuySheet(
applePayEnabled: applePayEnabled,
googlePayEnabled: googlePayEnabled,
applePayMerchantId: applePayMerchantId,
squareLocationId: squareLocationId),
),
);
});

小开

Hello you can actually use insetPadding and use a column inside content that will contain a SizedBox(width:MediaQuery.of(context).size.width).The only difference is that I used AlertDialog. Bellow is the way it worked for me. You can set dialog width by changing padding inside insetPadding. Hope i helped :).

dialog(){
TextEditingController controller = TextEditingController();


return showDialog(
context: context,
barrierDismissible: true,
builder: (_) => AlertDialog(
insetPadding:  EdgeInsets.symmetric(
horizontal: MediaQuery.of(context).size.width * 0.08),
content: SingleChildScrollView(
child: Column(
mainAxisAlignment: MainAxisAlignment.start,
crossAxisAlignment: CrossAxisAlignment.start,
children: [
SizedBox(
height: 16,
width: MediaQuery.of(context).size.width,
),
Text(
'Hello',
),
SizedBox(
height: 15,
),
Text(
'Description',
),
TextField(
controller: controller,
style: TextStyle(
color: Colors.black,
),
),
],
),
),
actions: [
FlatButton(
child: Text("Close"),
onPressed: () {
Navigator.of(context).pop();
},
),
],
),
);

}

This is how it looks like https://i.stack.imgur.com/bvKpP.png

小开

return Dialog(
insetPadding: EdgeInsets.symmetric(
horizontal: X,
),
);

小开

:

 return Dialog(


backgroundColor: Colors.white,
insetPadding: EdgeInsets.all(10.0),
child: Container(
   

width: double.infinity,

use insetpadding where you are returning Dialog and give it a double value, For my case, i gave it a 10.0 insetPadding: EdgeInsets.all(10.0), you can give it a custom height

小开

I finally found a way to change the width of an AlertDialog. Just wrap the "content" with a Container, and set the width to it.

return AlertDialog(
...
content: Container(
width: MediaQuery.of(context).size.width*0.45,
child: ...

AlertDialog with width modified

小开

In my case, I was using listview inside the dialog box so I was not using shrink wrap inside ListView hopes this will help someone.

ListView.builder(
shrinkWrap : true...
...
};

小开

I found the simplest way... just add insetPadding: EdgeInsets.zero, and it will expand to max size width:

 showDialog(
context: context,
builder: (BuildContext context) {
return AlertDialog(
title: Center(child: Text("Send Message", style: TextStyle(
color: Colors.white, fontWeight: FontWeight.bold),)),
backgroundColor: Colors.indigo[700],
insetPadding: EdgeInsets.zero,
content:

小开

Add InsetPadding property like this

     insetPadding: EdgeInsets.zero








AlertDialog(
title: Center(child: Text("$title")),
------------------------->Here we added the property
insetPadding: EdgeInsets.zero,
titlePadding: EdgeInsets.only(top: 14.0, bottom: 4),
content: Container(
height: 50,
child: TextFormField(
controller: find_controller,
decoration: InputDecoration(
suffixIcon: context.watch<MediaProvider>().isChangeDialog
? IconButton(
onPressed: () {
clearController(find_controller);
},
icon: Icon(Icons.clear))
: null,
border: OutlineInputBorder(
borderSide: BorderSide(color: Colors.deepPurpleAccent)),
hintText: 'Id',
),
onChanged: (val) {
if (val.isNotEmpty)
context.read<MediaProvider>().isChangeDialog = true;
else
context.read<MediaProvider>().isChangeDialog = false;
},
),
),
actions: [
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Padding(
padding: const EdgeInsets.all(4.0),
child: OutlinedButton(
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Align(
child: Padding(
padding: const EdgeInsets.symmetric(horizontal: 12.0),
child: Icon(Icons.clear),
),
),
Text("Cancel")
],
),
onPressed: () {
context.read<MediaProvider>().isChangeDialog = false;
Navigator.of(context).pop();
}),
),
Padding(
padding: const EdgeInsets.all(4.0),
child: ElevatedButton(
onPressed: context.watch<MediaProvider>().isChangeDialog
? () {
context.read<MediaProvider>().isChangeDialog = false;
okCallback;
}
: null,
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Align(
child: Padding(
padding: const EdgeInsets.symmetric(horizontal: 12.0),
child: Icon(Icons.check),
),
),
Text("OK")
],
)),
)
],
),
],
);

