Fixed header height issue for grouped headers (#15001)

Author: MarielaTihova

projects/igniteui-angular/src/lib/grids/grid-base.directive.ts

@@ -2270,9 +2270,6 @@ export abstract class IgxGridBaseDirective implements GridType,
             this._allowFiltering = value;
             this.filteringService.registerSVGIcons();
 
-            if (!this._init) {
-                this.calcGridHeadRow();
-            }
 
             this.filteringService.isFilterRowVisible = false;
             this.filteringService.filteredColumn = null;
@@ -6840,25 +6837,11 @@ export abstract class IgxGridBaseDirective implements GridType,
         }
     }
 
-    /**
-     * @hidden
-     * @internal
-     */
-    protected calcGridHeadRow() {
-        if (this.maxLevelHeaderDepth) {
-            this._baseFontSize = parseFloat(getComputedStyle(this.document.documentElement).getPropertyValue('font-size'));
-            const hasFilterRow = this._allowFiltering && this._filterMode === FilterMode.quickFilter;
-            const minSize = (this.maxLevelHeaderDepth + 1 + (hasFilterRow ? 1 : 0)) * this.defaultRowHeight / this._baseFontSize;
-            this.theadRow.nativeElement.style.minHeight = `${minSize}rem`;
-        }
-    }
-
     /**
      * @hidden
      * Sets TBODY height i.e. this.calcHeight
      */
     protected calculateGridHeight() {
-        this.calcGridHeadRow();
 
         this.calcHeight = this._calculateGridBodyHeight();
         if (this.pinnedRowHeight && this.calcHeight) {
@@ -7786,7 +7769,7 @@ export abstract class IgxGridBaseDirective implements GridType,
             } else {
                 this._shouldRecalcRowHeight = true;
             }
-        }
+        } 
     }
 
     // TODO: About to Move to CRUD

projects/igniteui-angular/src/lib/grids/grid/column-group.spec.ts

@@ -67,6 +67,19 @@ describe('IgxGrid - multi-column headers #grid', () => {
             expect(grid.getColumnByName('ContactName').level).toEqual(expectedLevel);
         });
 
+        it('should initialize a grid with correct header height', () => {
+            fixture = TestBed.createComponent(ColumnGroupTestComponent);
+            fixture.detectChanges();
+            grid = fixture.componentInstance.grid;
+
+            const expectedGridHeaderHeight = 151;
+            const headerHeight = grid.nativeElement
+            .querySelector("igx-grid-header-row")
+            .getBoundingClientRect().height;
+            
+            expect(Math.round(headerHeight)).toEqual(expectedGridHeaderHeight);
+        });
+
         it('Should render column group headers correctly.', fakeAsync(() => {
             fixture = TestBed.createComponent(BlueWhaleGridComponent);
             fixture.detectChanges();

projects/igniteui-angular/src/lib/grids/grid/grid-filtering-ui.spec.ts

@@ -2746,6 +2746,7 @@ describe('IgxGrid - Filtering Row UI actions #grid', () => {
 
                 GridFunctions.clickFilterCellChip(fix, 'AnotherField');
                 fix.detectChanges();
+                grid.cdr.detectChanges();
 
                 // check if it is positioned at the bottom of the thead.
                 const theadWrapper = grid.theadRow.nativeElement.firstElementChild;

projects/igniteui-angular/src/lib/grids/headers/grid-header.component.ts

@@ -109,15 +109,6 @@ export class IgxGridHeaderComponent implements DoCheck, OnDestroy {
         return this.selected;
     }
 
-    @HostBinding('style.height.rem')
-    public get height() {
-        if (!this.grid.hasColumnGroups || this.grid.type === 'pivot') {
-            return null;
-        }
-
-        return (this.grid.maxLevelHeaderDepth + 1 - this.column.level) * this.grid.defaultRowHeight / this.grid._baseFontSize;
-    }
-
     /**
      * @hidden
      */

projects/igniteui-angular/src/lib/grids/pivot-grid/pivot-grid.component.ts

@@ -2106,13 +2106,6 @@ export class IgxPivotGridComponent extends IgxGridBaseDirective implements OnIni
         }
     }
 
-    /**
-     * @hidden
-     * @internal
-     */
-    protected override calcGridHeadRow() {
-    }
-
     protected override buildDataView(data: any[]) {
         this._dataView = data;
     }