add flyout spec

specs/README.md

@@ -19,6 +19,7 @@ Here you'll find specifications for custom elements and other library features.
 | Combobox | -- | -- |
 | [Dialog](../packages/web-components/fast-foundation/src/dialog/dialog.spec.md) | :white_check_mark: | :white_check_mark: |
 | [Disclosure](../packages/web-components/fast-foundation/src/disclosure/disclosure.spec.md) | :white_check_mark: | -- |
+| [Flyout](./flyout.md) | :white_check_mark: | -- |
 | [Flipper](../packages/web-components/fast-foundation/src/flipper/flipper.spec.md) | :white_check_mark: | :white_check_mark: |
 | [Form associated custom elements](../packages/web-components/fast-foundation/src/form-associated/form-associated-custom-element.spec.md) | :white_check_mark: | :white_check_mark: |
 | Listbox | -- | -- |

specs/flyout/flyout.md

@@ -0,0 +1,168 @@
+# Flyout
+
+## Overview
+Flyout is a focusable floating container that shows over a pages content and displays UI related to what the user is doing. Similar to a Dialog, but with positioning controls and no specific action is required, a Flyout can be used to reveal a secondary control or show more detail about an item.
+
+### Background
+A Flyout can be less intrusive to the user experience than a Dialog and should be used instead of a Dialog when information or input is needed to be displayed, but not in the center of the screen, such as in the case of collection of additional info before an action, displaying information that is only relevant some of the time, or displaying more information.
+
+### Use Cases
+- As a Dropdown for a menu, navigation bar, etc.
+- In a context menu as the secondary menu/action.
+- As a popup showing additional info for an item on the page.
+- To display a larger image of a thumbnail image in a photo gallery.
+- To display an action related to a page item
+
+### Features
+**Placement Logic:** - This component will use *Anchored Region* to be positioned relative to the Flyouts anchor element. This way it can be dynamic and adapt to the available space if `responsive` is true for the Flyout.
+
+**Light Dismiss (aka Soft Dismiss):** - A way to quickly close the Flyout by clicking outside it, or pressing the `esc` key.
+
+**Overlay:** - A control of whether or not the Flyout has an overlay effect that dims the surrounding UI when the Flyout is active.
+
+### Prior Art/Examples
+##### Context Menu
+*Note:* the "Manage, Apply, Show more options" is the Flyout for this example.
+![Context Menu](https://docs.microsoft.com/en-us/windows/uwp/design/controls-and-patterns/images/flyout-nested.png)
+
+##### Text Only
+*Note:* the button is not part of the Flyout, but shown for context as an anchor element.
+![Text Only](https://docs.microsoft.com/en-us/windows/uwp/design/controls-and-patterns/images/flyout-wrapping-text.png)
+
+##### Actionable
+*Note:* the button is not part of the Flyout, but shown for context as an anchor element.
+![Actionable More Info](https://docs.microsoft.com/en-us/windows/uwp/design/controls-and-patterns/images/flyout-example2.png)
+
+---
+
+### API
+*Component Name*
+- `fast-flyout`
+
+*Attributes*
+- `anchor` - string, the html id of the HTMLElement that the Flyout is attached to, (viewport for anchored region defaults to the parent of the anchor)
+- `overlay` - boolean, specifies whether an overlay is drawn to dim the out of scope UI until the Flyout is dismissed
+- `light-dismiss` - boolean, specifies whether or not the flyout can be dismissed by clicking elsewhere or pressing `esc` key, defaults to true
+- `visible` - boolean, whether or not the Flyout is visible, defaults to undefined, as this is controlled by the author
+- `responsive` - boolean, whether or not the positioning is responsive based on available space, defaults to true, uses Anchored Region logic
+- `position` - enum, where the tooltip should appear relative to its target, uses Anchored Region logic
+
+    - above-centered, below-centered
+    ![X](./images/ab-centered.png)
+
+    - right-centered, left-centered
+    ![X](./images/rl-centered.png)
+
+    - top-left-corner, top-right-corner, bottom-right-corner, bottom-left-corner
+    ![X](./images/corner-positions.png)
+
+    - above-left-aligned, below-left-aligned