Before

After

小开

I am using get package and it is wonderful. use its dialog, easily sizable

Get.generalDialog(pageBuilder: (BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation,) {
return SimpleDialog(
shape: RoundedRectangleBorder( borderRadius: BorderRadius.circular(Constants.padding), ),
elevation: 0, backgroundColor: Colors.transparent,
children: [Center(child: Stack(
children: <Widget>[
Container(width: Get.width * 0.95,
padding: const EdgeInsets.only(left: Constants.padding,top: Constants.avatarRadius
+ Constants.padding, right: Constants.padding,bottom: Constants.padding
),
margin: const EdgeInsets.only(top: Constants.avatarRadius),
decoration: BoxDecoration(
shape: BoxShape.rectangle,
color: Get.theme.scaffoldBackgroundColor,
borderRadius: BorderRadius.circular(Constants.padding),
boxShadow: const [
BoxShadow(color: Colors.black,offset: Offset(0,10), blurRadius: 10 ),
]
),
child: Text('body'),
),
Positioned(
left: Constants.padding, right: Constants.padding,
child: CircleAvatar(
backgroundColor: Colors.blueAccent, radius: Constants.avatarRadius,
child: ClipRRect(
borderRadius: const BorderRadius.all(Radius.circular(Constants.avatarRadius)),
child: Icon(Icons.done, size: 24, color: Colors.white,)
),
),
),
Positioned(
left: 0,
//right: Constants.padding,
child: CircleAvatar(
backgroundColor: Colors.blueAccent, radius: Constants.avatarRadius,
child: ClipRRect(
borderRadius: const BorderRadius.all(Radius.circular(Constants.avatarRadius)),
child: InkWell(child: const Icon(Icons.close, size: 24, color: Colors.white,), onTap: (){Get.back();},)
),
),
),
],
))],
);
}, barrierDismissible: true, barrierLabel: '');

小开

The solution that worked for me.

Set the insetPadding of the AlertDialog.

Plus, wrap the content in a SizedBox and set the width to MediaQuery.of(context).size.width.

return AlertDialog(
content: SizedBox(
width: MediaQuery.of(context).size.width,
child: const Text("Content"),
),
insetPadding: const EdgeInsets.all(10),
);

Setting just the insetPadding alone does not work.

小开

/// this works for me paste your body and see result

Future _showDialog() async { return showDialog( context: context,

barrierDismissible: true,
builder: (BuildContext context) {
return Center(
child: Column(
mainAxisSize: MainAxisSize.min,
children: [
Material(
color: Colors.transparent,
child: Container(
padding: EdgeInsets.fromLTRB(5, 10, 5, 10),
decoration: BoxDecoration(
color: Colors.white,
borderRadius: BorderRadius.circular(5),
),
alignment: Alignment.center,
width: MediaQuery.of(context).size.width,
margin: EdgeInsets.all(10),
/// paste your item body
child:body,
),
),
],
),
);
},

); }

小开

Use width: MediaQuery.of(context).size.width to increase width of the alert

Example:

return AlertDialog(
title: Text("Select Birth Date"),
content: Container(
width: MediaQuery.of(context).size.width,
height: 300,
child: CupertinoDatePicker(
mode: CupertinoDatePickerMode.date,
initialDateTime: DateTime(1969, 1, 1),
onDateTimeChanged: (DateTime newDateTime) {
// Do something
           

},
),
),
actions: <Widget>[
FlatButton(
child: Text("Select"),
onPressed: () {
widget.onSelected(selectedDate);
Navigator.pop(context);
//.....
},
),
],
);