Add widget of the week video embeddings (#45362)

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

@@ -212,6 +212,8 @@ class DataCell {
 
 /// A material design data table.
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=ktTajqbhIcY}
+///
 /// Displaying data in a table is expensive, because to lay out the
 /// table all the data must be measured twice, once to negotiate the
 /// dimensions to use for each column, and once to actually lay out

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

@@ -137,6 +137,8 @@ class Dialog extends StatelessWidget {
 /// of actions. The title is displayed above the content and the actions are
 /// displayed below the content.
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=75CsnyRXf5I}
+///
 /// If the content is too large to fit on the screen vertically, the dialog will
 /// display the title and the actions and let the content overflow, which is
 /// rarely desired. Consider using a scrolling widget for [content], such as

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

@@ -165,6 +165,8 @@ enum ListTileControlAffinity {
 /// A single fixed-height row that typically contains some text as well as
 /// a leading or trailing icon.
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=l8dj0yPBvgQ}
+///
 /// A list tile contains one to three lines of text optionally flanked by icons or
 /// other widgets, such as check boxes. The icons (or other widgets) for the
 /// tile are defined with the [leading] and [trailing] parameters. The first

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

@@ -52,6 +52,8 @@ typedef ReorderCallback = void Function(int oldIndex, int newIndex);
 /// those children that are actually visible.
 ///
 /// All [children] must have a key.
+///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=3fB1mxOsqJE}
 class ReorderableListView extends StatefulWidget {
 
   /// Creates a reorderable list.

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

@@ -131,6 +131,8 @@ class _SelectableTextSelectionGestureDetectorBuilder extends TextSelectionGestur
 /// The string might break across multiple lines or might all be displayed on
 /// the same line depending on the layout constraints.
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=ZSU3ZXOs6hc}
+///
 /// The [style] argument is optional. When omitted, the text will use the style
 /// from the closest enclosing [DefaultTextStyle]. If the given style's
 /// [TextStyle.inherit] property is true (the default), the given style will

packages/flutter/lib/src/widgets/animated_cross_fade.dart

@@ -66,6 +66,8 @@ typedef AnimatedCrossFadeBuilder = Widget Function(Widget topChild, Key topChild
 /// A widget that cross-fades between two given children and animates itself
 /// between their sizes.
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=PGK2UUAyE54}
+///
 /// The animation is controlled through the [crossFadeState] parameter.
 /// [firstCurve] and [secondCurve] represent the opacity curves of the two
 /// children. The [firstCurve] is inverted, i.e. it fades out when providing a

packages/flutter/lib/src/widgets/animated_switcher.dart

@@ -66,6 +66,8 @@ typedef AnimatedSwitcherLayoutBuilder = Widget Function(Widget currentChild, Lis
 /// A widget that by default does a cross-fade between a new widget and the
 /// widget previously set on the [AnimatedSwitcher] as a child.
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=2W7POjFb88g}
+///
 /// If they are swapped fast enough (i.e. before [duration] elapses), more than
 /// one previous child can exist and be transitioning out while the newest one
 /// is transitioning in.

packages/flutter/lib/src/widgets/basic.dart

@@ -2122,6 +2122,8 @@ class SizedBox extends SingleChildRenderObjectWidget {
 /// pixels, you could use `const BoxConstraints(minHeight: 50.0)` as the
 /// [constraints].
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=o2KveVr7adg}
+///
 /// {@tool sample}
 ///
 /// This snippet makes the child widget (a [Card] with some [Text]) fill the
@@ -2269,6 +2271,8 @@ class UnconstrainedBox extends SingleChildRenderObjectWidget {
 /// For more details about the layout algorithm, see
 /// [RenderFractionallySizedOverflowBox].
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=PEsY654EGZ0}
+///
 /// See also:
 ///
 ///  * [Align], which sizes itself based on its child's size and positions
@@ -2375,6 +2379,8 @@ class FractionallySizedBox extends SingleChildRenderObjectWidget {
 /// parents' size, so that they behave reasonably in lists (which are
 /// unbounded).
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=uVki2CIzBTs}
+///
 /// See also:
 ///
 ///  * [ConstrainedBox], which applies its constraints in all cases, not just
@@ -3064,6 +3070,8 @@ class ListBody extends MultiChildRenderObjectWidget {
 /// way, for example having some text and an image, overlaid with a gradient and
 /// a button attached to the bottom.
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=liEGSeD3Zt8}
+///
 /// Each child of a [Stack] widget is either _positioned_ or _non-positioned_.
 /// Positioned children are those wrapped in a [Positioned] widget that has at
 /// least one non-null property. The stack sizes itself to contain all the
@@ -3262,6 +3270,8 @@ class Stack extends MultiChildRenderObjectWidget {
 ///
 /// If value is null, then nothing is displayed.
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=_O0PPD1Xfbk}
+///
 /// See also:
 ///
 ///  * [Stack], for more details about stacks.
@@ -4963,6 +4973,8 @@ class Flow extends MultiChildRenderObjectWidget {
 
