Bug fix for label-skip implementation (#6030)

- Previous implementation skipped the first n labels
- We want to skip cells, but print all labels
- New implementation is also cleaner

InvenTree/plugin/builtin/labels/label_sheet.py

@@ -94,11 +94,13 @@ class InvenTreeLabelSheetPlugin(LabelPrintingMixin, SettingsMixin, InvenTreePlug
         if n_cells == 0:
             raise ValidationError(_("Label is too large for page size"))
 
+        # Prepend the required number of skipped null labels
+        items = [None] * skip + list(items)
+
         n_labels = len(items)
 
         # Data to pass through to each page
         document_data = {
-            "skip": skip,
             "border": border,
             "landscape": landscape,
             "page_width": page_width,
@@ -117,8 +119,6 @@ class InvenTreeLabelSheetPlugin(LabelPrintingMixin, SettingsMixin, InvenTreePlug
 
         while idx < n_labels:
 
-            document_data['label_idx'] = idx
-
             if page := self.print_page(label, items[idx:idx + n_cells], request, **document_data):
                 pages.append(page)
 
@@ -165,9 +165,6 @@ class InvenTreeLabelSheetPlugin(LabelPrintingMixin, SettingsMixin, InvenTreePlug
 
         n_cols = kwargs['n_cols']
         n_rows = kwargs['n_rows']
-        n_skip = kwargs['skip']
-
-        label_idx = kwargs['label_idx']
 
         # Generate a table of labels
         html = """<table class='label-sheet-table'>"""
@@ -176,17 +173,19 @@ class InvenTreeLabelSheetPlugin(LabelPrintingMixin, SettingsMixin, InvenTreePlug
             html += "<tr class='label-sheet-row'>"
 
             for col in range(n_cols):
-                html += f"<td class='label-sheet-cell label-sheet-row-{row} label-sheet-col-{col}'>"
 
                 # Cell index
                 idx = row * n_cols + col
 
-                # If we are within the skip range, do not render a label
-                if (idx + label_idx) < n_skip:
-                    html += """<div class='label-sheet-cell-skip'></div>"""
-                    continue
+                if idx >= len(items):
+                    break
 
-                if idx < len(items):
+                html += f"<td class='label-sheet-cell label-sheet-row-{row} label-sheet-col-{col}'>"
+
+                # If the label is empty (skipped), render an empty cell
+                if items[idx] is None:
+                    html += """<div class='label-sheet-cell-skip'></div>"""
+                else:
                     try:
                         # Render the individual label template
                         # Note that we disable @page styling for this