tree: use dot decoration on folders

The following commit updates the rendering of tail decorations for
composite tree nodes (nodes that contain children nodes like folders).

The following updates the rendering of tail decorations for composite
tree nodes (nodes that contain children nodes like folders).  The
updates include :
- rendering a generic icon decoration (dot) for composite nodes with children with decoration data.
- updates to the rendering logic to only render the decoration data with the highest priority so no duplicate generic icons are present.

packages/core/src/browser/tree/tree-widget.tsx

@@ -729,26 +729,31 @@ export class TreeWidget extends ReactWidget implements StatefulWidget {
      * @param node the tree node.
      * @param icon the icon.
      */
-    protected decorateIcon(node: TreeNode, icon: React.ReactNode | null): React.ReactNode {
-        // eslint-disable-next-line no-null/no-null
-        if (icon === null) {
-            // eslint-disable-next-line no-null/no-null
-            return null;
+    protected decorateIcon(node: TreeNode, icon: React.ReactNode): React.ReactNode {
+        // icon can be null or undefined
+        if (!icon) {
+            return;
         }
-
         const overlayIcons: React.ReactNode[] = [];
-        new Map(this.getDecorationData(node, 'iconOverlay').reverse().filter(notEmpty)
-            .map(overlay => [overlay.position, overlay] as [TreeDecoration.IconOverlayPosition, TreeDecoration.IconOverlay | TreeDecoration.IconClassOverlay]))
-            .forEach((overlay, position) => {
-                const iconClasses = [TreeDecoration.Styles.DECORATOR_SIZE_CLASS, TreeDecoration.IconOverlayPosition.getStyle(position)];
+        // if multiple overlays have the same overlay.position attribute, we'll de-duplicate those and only process the first one from the decoration array
+        const seenPositions = new Set<TreeDecoration.IconOverlayPosition>();
+        const overlays = this.getDecorationData(node, 'iconOverlay').filter(notEmpty);
+
+        for (const overlay of overlays) {
+            if (!seenPositions.has(overlay.position)) {
+                seenPositions.add(overlay.position);
+                const iconClasses = [TreeDecoration.Styles.DECORATOR_SIZE_CLASS, TreeDecoration.IconOverlayPosition.getStyle(overlay.position)];
                 const style = (color?: string) => color === undefined ? {} : { color };
+
                 if (overlay.background) {
-                    overlayIcons.push(<span key={node.id + 'bg'} className={this.getIconClass(overlay.background.shape, iconClasses)} style={style(overlay.background.color)}>
-                    </span>);
+                    overlayIcons.push(<span key={node.id + 'bg'} className={this.getIconClass(overlay.background.shape, iconClasses)}
+                        style={style(overlay.background.color)}></span>);
                 }
-                const overlayIcon = (overlay as TreeDecoration.IconOverlay).icon || (overlay as TreeDecoration.IconClassOverlay).iconClass;
+
+                const overlayIcon = 'icon' in overlay ? overlay.icon : overlay.iconClass;
                 overlayIcons.push(<span key={node.id} className={this.getIconClass(overlayIcon, iconClasses)} style={style(overlay.color)}></span>);
-            });
+            }
+        }
 
         if (overlayIcons.length > 0) {
             return <div className={TreeDecoration.Styles.ICON_WRAPPER_CLASS}>{icon}{overlayIcons}</div>;
@@ -763,14 +768,23 @@ export class TreeWidget extends ReactWidget implements StatefulWidget {
      * @param props the node properties.
      */
     protected renderTailDecorations(node: TreeNode, props: NodeProps): React.ReactNode {
+        const tailDecorations = this.getDecorationData(node, 'tailDecorations').filter(notEmpty).reduce((acc, current) => acc.concat(current), []);
+        if (tailDecorations.length === 0) {
+            return;
+        }
+        return this.renderTailDecorationsForNode(node, props, tailDecorations);
+    }
+
+    protected renderTailDecorationsForNode(node: TreeNode, props: NodeProps, tailDecorations:
+        (TreeDecoration.TailDecoration | TreeDecoration.TailDecorationIcon | TreeDecoration.TailDecorationIconClass)[]): React.ReactNode {
         return <React.Fragment>
-            {this.getDecorationData(node, 'tailDecorations').filter(notEmpty).reduce((acc, current) => acc.concat(current), []).map((decoration, index) => {
+            {tailDecorations.map((decoration, index) => {
                 const { tooltip } = decoration;
                 const { data, fontData } = decoration as TreeDecoration.TailDecoration;
                 const color = (decoration as TreeDecoration.TailDecorationIcon).color;
-                const icon = (decoration as TreeDecoration.TailDecorationIcon).icon || (decoration as TreeDecoration.TailDecorationIconClass).iconClass;
                 const className = [TREE_NODE_SEGMENT_CLASS, TREE_NODE_TAIL_CLASS].join(' ');
                 const style = fontData ? this.applyFontStyles({}, fontData) : color ? { color } : undefined;
+                const icon = (decoration as TreeDecoration.TailDecorationIcon).icon || (decoration as TreeDecoration.TailDecorationIconClass).iconClass;
                 const content = data ? data : icon ? <span key={node.id + 'icon' + index} className={this.getIconClass(icon)}></span> : '';
                 return <div key={node.id + className + index} className={className} style={style} title={tooltip}>
                     {content}
@@ -787,7 +801,7 @@ export class TreeWidget extends ReactWidget implements StatefulWidget {
      *
      * @returns the icon class name.
      */
-    private getIconClass(iconName: string | string[], additionalClasses: string[] = []): string {
+    protected getIconClass(iconName: string | string[], additionalClasses: string[] = []): string {
         const iconClass = (typeof iconName === 'string') ? ['a', 'fa', `fa-${iconName}`] : ['a'].concat(iconName);
         return iconClass.concat(additionalClasses).join(' ');
     }

