PanelMenu: Fixes panel submenu not being accessible for panels close to the right edge of the screen (#28666)

* Dropdowns: Trying to fix dropdown menus

* Dropdowns: Trying to fix dropdown menus

* removed now unnessary wrapper ref

* Upodates

* Remove export

public/app/features/dashboard/components/SubMenu/DashboardLinks.tsx

@@ -44,7 +44,7 @@ export const DashboardLinks: FC<Props> = ({ dashboard, links }) => {
 
         const linkElement = (
           <a
-            className="gf-form-label"
+            className="gf-form-label gf-form-label--dashlink"
             href={sanitizeUrl(linkInfo.href)}
             target={link.targetBlank ? '_blank' : '_self'}
             aria-label={selectors.components.DashboardLinks.link}

public/app/features/dashboard/components/SubMenu/DashboardLinksDashboard.tsx

@@ -19,7 +19,6 @@ interface State {
 
 export class DashboardLinksDashboard extends PureComponent<Props, State> {
   state: State = { resolvedLinks: [] };
-  wrapperRef = createRef<HTMLDivElement>();
   listItemRef = createRef<HTMLUListElement>();
 
   componentDidMount() {
@@ -45,7 +44,7 @@ export class DashboardLinksDashboard extends PureComponent<Props, State> {
     const { link } = this.props;
 
     return (
-      <div className="gf-form" key={key} aria-label={selector} ref={this.wrapperRef}>
+      <div className="gf-form" key={key} aria-label={selector}>
         {link.tooltip && <Tooltip content={link.tooltip}>{linkElement}</Tooltip>}
         {!link.tooltip && <>{linkElement}</>}
       </div>
@@ -62,7 +61,7 @@ export class DashboardLinksDashboard extends PureComponent<Props, State> {
           resolvedLinks.map((resolvedLink, index) => {
             const linkElement = (
               <a
-                className="gf-form-label"
+                className="gf-form-label gf-form-label--dashlink"
                 href={resolvedLink.url}
                 target={link.targetBlank ? '_blank' : '_self'}
                 aria-label={selectors.components.DashboardLinks.link}
@@ -81,32 +80,26 @@ export class DashboardLinksDashboard extends PureComponent<Props, State> {
     );
   };
 
-  getDropdownLocationCssClass = (): string => {
-    const [pullLeftCssClass, pullRightCssClass] = ['pull-left', 'pull-right'];
-    const wrapper = this.wrapperRef.current;
-    const list = this.listItemRef.current;
-    if (!wrapper || !list) {
-      return pullRightCssClass;
-    }
-    return wrapper.offsetLeft > list.offsetWidth - wrapper.offsetWidth ? pullRightCssClass : pullLeftCssClass;
-  };
-
-  renderDropdown = () => {
+  renderDropdown() {
     const { link, linkInfo } = this.props;
     const { resolvedLinks } = this.state;
 
     const linkElement = (
       <>
         <a
-          className="gf-form-label pointer"
+          className="gf-form-label gf-form-label--dashlink"
           onClick={this.searchForDashboards}
           data-placement="bottom"
           data-toggle="dropdown"
         >
-          <Icon name="bars" />
+          <Icon name="bars" style={{ marginRight: '4px' }} />
           <span>{linkInfo.title}</span>
         </a>
-        <ul className={'dropdown-menu ' + this.getDropdownLocationCssClass()} role="menu" ref={this.listItemRef}>
+        <ul
+          className={`dropdown-menu ${getDropdownLocationCssClass(this.listItemRef.current)}`}
+          role="menu"
+          ref={this.listItemRef}
+        >
           {resolvedLinks.length > 0 &&
             resolvedLinks.map((resolvedLink, index) => {
               return (
@@ -126,7 +119,7 @@ export class DashboardLinksDashboard extends PureComponent<Props, State> {
     );
 
     return this.renderElement(linkElement, 'dashlinks-dropdown', selectors.components.DashboardLinks.dropDown);
-  };
+  }
 
