Expose insetPadding and clipBehavior in Dialog and AlertDialog. (#50775)

packages/flutter/lib/src/material/dialog.dart

@@ -26,6 +26,8 @@ import 'theme_data.dart';
 // enum Department { treasury, state }
 // BuildContext context;
 
+const EdgeInsets _defaultInsetPadding = EdgeInsets.symmetric(horizontal: 40.0, vertical: 24.0);
+
 /// A material design dialog.
 ///
 /// This dialog widget does not have any opinion about the contents of the
@@ -49,9 +51,12 @@ class Dialog extends StatelessWidget {
     this.elevation,
     this.insetAnimationDuration = const Duration(milliseconds: 100),
     this.insetAnimationCurve = Curves.decelerate,
+    this.insetPadding = _defaultInsetPadding,
+    this.clipBehavior = Clip.none,
     this.shape,
     this.child,
-  }) : super(key: key);
+  }) : assert(clipBehavior != null),
+       super(key: key);
 
   /// {@template flutter.material.dialog.backgroundColor}
   /// The background color of the surface of this [Dialog].
@@ -87,6 +92,26 @@ class Dialog extends StatelessWidget {
   /// {@endtemplate}
   final Curve insetAnimationCurve;
 
+  /// {@template flutter.material.dialog.insetPadding}
+  /// The amount of padding added to [MediaQueryData.viewInsets] on the outside
+  /// of the dialog. This defines the minimum space between the screen's edges
+  /// and the dialog.
+  ///
+  /// Defaults to `EdgeInsets.symmetric(horizontal: 40.0, vertical: 24.0)`.
+  /// {@endtemplate}
+  final EdgeInsets insetPadding;
+
+  /// {@template flutter.material.dialog.clipBehavior}
+  /// Controls how the contents of the dialog are clipped (or not) to the given
+  /// [shape].
+  ///
+  /// See the enum [Clip] for details of all possible options and their common
+  /// use cases.
+  ///
+  /// Defaults to [Clip.none], and must not be null.
+  /// {@endtemplate}
+  final Clip clipBehavior;
+
   /// {@template flutter.material.dialog.shape}
   /// The shape of this dialog's border.
   ///
@@ -109,8 +134,9 @@ class Dialog extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final DialogTheme dialogTheme = DialogTheme.of(context);
+    final EdgeInsets effectivePadding = MediaQuery.of(context).viewInsets + (insetPadding ?? const EdgeInsets.all(0.0));
     return AnimatedPadding(
-      padding: MediaQuery.of(context).viewInsets + const EdgeInsets.symmetric(horizontal: 40.0, vertical: 24.0),
+      padding: effectivePadding,
       duration: insetAnimationDuration,
       curve: insetAnimationCurve,
       child: MediaQuery.removeViewInsets(
@@ -127,6 +153,7 @@ class Dialog extends StatelessWidget {
               elevation: elevation ?? dialogTheme.elevation ?? _defaultElevation,
               shape: shape ?? dialogTheme.shape ?? _defaultDialogShape,
               type: MaterialType.card,
+              clipBehavior: clipBehavior,
               child: child,
             ),
           ),
@@ -229,9 +256,12 @@ class AlertDialog extends StatelessWidget {
     this.backgroundColor,
     this.elevation,
     this.semanticLabel,
+    this.insetPadding = _defaultInsetPadding,
+    this.clipBehavior = Clip.none,
     this.shape,
     this.scrollable = false,
   }) : assert(contentPadding != null),
+       assert(clipBehavior != null),
        super(key: key);
 
   /// The (optional) title of the dialog is displayed in a large font at the top
@@ -394,6 +424,12 @@ class AlertDialog extends StatelessWidget {
   ///    value is used.
   final String semanticLabel;
 
+  /// {@macro flutter.material.dialog.insetPadding}
+  final EdgeInsets insetPadding;
+
+  /// {@macro flutter.material.dialog.clipBehavior}
+  final Clip clipBehavior;
+
   /// {@macro flutter.material.dialog.shape}
   final ShapeBorder shape;
 
@@ -518,6 +554,8 @@ class AlertDialog extends StatelessWidget {
     return Dialog(
       backgroundColor: backgroundColor,
       elevation: elevation,
+      insetPadding: insetPadding,
+      clipBehavior: clipBehavior,
       shape: shape,
       child: dialogChild,
     );

packages/flutter/test/material/dialog_test.dart

@@ -155,6 +155,20 @@ void main() {
     expect(content.text.style, contentTextStyle);
   });
 
+  testWidgets('Custom clipBehavior', (WidgetTester tester) async {
+    const AlertDialog dialog = AlertDialog(
+      actions: <Widget>[],
+      clipBehavior: Clip.antiAlias,
+    );
+    await tester.pumpWidget(_buildAppWithDialog(dialog));
+
+    await tester.tap(find.text('X'));
+    await tester.pumpAndSettle();
+
+    final Material materialWidget = _getMaterialFromDialog(tester);
+    expect(materialWidget.clipBehavior, Clip.antiAlias);
+  });
+
   testWidgets('Custom dialog shape', (WidgetTester tester) async {
     const RoundedRectangleBorder customBorder =
       RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(16.0)));
@@ -750,6 +764,47 @@ void main() {
     );
   });
 
+  testWidgets('Dialog insetPadding added to outside of dialog', (WidgetTester tester) async {
+    // The default testing screen (800, 600)
+    const Rect screenRect = Rect.fromLTRB(0.0, 0.0, 800.0, 600.0);
+
+    // Test with no padding
+    await tester.pumpWidget(
+      const MediaQuery(
+        data: MediaQueryData(
+          viewInsets: EdgeInsets.all(0.0),
+        ),
+        child: Dialog(
+          child: Placeholder(),
+          insetPadding: null,
+        ),
+      ),
+    );
+    await tester.pumpAndSettle();
+    expect(tester.getRect(find.byType(Placeholder)), screenRect);
+
+    // Test with an insetPadding
+    await tester.pumpWidget(
+      const MediaQuery(
+        data: MediaQueryData(
+          viewInsets: EdgeInsets.all(0.0),
+        ),
+        child: Dialog(
+          insetPadding: EdgeInsets.fromLTRB(10.0, 20.0, 30.0, 40.0),
+          child: Placeholder(),
+        ),
+      ),
+    );
+    await tester.pumpAndSettle();
+    expect(tester.getRect(find.byType(Placeholder)),
+        Rect.fromLTRB(
+          screenRect.left + 10.0,
+          screenRect.top + 20.0,
+          screenRect.right - 30.0,
+          screenRect.bottom - 40.0,
+        ));
+  });
+
   testWidgets('Dialog widget contains route semantics from title', (WidgetTester tester) async {
     final SemanticsTester semantics = SemanticsTester(tester);
     await tester.pumpWidget(