packages/navigator/src/browser/navigator-widget.tsx

@@ -17,13 +17,17 @@
 import { injectable, inject, postConstruct } from '@theia/core/shared/inversify';
 import { Message } from '@theia/core/shared/@phosphor/messaging';
 import URI from '@theia/core/lib/common/uri';
-import { CommandService, SelectionService } from '@theia/core/lib/common';
-import { CorePreferences, Key, TreeModel, SelectableTreeNode } from '@theia/core/lib/browser';
+import { CommandService, notEmpty, SelectionService } from '@theia/core/lib/common';
+import {
+    CorePreferences, Key, TreeModel, SelectableTreeNode,
+    TREE_NODE_SEGMENT_CLASS, TREE_NODE_TAIL_CLASS,
+    TreeDecoration, NodeProps
+} from '@theia/core/lib/browser';
 import {
     ContextMenuRenderer, ExpandableTreeNode,
     TreeProps, TreeNode
 } from '@theia/core/lib/browser';
-import { FileTreeWidget, FileNode, DirNode } from '@theia/filesystem/lib/browser';
+import { FileTreeWidget, FileNode, DirNode, FileStatNode } from '@theia/filesystem/lib/browser';
 import { WorkspaceService, WorkspaceCommands } from '@theia/workspace/lib/browser';
 import { ApplicationShell } from '@theia/core/lib/browser/shell/application-shell';
 import { WorkspaceNode, WorkspaceRootNode } from './navigator-tree';
@@ -139,6 +143,37 @@ export class FileNavigatorWidget extends FileTreeWidget {
         return super.renderTree(model);
     }
 
+    protected renderTailDecorations(node: TreeNode, props: NodeProps): React.ReactNode {
+        const tailDecorations = this.getDecorationData(node, 'tailDecorations').filter(notEmpty).reduce((acc, current) => acc.concat(current), []);
+
+        if (tailDecorations.length === 0) {
+            return;
+        }
+
+        // Handle rendering of directories versus file nodes.
+        if (FileStatNode.is(node) && node.fileStat.isDirectory) {
+            return this.renderTailDecorationsForDirectoryNode(node, props, tailDecorations);
+        } else {
+            return this.renderTailDecorationsForNode(node, props, tailDecorations);
+        }
+    }
+
+    protected renderTailDecorationsForDirectoryNode(node: TreeNode, props: NodeProps, tailDecorations:
+        (TreeDecoration.TailDecoration | TreeDecoration.TailDecorationIcon | TreeDecoration.TailDecorationIconClass)[]): React.ReactNode {
+        // If the node represents a directory, we just want to use the decorationData with the highest priority (last element).
+        const decoration = tailDecorations[tailDecorations.length - 1];
+        const { tooltip } = decoration as TreeDecoration.TailDecoration;
+        const { fontData } = decoration as TreeDecoration.TailDecoration;
+        const color = (decoration as TreeDecoration.TailDecorationIcon).color;
+        const className = [TREE_NODE_SEGMENT_CLASS, TREE_NODE_TAIL_CLASS].join(' ');
+        const style = fontData ? this.applyFontStyles({}, fontData) : color ? { color } : undefined;
+        const content = <span className={this.getIconClass('circle', [TreeDecoration.Styles.DECORATOR_SIZE_CLASS])}></span>;
+
+        return <div className={className} style={style} title={tooltip}>
+            {content}
+        </div>;
+    }
+
     protected shouldShowWelcomeView(): boolean {
         return this.model.root === undefined;
     }