[markers] add problem decorator fontData

- added `fontData` to the problem decorators in the explorer which
decorates the node with a foreground color with the highest marker
severity.
- added a new method `getPriority()` which takes as argument
a marker diagnostic and returns it's priority which is used when
decorating. Markers with a higher severity have a higher priority.

Signed-off-by: vince-fugnitto <vincent.fugnitto@ericsson.com>

packages/markers/src/browser/problem/problem-decorator.ts

@@ -130,7 +130,12 @@ export class ProblemDecorator implements TreeDecorator {
         const position = TreeDecoration.IconOverlayPosition.BOTTOM_RIGHT;
         const icon = this.getOverlayIcon(marker);
         const color = this.getOverlayIconColor(marker);
+        const priority = this.getPriority(marker);
         return {
+            priority,
+            fontData: {
+                color,
+            },
             iconOverlay: {
                 position,
                 icon,
@@ -139,7 +144,7 @@ export class ProblemDecorator implements TreeDecorator {
                     shape: 'circle',
                     color: 'transparent'
                 }
-            }
+            },
         };
     }
 
@@ -163,6 +168,21 @@ export class ProblemDecorator implements TreeDecorator {
         }
     }
 
+    /**
+     * Get the decoration for a given marker diagnostic.
+     * Markers with higher severity have a higher priority and should be displayed.
+     * @param marker the diagnostic marker.
+     */
+    protected getPriority(marker: Marker<Diagnostic>): number {
+        const { severity } = marker.data;
+        switch (severity) {
+            case 1: return 30; // Errors.
+            case 2: return 20; // Warnings.
+            case 3: return 10; // Infos.
+            default: return 0;
+        }
+    }
+
     /**
      * Returns `true` if the diagnostic (`data`) of the marker argument has `Error`, `Warning`, or `Information` severity.
      * Otherwise, returns `false`.