   render() {
     if (this.props.link.asDropdown) {
@@ -174,3 +167,22 @@ export function resolveLinks(
       return { id, title, url };
     });
 }
+
+function getDropdownLocationCssClass(element: HTMLElement | null) {
+  if (!element) {
+    return 'invisible';
+  }
+
+  const wrapperPos = element.parentElement!.getBoundingClientRect();
+  const pos = element.getBoundingClientRect();
+
+  if (pos.width === 0) {
+    return 'invisible';
+  }
+
+  if (wrapperPos.left + pos.width + 10 > window.innerWidth) {
+    return 'pull-left';
+  } else {
+    return 'pull-right';
+  }
+}

public/app/features/dashboard/dashgrid/PanelHeader/PanelHeaderMenuItem.tsx

@@ -1,4 +1,4 @@
-import React, { FC } from 'react';
+import React, { FC, useState } from 'react';
 import { css } from 'emotion';
 import { PanelMenuItem } from '@grafana/data';
 import { Icon, IconName, useTheme } from '@grafana/ui';
@@ -9,6 +9,7 @@ interface Props {
 }
 
 export const PanelHeaderMenuItem: FC<Props & PanelMenuItem> = props => {
+  const [ref, setRef] = useState<HTMLLIElement | null>(null);
   const isSubMenu = props.type === 'submenu';
   const isDivider = props.type === 'divider';
   const theme = useTheme();
@@ -24,10 +25,11 @@ export const PanelHeaderMenuItem: FC<Props & PanelMenuItem> = props => {
     right: ${theme.spacing.xs};
     color: ${theme.colors.textWeak};
   `;
+
   return isDivider ? (
     <li className="divider" />
   ) : (
-    <li className={isSubMenu ? 'dropdown-submenu' : undefined}>
+    <li className={isSubMenu ? `dropdown-submenu ${getDropdownLocationCssClass(ref)}` : undefined} ref={setRef}>
       <a onClick={props.onClick} href={props.href}>
         {props.iconClassName && <Icon name={props.iconClassName as IconName} className={menuIconClassName} />}
         <span className="dropdown-item-text" aria-label={selectors.components.Panels.Panel.headerItems(props.text)}>
@@ -44,3 +46,22 @@ export const PanelHeaderMenuItem: FC<Props & PanelMenuItem> = props => {
     </li>
   );
 };
+
+function getDropdownLocationCssClass(element: HTMLElement | null) {
+  if (!element) {
+    return 'invisible';
+  }
+
+  const wrapperPos = element.parentElement!.getBoundingClientRect();
+  const pos = element.getBoundingClientRect();
+
+  if (pos.width === 0) {
+    return 'invisible';
+  }
+
+  if (wrapperPos.right + pos.width + 10 > window.innerWidth) {
+    return 'pull-left';
+  } else {
+    return 'pull-right';
+  }
+}

public/sass/components/_dropdown.scss

@@ -59,7 +59,7 @@
   text-align: left;
 
   // Aligns the dropdown menu to right
-  &.pull-right {
+  &.pull-left {
     right: 0;
     left: auto;
   }
@@ -238,6 +238,7 @@
 .dropdown-submenu {
   position: relative;
 }
+
 // Default dropdowns
 .dropdown-submenu > .dropdown-menu {
   top: 0;
@@ -277,16 +278,21 @@
 .dropdown-submenu.pull-left {
   // Undo the float
   // Yes, this is awkward since .pull-left adds a float, but it sticks to our conventions elsewhere.
-  float: none;
+  float: none !important;
 
   // Positioning the submenu
   > .dropdown-menu {
     left: -100%;
-    margin-left: 10px;
+    width: 100%;
+    margin-left: 2px;
     @include border-radius(6px 0 6px 6px);
   }
 }
 
+.dropdown-submenu.pull-right {
+  float: none !important;
+}
+
 // Tweak nav headers
 // -----------------
 // Increase padding from 15px to 20px on sides

public/sass/components/_gf-form.scss

@@ -148,6 +148,11 @@ $input-border: 1px solid $input-border-color;
     border: $panel-border;
   }
 
+  &--dashlink {
+    background: $panel-bg;
+    border: $panel-border;
+  }
+
   &--justify-left {
     justify-content: left;
   }