microsoft · joschect · Apr 13, 2018 · Apr 11, 2018 · Apr 11, 2018 · Apr 11, 2018
@@ -33,6 +33,9 @@ export class BaseButton extends BaseComponent<IBaseButtonProps, IBaseButtonState
   }
 
   private get _isExpanded(): boolean {
+    if (this.props.persistMenu) {
+      return !this.state.menuProps!.hidden;
+    }
     return !!this.state.menuProps;
   }
 
@@ -65,8 +68,13 @@ export class BaseButton extends BaseComponent<IBaseButtonProps, IBaseButtonState
     this._labelId = getId();
     this._descriptionId = getId();
     this._ariaDescriptionId = getId();
+    let menuProps = null;
+    if (props.persistMenu && props.menuProps) {
+      menuProps = props.menuProps;
+      menuProps.hidden = true;
+    }
     this.state = {
-      menuProps: null
+      menuProps: menuProps
     };
   }
 
@@ -401,12 +409,21 @@ export class BaseButton extends BaseComponent<IBaseButtonProps, IBaseButtonState
   }
 
   private _dismissMenu = (): void => {
-    this.setState({ menuProps: null });
+    let menuProps = null;
+    if (this.props.persistMenu && this.state.menuProps) {
+      menuProps = this.state.menuProps;
+      menuProps.hidden = true;
+    }
+    this.setState({ menuProps: menuProps });
   }
 
   private _openMenu = (): void => {
     if (this.props.menuProps) {
-      this.setState({ menuProps: this.props.menuProps });
+      let menuProps = this.props.menuProps;
+      if (this.props.persistMenu) {
+        menuProps.hidden = false;
+      }
+      this.setState({ menuProps: menuProps });
     }
   }
 
@@ -416,7 +433,11 @@ export class BaseButton extends BaseComponent<IBaseButtonProps, IBaseButtonState
     }
     const { menuProps } = this.props;
     const currentMenuProps = this.state.menuProps;
-    currentMenuProps ? this._dismissMenu() : this._openMenu();
+    if (this.props.persistMenu) {
+      currentMenuProps && currentMenuProps.hidden ? this._openMenu() : this._dismissMenu();
+    } else {
+      currentMenuProps ? this._dismissMenu() : this._openMenu();
+    }
   }
 
   private _onRenderSplitButtonContent(tag: any, buttonProps: IButtonProps): JSX.Element {
@@ -517,7 +538,7 @@ export class BaseButton extends BaseComponent<IBaseButtonProps, IBaseButtonState
       'aria-expanded': this._isExpanded,
       'data-is-focusable': false
     };
-    return <BaseButton {...splitButtonProps} onMouseDown={ this._onMouseDown } tabIndex={ -1 } />;
+    return <BaseButton { ...splitButtonProps } onMouseDown={ this._onMouseDown } tabIndex={ -1 } />;
   }
 
   private _onMouseDown = (ev: React.MouseEvent<BaseButton>) => {

@@ -234,6 +234,15 @@ export interface IButtonProps extends React.AllHTMLAttributes<HTMLAnchorElement
   * The default KeyCode is the down arrow. A value of null can be provided to disable the key codes for opening the button menu.
   */
   menuTriggerKeyCode?: KeyCodes | null;
+
+
+  /**
+   * Menu will not be created or destroyed when opened or closed, instead it
+   * will be hidden. This will improve perf of the menu opening but could potentially
+   * impact overall perf by having more elemnts in the dom. Should only be used
+   * when perf is important.
+   */
+  persistMenu?: boolean;
 }
 
 export enum ElementType {

@@ -27,8 +27,9 @@ export class ButtonContextualMenuExample extends React.Component<IButtonProps, {
                   key: 'calendarEvent',
                   name: 'Calendar event',
                   icon: 'Calendar'
-                }
-              ]
+                },
+              ],
+              directionalHintFixed: true
             }
             }
           />

@@ -240,9 +240,10 @@ export interface ICalloutContentStyleProps {
   overflowYHidden?: boolean;
 
   /**
+   * @deprecated will be removed in v6. Do not use.
    * Max height applied to the content of a callout.
    */
-  contentMaxHeight?: number;
+  contentMaxHeight?: number
 
   /**
    * Background color for the beak and callout.

@@ -68,7 +68,7 @@ export class CalloutContentBase extends BaseComponent<ICalloutProps, ICalloutSta
     directionalHint: DirectionalHint.bottomAutoEdge
   };
 
-  private _classNames: {[key in keyof ICalloutContentStyles]: string };
+  private _classNames: { [key in keyof ICalloutContentStyles]: string };
   private _didSetInitialFocus: boolean;
   private _hostElement = createRef<HTMLDivElement>();
   private _calloutElement = createRef<HTMLDivElement>();
@@ -172,8 +172,8 @@ export class CalloutContentBase extends BaseComponent<ICalloutProps, ICalloutSta
     target = this._getTarget();
     const { positions } = this.state;
 
