Fix hierarchical grid to render nested child tables correctly

Fixed issue where grandchildren (child tables of child tables) were being
rendered as regular rows instead of separate nested tables.

Changes:
- Moved grandchildren detection logic before drawing the parent row
- If a child record has grandchildren, draw it as a parent row first, then
  recursively render its children as a nested child table
- If a child record has no grandchildren, draw it as a regular row
- This ensures proper nested table structure at all levels
- Each level of nesting gets its own child table with headers

Now hierarchical grids correctly render child tables at all nesting levels,
with proper indentation and table structure maintained throughout.

Co-authored-by: kdinev <[email protected]>

Author: Copilot

projects/igniteui-angular/src/lib/services/pdf/pdf-exporter.ts

@@ -324,24 +324,13 @@ export class IgxPdfExporterService extends IgxBaseExporter {
         while (childIndex < childRecords.length) {
             const childRecord = childRecords[childIndex];
 
-            // Check if we need a new page
-            if (yPosition + rowHeight > pageHeight - margin) {
-                pdf.addPage();
-                yPosition = margin;
-                // Redraw headers on new page
-                this.drawTableHeaders(pdf, childColumns, childTableX, yPosition, childColumnWidth, headerHeight, childTableWidth, options);
-                yPosition += headerHeight;
-            }
-
-            this.drawDataRow(pdf, childRecord, childColumns, childTableX, yPosition, childColumnWidth, rowHeight, 0, options);
-            yPosition += rowHeight;
-
             // Check if this child record has its own children (next level in hierarchy)
             const childRecordIndex = allData.indexOf(childRecord);
+            const grandchildRecords: IExportRecord[] = [];
+            let grandchildOwner: string | null = null;
+            
             if (childRecordIndex >= 0 && childRecordIndex + 1 < allData.length) {
                 // Look for grandchildren
-                const grandchildRecords: IExportRecord[] = [];
-                let grandchildOwner: string | null = null;
                 let k = childRecordIndex + 1;
 
                 // Collect all grandchildren that belong to this child
@@ -355,24 +344,51 @@ export class IgxPdfExporterService extends IgxBaseExporter {
                     }
                     k++;
                 }
+            }
 
-                // Recursively draw grandchildren if they exist
-                if (grandchildRecords.length > 0 && grandchildOwner) {
-                    yPosition = this.drawHierarchicalChildren(
-                        pdf,
-                        allData,
-                        grandchildRecords,
-                        grandchildOwner,
-                        yPosition,
-                        margin,
-                        indentPerLevel + 30, // Increase indentation for next level
-                        usableWidth,
-                        pageHeight,
-                        headerHeight,
-                        rowHeight,
-                        options
-                    );
+            // If this child has grandchildren, render them as a nested child table
+            if (grandchildRecords.length > 0 && grandchildOwner) {
+                // Check if we need a new page for parent row
+                if (yPosition + rowHeight > pageHeight - margin) {
+                    pdf.addPage();
+                    yPosition = margin;
+                    // Redraw headers on new page
+                    this.drawTableHeaders(pdf, childColumns, childTableX, yPosition, childColumnWidth, headerHeight, childTableWidth, options);
+                    yPosition += headerHeight;
+                }
+
+                // Draw the parent row (child record)
+                this.drawDataRow(pdf, childRecord, childColumns, childTableX, yPosition, childColumnWidth, rowHeight, 0, options);
+                yPosition += rowHeight;
+
+                // Recursively draw grandchildren as a nested child table
+                yPosition = this.drawHierarchicalChildren(
+                    pdf,
+                    allData,
+                    grandchildRecords,
+                    grandchildOwner,
+                    yPosition,
+                    margin,
+                    indentPerLevel + 30, // Increase indentation for next level
+                    usableWidth,
+                    pageHeight,
+                    headerHeight,
+                    rowHeight,
+                    options
+                );
+            } else {
+                // No grandchildren, just draw this child as a regular row
+                // Check if we need a new page
+                if (yPosition + rowHeight > pageHeight - margin) {
+                    pdf.addPage();
+                    yPosition = margin;
+                    // Redraw headers on new page
+                    this.drawTableHeaders(pdf, childColumns, childTableX, yPosition, childColumnWidth, headerHeight, childTableWidth, options);
+                    yPosition += headerHeight;
                 }
+
+                this.drawDataRow(pdf, childRecord, childColumns, childTableX, yPosition, childColumnWidth, rowHeight, 0, options);
+                yPosition += rowHeight;
             }
 
             childIndex++;