[1.5.4] Add CupertinoPageScaffold

Author: IIzzaya

Runtime/cupertino/page_scaffold.cs

@@ -0,0 +1,143 @@
+using System;
+using System.Collections.Generic;
+using Unity.UIWidgets.animation;
+using Unity.UIWidgets.foundation;
+using Unity.UIWidgets.painting;
+using Unity.UIWidgets.ui;
+using Unity.UIWidgets.widgets;
+
+namespace Unity.UIWidgets.cupertino {
+    public class CupertinoPageScaffold : StatefulWidget {
+        /// Creates a layout for pages with a navigation bar at the top.
+        public CupertinoPageScaffold(
+            Widget child,
+            Key key = null,
+            ObstructingPreferredSizeWidget navigationBar = null,
+            Color backgroundColor = null,
+            bool resizeToAvoidBottomInset = true
+        ) : base(key: key) {
+            D.assert(child != null);
+            D.assert(resizeToAvoidBottomInset != null);
+
+            this.child = child;
+            this.navigationBar = navigationBar;
+            this.backgroundColor = backgroundColor;
+            this.resizeToAvoidBottomInset = resizeToAvoidBottomInset;
+        }
+
+        public readonly ObstructingPreferredSizeWidget navigationBar;
+        public readonly Widget child;
+        public readonly Color backgroundColor;
+        public readonly bool resizeToAvoidBottomInset;
+
+
+        public override State createState() {
+            return new _CupertinoPageScaffoldState();
+        }
+    }
+
+    class _CupertinoPageScaffoldState : State<CupertinoPageScaffold> {
+        public readonly ScrollController _primaryScrollController = new ScrollController();
+
+        void _handleStatusBarTap() {
+            // Only act on the scroll controller if it has any attached scroll positions.
+            if (this._primaryScrollController.hasClients) {
+                this._primaryScrollController.animateTo(
+                    0.0f,
+                    duration: new TimeSpan(0, 0, 0, 0, 500),
+                    curve: Curves.linearToEaseOut
+                );
+            }
+        }
+
+        public override Widget build(BuildContext context) {
+            List<Widget> stacked = new List<Widget>();
+
+            Widget paddedContent = this.widget.child;
+
+            MediaQueryData existingMediaQuery = MediaQuery.of(context);
+            if (this.widget.navigationBar != null) {
+                float topPadding = this.widget.navigationBar.preferredSize.height + existingMediaQuery.padding.top;
+
+                float bottomPadding = this.widget.resizeToAvoidBottomInset
+                    ? existingMediaQuery.viewInsets.bottom
+                    : 0.0f;
+
+                EdgeInsets newViewInsets = this.widget.resizeToAvoidBottomInset
+                    ? existingMediaQuery.viewInsets.copyWith(bottom: 0.0f)
+                    : existingMediaQuery.viewInsets;
+
+                bool fullObstruction =
+                    this.widget.navigationBar.fullObstruction == false
+                        ? CupertinoTheme.of(context).barBackgroundColor.alpha == 0xFF
+                        : this.widget.navigationBar.fullObstruction;
+
+                if (fullObstruction) {
+                    paddedContent = new MediaQuery(
+                        data: existingMediaQuery
+                            .removePadding(removeTop: true)
+                            .copyWith(
+                                viewInsets: newViewInsets
+                            ),
+                        child: new Padding(
+                            padding: EdgeInsets.only(top: topPadding, bottom: bottomPadding),
+                            child: paddedContent
+                        )
+                    );
+                }
+                else {
+                    paddedContent = new MediaQuery(
+                        data: existingMediaQuery.copyWith(
+                            padding: existingMediaQuery.padding.copyWith(
+                                top: topPadding
+                            ),
+                            viewInsets: newViewInsets
+                        ),
+                        child: new Padding(
+                            padding: EdgeInsets.only(bottom: bottomPadding),
+                            child: paddedContent
+                        )
+                    );
+                }
+            }
+
+            stacked.Add(new PrimaryScrollController(
+                controller: this._primaryScrollController,
+                child: paddedContent
+            ));
+
+            if (this.widget.navigationBar != null) {
+                stacked.Add(new Positioned(
+                    top: 0.0f,
+                    left: 0.0f,
+                    right: 0.0f,
+                    child: this.widget.navigationBar
+                ));
+            }
+
+            stacked.Add(new Positioned(
+                    top: 0.0f,
+                    left: 0.0f,
+                    right: 0.0f,
+                    height: existingMediaQuery.padding.top,
+                    child: new GestureDetector(
+                        onTap: this._handleStatusBarTap
+                    )
+                )
+            );
+
+            return new DecoratedBox(
+                decoration: new BoxDecoration(
+                    color: this.widget.backgroundColor ?? CupertinoTheme.of(context).scaffoldBackgroundColor
+                ),
+                child: new Stack(
+                    children: stacked
+                )
+            );
+        }
+    }
+
+    public abstract class ObstructingPreferredSizeWidget : PreferredSizeWidget {
+        public bool fullObstruction { get; }
+    }
+}