-    const getContentMaxHeight: number = this._getMaxHeight() + this.state.heightOffset!;
-    const contentMaxHeight: number = calloutMaxHeight! && (calloutMaxHeight! < getContentMaxHeight) ? calloutMaxHeight! : getContentMaxHeight!;
+    const getContentMaxHeight: number | undefined = this._getMaxHeight() ? this._getMaxHeight() + this.state.heightOffset! : undefined;
+    const contentMaxHeight: number | undefined = calloutMaxHeight! && getContentMaxHeight && (calloutMaxHeight! < getContentMaxHeight) ? calloutMaxHeight! : getContentMaxHeight!;
     const overflowYHidden = !!finalHeight;
 
     const beakVisible = isBeakVisible && (!!target);
@@ -184,15 +184,14 @@ export class CalloutContentBase extends BaseComponent<ICalloutProps, ICalloutSta
         className,
         overflowYHidden: overflowYHidden,
         calloutWidth,
-        contentMaxHeight,
         positions,
         beakWidth,
         backgroundColor,
         beakStyle
       }
     );
 
-    const overflowStyle: React.CSSProperties = overflowYHidden ? { overflowY: 'hidden' } : {};
+    const overflowStyle: React.CSSProperties = overflowYHidden ? { overflowY: 'hidden', maxHeight: contentMaxHeight } : { maxHeight: contentMaxHeight };
     const visibilityStyle: React.CSSProperties | undefined = this.props.hidden ? { visibility: 'hidden' } : undefined;
     // React.CSSProperties does not understand IRawStyle, so the inline animations will need to be cast as any for now.
     const content = (
@@ -384,7 +383,11 @@ export class CalloutContentBase extends BaseComponent<ICalloutProps, ICalloutSta
         // Since the callout cannot measure it's border size it must be taken into account here. Otherwise it will
         // overlap with the target.
         const totalGap = gapSpace + beakWidth! + BORDER_WIDTH * 2;
-        this._maxHeight = getMaxHeight(this._target, this.props.directionalHint!, totalGap, this._getBounds());
+        this._async.requestAnimationFrame(() => {
+          if (this._target) {
+            this._maxHeight = getMaxHeight(this._target, this.props.directionalHint!, totalGap, this._getBounds());
+          }
+        });
       } else {
         this._maxHeight = this._getBounds().height! - BORDER_WIDTH * 2;
       }

@@ -130,20 +130,29 @@ export class ContextualMenu extends BaseComponent<IContextualMenuProps, IContext
       const newTarget = newProps.target;
       this._setTargetWindowAndElement(newTarget!);
     }
+    if (newProps.hidden !== this.props.hidden) {
+      if (newProps.hidden) {
+        this._onMenuClosed()
+      } else {
+        this._onMenuOpened()
+        this._previousActiveElement = this._targetWindow ? this._targetWindow.document.activeElement as HTMLElement : null;
+      }
+    }
   }
 
   // Invoked once, both on the client and server, immediately before the initial rendering occurs.
   public componentWillMount() {
     const target = this.props.target;
     this._setTargetWindowAndElement(target!);
-    this._previousActiveElement = this._targetWindow ? this._targetWindow.document.activeElement as HTMLElement : null;
+    if (!this.props.hidden) {
+      this._previousActiveElement = this._targetWindow ? this._targetWindow.document.activeElement as HTMLElement : null;
+    }
   }
 
   // Invoked once, only on the client (not on the server), immediately after the initial rendering occurs.
   public componentDidMount() {
-    this._events.on(this._targetWindow, 'resize', this.dismiss);
-    if (this.props.onMenuOpened) {
-      this.props.onMenuOpened(this.props);
+    if (!this.props.hidden) {
+      this._onMenuOpened();
     }
   }
 
@@ -270,6 +279,7 @@ export class ContextualMenu extends BaseComponent<IContextualMenuProps, IContext
           onScroll={ this._onScroll }
           bounds={ bounds }
           directionalHintFixed={ directionalHintFixed }
+          hidden={ this.props.hidden }
         >
           <div
             role='menu'
@@ -316,6 +326,16 @@ export class ContextualMenu extends BaseComponent<IContextualMenuProps, IContext
     }
   }
 
+  private _onMenuOpened() {
+    this._events.on(this._targetWindow, 'resize', this.dismiss);
+    this.props.onMenuOpened && this.props.onMenuOpened(this.props);
+  }
+
+  private _onMenuClosed() {
+    this._events.off(this._targetWindow, 'resize', this.dismiss);
+    setTimeout(() => this._previousActiveElement!.focus(), 0);
+  }
+
   /**
    * Gets the focusZoneDirection by using the arrowDirection if specified,
    * the direction specificed in the focusZoneProps, or defaults to FocusZoneDirection.vertical

@@ -242,6 +242,15 @@ export interface IContextualMenuProps extends React.Props<ContextualMenu>, IWith
    * @default {direction: FocusZoneDirection.vertical}
    */
   focusZoneProps?: IFocusZoneProps;
+
+  /**
+   * If specified, renders the ContextualMenu in a hidden state.
+   * Use this flag, rather than rendering a ContextualMenu conditionally based on visibility,
+   * to improve rendering performance when it becomes visible.
+   * Note: When ContextualMenu is hidden its content will not be rendered. It will only render
+   * once the ContextualMenu is visible.
+   */
+  hidden?: boolean;
 }
 
 export interface IContextualMenuItem {