 /// A paragraph of rich text.
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=rykDVh-QFfw}
+///
 /// The [RichText] widget displays text that uses multiple different styles. The
 /// text to display is described using a tree of [TextSpan] objects, each of
 /// which has an associated style that is used for that subtree. The text might
@@ -6179,6 +6191,8 @@ class MetaData extends SingleChildRenderObjectWidget {
 /// Used by accessibility tools, search engines, and other semantic analysis
 /// software to determine the meaning of the application.
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=NvtMt_DtFrQ}
+///
 /// See also:
 ///
 ///  * [MergeSemantics], which marks a subtree as being a single node for

packages/flutter/lib/src/widgets/container.dart

@@ -165,6 +165,8 @@ class DecoratedBox extends SingleChildRenderObjectWidget {
 /// A convenience widget that combines common painting, positioning, and sizing
 /// widgets.
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=c1xLMaTUWCY}
+///
 /// A container first surrounds the child with [padding] (inflated by any
 /// borders present in the [decoration]) and then applies additional
 /// [constraints] to the padded extent (incorporating the `width` and `height`

packages/flutter/lib/src/widgets/draggable_scrollable_sheet.dart

@@ -32,6 +32,8 @@ typedef ScrollableWidgetBuilder = Widget Function(
 /// A container for a [Scrollable] that responds to drag gestures by resizing
 /// the scrollable until a limit is reached, and then scrolling.
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=Hgw819mL_78}
+///
 /// This widget can be dragged along the vertical axis between its
 /// [minChildSize], which defaults to `0.25` and [maxChildSize], which defaults
 /// to `1.0`. These sizes are percentages of the height of the parent container.

packages/flutter/lib/src/widgets/implicit_animations.dart

@@ -779,6 +779,8 @@ class _AnimatedContainerState extends AnimatedWidgetBaseState<AnimatedContainer>
 /// Animated version of [Padding] which automatically transitions the
 /// indentation over a given duration whenever the given inset changes.
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=PY2m0fhGNz4}
+///
 /// Here's an illustration of what using this widget looks like, using a [curve]
 /// of [Curves.fastOutSlowIn].
 /// {@animation 250 266 https://flutter.github.io/assets-for-api-docs/assets/widgets/animated_padding.mp4}
@@ -942,6 +944,8 @@ class _AnimatedAlignState extends AnimatedWidgetBaseState<AnimatedAlign> {
 /// Animated version of [Positioned] which automatically transitions the child's
 /// position over a given duration whenever the given position changes.
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=hC3s2YdtWt8}
+///
 /// Only works if it's the child of a [Stack].
 ///
 /// This widget is a good choice if the _size_ of the child would end up
@@ -1238,6 +1242,8 @@ class _AnimatedPositionedDirectionalState extends AnimatedWidgetBaseState<Animat
 /// Animated version of [Opacity] which automatically transitions the child's
 /// opacity over a given duration whenever the given opacity changes.
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=QZAvjqOqiLY}
+///
 /// Animating an opacity is relatively expensive because it requires painting
 /// the child into an intermediate buffer.
 ///

packages/flutter/lib/src/widgets/placeholder.dart

@@ -49,6 +49,8 @@ class _PlaceholderPainter extends CustomPainter {
 /// By default, the placeholder is sized to fit its container. If the
 /// placeholder is in an unbounded space, it will size itself according to the
 /// given [fallbackWidth] and [fallbackHeight].
+///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=LPe56fezmoo}
 class Placeholder extends StatelessWidget {
   /// Creates a widget which draws a box.
   const Placeholder({

packages/flutter/lib/src/widgets/scroll_view.dart

@@ -565,6 +565,8 @@ abstract class BoxScrollView extends ScrollView {
 
 /// A scrollable list of widgets arranged linearly.
 ///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=KJpkjHGiI5A}
+///
 /// [ListView] is the most commonly used scrolling widget. It displays its
 /// children one after another in the scroll direction. In the cross axis, the
 /// children are required to fill the [ListView].