+    ![X](./images/ab-left-aligned.png)
+    - above-right-aligned, below-right-aligned
+    ![X](./images/ab-right-aligned.png)
+
+    - left-top-aligned, right-top-aligned
+    ![X](./images/rl-top-aligned.png)
+
+    - left-bottom-aligned, right-bottom-aligned
+    ![X](./images/rl-bottom-aligned.png)
+
+
+        - **ASK (1)**
+- `aria-labelledby` - optional based on implementation**
+- `aria-describedby` - optional based on implementation**
+- `aria-label` - optional, based on implementation**
+
+    ** See the [W3C Specification](https://w3c.github.io/aria-practices/#dialog_roles_states_props) for requirements and details.
+
+*Properties*
+- `anchorElement` - the reference to the HTMLElement used as an anchor
+- `visible` - boolean, whether or not the Flyout is visible
+
+*Methods*
+- `isNonFocusableContent()` - check if the slotted content is a focusable element or not, could use a filter to check the node type.
+
+*Slots*
+- default for content
+
+*Events*
+- `dismiss` - event fired when the Flyout is dismissed
+
+### Anatomy and Appearance
+Parts:
+- `overlay` - the overlay.
+    - *Note:* the overlay div will always be present, but will have different styles whether or not the overlay is enabled.
+- `content` - the region where the content is rendered, has `role=dialog`
+
+
+*Template:*
+**ASK (2)**
+```html
+${when(
+    x => x.visible,
+    html<Flyout>`
+        <div>
+            ${when(
+                x => x.overlay,
+                html<Flyout>`
+                    <div
+                        class="overlay"
+                        part="overlay"
+                        role="presentation"
+                        tabindex="-1"
+                        @click="${x => x.dismiss()}"
+                    ></div>
+                `
+            )}
+            <fast-anchored-region
+                anchor="${x => x.anchorElement}"
+                vertical-positioning-mode="${x => x.responsive ? 'dynamic' : 'uncontrolled'}"
+                horizontal-positioning-mode="${x => x.responsive ? 'dynamic' : 'uncontrolled'}"
+                horizontal-default-position="${x => x.getHorizontalPosition()}"
+                vertical-default-position="${x => x.getVerticalPosition()}"
+                horizontal-inset="${x => x.getHorizontalInset()}"
+                vertical-inset="${x => x.getVerticalInset()}"
+                ${ref("anchoredRegion")}
+            >
+                <div
+                    class="content"
+                    part="content"
+                    role="dialog"
+                    tabindex="${x => x.isNonFocusableContent() ? '-1' : '0'}"
+                >
+                    <slot></slot>
+                </div>
+            </fast-anchored-region>
+        </div>
+    `
+)}
+```
+
+---
+
+## Implementation
+```html
+<fast-flyout light-dismiss overlay responsive>
+    <p>This is a flyout</p>
+    <fast-button>Action</fast-button>
+</fast-flyout>
+```
+
+### States
+`visible` - Whether or not Flyout is hidden. This state is managed solely by the app author via the visible attribute.
+`responsive` - Whether or not the positioning of the Flyout moves depending on if it fits where it is located within the viewport of the Anchored Region.
+
+### Accessibility
+*Keyboard Navigation and Focus*
+Keyboard and navigation will follow the same rules as Dialog per the [W3C Specification](https://w3c.github.io/aria-practices/#dialog_modal), expect when there is no focusable content then the Flyout itself will receive focus.
+
+### Globalization
+The component visuals should change when in RTL scenarios as the component is positioned relative to it's anchor.
+
+### Dependencies
+This component should be positioned using [anchored region](../packages/web-components/fast-foundation/src/anchored-region/anchored-region.spec.md).
+
+## Resources
+[W3C Specification](https://w3c.github.io/aria-practices/#dialog_modal)
+[Flyout Menus](https://www.w3.org/WAI/tutorials/menus/flyout/#flyoutnavmousefixed)
+[Dialogs and Flyouts](https://docs.microsoft.com/en-us/windows/uwp/design/controls-and-patterns/dialogs-and-flyouts/#:~:text=A%20flyout%20is%20a%20lightweight%20contextual%20popup%20that,control%20or%20show%20more%20detail%20about%20an%20item.)