Support list collapsing and jumping

Fixes element-hq/element-web#14036

Author: turt2live

res/css/views/rooms/_RoomSublist2.scss

@@ -138,6 +138,34 @@ limitations under the License.
             text-overflow: ellipsis;
             overflow: hidden;
             white-space: nowrap;
+
+            .mx_RoomSublist2_collapseBtn {
+                display: inline-block;
+                position: relative;
+
+                // Default hidden
+                visibility: hidden;
+                width: 0;
+                height: 0;
+
+                &::before {
+                    content: '';
+                    width: 12px;
+                    height: 12px;
+                    position: absolute;
+                    top: 1px;
+                    left: 1px;
+                    mask-position: center;
+                    mask-size: contain;
+                    mask-repeat: no-repeat;
+                    background: $primary-fg-color;
+                    mask-image: url('$(res)/img/feather-customised/chevron-down.svg');
+                }
+
+                &.mx_RoomSublist2_collapseBtn_collapsed::before {
+                    mask-image: url('$(res)/img/feather-customised/chevron-right.svg');
+                }
+            }
         }
     }
 
@@ -251,6 +279,17 @@ limitations under the License.
                 background-color: $roomlist2-button-bg-color;
             }
         }
+
+        .mx_RoomSublist2_headerContainer {
+            .mx_RoomSublist2_headerText {
+                .mx_RoomSublist2_collapseBtn {
+                    visibility: visible;
+                    width: 12px;
+                    height: 12px;
+                    margin-right: 4px;
+                }
+            }
+        }
     }
 
     &.mx_RoomSublist2_minimized {

res/img/feather-customised/chevron-right.svg

@@ -105,13 +105,11 @@ export default class LeftPanel2 extends React.Component<IProps, IState> {
             const header = sublist.querySelector<HTMLDivElement>(".mx_RoomSublist2_stickable");
 
             if (slRect.top + headerHeight > bottom && !gotBottom) {
-                console.log(`${header.textContent} is off the bottom`);
                 header.classList.add("mx_RoomSublist2_headerContainer_sticky");
                 header.classList.add("mx_RoomSublist2_headerContainer_stickyBottom");
                 header.style.width = `${headerStickyWidth}px`;
                 gotBottom = true;
             } else if (slRect.top < top) {
-                console.log(`${header.textContent} is off the top`);
                 header.classList.add("mx_RoomSublist2_headerContainer_sticky");
                 header.classList.add("mx_RoomSublist2_headerContainer_stickyTop");
                 header.style.width = `${headerStickyWidth}px`;

src/components/structures/LeftPanel2.tsx

@@ -134,7 +134,28 @@ export default class RoomSublist2 extends React.Component<IProps, IState> {
         this.forceUpdate(); // because the layout doesn't trigger a re-render
     };
 
+    private onHeaderClick = (ev: React.MouseEvent<HTMLDivElement>) => {
+        let target = ev.target as HTMLDivElement;
+        if (!target.classList.contains('mx_RoomSublist2_headerText')) {
+            // If we don't have the headerText class, the user clicked the span in the headerText.
+            target = target.parentElement as HTMLDivElement;
+        }
+
+        const possibleSticky = target.parentElement;
+        const sublist = possibleSticky.parentElement.parentElement;
+        if (possibleSticky.classList.contains('mx_RoomSublist2_headerContainer_sticky')) {
+            // is sticky - jump to list
+            sublist.scrollIntoView({behavior: 'smooth'});
+        } else {
+            // on screen - toggle collapse
+            this.props.layout.isCollapsed = !this.props.layout.isCollapsed;
+            this.forceUpdate(); // because the layout doesn't trigger an update
+        }
+    };
+
     private renderTiles(): React.ReactElement[] {
+        if (this.props.layout && this.props.layout.isCollapsed) return []; // don't waste time on rendering
+
         const tiles: React.ReactElement[] = [];
 
         if (this.props.rooms) {
@@ -249,6 +270,11 @@ export default class RoomSublist2 extends React.Component<IProps, IState> {
                         );
                     }
 
+                    const collapseClasses = classNames({
+                        'mx_RoomSublist2_collapseBtn': true,
+                        'mx_RoomSublist2_collapseBtn_collapsed': this.props.layout && this.props.layout.isCollapsed,
+                    });
+
                     const classes = classNames({
                         'mx_RoomSublist2_headerContainer': true,
                         'mx_RoomSublist2_headerContainer_withAux': !!addRoomButton,
@@ -264,7 +290,9 @@ export default class RoomSublist2 extends React.Component<IProps, IState> {
                                     className={"mx_RoomSublist2_headerText"}
                                     role="treeitem"
                                     aria-level={1}
+                                    onClick={this.onHeaderClick}
                                 >
+                                    <span className={collapseClasses} />
                                     <span>{this.props.label}</span>
                                 </AccessibleButton>
                                 {this.renderMenu()}

src/components/views/rooms/RoomSublist2.tsx

@@ -21,11 +21,13 @@ const TILE_HEIGHT_PX = 44;
 interface ISerializedListLayout {
     numTiles: number;
     showPreviews: boolean;
+    collapsed: boolean;
 }
 
 export class ListLayout {
     private _n = 0;
     private _previews = false;
+    private _collapsed = false;
 
     constructor(public readonly tagId: TagID) {
         const serialized = localStorage.getItem(this.key);
@@ -34,9 +36,19 @@ export class ListLayout {
             const parsed = <ISerializedListLayout>JSON.parse(serialized);
             this._n = parsed.numTiles;
             this._previews = parsed.showPreviews;
+            this._collapsed = parsed.collapsed;
         }
     }
 
+    public get isCollapsed(): boolean {
+        return this._collapsed;
+    }
+
+    public set isCollapsed(v: boolean) {
+        this._collapsed = v;
+        this.save();
+    }
+
     public get showPreviews(): boolean {
         return this._previews;
     }
@@ -100,6 +112,7 @@ export class ListLayout {
         return {
             numTiles: this.visibleTiles,
             showPreviews: this.showPreviews,
+            collapsed: this.isCollapsed,
         };
     }
 }